SPM8002: Process Management Network Analysis BALI BEACH PROJECT AN EVALUATION OF THE COASTAL STRUCTURES IN BALI, INDONESIA

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1 SPM8002: Process Management Network Analysis BALI BEACH PROJECT AN EVALUATION OF THE COASTAL STRUCTURES IN BALI, INDONESIA CIE4160 Multidisciplinary Project Q1 Faculty of Civil Engineering and Geosciences Delft University of Technology

2 A COLLABORATION OF 2

3 AUTHORS MSc. Students Construction Management and Engineering Rickwin Robbert Huisman Real Estate & Housing Johannes Franciscus Kusters Urbanism Vincent Ringoir Architecture MSc. Students Offshore and Dredging Engineering Ben Arntz Mechanical Engineering Kristel Knoppe Tecnology, Policy and Management 3

4 SUPERVISORS FROM DELFT UNIVERSITY OF TECHNOLOGY Dr. Ir. Marian Bosch-Rekveldt Assistant Professor of Project Management Prof. dr. ir. R.H.M. Huijsmans Professor Ship Hydromechanics and Structures CONTACT PERSON MINISTRY OF PUBLIC WORKS, INDONESIA Putu Eddy BWS-BP CONTACT INFORMATION INDONESIA 4

5 CONTENTS Executive Summary... 7 Abbreviations Introduction Background Bali Beach conservation Project BWS-BP Outline Project, Bali Characteristics Tourism Economy Culture Infrastructure Fundamentals of coastal erosion and accretion Definition of coastal erosion Coastal landforms and beach dynamics Coastal processes Overview of the coastal erosion process Natural Causes Time scale of natural processes and human intervention on erosion Hazards related to coastal erosion Coastal Area Analysis Listing of Beaches Selection Criteria Preliminary Selection Candidasa, North Kuta ~ Legian and Seminyak Bali Beach Project Site Evaluation of Candidasa Characteristics of Candidasa Stakeholders Current situation Analysis Economical Evaluation Existing Infrastructure Tourism State of the Candidasa beach Coastal defence structures

6 Environmental data Sand composition of Candidasa Beach Coral reefs MetOcean Data Meteorological conditions Bathymetry Sediment transport Coastal Structures Conventional and innovative coastal defence structures Structures in Bali Alternatives Marine Life Big Bali Beach Cultural Heritage Sustainable Awareness High-end Tourism Conclusion Eligible structures for Candidasa Criteria Eligible and Selected Structures Final concept Stakeholders Perspectives Overview Final Concept Structure Packages Nourishment and Retainment of Public Beach Economic Analysis Costs Funds/Resources Phasing Monetary Benefits Non-monetary Benefits Distribution of Welfare Mitigation strategies Stakeholders Proposed framework for process management Conclusion Limitations and further research Bibliography

7 EXECUTIVE SUMMARY Problem Definition The coastline, the beach in particular, of Bali is subject to increasing erosion. Tourism is largely dependent on these beaches, which contribute to Bali s exotic character. The beaches are also extensively used by local inhabitants for their religious ceremonies. Due to these utilizations the reduction of beach area caused by erosion is an acute problem in Bali. Goal Description The Bali Beach project team will be focusing on a particular part of the coastline, a five kilometre stretch of beach in the northeast of Bali, in the area of Candidasa. The goal of the project is to design and form an integral solution, comprising technical, economic and social aspects, for the problems concerning the town and the beach of Candidasa. This solution will be presented to BWS-BP in Bali, a division of the Ministry of Public Works. This solution will also give them new insights how to prevent coastal erosion in the rest of Bali and Indonesia. Research Design In order to reach our goal as described above, the following approach is used. First information concerning the subject is gathered. The main sources for input of information will be the (scientific) website(google scholar, scopus), scientific books, field and the information provided by the experts of the Ministry of Public Works. Using this information and knowledge, eligible solutions for the problem are created. Finally these will be translated into an final concept for the beach and town of Candidasa. Location Characteristics In 1969 Bali s beaches and waves were discovered by mass tourism, this led to a vast increase in construction to accommodate the large amount of tourists. This caused large scale coral mining and natural shorelines were used as construction grounds, both causing erosion in the process Candidasa is chosen as project location mainly based on the selection criteria economic contribution and beach condition. Candidasa beach is divided in two areas: Area 1, stretching from the peninsula to Mendira Beach and Area 2, stretching from Mendira Beach to Alila Manggis. Structures All available conventional and innovative coastal structures are described and alternative concepts are made according to the expected feasibility of the structures in Candidasa. Alternatives The created alternatives are: Marine Life, Big Bali Beach, Cultural Heritage, Sustainable Awareness and High-end Tourism. The structures were placed in alternatives to see in what circumstance certain structures would flourish and become eligible for the final design of Candidasa. These eligible structures were compared with a number of technical, economic and social criteria. Final Concept A final concept was constructed from combining the highest scoring structures, taking into account the ability of the structures to form a suitable and realistic solution. This final concept, as stated in the goal description, will give new insights besides their conventional solutions. 7

8 The final concept consists of five structure packages that each serve a different purpose. The structure packages, including structures, are; Nourishment and Retainment of Public Beach : beach dewatering, energy harvesting, sand motor, beach nourishment Beach Nourishment and Mangrove Forests : mangrove forests, beach nourishment Coral Restoration: coral nurseries, Biorock, Reef Balls Recycled Revetment : revetment Offshore Bungalows: offshore bungalows Economic Analysis The costs for the final concept are based on the costs for each individual structure and demolishing of the old structures. The total costs of the final concept will amount to 48.3 million with the right phasing. Referencing the financial arrangement agreed upon in BBCP phase I, 75% of the planned project costs will be a JICA loan. This means that approximately 36.2 million of the planned project costs should be arranged by a loan. Because the initial investment of the Indonesian government is therefore only 25% of the total amount the project will be more susceptible for approval. In the first phase of the project, Area 1 is constructed together with 50% of the coral reef and biorock over the full length. Structures in Area 2 are constructed 5 years later. Coral reef completion follows stepwise 10 and 20 years after the project has started. This phasing results in a saving of 15%. Stakeholders and Mitigations The most influential stakeholders during this project are; the Province of Bali, BWS-BP and the local inhabitants of Candidasa. With the local inhabitants being the stakeholder which will need the most convincing on the implementation of the final concept. The structures that require mitigation strategies, such as, informing, consulting, involving, collaborating or empowering, to change perspectives and protect interests of the local inhabitants, are the beach nourishment method, energy harvesting, mangrove patches, coral restoration and offshore bungalows. The strategies are applied and all risks are mitigated accordingly. Therefore the final design is not expected to face large resistance from these stakeholders. ABBREVIATIONS BBCP Bali Beach Conservation Project BWS-BP Balai Wilaya Sungai Bali Penida C Degree Celcius CCA Chromated Copper Arsenate cm centimeter lbs/cu pound per cubic foot GDP Gross Domestic Product GSC Geo-textile Sand Filled Container 8

9 HWL JICA kg km kn kw kwh LWL m m2 m3 mln mm MSL MWL NGO OECD RTR s High Water Level Japanese International Cooperation Agency kilogram kilometre kilo Newton Kilowatt Kilowatt hour Low Water Level meter square meter cubic meter million millimeter Mean Sea Level Mean Water Level Non governmental organization Organization for Economic Co-operation and Development Rigs-to-Reef second 9

10 0 INTRODUCTION BACKGROUND Since 1970 tourism has been booming which generated a large strain on Bali s natural resources. On this island 30% of the area is used for tourism, this eventually translates to a large amount of beaches affected by erosion. One of the main causes of erosion is the indelicate way of construction of tourist facilities near these beaches. A division of the Ministry of Public Works, Balai Wilaya Sungai Bali Penida (BWS-BP), is involved in the beach monitoring, evaluation and developing of technical concepts to restore and protect the beaches from further erosion (JICA, 2013). BALI BEACH CONSERVATION PROJECT To recover the severely eroded beaches at Nusa Dua, Kuta, Sanur and Tanah Lot, the preparations for the Bali Beach Conservation Project (BBCP) phase I started in These locations were chosen based on their touristic and religious value. The project was undertaken by the Indonesian Government and financed through a loan provided by the Japanese International Cooperation Agency (JICA). The construction of phase I started in 2000 with beach nourishments of 1.3 million m 3 in total and supplementary coastal structures such as groins, headlands and offshore breakwaters. Construction work was finished in 2003 at Tanah Lot, 2004 at Nusa Dua and Sanur and 2008 at Kuta Beach. The performance of BBCP phase I is still monitored at all four locations (Onaka, Endo, & Uda, 2013). At this moment, preparatory studies are being performed for the realisation of BBCP phase II which will start in BWS-BP BWS-BP: Department of River Region Bali-Penida, has been responsible for the technical details concerning the beach management in Bali. The principle monitoring activities of BWS-BP and the Environmental Agency of Bali consist out of beach profile survey and the monitoring of seawater, coral reef, seagrass and mangroves. The beach erosion is monitored continuously, based on topographic survey. To assist in the monitoring, BWS-BP has contracted a local consultant. All maintenance work in the areas renovated in Phase I of the BBCP has been undertaken by BWS-BP as well. BWS-BP will deliver technical suggestions to the local governments in respect to the management of the beaches in Bali. Ultimately, the local governments and BWS-BP are the main players of beach management and maintenance (JICA, 2013). OUTLINE PROJECT, The outline of the Bali Beach Project is to describe the erosion suffered by the beaches of Bali and the erosion measures taken to protect them. This gives rise to the our research question: What measures have to be taken to ensure that the critical coastal area performs optimally, taking technical, economic and social aspects into account?. A specific beach will be selected, based on priority, on which the focus for beach protection will lie. Whilst also documenting all possible erosion prevention structures, designs are made to form innovative alternative concepts to prevent beach erosion. These will include the type of structures involved, a stakeholder engagement plan and the economic, financial, social and environmental consequences that come along with the alternative concept. From these alternatives the most promising structures are extracted and combined to a final concept. The final concept will be further visualized and elaborated taking construction, implementation, stakeholders and maintenance into account. The report will also follow this order of subjects. 10

11 1 BALI CHARACTERISTICS Often described as paradise on earth, Bali (Figure 1-1) is one of the over islands in Indonesia. Bali, 144 kilometre by 80 kilometre in size, is located between Java and Lombok in the Bali Sea and inhabits four million people. Bali has a varied landscape including hills, mountains, rugged coastlines, sandy beaches, lush rice terraces and barren volcanic hillsides. With Bali being a volcanic island, its geometry prevents larger areas to flood due to sea level rise. The mountain chain splits the island, with eight regencies, into two parts. The north and south parts of Bali are vastly different in respect to tourism, economy and infrastructure. (Wiki Travel, 2015) Figure 1-1: Map of Bali (own Figure). TOURISM Bali is known around the world for its surfing, diving, cultural and historic attractions and enormous range of accommodations. With its high seasons in late summer and begin winter the island is often occupied by a large amount of tourists. Bali s tourism potential has become responsible for the majority of the income on this island. In 1969 Bali s beaches and waves were discovered by mass tourism, made accessible by the construction of the Ngurah Rai International Airport. A Master Plan for the Development of Tourism in Bali was drawn in 1972 by the government of Indonesia intended to make Bali the jewel of Indonesia, with the main focus lying on the south part of the island (TED, 2013). Originally the plan was to attract wealthy tourists from Australia, Japan, Europe and North America. Unexpectedly, the island started to draw many young and budget-conscious travelers, whose main interest was to see and experience the island outside of the resorts. Eventually Bali evolved to cater for two types of tourists: the group package-tour high spending tourist and the individual low-spending tourists. The ever increasing amount of budget travellers mostly turn to Kuta, Ubud, Batur, Lovina and Candidasa (Bali Tourism Board, 2015). 11

12 By focussing on the south of Bali, the intention was to minimise the impacts of tourism on the island s cultural life and protect its cultural integrity. However, this plan inadvertently led to inequities between the south of Bali and other parts of the island. This inequity has increased due to income generated from tourism not being evenly distributed across Bali. The districts where tourism is concentrated have become wealthier than the rest of the island. On top of this, Bali s development and growing population has led to a predicted water crisis by Caused by factors such as the growing tourism industry, the existing inefficient water infrastructure system, a changing environment and a lack of sanitation services (Asbury, 2015). Another factor in the tourism increase was the change in airline services. Garuda Indonesia used to have a monopoly on international flights to Bali but in 1980, due to an oil market collapse, Indonesia was forced to promote other exports and investments in order to reach set tourism targets. This allowed foreign airlines to fly directly to Bali and tourism started to soar. The amount of tourist arrivals per year grew from in 1969 to in 1989 has since then skyrocketed to 3,76 million foreign tourists in 2014 (Bali Government Tourism Office, 2015). Figure 1-2 shows the increase in foreign and domestic tourists arriving in Bali from Figure 1-2: Increase in tourists (JICA, 2013). Despite a brief dip due to the terrorist attacks, in 2002 and 2005 on popular foreign tourist locations, tourism continues to increase. However already in 1991 the cracks started to show. The pressure that tourism had brought to Bali s infrastructure and natural resources had gotten so high, it eventually forced the Indonesian government to impose a halt to hotel construction. Tourism is both a blessing and a curse as it has helped Bali transition from being one of the poorest to one of the richest provinces in Indonesia. But Bali s resources are becoming overwhelmed and its natural beauty, which once led Bali to be glorified as a paradise island, has become threatened. ECONOMY Tourism has replaced farming, fishing, trading and craftsmanship as a primary source of income. This showed as tourism contributed 4,1% to Indonesia s GDP and employed 6,9% of the workforce in This led to the tourism being strongly encouraged by the Balinese and national government. A standalone Ministry of Tourism and Creative Economy even exists within the government with a full time sitting minister. 12

13 Nowadays, Bali s tourism and economy cannot be seen as separate entities, these concepts are so intertwined that it causes difficulties for the Balinese regional government. One of which is striking the balance between the economic growth tourism provides and the sustainable development that will eventually help Bali grow and sustain their nature. This is proving to be a serious challenge as most regulations for development are often ignored or executed in an unsustainable manner. Most local employment is found in the south of Bali, which is mostly in the tourist or hotel sector, aside from the major farming industry (Bourke & Tretheway, 2010, pp ). The smaller scale home businesses are textile or garment, handicraft and souvenirs with exports increasing around 6,7% annually. These small and medium-sized businesses in Bali need support of businesses with good long-term prospects to ensure their survival. But as it is a big source of economic growth, the Indonesian government has gone to great lengths to push the Indonesian tourism industry forward to eventually propel Indonesia into the top ten global economies by 2025 (Parker, 2013). Overall contribution of tourism to Bali s economy is estimated to be in the region of 60-70% (Euro Bali, 2006). The average expenditure per person on vacation with an average stay of just over one week in Bali, according to a 2013 OECD report, is 1,016.4 (Parker, 2013). As a result, Bali is becoming increasingly commercialized. To facilitate the tourism growth large areas of previously pristine rice paddies are lost to make way for new construction and development in the form of large scale urbanization, international fast food franchises and an array of bars and clubs. This threatens the very characteristics of Bali which it is trying to promote amongst tourists (Parker, 2013). The economy of Bali depends majorly on tourism and is not diversified. This is especially affects the districts where tourism does not play a significant role in the economy and prohibits further growth and development in these areas. CULTURE Balinese life is very religious and is full of spiritual and unique rituals. Although Indonesia is largely Muslim, Bali is a hub of Hindu religion and culture. This Hindu, however, differs vastly from the Hindu culture in India. Bali is very communal under the organization of villages, this shows in the manner of water distribution (Collinson, 2012) and the placing and upkeep of the village temples (Euro Bali, 2006). Temples are of utmost importance, each village is required by customary law to construct and maintain at least three temples: Pura Puseh (temple of origin), Pura Desa (village temple) and Pura Dalem (temple of the dead) (Leong, 2015). The beach and the ocean play a significant role in the Balinese religion, the beach is believed to be a place to spiritually cleanse oneself and other objects. For example, at the Melasti ceremony all Hindu people in Indonesia, especially in Bali, come together to carry the holy symbol of Hindu religion to the sea. Here it is to be cleaned and looked at from alongside the road (Bali Star Island, 2006). Also, additional temples can often be found on higher ground or near the ocean, as these are places where the Balinese believe that demons and bad spirits live. The temples, along with daily offerings help keep the demons at bay. Overall, religion is a high priority in Bali and even supersedes the implementation of certain conventional projects, this occasionally causes problems between the local Balinese people and the government. 13

14 INFRASTRUCTURE Bali has several ways of entry available, one airport, two ferries and one fast boat operator (Bali Guide, 2015). The main connection point, where visitors and residents enter and depart from Bali, is the newly renovated Ngurah Rai airport, which increased the capacity of 7 million to 25 million passengers per year (Indonesia Investements, 2013). The renovation included extending the runway into the ocean. The ferry to Bali departs from Java and arrives at Gilimanuk with the other ferry departing from Padang Bai. Lastly, the fast boat from the Gili Islands to Sanur and Padang Bai. Bali s further infrastructure used to be simple and functional with often only one road leading to and from locations around the island. This infrastructure is no longer up to par with Bali s needs. The roads struggle to cope with the rapid, seemingly uncontrolled, development that is occurring. Already, major tourist areas have been affected by chaotic traffic and daily traffic jams. Improvements are slowly being implemented, for example the Denpasar-Nusa Dua toll road (Indonesia Investments, 2013) or the potential plan for a Buleleng Airport (Tempo, 2015). But the hold ups are also apparent; for instance, a potential connection between Gilimanuk and Java would remove the infrastructural bottleneck currently in place and relieve a lot of the traffic jams around this area. However, this potential solution is currently not being implemented due to the resistance of the local community. The reason being that Java and Bali were purposely separated by their ancestors and therefore should not be physically reconnected. This shows how much impact cultural beliefs have on future developments in Bali. If Bali wants to keep attracting more tourists every year, as it has been (Nurhayati, 2015), the problems of unchecked development, poor infrastructure, lack of public transportation and basic things like traffic need to be addressed and improved in all regencies. The lack of infrastructure also causes problems, in terms of local product distribution. Due to the difficult travel logistics, domestic products sometimes turn out to be more expensive than imported products. The combination of the lack of quality of infrastructure and weather phenomenons can cause disruption to the overall flow of goods and services e problems of unchecked development, poor infrastructure, lack of public transportation and basic things like traffic need to be addressed and improved in all regencies. The lack in infrastructure also causes problems in the economy in terms of local product distribution. Due to the difficult travel logistics, domestic products sometimes turn out the be more expensive than imported products. The combination of the lack of quality of infrastructure and weather phenomenons can cause disruption to the overall flow of goods and services (Indonesia Investments, 2013). The quality and quantity of Bali s infrastructure cannot keep up with the economic and social development occurring in Bali. Past investments to address this issue, were intended for the improvement for the entire island but turned out to apply mostly to South Bali. This is due to the fact that the condition and availability of infrastructure influences the interest of future investors (Atmodjo, 2013). So in turn, this part of Bali has better and more complete infrastructure compared to other parts of the island. This infrastructural difference has become the main reason for the wide gap in economic development between South Bali and the rest of the island. 14

15 2 FUNDAMENTALS OF COASTAL EROSION AND ACCRETION To understand coastal erosion comprehensively, this chapter will elaborate the foundations of coastal erosion and accretion. Firstly, the various landforms near the coast will be described. Secondly, the influencing factors on coastal landforms in the form of natural coastal processes and human intervention will be elaborated. Finally, an overview of the coastal erosion processes, the time- and spatial- scale of processes, and hazards related to coastal erosion are described. DEFINITION OF COASTAL EROSION Fundamentally, coastal erosion and accretion are complex processes of wearing away material from a coastal profile due to imbalance in the supply and export of material from a certain section. It takes place in the form of scouring at the foot of the cliffs, dunes or at the sub tidal foreshore of different coastal landforms (Conscience, 2010). The rate of erosion is correctly expressed in volume/length/time, e.g. in m 3 /m/year, but erosion rate is often used synonymously with coastline retreat, and thus expressed in m/year. COASTAL LANDFORMS AND BEACH DYNAMICS The effect of different coastal processes is highly dependent on the coastal landforms. The coastal landforms are the protection barrier between the ocean and the hinterland. Over time the coastal processes will affect the landforms. The coastal erosion factors on these landforms are mainly determined by the rock type, rock structure, shape of coastline and type of wave. The shape of the coastline determines if and how coastal areas are exposed to the waves and currents of the oceans. Vegetation on and in front of coastal landforms reduces the erosion by improving slope stability, consolidating sediments and providing shoreline protection. Coastal landforms in Bali The natural features of coastlines depend on the type of rocks exposed, the action of natural processes and work of vegetation and animals. Four main types of coasts are described: cliff coasts, clayey bank coast, sand dune coast, and sandy coast (Prasetya, 2007). Cliff and the sandy coasts are the two distinctive types that are spread around most of Bali. Cliff coast Classified as a hard coast, a cliff coast is formed from resistant materials such as sedimentary or volcanic rocks. This type typically exposes a short shore platform during low tide. Regression of the shoreline due to wave action, weathering and slope instability leads to natural erosion of the cliffs. As illustrated in Figure 2-1, extreme wave conditions like storm waves and tsunamis will have a less erosive effect on this type of coast (Prasetya, 2007). Sandy coast The sandy coast type exists of unconsolidated material, such as sand from rivers and eroded headlands, broken coral branches and shell from surrounding reefs. This type can be classified as a soft coast whether or not with reef protection offshore. The range in intensity of natural forces attacking the beaches determines the beach slope from gentle to steep. A steep slope stems from high intensity of natural forces. Most erosion is due to loss of the protective function of the coastal habitat, especially coral reefs that protect the coast from wave action, and the coastal trees that protect the coast from strong winds. Common forms of vegetation in this coastal area are coconut trees, waru, pine trees and other beach woodland trees. In the occurrence of extreme events healthy coral reefs and trees protect coast to a certain amount by reducing wave height and energy as well as severe coastal erosion (Figure 2-2) (Prasetya, 2007). 15

16 Figure 2-1: Erosion of Cliff coasts (Adapted from Prasetya, 2007). Figure 2-2: Erosion of Sandy beach (Adapted from Prasetya, 2007). COASTAL PROCESSES Various coastal processes influence the erosion of an area. The fundamental processes are divided into the following categories: waves, erosion on beaches and erosion on cliffs and rocks. Waves are the most important forces for sediment erosion and transport as they transfer energy and different currents to the coast. Mostly, transferring wind energy to the surface of the sea generates waves and as the strength of the wind increases, wave size increases together with frictional drag. Two different types of waves are distinguished: swell-waves and sea-waves. Swell waves result from distant storms and strong winds and can travel long distances. They are characterised by waves with low wave height, gentle steepness, long wavelength and a long period. Sea waves result from local wind and therefore only travel short distances. During storms the surge is higher and attack on the coastal areas is more intense and hence the erosion bigger (Prasetya, 2007). Erosion process on Beaches Close to the shore the waves will break and wash up as dynamic layer of water. It can result in an uprush transporting sand land inwards (constructive current) or a backwash that result from the receding swash (destructive current). Both transport sediment to and from the shore and if this equilibrium is disturbed it leads to the erosion or accretion. 16

17 The length with which the swash and backwash reaches the coast depends on the tides. Hence, during high and low tide the waves will attack a different part of the beach. Second, tides modulate wave action, influencing energy arriving on the coast and drive groundwater fluctuation and tidal currents. The interaction of groundwater with tides in the coastal forest environments is important for understanding why coastal forest clearance causes intensive coastal erosion in particular environments (Prasetya, 2007). The angle at which waves will enter the coast depends on the current, a continuous flow of water in a particular direction, in that area. Longshore drifts are movements of sediments along a beach or shore caused by longshore currents. The drift has a particular direction, mostly parallel to the shoreline. The aforementioned swash and backwash are major phenomena that support this process. Currents together with waves cause sediment to be eroded from beaches or disturb the equilibrium in sediment supply and discharge (Sharma, 2012). Erosion process on cliffs and rocks Besides waves washing up on beaches, waves will also encounter cliffs and rocks. In these areas a process of abrasion and attrition will occur. In the process of abrasion waves pick up the sediment and hurl it against the cliffs. As the sediment is hurled against the cliff, parts are chipped off and the sediment gets smaller and rounder: this is called attrition. Second, salt and other chemicals in the sea water attack and dissolve the cliffs. Limestone and calcium rich cliffs are highly affected by the salt and chemicals and dissolve faster, which can cause large amounts of cliffs to slide into the water. Thirdly, hydraulic action occurs when a wave impacts a cliff and air is forced into cracks under high pressure which widening the cracks. Over long periods over time, the growing cracks destabilise the cliff and fragments of rock chipped off the cliff (Dias, 2012) Overview of the coastal erosion process As described, various coastal processes lead to erosion or accretion. These coastal processes on shore are the result of natural causes and human interventions. Figure 2-3: The processes: Coastal erosion and accretion (Gonsalves & Mohan, 2011). The natural factors mostly lead to the process of sediment scouring and transport and in extreme conditions directly to coastal flooding. Human interference generally leads to sediment deficit, which results in coastal erosion. Figure 2-3 is an overview of the erosion process 17

18 and its consequences. An elaboration on the natural and artificial causes, direct effects and consequences leading to erosion can be found in the next paragraphs and in Appendix B Natural Causes Multiple natural causes are defined that lead to erosion. Main causes are sea level rise growth or diminishing of natural vegetation, diversion of river outlets, wind and rain activities, and currents that influence the coastal processes. In general the causes lead to increase of energy, duration and frequency of waves or change in sand and shingle supply and discharge. An exceptional cause is rendering the beach wetter by rainfall, which leads to change in sand characteristics. A major complex issue for Bali s beaches is sea level rise. As the sea level rises, the near shore waters deepen and the waves becomes deeper (Bird, 1996). Therefore, the waves reaching the coast have more energy and can erode and transport larger quantities of sediment. Consequently, the coast will start to adjust to the new sea level and will establish a new dynamic equilibrium (Prasetya, 2007). Human interventions Equally important to natural processes are the human interferences over the range of spatial and time scales. Activities along the coast, such as construction via land reclamation or within sand dune areas and harbour development, have a long-term impact on the coastline change. Protective measures are taken for the economic importance and safety of these areas. Removal of natural coastal dune vegetation and mangroves will expose low energy shoreline to increased energy and reduced sediment stability (Bird, 1996). Activities within river catchments are mostly dam construction and river diversion, which causes a reduction of sediment supply to the coast. A lack of sediment supply leads to imbalance in sediment transport and consequently erosion, but the effects of dam and river diversion in terms of coastal erosion are not straightforward. However, there are mid- to long-term impacts (20 to 100 years) with a spatial scale of approximately one to 100 kilometres (Prasetya, 2007). Onshore and offshore activities include sand and coral mining affecting coastal processes in multiple ways such as contribution to sediment deficit in the coastal system and modification of water depth, which lead to altered wave refraction and long shore drift. A comprehensive analysis of the human interferences can be found in Appendix B Time scale of natural processes and human intervention on erosion The natural and human factors affect erosion by a range of time scales. Natural processes, such as different kind of waves and currents, will directly impact the shoreline within hours, days or months. While sediment deficit, sea level rise and alongshore currents will impact erosion on the long-term. The consequences of human interventions are short, mid- or long-term effects that start from one year up to 1000 years. Erosion from seawalls can occur within less than five years (short-term), while groins and jetties lead to erosion within five to ten years. As well, the removal of vegetation and mangroves affect the coast in five to ten years. Major indirect activities such as harbour development, river damming and land reclamation only affects erosion after 50 years. Due to this large timespan many human interventions have caused unexpected erosion problems for their next generations to solve. The various time spans are comprehensively displayed in Appendix B-2 (Prasetya, 2007). 18

19 2.3.4 Hazards related to coastal erosion Coastal erosion generally leads to mass wasting, risk to urbanization and marine life and topographical changes. Firstly, mass wasting consists of landsliding or rockfalls. Landsliding causes the sediment to erode in large amounts, where rockfall is caused by waves that undercut hard cliffs resulting in large bulks that harm the surrounding structures. Secondly, erosion may endanger urbanization due to loss of property or human lives and also due to the intrusion of seawater with drinking water. Thirdly, coastal processes affect every year large percentages of all the marine life. Due to erosion the shelf life gets heavily buried and become extinct. Finally, topographical changes occur where the shelf is moved further land inwards. Coastal structures implemented to control the transport of sediments are not able to completely solve the problem, resulting in an unbalanced sand sedimentation process (Sharma, 2012). 19

20 3 COASTAL AREA ANALYSIS With knowledge of Bali s characteristics and erosion, this chapter analyses the coastal areas in Bali. Firstly, the analysis will start with a broad overview of possible beaches subject to erosion. From that list beaches will be selected for a more thorough research on the causes and effects of erosion, impact on economy and environment. Subsequently a project location will be chosen. The project location is the beach which is most urgent, measured by several factors, to preserve and/or restore. This analysis is based on the information from the JICA 2013 report, provided by BWS-BP. LISTING OF BEACHES To determine the location for our Bali Beach Project, the recommendations of the preparatory study for BBCP phase II will be used as a starting point. From this study, 13 candidate locations can be extracted. These locations are chosen based on research of Balai Pantai which focussed on the condition of the coastal area with respect to coastal erosion in Bali(JICA, 2013). The candidate locations are displayed in Figure 3-1. Figure 3-1: Candidate Beaches (Adapted from JICA, 2013). SELECTION CRITERIA Figure 3-2 shows the basic procedure for the selection of candidate sites for BBCP phase II. The candidate sites will be evaluated based on the two main criteria: a) economic contribution to world tourism and b) beach condition. The preliminary selected sites are the ones that meet the above mentioned requirements best. This means that even if a beach does not suffer from major erosion but its potential as world tourist area is high or vice versa, it can still be selected as candidate site for BBCP phase II and the Bali Beach Project. 20

21 The preliminary selected beaches that met the two criteria will be assessed using a set of three criteria on the following areas: c) socio-environment, d) coastal environment and e) realization of beach management. The input and scoring for these criteria are documented in Appendix C. If there are no issues or negative impact on the above areas to the preliminary selected beaches, these beaches will be selected. This procedure results in three beaches/sites that will be further investigated. Figure 3-2: Basic Selection Procedure (Adapted from JICA, 2013). In Table 3-1 the scores of the thirteen candidate sites on the two main criteria (subdivided in five subcriteria) are displayed. The scores are distributed from 0 till 5, 0 meaning that the criterion is not applicable at all on the site and 5 meaning that the criterion is highly applicable. The maximum score for a candidate site therefore becomes a total of 25 points. Table 3-1: Scoring of the 13 Candidate Beaches (Adapted from JICA 2013). 21

22 PRELIMINARY SELECTION Five candidate sites are selected by employing appropriate evaluation criteria and checking items. As it turns out, Candidasa, North Kuta ~ Legian and Seminyak scored highest on the criteria and are assigned to a priority accordingly. Lebih and Canggu both scored fifteen points. They will also be incorporated in the preliminary selection. The preliminary selected beaches are displayed in Table 3-2: Preliminary Selection (Adapted from JICA, 2013., high urgency for restoration of these beaches exists. For the upper three, no problems were found in the relation between hotel and community, should beach conservation take place. In Candidasa the coastal environment must be checked regularly, the other sites coastal environment are not impacted. This is because Candidasa is a coral reef beach where many corals, sea grasses and several species of fish live. The other beaches have relatively sandy beaches facing the open sea (JICA, 2013, p. 207). Regulation is not a problem on any of the candidate sites. In Lebih a decent beach management system is lacking. In the area from Kuta to Seminyak, stakeholders are intrinsically involved in the beach management. This could be a very important aspect in the feasibility and execution of the Bali Beach Project. Although the stakeholders do not yet manage the beach actively, Candidasa is nonetheless selected. The three residual candidate sites will be shortly described below. CANDIDASA, NORTH KUTA ~ LEGIAN AND SEMINYAK North Kuta ~ Legian and Seminyak are located on the south-west coast and belong to a continuous stretched sandy beach consisting of sandy beaches with mixed corals and volcanic sand. This is the highest international beach resort area in Bali. A lot of tourists take part in beach and marine activities here. Candidasa is the major tourism beach in the east coast area of Bali. It is located 30 kilometres from the main south tourism spots and consists out of multiple beaches situated alongshore. The beaches mostly consist out of white coral sand. BALI BEACH PROJECT SITE As previously deducted from Table 3-1, Candidasa ranks first amongst the selected beaches with top priority. The once sandy beach has nearly disappeared due to beach erosion and beach utilisation, beach approaching and landscaping. Even though erosion prevention measures were taken, the tourism area has further deteriorated. The Bali Beach Project will therefore focus on Candidasa, its erosion and its existing erosion prevention. Most importantly, it will further analyse innovative, alternative concepts to increase erosion prevention in Candidasa. 22

23 4 EVALUATION OF CANDIDASA The following chapter describes the area of Candidasa on multiple disciplines with the purpose to obtain a sufficient understanding of the area in order design of a new comprehensive coastal protection for Candidasa beach. The following disciplines are considered of importance for the understanding of the current state of the coastal area of Candidasa; general characteristics of Candidasa area, a stakeholder analysis and evaluation, economical evaluation with tourism being the most important source of income, current state of Candidasa beach, existing coastal defenses and environmental data. CHARACTERISTICS OF CANDIDASA Candidasa is a small fishing village sitting at the edge of a freshwater lagoon, with a beach stretching from Manggis to Bugbug. Candidasa is also known by other names such as Teluk Kehen (Bay of Fire) and Cilidasa. Its beach is characterised by a narrow stretch of sand which disappears at high tide. The beach mainly consists of white coral sand, but volcanic black sand can also be found in some areas. West to Candidasa beach lies a black sand beach called Pantai Labuan Amok. Despite a Pertamina oil terminal located at one end which is considered unsightly, tourists are known to roam here in small numbers. The beach is clean, located in a pretty bay including many small coves and bays and the offshore waters offer good snorkeling including live coral in shallow waters. Five kilometres north east of Candidasa beach a white-sand beach is located, named Pasir Putih. With its 500 meter long white sand beach fringed with coconut palms, it creates another little hub for tourists to enjoy the ocean. The vendors consist of a few small shops mainly for sunbeds and umbrellas. STAKEHOLDERS In this chapter the current situation of stakeholder management is elaborated and stakeholders that will be involved in redeveloping the beach of Candidasa are analysed, in order to develop strategies that enhance the partnerships and support of stakeholders of the Bali Beach Project Current situation In Bali the perspective of local stakeholders has previously delayed the original plans for public works. Local stakeholders that are present during the initial phase of a project often differ from the stakeholders that are present during the implementation phase of the project, resulting in discrepancy in opinions on the appearance of a project, causing a delay of the project. For example, during the redevelopment of Kuta Beach, the design raised large opposition from the local stakeholders during the detailed design phase. This resulted in dozens of meetings, leading to quantity changes and cancellations of the initial coastal structures, and thus in a delay of construction (Inazawa, 2011). The method used in Bali is the so called DAD(Design, Announce, Defend)-approach (de Bruijn & ten Heuvelhof, 2008) and does not take the interest of all involved stakeholders into account during the right phases of a project. Figure 4-1 shows how the interested stakeholders should be involved during the initiate, design, construct and use phase of a project. 23

24 After the construction of BBCP Phase I projects a lot of problems arose on the field of responsibilities of beach maintenance during the use phase of a project, which is solved with a beach management strategy that is elaborated in Appendix D.4 (JICA, 2013). Figure 4-1: Scope of the stakeholder analysis based on the project cycle(own Figure). Although the beach management is elaborated carefully, no process management strategies are elaborated to avoid situations where stakeholders are involved in the wrong phase of a project. In the next paragraph an analysis is done that will be used to develop an engagement plan and mitigation strategies in order to increase the support of stakeholders in redeveloping Candidasa Analysis Based on the basic stakeholder analysis technique (Bryson, 2004, p. 29) the stakeholders involved in redevelopment of Candidasa beach are identified and listed in Appendix D.4, together with their interests, problem perceptions and goals. In Appendix D.5 the resources, replaceability and dependency of each actor are listed, in order to determine which stakeholder is critical during the process of the project. The stakeholders are placed in a powerinterest grid(figure 4-2) in order to determine the importance of the stakeholders. The key stakeholders that have to be managed closely are the local village organization, the province of Bali, Karangasem Regency and BWS-BP. Secondly, the environmental agency, tourists and JICA should be kept informed. Thirdly, the hotel and restaurant association, cleanliness agency, experimental laboratory and the developers/contractors should be kept satisfied. Fourthly, the environmental interest groups and the highway and irrigation agency should be monitored with minimum effort. In order to manage the most important players closely, their interest, problem perception and goals are elaborated below. The information of the other stakeholders can be found in Appendices D.4 and D.5. The province of Bali wants to increase the economy, safety, environmental and social value of Bali. They perceive the problem that there are too many tourists in the South of Bali, resulting in heavy traffic jams and over occupation during high seasons. There also is too much erosion and waste on potential beaches, which is why they want to attract and spread a variety of tourists around the beaches of Bali, by developing attractive infrastructure and beaches. 24

25 BWS-BP is responsible for the construction of coastal structures, dams and water/sand storages. The severe erosion of beaches endangers homes, temples, agriculture and tourism areas in vicinity to the beach, which is why they want to develop multifunctional structures used both for protection of the beaches as for recreational purposes. The local inhabitants want to maintain or enhance their current quality of living and working. The redevelopment of Candidasa makes them concerned that tourism will prevail over their interest or that they will not benefit from the potential growth of tourism, so taking advantage of the new developments in their surroundings is their main goal. Figure 4-2: Power-interest grid of the involved stakeholders for Candidasa(own Figure). ECONOMICAL EVALUATION The area of Candidasa has been chosen for its economic potential which could attribute to the common welfare of region. To understand the economic situation in the area the existing infrastructure and land use by the population are elaborated. The land use consists primarily of tourism and agriculture Existing Infrastructure The main road to the east of Bali runs through Candidasa. All accommodations are situated along this road. This road could form a large bottleneck when tourism in Candidasa should grow. To the west of Candidasa a ferry and international cruise port are situated. Land use by population Candidasa primarily depends on agriculture and tourism as sources of income. According to the spatial plan from the government of Karangasem regency, the Candidasa coastal area is to be developed and utilised as an attractive tourist natural resource. The use of land in Candidasa is shown in Figure

26 Buildings are coloured red and green represents agriculture. Due to the expected growth in the tourism sector in the area, agriculture could be endangered, leading to resistance of local farmers. Proposed areas of renovation are indicated in Figure 4-3. Figure 4-3: Land use of Candidasa with proposed coastal renovation areas (Adapted from JICA, 2013). Coastal development The development of tourist accommodations has extended eastward with the construction of several high end villas. Because the tourism grew with a sudden surge, construction had to be completed in limited time. This created a situation where the main objective was construction of accommodations whilst dismissing the consequences this would have on the environment. Like in the rest of Bali, due to the tourist increase, some hotels and cottages were built too close to the shoreline, speeding up the erosion process. No suitable regulations to prevent this had been made. Eventually the consequences of the fast and large amount of construction started to show in the surroundings, especially on the beach. The sand washed away and left only small pockets of beach between the constructed groins Tourism Candidasa is a popular tourist stop because it is a sedate, laid back beach with ample opportunities for marine activities. Snorkelling and diving are the main tourist attractions available in Candidasa due to the high transparency of the seawater, including the possibility to venture out to the nearby islands of Nusa Penida and Nusa Lembongan. The town includes some local cafes that double as bars but other than that, there are no nightlife activities. Tourism could grow significantly, on the condition that the existing infrastructure is able to handle the traffic and local community is willing to co-operate. The erosion taking place at the beaches and the lack of sand are the bottlenecks in this growth. Extra information on the tourism in Candidasa can be found in Appendix D.6. 26

27 STATE OF THE CANDIDASA BEACH In the Candidasa area, two main kinds of sand composition are examined, volcanic sand and sand with an organic origin. Volcanic sand is supplied by rivers and sea cliffs. Organic sand is supplied by coral, foraminifera, shell, etc. The volcanic sand supply from the rivers depends on the geographical characteristics of the river and the catchment area. There are no major rivers present in the area of Candidasa and therefore the volcanic sand originates only from the peninsula situated in the east end of Candidasa. The inflow of this sand seems to have slightly increased, but is still insufficient to form large sections of beach. The white sandy beach is formed by the coral reef situated offshore. Natural deterioration from the reef of Candidasa has contributed to the deposit of organic sand on the beach. However, large-scale coral mining in Candidasa, from 1969 until 1974 for construction, have disturbed the sediment transport. The coral mining has changed the reef profile, deepening the reef flat, decreasing organic sand sources and trapping sand in the mining areas (JICA, 2013, p. 177). As a consequence, the protection of the beachland supply of sand by the coral reef has been compromised. Retreat of the beach has occurred around 20 to 40 meters in the east and 40 to 60 meters in the west side of Candidasa. Monitoring of the beach in Candidasa shows no significant difference in the white coral sand area between 2004 and 2011 (Appendix D.1). The results from a dive survey indicate that the productivity of organic sand from the reef flat has not changed and is still not expected to increase on short-term notice. On the other hand, the volcanic black sand in the west of Puri Bagus Hotel seems to have increased, due to inflow from the peninsula. COASTAL DEFENCE STRUCTURES Beach erosion in Candidasa started in the 1970 s. To combat this erosion the Ministry of Public Works carried out beach protection measures starting from 1989 to The constructed T- shape groins, offshore breakwaters, and submerged breakwaters are shown in Figure 4-4. A total number of 25 groins and breakwaters were built along the four kilometre shoreline. However, this could not prevent the occurring erosion. Their crown height of +2.2 metres is not high enough to fulfill their function to interrupt the westward drift during high tide (+2.6 meter) properly. Hotels and villas along the coast have continued to construct vertical impermeable concrete seawalls to protect their property, as shown in Figure 4-5. The construction of these seawalls caused accelerated erosion of the foreshore area, and also eroding the coast further eastward. A walk along the beach is not possible anymore because of the construction of seawalls, groins and brick walls. Neither is there any space for beach activities, religious events or room for boat parking. Figure 4-4: Existing T-shaped groins and breakwaters at Candidasa (JICA, 2013). 27

28 Figure 4-5: Privately constructed seawalls close to the shore (JICA, 2013). In 2006 to 2007 a beach conservation project in Candidasa was carried out which comprised the following measures; the extension of the existing T-shape groins and beach nourishment with black volcanic sand. This sand was transported from the mountain side. However, the expected function to protect the nourished beach was not achieved. ENVIRONMENTAL DATA In order to make design for protection of Candidasa beach, a comprehensive survey of the area was done by the JICA team in 2013 and summarized in the section below. The following aspects are described: Sand composition of Candidasa beach, coral reef, current, waves, meteorological conditions, tides, bathymetry and sediment transport Sand composition of Candidasa Beach The sand composition and grain size is of great importance for the design, in particular the sand type used for beach nourishment. Sand samples are taken from three positions; berm top, sloping part and flat part. The difference in grain size taken from the berm top and sloping parts are compared and the grain size particles can be roughly evaluated. The grain sizes are measured on 34 locations on the beach which are shown in Figure 4-6. B, S and F represent Berm, Slope and beach Flat respectively. In general, the grain size distribution has a Figure 4-6: Alongshore distribution of Medium Grain Size (D50) and Contents of fine sand(jica, 2013). 28

29 high percentage of fine sand. An exception to this, is the area surrounding Sunrise Hotel, where the beach was nourished with volcanic mountain sand and transformed into a gravel beach. As an outcome of the data obtained, from the three different positions, the coastal area shows the tendency of an increasing percentage of fine sand in westward direction. Organic contents, such as foraminifera, coral and shell dominate the beach sand material, which means the main sand source is the coral reef. However, volcanic sand is dominant in two areas. There areas are 1 to 7 and 14 to 22 which is shown in Appendix D.2. The presence of volcanic sand in area 1 to 7 is due to the existence of the peninsula. The volcanic sand in area 14 to 22 is due to beach nourishment with volcanic sand Coral reefs The coral inner reef in Candidasa starts approximately 100 meters from the shore and has a width of 100 to 200 meters. Although living corals are mainly attached to the fore reef in Candidasa, dense coral habitats are also observed in reef flat areas. Clusters of corals can also be attached to breakwaters. In Candidasa a survey was carried out as a part of the BBCP phase II preparatory study. Clusters of corals were found in certain areas. The dive areas are shown in Figure 4-7. Figure 4-7: Areas of the survey of coral in Candidasa (JICA, 2013). The coral reef in Candidasa is situated from point 1 up to point 8. From point 9 on westward no significant coral population is found. This is illustrated in Figure 4-8. Figure 4-8: Aerial view of groin 1 to 11 and coral survey points (JICA, 2013). 29

30 4.6.3 MetOcean Data Near Candidasa, the dominant wave direction is from the SE during the wet season and from the SW during the dry season. However, this is an estimation since there are no permanent measure stations around Bali. The incident waves and their wave period and heights are predicted with this assumption using numerical modelling. The results shown in Figure 4-9. This model shows that the waves at Candidasa beach are small compared to the rest of the southeast coast of Bali due to the presence of the island Nusa Penida. In the west side of Candidasa, parts of the shoreline are almost perpendicular to the predicted wave direction and on these parts a stable black sandy beach is formed. However, in the other parts the angle of the shoreline induces a westward littoral drift. Figure 4-9: The numerical models with wave interval of 16s., Incident wave direction: south-east(above) and south-west(below) (JICA, 2013). 30

31 4.6.4 Meteorological conditions Precipitation and Temperature Like most tropical climates, the climate of Bali is divided in the rainy season and dry season. The precipitation and temperature is shown in below. The rainy season takes place from October until March. Throughout the year the temperature ranges from 24 0 C to 31 0 C. Figure 4-10: Temperature and Precipitation Denpasar from 1961 to 1990 (JICA, 2013). Wind The predominantly wind direction and average wind velocity observed in Bali are shown in Figure 4-11, using wind roses. The wind from SSE to SE direction is dominant during the dry season. The wind from WNW direction is dominant during the rainy season. Figure 4-11: Wind roses of Sanur during rainy and dry season (JICA, 2013). 31

32 Tides Measurements of sea water level are carried out to check the difference in tidal change between the southwest and east coast. Self-recording pressure sensors are used to continuously measure the tidal fluctuation in Kuta and Candidasa. The measurements were carried out for one month from November 22 to December 22, Tidal change in Candidasa is different from that in Kuta. The difference might be caused by the effect of the coral reef in Candidasa. On the other hand, significant differences in high water level (HWL), which is +2.6 meter, were not observed. This means the same tide conditions can be used for both the southwest coast and the east coast design. Results from the measurement are shown in Figure Figure 4-12: Tidal changes in Candidasa, Kuta and Benoa from 12/9 to 12/22 (JICA, 2013) Bathymetry The bathymetry around Candidasa is shown in Figure The water depths at the eastern and western part of Candidasa are quite shallow with a depth of about 10 meter 400 meter from the coast. Unlike the water depth of the central part, which is relatively deep. Around 20 meter in the vicinity of 400 meter from the coast. Figure 4-13: Bathymetry chart of Candidasa (JICA, 2013). 32

33 The sea bottom at a shallower depth than 10 meter has a gentle slope of 1:20 to 1:50. However at greater depth the bottom has a slope of 1:10 to 1:30. This makes the return of littoral drift sand to the beach nearly impossible once it has been transported to this part of the sea bottom. Cross-sections are taken at 10 intervals on Candidasa beach to determine the slope gradient, these are shown in Appendix D.3. In a more detailed survey, the slope of the beach is measured on the same locations as the sand composition measurements. The measured slopes of the beach of Candidasa are shown in Figure The slope of the beach is between 1:9 and 1:16. This must be taken into account when considering beach nourishment, since the chosen grain size depends on the slope of the beach. Figure 4-14: Foreshore slope of Candidasa (JICA, 2013) Sediment transport A westward littoral drift due to S to SSE incident wave direction occurs over the whole Candidasa area. The strength of the littoral drift is influenced by the geometric changes along shoreline and by the difference in wave action which is caused by the changing width of coral reef. The main sand source in Candidasa is of organic origin, which is provided by the coral reef flat. However, volcanic sand was found near the peninsula, which is due to inflow occurrence through the peninsula. 33

34 5 COASTAL STRUCTURES CONVENTIONAL AND INNOVATIVE COASTAL DEFENCE STRUCTURES This chapter is used to provide an overview of the basic knowledge of conventional and innovative coastal defense structures methods. Coastal defence structures are used to dissipate wave energy, prevent detrimental littoral drift, restore beaches or retain shorelines. Conventional structures are mostly applied, because of the availability of required knowledge and resources. These structures, though often functional, can be costly and can detract from the natural environment (Comoss, Kelly, & Leslie, 2002, p. 203). ). Innovative structures can be applied for the same purposes but give alternatives to bypass some of these issues. Another distinction which can be made is the difference between hard and soft structures. Hard structures are non-compliant, and have a human-made appearance. When shorelines are being restored or extended, hard structures are used in conjunction with natural-looking compliant soft structures. An overview of structures is summarized in Table 5-1. An elaboration of each structure can be found in Appendix E. Conventional Innovative Hard Soft Hard Soft Revetment 4 Beach Nourishment 3 Natural Revetment 4 Sand Motor 3 Seawalls 4 Mangrove Forest 1 Geotextile Sand Filled Beach Dewatering 3 Breakwaters 1 Dunes 4 Containers (GSC) 1,2,4 Coral Nurseries 1 Groins 2 Vegetation 4 Biorock Process 1 Degradable Artificial Reefs & Sills 1 Coral 1 Reef Ball 1 breakwater 1 Navigational Tyres 1 structures 2 Rigs to Reef (RTR) 1 Tetrapods 1 Energy generating buoy 5 Pelamis 5 Wave Dragon 5 Magic Carpet 5 Table 5-1: Coastal structures overview (Own Table). Footnotes of functions In order to determine which structures would be of use in Candidasa, it is important to understand the different functions of these structures. The structures are numbered according to their function in Table 5-1 and their functions are elaborated below. 1. Wave Energy Dissipation: The structures which dissipate wave energy, as for instance breakwaters or reef balls, are structures which decrease wave energy impact on the shoreline, and thus reducing its erosion. 2. Littoral drift prevention: Littoral drift preventing structures can be used to reduce beach erosion, maintain beach fills or fill project areas with intercepted drifting sediment, by trapping 34

35 or slowing down its longshore transport. They can also be used to repel or attract the flow, allowing or preventing sediment to settle. 3. Beach Nourishment: Eroded beaches need, besides protective structures, restoration of the sand supply. This is called beach nourishment. Beach nourishment structures are often built together with other coastal defence structures. 4. Shoreline retainment: Shoreline retainment structures are used when shorelines are retreating and this directly endangers the valuable upland infrastructure. They can also be used to stabilize beach nourishments. 5. Energy Harvesting Energy: harvesting structures are to a large extent similar to wave energy dissipating structures. The only difference is that energy harvesting structures do not only absorb wave energy, but transform it into electrical energy. STRUCTURES IN BALI In this part, a short overview is given which solutions have already been implemented in Bali. Known solutions can be used as examples in this project if the natural circumstances are alike. Also, if local authorities have affinity which a specific solution, it is more likely that the proposed solution will have political support. They are used to compare alternatives and find the most innovative solution for Candidasa. In the period from 1991 till 2008 BBCP phase I has been executed. The project focussed on the southern beach areas of Sanur, Kuta, Nusa Dua and the Tanah Lot temple because of their touristic and religious value. Table 5-2 illustrates the situation before BBCP. Table 5-3 gives a concise overview of what has been constructed on these four locations. Location Situation before BBCP Sanur Beach Serious overexploitation of coral reefs used as construction materials. Beach had receded by approximately m. Kuta Beach The coastline receded significantly along the 2.5 km beach on the northern side of the runway at Denpasar International Airport. Nusa Dua Beach Due to the overexploitation of coral reefs, erosion over a distance of 1km was noticeable in some areas. Tanah Lot Temple The rocks protective walls were damaged by waves in the area surrounding the temple and erosion progressed greatly. There was also a risk of collapse. Table 5-2: Situation before BBCP phase 1. Adapted from (Inazawa, 2011). 35

36 Location BBCP Output Sanur Beach - Beach Nourishment (4 sections 6,960 m; the nourishment sand: 301,196 m3, Walkway 5,830 m) - Offshore Breakwater (1 unit) - Straight Groin (6 were constructed and 7 units are rebuilt) - Submerged Breakwater/Artificial Reef (Cancelled) Kuta Beach - Beach Nourishment (4 sections 7,000 m: the nourishment sand: 519,605 m3, Walkway 3,400 m) - Offshore Breakwater (3 units) - Coral Reef Restoration (17,000 m² for 2 places) - Coral Transplant (10,000 m², 34 Species and 111,742 fragments) - T-type Groin (Cancelled) - Straight Groin (Cancelled) Nusa Dua Beach - Beach Nourishment (5 sections 6,400 m: the nourishment sand: 342,562 m3, Walkway 3,280 m) - Straight Groin (6 were constructed and 7 units are rebuilt) - Offshore Breakwater (Cancelled) Tanah Lot Temple - Submerged Breakwater (1 unit) - Tetrapod (7,110 units) - Offshore Breakwater (Cancelled) Table 5-3: Constructed output BBCP phase 1. Adapted from (Inazawa, 2011) 36

37 The different regencies of Bali and BWS-BP try to tackle the erosion problem with a collective approach. Table 5-4 shows the type and amount of coastal protection structure which has been constructed from 2009 till 2014 (Chon, 2000, p. 119). Regency Length of protection structure (km) Type of protection structure Buleleng 7,22 Revetment Jembrana 2,54 Revetment Tabanan 0,94 Revetment and Breakwater Badung 1,60 Revetment and groin(s) Denpasar 2,04 Revetment (rubble mound) Gianyar 5,14 Revetment (rubble mound) Klungkung 2,38 Revetment (rubble mound) Karangasem 0,56 Revetment (rubble mound) Table 5-4: Coastal protection constructed Adapted from (Parama Krida Pratama, 2014) The aforementioned structures in Table 5-3 and Table 5-4 can be completed with jetties which are used at harbours and channel inlets. Combining this list with several innovative of natural coastal defence structures provides a useful range of possibilities to find a technical, economic and social feasible solution for Candidasa. 37

38 6 ALTERNATIVES Various alternatives have been made to understand the different structures in the environmental aspects around Candidasa. The gained knowledge is used to produce a final concept design. Five alternatives are designed, named: Marine life, Big Bali Beach, Cultural Heritage, Sustainable Awareness, and High-end tourism. A brief description of the alternatives is given and the alternatives are extensively elaborated in Appendix F. Due to the current state, existing structures such as seawalls, groins and revetments will be removed and the material will be recycled where possible for the new structures. As well, in all the alternatives sand nourishment is applied to enlarge the beach. However, the sand nourishments can differ in method, spatial scale and time scales. MARINE LIFE The first alternative focusses on marine life. This entails the stimulation of new marine life and preservation of existing marine life. As diver's paradise, the target audience is active visitors, both high-end and backpackers alike. The comfort of divers are determined by the visibility of the water and the strength of current. The structures that will be implemented are separated in two sections: structures to stimulate the growth of coral and increasing the fish population and structures that enlarge the beach surface. Individually the artificial reef structures are Rigsto-Reef, Reef Balls and (degradable) Biorock. The beach is nourished and protected for wave energy by the (artificial) coral reef and mangroves. Mangroves will divide the beach in small patches. A tempered, but sustainable growth in tourism is expected in this alternative which makes it feasible to steer on proper spatial planning in this area. Structures: Sand nourishment, Rigs-to-Reef, Reef Balls, BioRock, coral nursery, degradable (temporary) breakwater, jetty, mangroves BIG BALI BEACH The second alternative is about unburdening the tourism congestion from the southern area of Bali, by creating a practically similar or even better area in Candidasa. Large amounts of tourists will be attracted with large white sandy beaches, residential cabins located in the sea, a harbour and a boulevard with palm trees and shopping facilities. A long and broad white beach, without large unsightly structures, will be constructed using sand nourishment via a sand motor. Residential cabins located in the sea, designed in such a way that they can be used as both hotel rooms and coastal breakwaters, will support the performance of the sand motor and offer a unique residential opportunity for tourists. A challenge would be to guide the extensive tourism growth in the right manner as not to oppose inhabitants and ruin the local environment. Structures: Sand nourishment by sand motor, residential breakwaters, harbour, boulevard, road diversion CULTURAL HERITAGE This alternative focuses on the rich Balinese culture which can be made more evident in Candidasa. The beach needs to be restored to facilitate traditional ceremonies, yoga classes and create room for traditional fishery. Besides that, a cultural town center must be identified or constructed to make room for a cultural museum and a handicraft market. Infrastructure must be in such condition that all activities and facilities can be reached easily. Finally, care should be given to nature and surroundings, which both contribute to the envisioned experience of Candidasa. Large resorts, mass tourism, a strip full of nightclubs and large yacht or cruise harbours are not desirable in this alternative. Because the goal of this alternative is not to attract a lot of beach seeking tourists, the sand can be sourced locally and there is no urge 38

39 for white sand specifically. The beach nourishment will be maintained by a series of newly built groins and offshore breakwaters or artificial reefs or sills. An important social advantage of this alternative is that the Balinese culture is respected and preserved. Structures: Local sand beach nourishment, groins, offshore breakwaters or artificial reefs, revetment, natural revetment, small headlands. SUSTAINABLE AWARENESS This alternative has to become a long-term oriented example in sustainable development, utilization and maintainability for tourism growth and erosion prevention methods. This concept entails the eco-tourism, small-scale culture, sustainable energy generation and employment by locals. The beach will be restored in its natural state of beauty. Natural boundaries will be used to divide the beaches into smaller section to avoid the feeling of mass tourism and to enhance natural population growth. Important aspects for the structures are; building with nature, recycling, sustainable and local materials, energy harvesting and simple construction methods. A large investment is made in educating local contractors and governmental bodies, this will create an extensive knowledge and experience bases for upcoming projects. They will recognize the urgency of erosion better and will respond adequately to future erosion problems. Structures: Sand nourishment, mangroves, coral nursery, Biorock process, Beach dewatering, Natural Revetment, groin (hergebruik) and different kinds of energy harvesting. HIGH-END TOURISM The purpose of this alternative is to provide an exclusive holiday experience for the more fortunate amongst us. With a scala of beachclubs, luxury hotels, gourmet restaurants and a deepwater yachtharbor, Candidasa will be Bali s retreat for the rich and famous. This requires a design which includes beach nourishment, a single large groin, offshore breakwaters, a revetment and small mangrove patches create the private beaches. Most structures will have a double function of protection and the stimulation of the high-end tourism. In order to realise this concept, large initial and private investments have to be made and the government have to get involved with private parties. Conflicts may arise due to different interest of investors and national government on one side and local government and inhabitants on the other side. Structures: White sand beach nourishment, large groin, offshore breakwaters, a revetment and small mangrove patches, submerged tunnel breakwater, harbour, road diversion CONCLUSION The alternatives differ substantially on many aspects such as costs, tourism, environment, local content and culture. However, in the alternatives the same or similar structures are shown repeatedly. These structures showcase their multi-purpose potential in the different alternatives. Therefore these added qualities to the structures will be assessed by a cross criteria comparison to determine the best set of structures for the final design. This will lead to a final design which incorporates the correct erosion prevention measures in the given environmental conditions. 39

40 7 ELIGIBLE STRUCTURES FOR CANDIDASA This chapter describes the criteria on which the structures are evaluated. The influence the criteria have on each other is checked with a cross comparison matrix, after which the structures, extracted from the alternatives in Chapter 6, are scored with the criteria and the eligible structures are found. CRITERIA The criteria are defined in Table 7-1 and are weighed by a cross comparison analysis, which describes the dependency of a certain criteria on another criteria. If a criteria has a high weight factor many other criteria are dependent of this specific criteria. The criteria are like the research question divided in three categories, technical, economic and social aspects. This is further elaborated in Appendix G. Criteria Weight factor [%] Description Technical Design complexity 5.9 Complexity of the design of the structure Construction complexity 4.9 Complexity of construction of the structure Maintenance 5.4 Amount of maintenance required on the structure Erosion preservation 4.3 Amount of erosion prevention the structure supplies Accretion 4.9 Amount of accretion the structure supplies Implementation time 1.1 Time between installment and actual erosion prevention Economic CapEx 7.6 Capital expenditures: investments in advance for the structure OpEx 7.0 Operational expenditures: costs during operating the structures Availability 5.9 Availability of the specific material the structure requires Lifetime 4.3 Amount of time the structure is operating Local Content 6.5 Amount of local workers and materials used Economical benefit 4.9 Profitability for the local community Tourist attraction 5.9 Amount of tourist the structure will attract Social Safety 5.9 Protection from danger, risk or injury Environmental impact 7.0 Amount of environmental impact Visibility 5.9 Visibility of the structure Innovative 4.9 Amount of, and room for innovation Local Support 7.6 Amount of local support the structure will receive Table 7-1: Criteria Weighting (Own Table). 40

41 ELIGIBLE AND SELECTED STRUCTURES In the previous chapter, five different alternatives have been developed. Each alternative contains a multitude of structures that support the potential success of the alternative. The structures were placed in alternatives to see in what kind of circumstances certain structures would flourish and become eligible structures for the final design of Candidasa. The selected structures for the final concept are highlighted in Table 7-2, according to their score on the criteria. The calculation of the scores per structure and their descriptions are found in Appendix G.2. Also the ability of the structures to form a suitable and realistic solution when put together in one system has been taken into account. The packages which these structures form are further elaborated in Chapter 8. Eligible Structures Score Description Wave Energy Dissipation Coral Nurseries Grows new coral on submerged trees Coral Absorbs wave energy and acts as a small continuing permeable breakwater Biorock Process Grows coral on steel structure through voltage currents Degradable Breakwater Made out of coral sand, degrades by time whilst acting as a temporary breakwater Offshore Breakwaters Reducing wave action on beach and alters longshore current and sediment flow Reef Balls Hollow concrete unit acts as submerged breakwaters and attracts marine life Rigs-to-Reef Turns decommissioned offshore oil and petroleum rigs into artificial reefs Residential Cabins Absorbs wave energy through structure and semi-submersible deck Yacht Docks Offshore breakwaters reducing wave action on the breach Glass Tunnel Submerged offshore breakwater, grows coral, reduces wave height Littoral Drift Prevention Mangrove Patches Protects coast from storm surges with roots, attracts marine life and contributes to seawater quality Jetty Facilitates walkway and attracts marine life Groin 2.8 Interrupts downdrift flow of sediment caused by currents with rigid hydraulic structures built from the shore 41

42 Shoreline Retainment Revetment Walkway Enhances wave energy absorption and protects its bank to erosion with permeable structures with walkway on top Recycled Revetment Enhances wave energy absorption and protects its bank to erosion with permeable structures made out of recycled material Energy Harvesting CETO Converts ocean wave energy into zeroemission electricity Oyster Wave Functions as a wave-powered pump powering a hydro-electric turbine Sand Nourishment Beach Dewatering System Drains water from the sand Sand Nourishment by land Sand retrieved through harbor outside of Candidasa and transported by land Sand Motor Transports upstream sediment with longshore current Table 7-2: Eligible Structure Scores (Own Table). 42

43 8 FINAL CONCEPT This chapter describes how the highest scoring structures of Chapter 7 are combined with the stakeholder perception into a final concept. Firstly the perception of the stakeholders is elaborated and a stakeholder engagement plan is advised. Secondly an overview is given of all potential structures in Candidasa incorporating the final concept. The structures that serve the same purpose are combined into packages and explained in detail. Finally, this an economic analysis is described and several mitigation strategies for stakeholders are given. STAKEHOLDERS PERSPECTIVES In this paragraph the perspective of stakeholders is elaborated, together with its contribution to the final concept. After this an engagement plan shows how latent stakeholders can be activated in order to enhance the potential of the final concept. In paragraph 8.5 mitigation strategies are proposed in order to avoid potential reluctance of stakeholders, after which a framework is proposed to BWS-BP which can be used in the development of new projects. Stakeholders perception Based on the stakeholders analysis, dialogues with experts from BWS-BP and a limited survey, the highest scoring structures and the perception of all the stakeholders are placed in a matrix, shown in Figure 8-1. The explanation behind the scores and the content of the surveys can be found in Appendices H.2. Figure 8-1. Perception of stakeholders on specific structures. Supportive(+), neutral(o) or resistant(-) (Own Figure). It shows that the biggest part of the structures are supported because of the urgency for change. The high amount of uncertainty is due to the lack of knowledge about the specific structures. The most commonly shared opinion by the stakeholders was that the structures with the highest contribution to the natural appareance of the beach were appreciated the most. The perspective of restoring the natural balance of the beach is used to develop packages that together form the final concept, described in Chapter

44 Stakeholder engagement plan Before the final concept is explained, a stakeholder engagement plan is drawn. This plan can have a positive contribution to developing a concept which restores the natural balance, by changing the interests in order to develop sustainable relationships and stretch the goal of the project. The shifts of interests can be seen in Figure 8-2. Figure 8-2. Stakeholder engagement in a power-interest grid (Own Figure). In Appendix H.2 the engagement plan is elaborated per stakeholder. The most important shifts are the environmental agency, from context setter to player, for using their knowledge and get around their blocking power. Their knowlegde will be used in a dialoque on the effectiveness and effienciency of several natural soft structures, such as mangrove patches, Biorock Process and coral nurseries. The highway irrigation agency shifts from crowd to subject/player, by coupling the issues to get them involved in order to use their production power. The relieving of tension on the infrastructure in the South of Bali, the boulevard and local infrastructure are the main common interests of BWS-BP and Highway and irrigation agency and a mutual big win could be achieved by extensive cooperation on resources. The NGO's shift from crowd to subject, in order to make use of their corporate social responsibility, financial liquidity and knowledge. The local inhabitants should be freezed as a player and a good collaboration is essential in avoiding them use their blocking power, because their opinion is highly valuable. 44

45 OVERVIEW FINAL CONCEPT Figure 8-3: Visual overview of final concept (Own Figure). As Figure 8-3: Visual overview of final concept (Own Figure).shows, several structures have been implemented and are sorted in several structure packages. The packages and their structures are displayed in Table 8-1. Structure Package Nourishment and Retainment of Public Beach Beach Nourishment and Mangrove Forests Coral Restoration Recycled Revetment Structures Beach dewatering Energy harvesting Sand motor Beach nourishment Mangrove forests Beach nourishment Coral nurseries Biorock Reef Balls Revetment Offshore Bungalows Table 8-1: Structure Packages and Structures (Own Table). Offshore Bungalows 45

46 STRUCTURE PACKAGES The five structure packages are; nourishment and retainment of public beach, beach nourishment and mangrove forests, coral restoration, recycled revetment and offshore bungalows. Each package will now be explained, details of the structure packages can be found in Appendix H Nourishment and Retainment of Public Beach Retaining and nourishing of the public beach will be accomplished with a number of methods working together as one system. Initially, the beach will be nourished with the conventional method of direct fillment accompanied with the installation of three sand motors at intervals along the beach. Due to the close proximity of the coral reef to the beach, a design of three sand motors is chosen which, with the same volume, do not interfere with the coral reef. Together with the beach dewatering system, powered by energy harvesting buoys, the beach will be retained and nourished in a controllable manner. This control is achieved by the ability of switching the beach dewatering system on and off, slowing down or speeding up the erosion at the given section. Refilling of the sand motors which feed the eroding beach section will provide the sediment necessary for the beach dewatering system to be effective. A layout of the combined system is shown in Figure 8-4. Figure 8-4: Layout of the public beach retainment system (Own Figure). The cross section of the beach retainment system, which includes the beach nourishment, one of the sand motors and the beach dewatering system, is shown in Figure

47 Figure 8-5: Cross section AA of beach nourishment, sand motor and dewatering system (Own Figure) Sand motors and beach nourishment To restore the beach in Candidasa, three sand motors will be placed to provide a continuous supply of sediment, since the natural source of sediment of the beach is missing. These sand motors will be placed on regular intervals of 750 meter apart from each other. The natural transport of sand by the longshore current will nourish the beach continuously and when it is depleted, will be refilled according to the speed of erosion, in order to keep the process going. The beach nourishment and sand motors will give a large amount of beach area which will not only attract tourists but can also be utilized by the local inhabitants for ceremonies and the docking of fishing boats. Design The design of the beach nourishment and the sand motors covers the dimensions and volume of the sand deposits, the grain size and source of the sand and the method used to place the sand. The volume of the sand deposits depends on the littoral sediment transport by the longshore current, required size of the beach, distance from the coastline to the coral flat and the desired refilling time. From previous experience at Kuta, Nusa Dua and Sanur beach, the average erosion of the nourished volume is approximately 10% every four years (JICA, 2013). Assuming the fillment of the sand motors every four years is acceptable and 50% of the sand of the motors will be deposited on the beach, the volume of the beach nourishment and the three motors can be calculated. The dimensions of the cross sectional area are shown in Figure 8-5. Which gives a total volume of 60,000 m3 for the sand motors and a volume of 300,000 m3 for the beach nourishment when multiplied with the length. The coral reef should not get affected by the sand, therefore the sand deposits can not extend further than 100 meters from the coastline, which is the revetment line. To prevent scouring at the base and in order to stimulate the transport of sediment, the sand motor will have a height of 2.5 m above LWL and therefore be submerged during high tide of +2.6 meter. The grain size should reflect the natural composition of the sand found on the beach in Candidasa, which is fine to medium as shown in Appendix D Beach dewatering Beach dewatering is an unconventional but proven method to prevent beach erosion (Curtis & Davis, 1996). This follows from the fact that dry sand can absorb more wave energy than wet sand and therefore decreasing the outflow of sand when impacted by waves. The main criteria 47

48 for beach dewatering to be effective, are the slope, which has to be between 1:10 and 1:50, and the grain size, which has to be fine to medium. Candidasa meets both criteria, which is shown in Appendix D.3. Beach dewatering has been successfully applied in a number of beaches, Nantucket beach in the USA among else. This case is used as a reference for the design of the beach dewatering system in Candidasa. Design The system will consist of three 900 meter perforated HDPE pipe segments, which are situated in the swash zone underneath the beach between the three sand motors and the peninsula covering the entire length of the public beach. The water in the beach will flow into the pipes and in the center of each 900 meter segment a drainage well and pump are placed. By dividing the beach in three segments, dewatering can be switched on in the section which is eroding and off where it is large enough. The power of these pumps are 54 kw each, which is calculated with a hydraulic head of 3 meters, a debit of one kg/s per meter of beach, a length of 900 meters of each section and a total efficiency of 50%. As shown in Figure 8-5, the beach dewatering pipe will be installed 40 meters from the base of the revetment at 2 meters below the MWL. This is in the center of she swash zone at MWL. The distance to the freshwater aquifer is sufficiently large. The discharge pipe will therefore be 30 meters, travelling perpendicular to the beach directly to the sea. An one-way valve at the end will prevent seawater from flowing back in. The trench which has to be dug in order to install the dewatering system will be relative shallow since the beach nourishment will be done in a later stage and therefore covers the system to the required depth. Costs Costs are calculated based on the reference beach dewatering project on Nantucket Island. The beach dewatering system in Candidasa will have a length of approximately three kilometres. The projected construction costs will therefore be 636,363. Maintenance costs are also expected to be proportional to the length with 63,636 annually. Maintenance The beach dewatering system will require maintenance in order to keep the pumps running and the pipes free of sediment, which can block the flow of water. The maintenance can be conducted by local contractors which creates employment for local inhabitants Energy harvesting buoys The required energy for the dewatering system and the Biorock will be provided by energy harvesting buoys which simultaneously act as submerged breakwaters. The CETO 5 buoy is used as a reference for the dimensions and power outfit of the buoys. The excess of energy created by the buoys can be used to supply power to the offshore bungalows or produce fresh drinking water from seawater. Using renewable energy from waves will not only be beneficial as a power source but will also give Candidasa the reputation of a sustainable tourist destination. Which, especially among western tourists, is a valuable reputation. Design With a diameter of 11 meters and an average power output of 240 kw, one buoy should be sufficient to power the pumps for the dewatering system. One buoys costs around 7.3 million, which gives a return period of 34 years with a price of 0.10 per kwh. More buoys can be installed to provide the power for the offshore bungalows. The buoys will be placed in a water depth between 20 and 50 meters in an area off the coast where the waves are the highest. 48

49 The main components are the anchors to the seafloor, which holds the buoy in place. The buoyant actuator, which is excited by the wave action and holds a hydraulic pump, which is connected to an electrical generator. A tether runs from the anchor to the actuator to hold the buoys in place. An overview of the design of a single buoys is shown in Figure 8-6 below. Figure 8-6: Design of the CETO 5 energy harvesting buoy (CETO, 2015) Beach Nourishment and Mangrove Patches In the area between Alila Manggis and Mendira beach (Area 2) two patches of mangrove forest will be planted. These will act as natural groins and will protect the nourished sections of beach from erosion. The location of the patches are chosen in such a way that they will have a habitat in which they can thrive, which is where fresh water with nutrients meets the ocean to create a less saline area. This means they are placed in the outflow region of two small rivers shown in Figure 8-7 below. Figure 8-7: Location of the mangrove forests (Own Figure). 49

50 Design The aim is to place the mangroves as far as possible into the sea to create a groin-like effect in order to partly block the littoral drift and catch sediment which is otherwise lost to the offshore. This means a species of mangrove has to be chosen which can survive these conditions. The mangrove type which can grow farthest from shore and in the most saline water, and is therefore chosen, is the red mangrove tree. The amount of sand nourishment done at area 2 will be 170,000 m3 over a segment of 1.7 kilometre. Two sections of the beach will be extended further into sea, this will be sand mixed with mud to provide a fertile soil for the mangrove seedlings. The sections of mangrove forest have a combined surface area of 30,000 m2. This will require around 30,000 seedlings to plant the forest. To elevate the forest floor just below HWL, 2.5 meter of fillment is required. This is the same elevation as the sand motors, which gives the same cross section of the nourished beach. The volume of sand/mud mixture for the mangrove forest will therefore be approximately 75,000 m3. A cross section of the area where mangrove forests are planted is shown in Figure 8-8 below. Figure 8-8: cross section of mangrove forest with sand nourishment (Own Figure). Planting process The type of soil in which red mangroves thrive are muddy and sandy soils. The soil on the beach of Candidasa has a high percentage of fine sand which makes it suitable for red mangroves to grow. In order to plant the mangrove trees as far into the sea as possible, initial nourishment of a sand/mud mixture is executed to just below the HWL to create a growing area for the seedlings. It is not advised to transplant trees. The area in which they have previously grown will always differ in some way to their new habitat which causes a large failure rate. Around one seedling per square meter is required to create a dense and healthy mangrove forest. These seedlings will be harvested from existing mangrove forests in Bali, near Benoa. Maintenance The first two years, the trees have to be regularly maintained which includes the removing of debris, algae, barnacles and dead plants. Also the planting of new seedlings where trees have died is required. After two years, the mangrove forest will be strong enough to be self-sustaining. The maintenance can be done by a small group of inhabitants of Candidasa. Ecological benefits of mangrove forests Beside the prevention of beach erosion, mangrove forests have another great advantage. The dense root systems of the mangrove forests form a home for fish, crabs, shrimps, and molluscs. They also serve as nurseries for juvenile fish. Several coral reef fish species spawn in mangrove forests. The young fish stay in the forest, where there is plenty of food and they can shelter from predators, until they are old enough to move to the reef (LeGuen, 2014). This will enhance the fish population on the reef, which in its turn provides benefits for diving and fishery. 50

51 Coral Restoration To restore the natural dynamics, the coral reef will be restored, strengthened and extended to sustainably and cost-effectively withstand the current and future severe conditions leading to erosion. Coral reef rehabilitation has multiple benefits towards conventional measures for breakwaters, such as stimulation of important ecosystems, protection against tropical storms, ability to adapt to sea-level rise and to save initial maintenance cost of breakwaters. A breakwater in the form of coral reef and Biorock will reduce the wave height energy and restore the balance in supply of sedimentation. Figure 8-9 the location of the coral nursery and Biorock is displayed Figure 8-9: Fragment 1 coral reef and Biorock location (Own Figure). Design As outer layer, the Biorock is situated furthest from the coast and will form the first wave reduction layer for the Candidasa beach. The majority (86%) of wave energy is reduced at the biorock reef crest alone. Behind the crest, the first 150 meters of reef flat reduces half of the remaining wave energy (Ferrario, Beck, & Storlazzi, 2014). Behind this layer a calm environment is created for the coral nursery to grow on the old reef flat. If the coral reef is sufficiently grown it will protect the beaches and stimulate marine life in the region. Candidasa has a rather calm wave climate as Nusa Penida islands form a shelter. Therefore, a reduction range of 50-80% is sufficient to reduce the wave energy in Candidasa. This implies that a full-grown coral reef crest with meters of coral reef should be able to offer enough support against coastal erosion. Secondary goals for the development of this coastal reef are: retain water quality, sediment supply, stimulate marine life and specific fish populations for fishery. These secondary goals should stimulate economic growth by tourism as well fishery. An attractive coral reef in combination with the Biorock structures attracts many snorkelling and diving tourist. An opportunity for a diving based ecotourism will rise. Human art structures and coral reef will be admired, but could also learn about the marine eco-system and its fragility. In this case tourism goes hand in hand with education for a better future planet. As 51

52 well, many dive shops encourage participation in clean-up days and there is a PADI certification for completing the Biorock or coral nursery Specialty Course (Deville, 2012). Spatial Area The coral reef will be replanted for a length of four kilometres with one kilometre of existing coral that will be strengthened. The average width of the coral reef will be around meters when completed. Initially, during the first phase, the width of the coral will be 50 meters. Afterwards, the coral will grow and extended in landwards direction to widen the coral fleet. This will be done in two phases of 25 meters after 10 years and 20 years. In total an area of m2 will be redeveloped in future years. The area is divided in accordance with the secondary goals set for the coral reef development. Specific regions are assigned to tourism, transport, recreation, nursery or fishery activities. Fishery could focus on special target species, such as lobster, groupers or octopus. Additionally, the selection of coral should also be in compliance with assigned purpose. In Figure 8-10, a division of the coral reef is suggested. However, extensive research and consultation with coral planting strategists should be done to deliver a final suggestion on coral habitat. Figure 8-10: Coral area division (Own Figure). Implementation period and deployment The start of dry season is the best time in Candidasa to plant a coral fragment, otherwise rain and runoff can impact coral health and reduce the efficiency of diver and propagation efforts. Additionally, as a rule of thumb, all coral planting activity must be completed between days after the substrate is deployed. The coral will be attached in coral plug adapters to the artificial substrate by divers. These are depressions in the material of a uniform shape and size. A skilled diver can attach 100 plugs per hour. Most coral species can be planted using the standard coral plug, which has the size of a medicine cup (RB Foundation, 2008). For Candidasa it is expected to take between years for the coral to be grown enough to reduce the wave energy (US Department of Commerce, 2008). A fully-grown reef will take more than 50 years. Seabed, water characteristics and substrate The current seabed exists of the remaining limestone covered with a layer of sand degraded from the beaches (JICA, 2013). Excellent conditions for the start a new coral reef, from a substrate point of view. The water characteristics of Candidasa, such as temperature range, saliently range, current, waves and tides match the climate required for coral growth. In the final concept, a mixture of substrates is used due to the characteristics of the reef plateau. If possible, the plantation is done directly to natural rocks or existing coral reef parts. 52

53 Biorock To stabilize, support and reinforce the reef crest Biorock is placed. Biorock is already used in Bali and the Gili islands and has proven to be a proper solution. It is essential that the artificial reef crest will be implemented at the start of the project to directly function. A major benefit of Biorock reef structures is that the corals survival expectation exceeds the adjacent natural coral reef formations under severely degrading environmental conditions (Hilbertz & Goreau, 1978). After several months time, the limestone and coral will have attached and sufficiently grown to contribute to the process against coastal erosion. Design The modules for Biorock come in diameters from 5-10 meters. They will be placed in one long line of four kilometres near the reef crest. On most places normal units will be placed in the form of staggered rows to provide maximal effect. To ensure direct effect, the Biorock compartments will be filled with rocks. Although some of the rocks compartments are left empty to provide habitat for fish (Goreau & Trench, 2012). To stimulate tourism and awareness the possibility for artistic forms are implemented. This interactive ecology art will help sustain communities and marine ecosystems, which depend on coral reefs. Design and nature are converged in these art forms and it is the perfect way to pass on important information about environment and encourage curiosity and enquiry. In Figure 8-11, an example of artistic use of Biorock is presented (Deville, 2012). Figure 8-11: example artistic design (BIC, 2012). Construction The electrically frame will be built from ordinary construction materials available on Bali, such as steel rods, pipe or rebar. Other materials necessary for the project include electrical cables and epoxy or silicone sealants to protect the electric connections. As the main structure act as the cathode, the anode will be a special titanium mesh that does not corrode (BIC, 2012). The total construction cost for Biorock are estimated around 3.2 million for a length of four kilometres. Energy for Biorock will be provided by the CETO energy unit placed near the reef. The usage of electricity depends on the total amount of steel that will be used and how fast the limestone needs to grow. Based on Goreau s paper (Goreau & Trench, 2012) the total Biorock structure for Candidasa uses 2800 Watt, which is around the amount of electricity for shore lights. Maintenance plan Coral and Biorock The main goal in maintenance is to give space for coral to grow and monitor the condition of the Biorock and coral nursery. Undesirable weedy organisms, certain sponges and algae that could overgrow corals will be removed periodically. Also, organisms that kill corals, such as crown or thorns starfish and certain eating snails are eliminated. Biorock will be checked periodically to ensure that cables and connections are intact. Broken wires cause a hold on accretion of mineral, reduce coral growth speed and ability to resist adverse conditions (BIC, 2012). 53

54 Involved stakeholders construction & maintenance The success of the project can be enhanced if local community, such as head of the villages, dive shop owners, fishermen and tourism professionals are involved and work together. This has been successfully done in the Pemuteran area of Bali. Mainly, due to villagers understanding they can also benefit from the expansion of the coral nurseries as they can generate direct and alternative income (Deville, 2012). The Biorock process is elegantly simple and easily executed by locals. However, it will fail if imitated without authorized expertise and maintenance (Goreau & Trench, 2012) Recycled Revetment The current revetments in Candidasa consist out of a vertical impermeable type of sea wall and have mostly been constructed by individual parties (JICA, 2013). This caused the inconsistency in the revetment along the coastline and the inability for a possible walkway on the revetment. By creating a consistent revetment that runs along the entire coast of Candidasa, a stable foundation for beach nourishment is present. In order to create a consistent revetment that includes a walkway, the existing seawalls have to be modified to a sloping permeable type revetment. By removing the seawalls, breakwaters and groins a lot of material is available for recycling. The revetment will be 1.5 meters wide at the top and, from top to bottom, 5 meters high (JICA, 2013) with a slope of 1:3 (Lake Ontario Riparian Alliance, 2011). The revetment in this design will be made from the recycled material of the old sea walls, groins and breakwaters. About 30% of the new revetment will consist of recycled material. The new revetment will be a rubble mound type structure with armor type-sloping. It incorperates a 1.5 meters wide walkway, will be 5 meters high and have a slope of 1:3. The core layer and under layers will have the recycled material incorperated. This material has to be processed and washed before it can be used. For the upper armor layer, light colored limestone is chosen in order to blend in with the surrounding landscape. This material will be transported from Sumbawa Island. Andesite is employed as lower armor layer, two under-layers and core layer material. recoating (Masters, 2001). Alongside the entire coast of Candidasa the revetment will be constructed. This accumulates to 5,261 linear meters of revetment construction. Which will consist of 124,000 m3 of andesite and 56,500 m3 of limestone Offshore Bungalows An offshore overwater bungalow is a housing facility located over water and is one of the more innovative structures, shown in Figure In combination with being an unique hotel accommodation and therefore attracting tourists the structures on which the bungalows are positioned attribute to erosion prevention. This is done by altering wind and wave flows due to the water flowing under the bungalows and being obstructed by the structures. As overwater bungalow construction is a specific construction project with specific requirements, it can be assumed that local content will be minimal. Expert knowledge is essential during the construction. 54

55 Design Bungalows are limited to one story, with its height, width and location in a manner that minimizes direct impacts on vegetation (Scott & Co., 2012). The bungalows are located 0.5 kilometres from the coast. Locations with higher waves and tides would cause excessive noise (OB, 2015). Shuttle boats will sail between shore and the offshore bungalows to transport the guests. Figure 8-12: Location of offshore bungalows (Own Figure). A main pier will be constructed that functions as a dock for the shuttle boats sailing to and from the bungalows. There will be a floating pier attached to the offshore bungalows that will extend 20 metres into the ocean for docking at sea. The offshore pier has a T-shaped ending (Buckley, 2003) with the bungalows located at the ocean side of their pier for an ocean view. The bungalow at the end of the offshore pier is the hotel restaurant and bar. This bungalow will have a communal infinity pool with an accompanying lounge deck. Every need from onshore will be here or can be ordered here. Aside from the restaurant and bar, there are two types of bungalows. Ten honeymoon bungalows intended for couples, with one bed- and one bathroom and a floor plan of 25 m2. The four family bungalows are slightly bigger, with two bedrooms and one bathroom and a floor plan of 42 m2. The lobby will be located on shore, near the beginning of the onshore pier. Land and water activities such as kayaking, snorkeling, diving and boat tours can be arranged here and in the offshore restaurant/bar. The beach adjacent to the stretch of the bungalows will become private beach, intended for hotel guests exclusively. 55

56 Underneath the bungalow the deck will be located, this deck has shade from the bungalow construction and will extend along the sides for entry and exit. The pier will be attached to this deck, from which a flexible staircase will lead up to the bungalow. The deck will function as a semi-submersible breakwater and floats accompanying the tide change. The deck will be attached to the structure of the bungalow by holes, with a diameter of 0.5 meter, through which the structure beams, with a diameter of 0.4 meter, will be placed. Should the ocean conditions become too harsh for the deck to survive without damage, the deck can be flooded by water and sink to underneath the water level. The structures on which the bungalows stand, will be risen to 5.15 meter above the MSL of 10 meters. Material The entire structure and frame of the bungalow will be constructed out of wood. To minimize rotting a wood preservative, chromated copper arsenate (CCA), designed for marine use is applied to the wood. The deck will be hollow, for potential flooding, and consist of concrete. Wood with CCA could be layered on the top of the deck for esthetic reasons. Maintenance can be simplified by careful selection of building materials. Construction The installation method for pile installation that is preferred, during similar projects in the Bahamas, is socketing. The piles have to extend 1.94 metres, calculated in Appendix H.1, into the soil for the wind and wave forces not to tip them over. Prefabricated bungalows will be made and placed on the structures. The structures are placed with help of barges, on which the bungalows and cranes stand, which will be able to lower them onto the structure. Environmental Environmentally speaking the bungalows have an impact on their surroundings. In terms of light, the bungalows form shade and lessen the light intensity through the water column. This can be mitigated by not placing the structures above seagrass beds or other sea water plants. The physical disturbance is greatest when the piles are installed and sediments get displaced. This impact can be mitigated by appropriate pile installation methodology and sediment dispersal management. In order to mitigate construction waste impacts, a boat or barge sits under the construction site to catch all the debris that falls due to construction. Waste from the bungalows whilst in operation is split in liquid and solid waste. Liquid waste is processed by compact, yet highly efficient, macerators and vacuum systems that have an application to overwater structures. 56

57 ECONOMIC ANALYSIS In this chapter the economic aspects of the final concept are analysed. In order to determine the economic feasibility the monetary costs and benefits and the non-monetary benefits such as knowledge are elaborated Costs The costs for the final concept are based on the costs for each individual structure and demolishing of the old structures, an overview is displayed in Table 8-2. The costs do not include costs for consultation, taxes, administration costs, price escalations and interest rates. Structure Amount Costs per structure or meter (JICA, 2013, p. 328) (McLeod & Leslie, 2009, p. 139) Costs Demolition works 15 Groins 5 km Seawall 9 Breakwaters Costs adapted from JICA, ,013,000 Beach nourishment 605,000 m 3 ~ 36/m 3 22,000,000 Mangrove forests 3 ha 9000/ha 27,000 Biorock Process 20,000 m 2 160/m 2 3,200,000 Coral nurseries 500,000 m 2 10/m 2 5,000,000 Beach dewatering 3000 m 640,000 for the complete system 640,000 Energy harvesting buoys 1 7,300,000 7,300,000 Revetment 5,261 m Recycled groin material used as filling material ~ 2800/m 14,856,000 Offshore bungalows 20 1-bedroom 4 2-bedroom 1 Restaurant Onshore Lobby 1-bedroom 91,000 2-bedroom 136,000 Restaurant 455,000 Lobby 230,000 3,049,000 Total Costs 57,085,000 Table 8-2: Cost overview (Own Table) Funds/Resources The costs for the Bali Beach Project are considerable. A loan construction, as used in BBCP phase I could therefore be an option to arrange financing. In BBCP phase I, 75% of the 95.5 million planned project costs were a JICA loan (Inazawa, 2011). If these ratios are held,approximately 42.8 million of the planned project costs should be arranged by a loan. The loan is provided to the Government of Indonesia (Directorate General of Water Resources) and the Ministry of Public Works. BWS-BP is the operational branch in this case. The Government of Indonesia and Ministry of Public Works contribute the residual 25% ( 14.3 million) from investment reserves. In order to lower project costs for the government other ways of financing can be thought of. 57

58 The final concept contains innovative ideas for beach nourishment, wave energy dissipation and the energy harvesting. Funds can be made available for these structures by NGO s and private investors by engaging them to the project. Especially the energy harvesting structure is relatively expensive. If no fund or investor(s) can be found to finance this structure, it is likely to be the first to be deleted although this would cost approximately 55,000 per year in electricity to power the beach dewatering pumps. The offshore bungalows with a wave dissipating function are likely to be constructed using a private/public partnership. Private investors will take the construction costs of the bungalows on their account. The wave energy dissipating foundation is realised using government resources. The Biorock Process and coral nurseries can be partly constructed by volunteers. An example of a similar project can be found in Pemuteran, Bali. However, costs for material and supervisors still have to be taken into account Phasing Another option to reduce the initial costs is to divide the project into phases. Phasing is financially beneficial due to the time value of money. For the phasing, three options have been calculated, which can be found in Appendix H.3. Coral reef planting is divided in the three phases which are elaborated in Chapter The option in which no phasing is applied will cost 57,085,000 million as can be found in Table 8-2. The alternative options 1 and 2 cost ,154 million and ,431 million respectively. These costs again only include construction. Option 2 (Figure 8-13) is recommended. Not only because it provides the most economic benefits, but also because the development of the sand motors can be monitored and adjusted if needed after 5 years. It is a safe and flexible option in which, if structures would fail, the design can be changed to a certain extent. Figure 8-13: Phasing of option 2 (Own Figure) Monetary Benefits Short-term As stated in Appendix D.6 annual tourist numbers are expected to grow from 585,095 to 672,859 if the project succeeds (a growth of 15%). To calculate the extra tourism income, the average spending of these tourists, their origin and the length of their stay has to be taken into account. If a 28/72 distribution of domestic/foreign tourists (JICA, 2013, p. 360) and a three-day visit length is assumed, the project can generate 28.4 million extra tourism income per year. In this way, 58