Challenges & Opportunities in the Water Sector (Mauritius) By Manta Devi Nowbuth (Dr) University of Mauritius
The island of Mauritius Mauritius
The island of Mauritius Geographical location: between longitude 57 o 17 and 57 o 48 E & latitude 19 o 50 and 20 o 32 S
General Information 1/2 DESCRIPTION REMARKS Area 2040km 2 11 times Washington DC Population 1,216,781 latest census (Dec. 2002) Landuse 43% agricultural cover 31% forest & scrubs, 25% built up areas & roads, 1% inland waterbodies Geology Volcanic origin Formed by volcanic activities (10 million to 25000 years ago) the island is shaped into a central caldera surrounded by discontinuous rings of mountain ranges (600-900m) & low undulating coastal plains (100m)
General Information 2/2 Climate Tropical climate, summer season November to April& winter May to October Rainfall Varies from 4000mm in the higher elevation (central caldera) to 900mm along the western coasts Overall average rainfall over the island is 2100mm 70% of total annual rainfall obtained during the summer period
Surface water Resources Dense network of rivers Catchment areas vary from 3 to 164km 2, with 2 catchments areas >100km 2 River levels gauged at 100 locations, with 60 continuous recorders 350 River offtakes 10 man made reservoirs with gross capacity 67.36Mm 3 + recent one of capacity 25.5Mm 3 Reuse of treated effluent from St Martin Treatment Plant (Yr 2006 to 2009)
5 Main aquifers Groundwater Resources Contributes around 50% domestic water supply Also exploited to a small extent for industrial and irrigation purposes Salt water intrusion detected along the northern perimeter Boreholes are on average 30cm diameter and 60m deep, but a few go up to 150m deep Currently about 360 boreholes in operation Exploitation industrial <100m 3 /d - agricultural <200m 3 /d - domestic, on average 2500m 3 /d
Water Balance Description Volume (Mm 3 ) % Precipitation 3900 100 Surface Runoff 2340 60 Groundwater recharge 390 10 Evapotranspiration 1170 30
THE INSTITUTIONAL AND LEGAL FRAMEWORK MINISTRY OF Energy & Public Utilities WMA CEB WRU CWA IA MINISTRY OF Agro Industry & Food Security
PORT LOUIS WATER SUPPLY DWS NORTH MAV LOWER DWS EAST MAV UPPER DWS SOUTH
Annual Water Utilisation (million cubic metres per year) Purpose Surface Water Ground water Total % Domestic, Industrial, Tourism River-run Offtakes 38 Storage Reservoirs 72 114 224 21 Private boreholes - - 11 11 1 Agricultural Hydropower 370 129 95 160 25-490 289 48 30 OVERALL UTILISATION 537 327 150 1014 100 TOTAL WATER MOBILISATION 512 261 150 923
Challenges Water infrastructure (storage capacity) Impacts of Climate Change Water quality Impacts from landuse activities Urbanisation (Increasing demands) High level of Non Revenue Water Institutions working in isolation Fragmented Legislation
Ongoing New dams (one under construction & for immediate construction Major developments: Tourism, Road network Challenge- Water Infrastructure Capacity Year of (in million m 3 ) construction Mare aux Vacoas 25.98 1885 La Ferme 11.52 1918 La Nicoliere 5.26 1928 Mare longue 6.28 1946 Tamarind Falls 2.3 1947 Piton du milieu 2.99 1954 Eau Bleue 6.2 1960 Midlands dam 25.5 2002
Challenges Climate Change Rainfall pattern changed: Spatially, Flood types
Challenges Climate Change
Challenges Water Quality Fertiliser consumption is at least 3 times times higher than uses in Western Europe 600kg per hectare With the exception of Nitrate level, quality of water is good.
Challenges - Urbanisation Most recent data compiled by the Central Statistical Office, noted that currently about 44% of the population is living in the urban areas. Water Demand Year m 3 /d 2015 80,000 2030 98,000 2050 103,000 Water Demand Year m 3 /d 2015 66,000 2030 77,000 2050 82,000 Water Demand Year m 3 /d 2015 29,000
Challenges NRW Up to 50% Not metered Default metering Leakage Illegal connections
Challenges - Sewer network
Opportunities Increase storage capacity Implement WDM optimise uses Review the water tariffs Review legislation - Rainwater Harvesting - Desalination along the coastal zones - Water Rights (surface water) Improve sewer network to cover larger area Monitor water quality more frequently Data Analysis & Forecasting Hydrographic network Intensify for more accurate estimates of water resources
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