Sustainable Solutions for Coastal Zone Management of Lowland and River Delta Coastlines

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Sustainable Solutions for Coastal Zone Management of Lowland and River Delta Coastlines By Nabil M. Ismail 1, M.ASCE, Robert L. Wiegel 2, Hon. M.ASCE 1] Prof.

1 Sustainable Solutions for Coastal Zone Management of Lowland and River Delta Coastlines By Nabil M. Ismail 1, M.ASCE, Robert L. Wiegel 2, Hon. M.ASCE 1] Prof. of Coastal Engineering, Maritime Academy, Miami, Alexandria, Egypt; Director, Costamarine Technologies, Davis, CA, USA, 2] Prof. Emeritus, Dept. of Civil and Environmental Eng., University of California, Berkeley, CA., USA

2 Background In recent years, the impacts of natural disasters are more and more severe on coastal lowland areas and barrier islands. Furthermore the impact of anthropogenic modifications produce coupled coastal problems. In the future, the impact of global warming and climate change (sea level rise, storm surges, coastal floods) will become more critical. People are increasingly occupying low-lying areas that are exposed to flooding, thus exacerbating their vulnerability to extreme events. The importance and scale of coastal defense structures will increase accordingly, and thus potentially generating greater environmental adverse impacts. At a global scale, effects of accelerated climate changes was demonstrated in autumn 2010 when the storm Becky reached the Santander Bay, Spain with a peak of nearshore (significant) wave height of about 8 m, and a storm surge reached 0.6m. On the Nile Delta Coast, effects of intense winter storms on Alexandria coastline and its adjacent shores appeared in the last decade to be more progressive in 2003, 2006 and recently in December The latest storm in December 2010, which hit the Nile Delta showed that generated surges, up to 1.0m as well as a maximum of 7.5m in the offshore presented a major natural hazard in coastal zones. The recent adverse impact of Super Sandy hurricane in late October 2012 on the east cost of the US is living example of progressive global climate changes.

3 Presentation Outline A. Status of World s River Delta Coastlines, Barrier Islands and Lowland Coastlines under Global Climatic Changes. Objectives and Methodology B. Case Studies; California-Pacific Ocean and France Gulf of Lions. C. Coastal Processes at Rosetta Headland and Seawall-Beach Interaction. D. Prediction of Large Scale Shoreline Modifications, Nile Delta Coastline and Wave Overtopping. E. Conclusions & Recommendations.

Changes River California USA Véran Seawall 2005 Monterey

Ventura Site location and survey N Lighthouse Véran Seawall

500 m Mississippi River Delta USA before 2005 Location of

4 A. Status of World s River Delta Coastlines, Barrier Islands and Lowland Coastlines under Global Climatic Changes River California USA Véran Seawall 2005 Monterey Pacific Ocean Véran Seawall - France Ventura River Delta Ventura Site location and survey N Lighthouse Véran Seawall St Anne Graude a Dent GI 17 GI 18 GI 16 GI 15` GI 15 GI m Mississippi River Delta USA before 2005 Location of case studies in the Gulf of Lions, France and the Gulf of Mexico, California, USA

Wave Dominated Nile Delta Deltaic barriers Islands ~parallel to shore 1900 1964 1971 1988 1990 1991 Nile Delta,

promontory * 1800 to 1909 Shoreline Advance (3.

5 Wave Dominated Nile Delta Deltaic barriers Islands ~parallel to shore Nile Delta, Egypt, as revealed by Satellite Imagery West Seawall East Seawall Rosetta promontory * 1800 to 1909 Shoreline Advance (3.5 km) 25 m/yr (E), 20 m/yr (W) * 1900 to 1996 Shoreline retreat 50 m/yr (4.8 km in 96 years) * Operation of Aswan High Dam 1965 Coastal Retreat of Rosetta Headland (1900 to 2000) and M. Ali Seawall

6 Beach erosion at barrier islands, Delaware, USA, (Galgano, 2007) Subsidence at Po river delta, Italy (Syvitski, 2008)

7 Impact of Global Climate Change on U.S Eastern Coastline Damaged boats in a marina Beachfront road and boardwalk damaged by Hurricane Jeanne ( Sept. 2004) Damages by Super Hurricane Sandy (Oct. 2012)

8 Brilliance of the Seas Cruise Ship Faces Heavy Mediterranean Weather, Alexandria, Dec. 13, 2010

9 Flooding at Mohamed Ali Seawall, Dec Mohamed Ali Seawall Restaurants Complex, Alexandria Coastal Road, Dec Flooding Abu Qir Bay Beach segment after 2010 storm Alexandria Coastal Road, Dec. 2010

10 Objectives & Methodology Assess the impact of anthropogenic modifications, such as the absence of river flow on coastal morphology of Deltas. Evaluate impact of recent storm surge and wave overtopping on upgrading of seawalls. The second aim is to highlight the opportunities to use coastal soft defense measures. Clarify literature controversial impact of the effectiveness of seawalls to slow, mitigate or increase coastal erosion at retreating shorelines. The derivation of the results is based on the examination of field data collected on the Nile Delta Rosetta seawalls, constructed in 1990, after the operation of the Aswan High Dam in 1965, as well as field data on seawalls in France and the USA. Use has been made of recent satellite remote sensing data for the Rosetta headland in 2007, 2008 and 2012, the numerical prediction of GENESIS, and scale analysis of the governing equations of the waveriver flow to obtain the length scale for reshaping of the Nile Delta coastline at Rosetta. Laboratory data are used for verification.

B. Seawall Case Studies Essential Methodology Review of previous case studies of field monitoring of coastal morphology modifications at two seawalls located in

11 B. Seawall Case Studies Essential Methodology Review of previous case studies of field monitoring of coastal morphology modifications at two seawalls located in Monterey Bay, CA, one seawall located at Ventura river mouth, CA, USA and one seawall located at the Rhone river mouth, the Gulf of Lions, French Mediterranean coast.

$, USA California USA Monterey Ventura Wave refraction analysis: for Monterey Bay, California (From Johnson, O Brien, and$

12 CASE STUDIES I - USA Seasonal and Storm Erosion Patterns Interaction of Seawalls and Monterey Beach, Calif., USA California USA Monterey Ventura Wave refraction analysis: for Monterey Bay, California (From Johnson, O Brien, and Isaacs, 1948 : Wiegel 1964)

13 Eight Years of Field Monitoring ( ) Gary Griggs, UC Santa Cruz, USA

14 Monterey Seawall, after Repair 4/98 Seawall Location 41a, Monterey Calif. Winter Storm 10/97

15 Ventura River Delta, California, USA (November 1999) River Mouth

16 Parking Lot and Bike Path Near the Mouth of the Ventura River (1995) Revetment Shoreline Erosion at Revetment, Surfer s Point, December 1996.

Fairgrounds Bke Path Dunes Water Rock Cobble Sand River Levee

Concrete Barriers 100 0 100 200 Sketch of Original Design at

Fairgrounds Beach Access Walks Bke Path Dunes Water Rock

17 Fairgrounds Bke Path Dunes Water Rock Cobble Sand River Levee Ventura River Mouth Groin Rip Rap Revetment Erosion Dunes Concrete Barriers Sketch of Original Design at Surfer s Point. Fairgrounds Beach Access Walks Bke Path Dunes Water Rock Cobble Sand Dunes Restoration Area Cobble Field Managed Retreat and Restoration for Surfer s Point.

CASE STUDY II France Seawall and Longshore

Cross Shore Depth Variation of the Inner Trough

18 CASE STUDY II France Seawall and Longshore Beach Erosion (Véran site, Gulf of Lions, France, Mediterranean), Samat Olivier et al, Rhone River N 1 FRANCE Lighthouse 3 Cross Shore Depth Variation of the Inner Trough in front of Véran Seawall (Since 1988) Site Location and Survey

19 Shoreline Retreat along Véran Seawall in the Long Term ( )

21 Morphological Changes at Rosetta Promontory Headland

Essential Methodology Analysis of the extensive field data collected by the Coastal Research Institute in Alexandria, Egypt and Coastal Protection Authority, Cairo, on the coastal changes astride

22 Essential Methodology Analysis of the extensive field data collected by the Coastal Research Institute in Alexandria, Egypt and Coastal Protection Authority, Cairo, on the coastal changes astride Rosetta Branch, Nile Delta Coast. Use has been made of the numerical prediction of GENESIS to confirm the measured rates of long shore and offshore sediment transport in the vicinity of the Rosetta Western Seawall. A wave-current momentum index was used to estimate the length scale of the coastline reshaping.

23 Evolution of Cross Shore Beach Profiles at the Western Seawall Section W1 Section W2

Rhythmic Sea Bottom Bathymetry Patterns at Rosetta Seawall (Ismail and El-Sayed, 2007) N W S E MEDITERRANEAN SEA Average shoreline 5 Predominant Waves NW/W NW ½ < H s (m) < 3 T P (s) < 8.

24 Rhythmic Sea Bottom Bathymetry Patterns at Rosetta Seawall (Ismail and El-Sayed, 2007) N W S E MEDITERRANEAN SEA Average shoreline 5 Predominant Waves NW/W NW ½ < H s (m) < 3 T P (s) < 8.5 EAST SEAWALL 3.5 km Average shoreline Rhythmic Sea Bottom Patterns: Length at the Seawalls = 270 m Rhythmic Sea Bottom Patterns: Length = 800 m Bathymetric Sea Bottom Contours (October 2002) Astride Rosetta Headland (CRI / CPA) Water Depth (m) - MSL Scale km WEST SEAWALL 1.5 km 4m 3m 2m 1m 0m 5m W2 6 m W1 N W E S West Seawall W1, W2 locations of cross shore profiles

25 Sediment Transport Rate (1000 m 3 ) Sediment Transport Rate (Genesis) along the Shoreline, West of Rosetta Headland for One Year Period ( Wave Data) 0.28x10 6 m 3 /yr (Offshore) 0.28x10 6 m 3 /yr (North) Test 1 Major Results Spit x10 6 m 3 /yr (South) Test 2 Fluorescent Tracer Experiment Theoretical Offshore Transport Rate 0.3x10 6 m 3 /year -400 Rosetta Western Seawall -600 NET Transport Rate Distance along the Shoreline (m)

26 D. Prediction of Large Scale Shoreline Modifications N Mediterranean Sea Western Revetment Spit Eastern Revetment Erosion Erosion Accretion Accretion Comparison of Shoreline Changes over the Period for Rosetta Promontory

27 Characterization of Relative Strength of Wave Momentum Thrust to Jet Momentum Flux, R sm WAVE LENGTH, L U C WAVES PHASE SPEED. C WAVES JET VELOCITY U C U C = 0.6 U C U C h BOTTOM JET OUTLET WIDTH, W O Velocity and length scales of wave-current system R sm 1 L a g C 2 h (C U) 2 0 S 0 g 0 2 / U w 0

28 Effects of Wave & Current Interaction on Coastal Circulation Flow Visualization of Wave Induced Mass Transport Pattern (Ismail, 1980) Flow Visualization of Momentum Jet in the Absence of Waves (Ismail, 1980) Flow Visualization of Momentum Jet in the presence of Waves (Ismail, Wegel 1981)

Alongshore accretion length / river outlet half-width Major Results Alongshore erosion length / river outlet half-width Correlation between Wave-jet Relative Momentum Thrust and Length Scale of the

29 Alongshore accretion length / river outlet half-width Major Results Alongshore erosion length / river outlet half-width Correlation between Wave-jet Relative Momentum Thrust and Length Scale of the Alongshore Zone of Accretion and Erosion * Rosetta headland before 1964 Wave and River dominated delta o Waves & Jet Stagnation zone Long shore currents Wave dominated delta S Shoreline Onshore currents Offshore Waves Jet Dyed Flow Shoreline JET Experimental Data (1980, 1981) * o R sm ; Ratio of Wave Momentum Flux to Initial Jet Momentum Flux

30 Major Results Satellite Images of Rosetta Seawalls & the Extent of Coastal Erosion Down-drift the Headland Eastern Seawall (1990) Groins Set 5 (2003) Western Seawall (1990) Mediterranean Sea Rashid (2005) Mediterranean Sea offshore currents Sand Spit Eastern Seawall Western Seawall More Erosion Groin Set (5) (2007) Flanking Erosion Rashid Comparison of satellite images of Rosetta headland and coastal zone in the years 2005 & 2007 (Google Earth). N. Ismail

31 Major Results Satellite Images of Rosetta Seawalls & the Extent of Coastal Erosion Down-drift the Headland (2012) Eastern Seawall (1990) Groins Set 5 (2003) 3.5 Km Mediterranean Sea Western Seawall (1990) 1.5 Km offshore currents Mediterranean Sea N. Ismail

32 D1. Wave Distribution across Abu Qir Bay with the Future Sea Level Rise and the Maximum Yearly Wave Condition (Wave overtopping analysis) Wave height (m) Abu Quir Bay El Amia Drain ImSed Tran-2D model (2005) El Tarh Seawall Wave height is denoted by the color scale in meters and wave direction by arrows.

33 Elevation, m tons Seawall Land Profile No.(18) L/s/m Boundary Wall Crest New Cross Section of Seawall in 2011 H. Tide + storm surge + wave height+ Run-up (+4.26) H. Tide + storm surge + wave height (+2.5m) H. Tide + storm surge (+1.0) H. Tide (+0.5) MSL (0.0) (-2.00m) Sea bottom Interaction between Abu Qir seawall and the sea in the current worst scenario L/s/m Overtopping (Euro- Overtopping Manual 2008) (de Waal &Van der Meer 1992) (Van der Meer & Janssen 1995) Overtopping Crest H. Tide + storm surge + SLR+ wave height+ Run-up (+5.37) H. Tide + storm surge + wave height+ SLR (+3.45m) Boundary Wall (Euro- Overtopping Manual 2008) (de Waal &Van der Meer 1992) (Van der Meer & Janssen 1995) H. Tide + storm surge (+1.0) Plus SLR (+0.5) H. Tide (+0.5) MSL (0.0) (-2.11 ml) Sea bottom Interaction between Abu Qir seawall and the sea in the future worst scenario due to sea level rise after 50 years.

E. Conclusions & Recommendations Modifications of bottom morphology in front of and astride seawalls depend on local wave climate and current conditions and sea level variations.

34 E. Conclusions & Recommendations Modifications of bottom morphology in front of and astride seawalls depend on local wave climate and current conditions and sea level variations. Further, the increased rate of longshore sediment transport is strongly influenced by the cross-shore location of the seawall in the surf zone. Wave reflection and the generated wave patterns in front of seawalls enhance the rate of offshore sediment transport as well as the alongshore rate. This trend of increase was confirmed by the results of fluorescent tracer experiments at Rosetta Western Seawall as well as the reported results for seawalls located in France and UK. Interaction of waves and seawalls influences coastal processes in front of the seawall. The rate of scour in front of Rosetta Western Seawall appears to be diminishing currently after reaching a quasi-steady cross-shore beach profiles. The continuation of collecting field data at Rosetta headland is highly recommended to provide reliable basis for future coastal zone management of the Nile Delta coastline.

The results show that current climatic changes and human interference require the improvement of existing coastal defense structures by upgrading, i.e. by elevating the top level of the rubble mound/armor revetments and seawalls as demonstrated from the analysis of the case study of Mohamed Ali seawall, Abu Quir.

35 The results show that current climatic changes and human interference require the improvement of existing coastal defense structures by upgrading, i.e. by elevating the top level of the rubble mound/armor revetments and seawalls as demonstrated from the analysis of the case study of Mohamed Ali seawall, Abu Quir. Further, it is becoming necessary to improve the stability of the cross shore-beach segment to create wave overtopping resistance conditions under future storm conditions. Despite the fact that low crested breakwaters proved to be successful in some coastal locations, the shoreline response to their placement needs to be identified. The results show that integratedinnovative systems, composed of hard and soft structures, should be explored to achieve the required level of coastal resilience.

Selection of soft protection alternatives for coastal zone management should be considered if the use of hard structures is proved to be adverse to the sustainability of the coastal zone.

36 Selection of soft protection alternatives for coastal zone management should be considered if the use of hard structures is proved to be adverse to the sustainability of the coastal zone. The soft engineering alternatives are such as beach nourishment, stabilized sand dunes and sustainable barrier islands and coastal lagoons. These natural systems would act as a buffer zone to defend main land. The sustainability of the integrated natural systems would require (1) barrier island with shoreline restoration and (2) quality management of hydrologic and vegetation restoration of coastal lagoons.

surface water flow paths and discharge locations

37 Highlights on Sustainability of Coastal Lagoons Mediterranean Schematic of groundwater and surface water flow paths and discharge locations at a coastal lagoon Mar Menor Wetlands, Spain N W S E

Future Outlook Passion for Coastal Regions Make no little plans: they have no magic to stir men s blood and probably themselves will not be realized.

thing, asserting itself with ever growing insistency. Remember that our sons and daughters are going to do things that would stagger us.

38 Future Outlook Passion for Coastal Regions Make no little plans: they have no magic to stir men s blood and probably themselves will not be realized. Make big plans; aim high in hope and work, remembering that a noble, logical diagram once recorded will never die, but long after we are gone will be a living thing, asserting itself with ever growing insistency. Remember that our sons and daughters are going to do things that would stagger us. Let your watchword be order and your beacon beauty. - Daniel Hudson Burnham ( ) Architect for the 1893 World s Columbian Exposition held at Chicago and lead author of the 1909 Plan of Chicago, USA.

Chapter 10 Lecture Outline. The Restless Oceans

Chapter 10 Lecture Outline. The Restless Oceans Chapter 10 Lecture Outline The Restless Oceans Focus Question 10.1 How does the Coriolis effect influence ocean currents? The Ocean s Surface Circulation Ocean currents Masses of water that flow from one