3 Baseline Environment

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1 3 Baseline Environment 3.1 Site Description The Region of Bel Ombre The south-western part of Mauritius is generally mountainous. In some parts, slopes, sometimes steep, run down towards the coast, leaving only a small strip of coastal flat. Several rivers and rivulets running towards the south cross the region. The high grounds are humid whereas the coastal areas are drier. In winter, winds blowing from the sea can be quite strong. Owing partly to its topography stretching from Bay du Cap village to Rivière des Galets, Bel Ombre has traditionally been an isolated area. Economic changes namely the closing down of textile factories and of Bel Ombre sugar mill has impacted on the population of the area. Since then, the social economic focus of the area has shifted towards tourism, leisure and property sectors. Further economic developments are planned for the area, which will have far reaching social and economic benefits as shown in the aerial photograph of Drawing EIA Site Location The proposed site is located on the Bel-Ombre coastal strip, to the east of the estuary of River Citronniers, as shown in Drawing EIA-05 attached in Appendix C, a reproduction of the local 1: Ordinance Survey map of the region. The site forms part of the Pas Géométriques de Bel Ombre extending in front of Outrigger Mauritius Beach Resort, LUX Tamassa Resort Hotel, Heritage Awali Resort and Heritage Le Telfair Resort, where the Developers intend to effect erosion protection works. The site is shown in the aerial photograph of Drawing EIA-06 attached in Appendix C Site Ownership The project site forms part of leased stretches of land obtained from Ministry of Housing and Lands as detailed in Table The copies of the site lease agreements issued by the Ministry of Housing and Lands are attached in Appendix B. Page 12

2 Table : Details of the site lease agreements Site Location Zoning Extent (m²) Status Heritage Le Telfair Golf & Spa Resort Heritage Awali Golf and Spa Resort Zone A 65,285 Bel-Ombre Pas Géométriques Zone B 19,800 Bel-Ombre Pas Géométriques Tamassa Resort Hotel Zone C 91, Bel-Ombre Pas Géométriques Outrigger Mauritius Beach Resort Zone D 88, Bel-Ombre Pas Géométriques The Project Zone The rehabilitation works, object of the present EIA, is the shoreline and the lagoon space extending from the River Citronniers to the beach front extending in front of Outrigger Mauritius Beach Resort. Beyond the HWM seawards, the works fall onto the Public Domain, which is governed by the Prime Minister s Office, the Ministry of Housing and Lands, the Ministry of Agro-Industries and Fisheries, the Ministry of Environment and the Beach Authority. 3.2 Marine Environment For the purpose of the assessment of the site, marine baseline data have been obtained from a study zone identified to be pertinent to the evaluation of the coastal process and potentially impacted by the proposed works. See Drawing EIA-02 attached in Appendix C. A copy of the marine biota survey carried out at Bel Ombre is attached in Appendix D Bathymetry A detailed survey of the beaches and the lagoon in the vicinity of the proposed works was carried out in June 2016 as shown in the Drawing EIA-06 attached in Appendix C. The beach transect as shown in Drawing EIA-07 and Drawing EIA- 08 attached in Appendix C Granulometry Sediment particle size distribution (granulometry curve) is of critical importance in seabed re-profiling works. Sand samples have been collected at 15 locations along the shoreline and at 3 locations on the seabed as shown in Drawing EIA-09 attached in Appendix C. Page 13

3 The granulometric analysis of the sand samples are shown in Drawing EIA-10 and Drawing EIA-11 attached in Appendix C. The results of the granulometric analysis of the sand samples are attached in Appendix F Current Meters Two Aquadopp (Doppler) current meters were deployed successively at 8 locations as detailed in Sanctuary Beach s report attached in Appendix E and shown in Drawing EIA-12 attached in Appendix C. To obtain a reference, one instrument was deployed 4 times at Site 3 (Sites 3, 3A, 3B and 3C) and the other instrument wave moved to four different locations (Sites 1, 2, 4 and 5) as shown in Figure 2.1 reproduced from Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. Figure 2.1: Current meter positions Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E All data were recorded continuously at 1Hz for up to 24 hours at each site. The instruments measured waves, sea levels, currents and water temperatures and the results are provided in the report of Sanctuary Beach Pte Ltd attached in Appendix E. Page 14

4 Site position Table : Current meter positions, depths and descriptions Label Easting Northing Depth Instrument Level (re-msl Date Site - 1 CR Aug 17 Site - 2 CR Aug 22 Site - 3 CR Aug 18 Site - 4 CR Aug 24 Site - 5 CR Aug 22 Site - 3a CR-03a Aug 24 Site - 3b CR-03b Aug 30 Site - 3c CR-03c Aug 30 The results showed that the tide at the sites are semi-diurnal with 2 cycles per day. The M2 is driven by lunar gravitation and has a period of hours per cycle. Currents are relatively fast, particularly at Site-3b, reaching up to 0.6m/s. The slowest is Site- 5 at the east of Outrigger (max. of 0.13m/s), but the nearby Site-1 is mildly faster (max. of 0.2m/s). The current paths are shown in Drawing EIA-13 attached in Appendix C. All sites flow generally from east to west. There were no reversals in the current recorded. Thus, the tidal current is very small. The flow is associated with waves driving water over the reef crest and through the lagoon to leave in the Passes. Significant wave heights are very small, mostly less than 0.09m, except for Site-5 at Outrigger which achieves 0.28m. Wave heights offshore at the time exceeded 2m Drogue Tracking Drogues consist of 2 crossed vanes supported by a float and are designed to drift with the currents to reveal the Eulerian circulation patterns and the net movement of water in the bay. Six drogues were constructed for release from selected transects and were tracked using a wrist watch GPS tied to each drogue post. A position was recorded every 5 minutes. During both drogue experiments, winds were mostly from the east-south-east and varied between 6-10 m/s from the east ( T). The drogue speeds with their paths are shown in Figure 2.6 as reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. Page 15

5 Figure 2.6: Drogue paths and average speeds recorded at Bel Ombre in 2015 and 2016 Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E From the drogue experiments, it has been noted that the drogues released east of Outrigger initially head shorewards and then travel to the west. They pass along the foreshore of the four resorts close to the beaches and were collected at the west end of the beach offshore of the river entrance. Drogues released further offshore travelled along a similar course but they turned offshore into the channel which heads seaward between the two passes near the end of the journey. Drogues released offshore near the Central Pass travelled initially offshore, but turned to the west to head for the Western Pass, rather than towards the closer Central Pass. From the experiments, it has been noted that: No drogues travelled to the Central Pass All were headed towards the larger Western Pass All drogues travelled from east to west, i.e., no drogues reversed with the tides and none were able to head to the east Tide Data Tide data for Port Louis was obtained from the WOCE website as detailed in Table 2.3 reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. Page 16

6 Table 2.3: Port Louis tidal constituents from the WOCE website. Mean Sea Level is 1.69 m from the gauge zero. Sa is an annual cycle showing a low frequency variation in the MSL during the year. Constituents with amplitudes less than 1 cm have been removed. 2 PORT LOUIS 20 o 09.2 S 57 o 29.4 E 1analysis of hourly tidal heights stn 103 From 0h 1/ 1/86 to 23h 31/12/97 no.obs.= no.pts.anal.= No. Name Freq (hr -1 ) Stn Amp(cm) Phase ( o ) Approx period 0 Z Sa year 69 Ssa months 65 Mf days 56 O day 50 P day 48 K day 36 N hrs 32 M hrs 26 S hrs 24 K hrs Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E From the Table 2.3, it can be inferred that the time series sits 1.69m above the MSL datum. The largest tidal constituents in order are M2, S2, K1, O1 and N2. The largest range captured by the current meters was 0.66m which is close to the sum of the largest four constituents namely 0.70m and is therefore a spring tidal condition. Smaller ranges were also recorded and so the current meter data provides a good spread across the tidal ranges occurring at Bel Ombre Global Ocean Wind and Wave Data A 36-year time series ( ) of waves and winds from numerical model hindcasts was obtained from Buoyweather. The data was taken from a node at 20.5 o S, 58 o E which lies in open water off south-east of Mauritius and thus ideal for examining typical wave conditions at Bel Ombre. Waverider buoy measurements were made by the Mauritius Oceanographic Institute at 20 o S, 57 o E off the east cost of Mauritius, which is close to the hindcast site. Comparison between measured and hindcast data is shown in Figure 2.11 as reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. 2 Available at: Page 17

7 Figure 2.11: Comparison of the hindcast wave heights (blue and cyan lines) with the measured wave heights from a waverider buoy. Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E Figure 2.12, as reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E, shows the comparison between the hindcast data and measured wave height at Pondicherry on the Indian east coast. Figure 2.12: Comparison of hindcast wave heights with measurements at Pondicherry on India s east coast Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E Page 18

3.2.6.1 Long-term winds The wind speeds and directions over the 36-year period show annual variations, being strongest in winter (July) and more constant in direction at the time as shown in Figure 2.

13: Offshore wind speed and direction for 2010-2015 Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix EThe direction focusses on 100-110 o T during the winter, but

8 Long-term winds The wind speeds and directions over the 36-year period show annual variations, being strongest in winter (July) and more constant in direction at the time as shown in Figure 2.13 reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. Figure 2.13: Offshore wind speed and direction for Source: Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix EThe direction focusses on o T during the winter, but varies more in summer. Some years the wind direction is more south-east in winter. The wave heights over the 36-year period show seasonal trends in accordance with the winds as shown in Figure 2.13 reproduced from the Beach Erosion Solutions, Bel Ombre, Mauritius Report attached in Appendix E. In as much as Bel Ombre is concerned, the wind is longshore from the east. The wind-driven currents will thereby support the currents generated by waves breaking on the offshore reef. Page 19

3.2.7 Seabed Description As per the Biota survey report attached in Appendix D, three different sub areas were defined for the survey as shown in Figure 1.

9 3.2.7 Seabed Description As per the Biota survey report attached in Appendix D, three different sub areas were defined for the survey as shown in Figure 1. Figure 1: Satellite map of Bel Ombre showing the various transects used for the survey and area surveyed The main findings of the survey are: Area A consists of shallow waters at low tide with some area even emerging at low tide. The area is mostly covered with sand and rubble and has a low fish abundance and no fish were encountered at low tide. The algae and benthic fauna abundance and diversity were found to be very low. Area B consists of 75 to 85% of sand and rubbles and has a low abundance but a good diversity of 38 fish species. The benthic fauna was properly established within Area B and 16 species of corals were found. The area also has an average abundance of algae comprising mostly of brown and red algae. The coastline, namely Transects T1 to T28 showed a big variation in biota composition. Transects T1 to T6 showed a habitat comprising mostly of seagrass and no corals with few fish abundance and diversity. The Transects T7 to T17 has a low percentage cover in terms of live coral cover and showed the highest fish and algae diversity. Seagrass was mostly absent from Transects T7 to T17. The Transects T18 to T24 showed highest percentage coral cover since the corals start closer to the shoreline with the first 40m of the transects comprising mainly of sand, rocks and rubbles. The transects T18 to T28 show a great diversity of corals and fish with 68 species found within the zone. The rich coral habitat comprise of 51 coral species which support a rich fish diversity Sensitivity Mapping As per the biota survey report attached in Appendix D and as reproduced on Drawing EIA- 14 attached in Appendix C, the area close to the River Citronniers mouth comprises mainly of bare sand. The seafloor close to the shore consists mainly of H. Ovalis and this becomes denser and continuous moving further away Page 20

10 from the shore. Large seagrass beds of Syringodium Isoetifolium can be found along the sea floor. During the survey, dense coral growth were found at 80m from the shoreline and are thus not part of transects shown in Figure 1 attached in section Corals colonies were also found sparsely distributed along seafloor. The areas surveyed in front of Tamassa Resort and Outrigger Resort show an extensive consistency in terms of coral mainly Porites species and branching Acropora species. The areas where the corals are found are quite shallow and hinder boat movement. Thus the water gets channelled between the shoreline and the corals generating strong water currents during tide shifts or bad weather conditions. The coral area in front of Outrigger emerges out partly during extreme low tides following the lunar cycles. Thus many massive Porites lutea colonies have partly died on the surface and algae has started to grow. The coral areas remain regions of high sensitivity and regions outside these consist of either rock deposits or sand covered by rubbles with some sparse coral colonies Fish Diversity The list of fish encountered during the survey is given in the Table Table : List of Fish # List of Fish # List of Fish # List of Fish 1 Abudefduf bengalensis 29 Ctenochaetus striatus 57 Parupeneus bisfasciatus 2 Abudefduf sexfasciatus 30 Dascyllus aruanus 58 Parupeneus cyclostomus 3 Abudefduf sordidus 31 Dascyllus trilobatus 59 Parupeneus macronema 4 Abudefduf sparoides 32 Dascyllus trimaculatus 60 Pomacentrus pikei 5 Acanthurus nigricauda 33 Epinephelus merra 61 Pterois miles 6 Acanthurus triostegus 34 Epinephelus spilotoceps 62 Rhinecanthus aculeatus 7 Anampses caeruleopunctatus 35 Fistularia commersonii 63 Scarus ghobban 8 Apogon cyanosoma 36 Gerres acinaces 64 Scarus psittacus 9 Arothron hispidus 37 Gnathodentex aureolineatus 65 Scarus russellii 10 Arothron nigropunctatus 38 Gomphosus caeruleus 66 Siderea grisea 11 Aulostomus chinensis 39 Halichoeres argus 67 Siganus argentus 12 Bothus mancus 40 Halichoeres hortulanus 68 Sphyraena barracuda 13 Cantherhines dumerilii 41 Halichoeres scapularis 69 Stegastes fasciolatus 14 Cantherines sp 42 Istigobius decoratus 70 Stegastes nigricans 15 Canthigaster valentini 43 Labroides dimidiatus 71 Stethojulis albovittata 16 Caranx ignobilis 44 Leptoscarus vaigiensis 72 Thalassoma genivittatum 17 Chaetodan interruptus 45 Lethrinus harak 73 Thalassoma hardwicke Page 21

18 Chaetodon auriga 46 Malacanthus latovittatus 74 Valamugil seheli 19 Chaetodon interruptus 47 Mugil cephalus 75 Zanclus cornutus 20 21 Chaetodon lunula 48 Chaetodon trifascialis 49 Mulloidichthys

sordidus 53 Ostracion meleagris 26 Chromis viridis 54 Oxymonacanthus longirostris 27 Chrysiptera unimaculata 55 Pardachirus marmoratus 28 Ctenochaetus binotatus 56 Parupeneus barberinus 76 Zebrasoma

11 18 Chaetodon auriga 46 Malacanthus latovittatus 74 Valamugil seheli 19 Chaetodon interruptus 47 Mugil cephalus 75 Zanclus cornutus Chaetodon lunula 48 Chaetodon trifascialis 49 Mulloidichthys flavolineatus Mulloidichthys vanicolensis 22 Chaetodon trifasciatus 50 Myripristis berndti 23 Chaetodon vagabundus 51 Naso unicornis 24 Cheilinus trilobatus 52 Novaculichthys taeniourus 25 Chlorurus sordidus 53 Ostracion meleagris 26 Chromis viridis 54 Oxymonacanthus longirostris 27 Chrysiptera unimaculata 55 Pardachirus marmoratus 28 Ctenochaetus binotatus 56 Parupeneus barberinus 76 Zebrasoma veliferum Benthic Organisms The benthic organisms comprise of: A rich diversity of benthic organisms were encountered in the area as shown in Drawing EIA-15. A good diversity of sea cucumbers were found with Stichopus chloronotus being most common within Area B. Two species of sea urchins were found within the Area B with Echinometra mathaei being the most abundant. Only a few Tripneustes gratilla were found within Area B. Few sea anemones and about 4 starfish were also encountered and a few Tridacna sp. were found anchored onto the hard calcareous substratum. Plate 1: Stichopus chloronotus (black_right) and brown seacucumber (left) found mostly below rubbles. Plate 2: Holothuria leucospilota Page 22

12 Plate 3: Tripneustes gratilla Plate 4: Echinometra mathaei Plate 5: Sea anemone Plate 6: Sea star Plate 7: Gastropod Plate 8: Terebra sp. Page 23

13 3.3 Storm Water Management This section of the report describes the hydrology and storm water infrastructure for the area under study. As shown in Drawing EIA-16 in Appendix C the existing catchments which affect the study area are described below; Catchment A covers approximately 0.13 km 2 which is entirely under sugarcane cultivation. An unnamed feeder crosses the B9 Coastal Road through an existing culvert 0.45m high by 0.6m wide. The watercourse is channelled along the western boundary of Tamassa Hotel before discharging to the lagoon. Catchment B covers approximately 0.42 km 2 which is entirely under sugarcane cultivation. An unnamed feeder crosses the B9 Coastal Road through an existing culvert 0.6m high by 0.45m wide. The watercourse is channelled along the western boundary of Outrigger Hotel before discharging to the lagoon Pre-Development Peak Flow Estimation With reference to Study of the Land Drainage System of the Island of Mauritius, a peak flow estimation has been made using the HEC HMS The following assumptions were made in predicting the existing peak flows from the various catchments: The catchments were treated as single units. Rainfall is uniformly distributed over the catchment area and is constant over time for each storm return period and intensity. The rainfall data used is taken from the IDF curves published by the Mauritius Meteorological Services. For the extreme rainfall condition (490mm over 24 hours) it is assumed that the rainfall is distributed triangularly over the time period. No allowance has been made for evapotranspiration, assuming that during flash flood, the amount of evapotranspiration is almost negligible. The surface runoff follows the natural drainage path of the catchment. Soil Type B; for moderate infiltration rate. (Ref: TR55, Urban Hydrology for small watershed manual). SCS Curve Number = 52; used for all catchments since they are mostly under sugarcane cultivation. (Ref: Study of the Land Drainage System of the Island of Mauritius). Overland Manning s Coefficient, n = 0.17; for cultivated soil >20% (Ref: TR55, Urban Hydrology for small watershed manual) Channel Manning s Coefficient, n = ; for stemmy grass (Ref: TR55, Urban Hydrology for small watershed manual) The existing pre-development peak surface water flows from each catchment have been calculated at outlet of each catchment for a range of storm return period (1:50 IDF, 1:100 IDF, 24 hour extreme rainfall = 490mm), and are summarised in Table Page 24

14 Catchment Area (km 2 ) Outlet Point Return Period (Years) Flow (m3/s) 1:50 year 1:100 year 24hr = 490mm A 0.13 B 0.42 Outfall No 1 - Awali/Tamassa drain Outfall No 2 Tamassa/Outrigger drain These pre-development flows are the maximum flows that are currently being channelled towards the two outlets The Socio-Economic Profile of the Bel Ombre Inhabitants The villages and localities of Bel Ombre are Baie du Cap, Choisy, St Martin, Bel Ombre, Beau Champ and Riviere des Galets. Altogether, these villages constitute up to circa 6,500 inhabitants. The inhabitants of the villages are principally labourers, fishermen, retail tradesmen and secondary agricultural activities Regional Tourism Activity Tourism earnings form a major part of the Mauritius economy. According to government statistics, the number of tourist arrivals for year 2015 increased by 10.9% compared to 2014 to reach 1,151, As a result of the revised forecast of tourist arrivals, the Bank of Mauritius is predicting tourism earnings for the year 2016 to reach Rs54 billion, an increase of 8% over the Rs50 billion estimated for The main hotels existing in the vicinity of the project site are: Table : Existing Hotel Resorts within the Project Site Components Operator No. of Rooms Category No of employees Heritage Le Telfair Golf & Spa Resort VLH Ltd stars 308 Heritage Awali Golf and Spa Resort VLH Ltd stars 296 Other leisure activities (Golf, C Beach Club, Chateau) VLH Ltd 155 LUX Tamassa Resort Hotel Néréide Ltd stars 300 Outrigger Mauritius Beach Resort Saltlake Resorts Ltd stars 340 Villas Valriche Les Villas de Bel Ombre Ltée 43 5-stars 47 So Sofitel Sofitel International 92 5-stars Page 25

15 Besides the above mentioned beach activities, other informal tourist accommodations, peripheral tourist activities in the area would include inter alia: Construction and property development Transport o Taxi o Mini-bus o Car hire Leisure activities o Frederica eco-tourism activities o Golf course o C-Beach Club and water sport o Le Château de Bel Ombre Restaurant Tour-operators and destination management companies o Mautourco o Summertimes o Coquille Bonheur o White Sand Tours o Connections Horticulture (vegetables, flowers and fruits) Artisanal fishing Page 26

VLH Ltd, Nereide Ltd, Saltlake Resorts Ltd Proposed Beach Erosion Protection Works at Bel Ombre Environmental Impact Assessment

VLH Ltd, Nereide Ltd, Saltlake Resorts Ltd Proposed Beach Erosion Protection Works at Bel Ombre TATO/EIA/01 Issue 15 February 2017 This report takes into account the particular instructions and requirements