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​​Water Sector


Water Resources in Mauritius

Ground Water Resources

Main Water Indicators, 2011 - 2015

Reservoirs

 

The Ministry of Energy and Public Utilities is responsible for the water sector. It formulates policies and strategies for the mobilization and conservation of water resources and management of supply and distribution of water.

The Water Resources Unit operates under the aegis of the Ministry and is responsible for the implementation of water mobilization projects. It was established in May 1993. The functions of the Water Resources Unit are as follows:-

study and formulate policies in relation to the control and use of water resources;

implement projects for the construction of reservoirs and related infrastructure;

keep a data base of water resources;

 prepare and follow-up plans for the conservation, utilisation, control and development of water resources;

co-ordinate and scrutinise the projects undertaken by any person relating to the conservation, utilisation and development of water resources and assess the technical possibilities, benefits and socio-economic feasibility of the project;

 conduct and co-ordinate research and investigation on the economic use of water;

 promote, design and construct, in consultation with appropriate authorities, schemes and works for the purpose of conservation and development of water resources;

ensure that water supply conforms with such standards as are laid by law;

monitor the construction of major dam projects;

ensure the regular maintenance of the dams; and

implement integrated water resources management.

 

Water Resources in Mauritius

The main source of domestic water supply is ground water (50%) which is abstracted through 163 boreholes. The remaining 50% is derived from surface sources such as impounding reservoirs and river in takes.

 

Water Resources

                      •           25 major catchment areas
    •           24 minor river basins
    •           107 flow measuring station
    •           350 river-run off takes
    •           3 major river abstractions,
    •           7 major impounding reservoirs total capacity = 92.2. Mm3 annual yield = 164.4 Mm3

                Ground Water Resources

                There are 5 main aquifers in Mauritius.

                604 boreholes - 163 domestic (91%) , 211 irrigation (4%),  230 industrial (5%)
       
Main water indicators1/, 2011 - 2015


(Source to be inserted)



DetailsUnit 20112012201320142015
Mid-year populationthousand1,212  1,215  1,217  1,219  1,263  
Mean annual rainfall  
            Island of Mauritius2/Millimetres1,948  1,621  2,126  2,094  2,377  
            Island of Rodrigues
                          Pte Canon2/
Millimetres849  1,041  978  1,145  1,272  
                          Plaine Corail2/Millimetres842  853  871  1,143  1,338  
Potable water producedMm3203  215  217  229  245  
Potable water consumedMm396  95  96  97  98  
Potable water produced per capita per daylitres458  484  487  514  549  
Potable water consumed per capita per daylitres218  214  216  218  220  
Consumption per capita  per day for 'Domestic' tariffslitres167  164  165  167  168  
Average price per m3Rs/m38.75  11.90  12.12  12.21  11.79  
​​​​​1/ All data refer to Island of Mauritius, except for rainfall where figures are available for Rodrigues as well.​
​​​​​2/   Revised 


RESERVOIRS

 

Mare aux Vacoas Reservoir

Purpose: Potable Water Supply

Mare aux Vacoas is the largest reservoir in Mauritius. It is located in the district of Plaines Wilhems, to the south of the town of Curepipe.(show on map – if a can be provided).  The reservoir has a capacity of 25.89 million cubic metres and supplies water to the upper Plaines Wilhems and  Moka.

​Origin of Mare aux Vacoas: In 1885, a one meter high masonry dam  was built across Riviere du Tamarin in the marshy land at Mare aux Vacoas draining an area of 13 km2. The purpose of the dam was to store water for domestic water supply. In 1892, the level of the dam was raised to an elevation of 558.54 m (amsl) and the capacity of the reservoir was increased to 2.58 Mm3 . In 1915, following a prolonged drought, the level of the dam was raised to an elevation of 560.06 m and the storage capacity increased to 5.27 Mm3. In 1922, Tatamaka feeder canal was constructed to divert water from Riviere du Poste into the reservoir. The carrying capacity of the canal is presently 4.25 m3 /s which represents an annual contribution of 15 Mm3.

The capacity of the reservoir was subsequently raised to 16.15Mm3in 1928, to 27.63Mm3. in1961 with a water spread area of 5.6 km2 .

Several feeder canals have thereafter been constructed to increase the inflow into the reservoir, namely:

    1.           Parc aux Cerf Feeder Canal constructed in 1971 to divert flows from the upper catchment area of River Citron and North East part of the local catchment Representing an  average annual contribution of the canal is 1.75 Mm3;
    2.            the Pradier Canal constructed in 2002; ;and

                
      The Arnaud diversion dam constructed in 2014 representing an annual contribution of up to 10Mm3.

           A hydrographic survey of the reservoir was carried out for the first time in the year 1996, and the gross storage capacity of the reservoir was determined as 25.89 Mm3.

 

La Nicoliere Reservoir

Purpose: Storage of Water Supply to potable use as well as for Industrial and Irrigation purposes

La Nicolière Reservoir, constructed in the year 1929 across River du Rempart, near Grande Rosalie, is one of the main sources of water supply to the northern districts of Mauritius and part of Port Louis. The reservoir has a storage capacity of 5.26 Mm3asdeterminedafter a hydrographic survey carried out in 1996.

In December 2002, the Midlands Dam was constructed to serve as a buffer reservoir to La Nicolière Reservoir. Water from Midlands Dam is released to the Grand River South East which connects to the La Nicolière Feeder Canal (LNFC). The LNFC was built in 1929. It has a design capacity of 4.25 m3 /s and is 27 km long. .Following the construction of the LNFC, the regulated annual yield of the Nicoliere Reservoir increased from 30Mm3 to 71 Mm3.

Salient features of La Nicolière Reservoir:


          •          Capacity:  5.26 Mm3
        •          Catchment Area: 1.08 km2
        •          Regulated Annual Yield: 71 Mm3Length of Dam: 819.08 m
        •          Spillway: Ungated ogee shaped concrete spillway
        •          Length of Spillway: 36.58 m (2 bays of 18.29 m each)
        •          Feeders: (i) River du Rempart(iii) Streams in local catchment Nicoliere Feeder Canal (iii) LNFC (iv) Local catchment of the La Nicoliere reservoir

 

Piton du Milieu

Purpose: Storage of water for potable use

Piton du Milieu Reservoir is situated in the district of Moka. It is fed mainly from River Vacoas and Bateau. It supplies water for domestic use to the eastern part of the island.

Salient features of Piton du Milieu Reservoir Location:


  •           Year of Construction : 1952
  •           Catchment Area : 6.30 km2
  •           Feeders : River Vacoas, River Bateau and Seasonal Streams
  •           RegulatedAnnual Yield : 8.3 Mm3
  •           Reservoir Capacity : 2.99 Mm3
  •           Dead Storage : 0.10 Mm3
  •           Full Reservoir Level : 438 m (amsl)
  •           Type of Dam : Earth dam
  •           Maximum height of dam : 13.5 m (above foundation level)
  •           Length of Dam : 836.16 m
  •           Type of spillway : Ungated concrete crest wall With of Spillway : 363.12 m (2 spillways) (please check)
  •           Maximum height of dam : 13.5 m (above foundation level)

 

La Ferme Reservoir 

Purpose: storage of water for irrigation purpose

La Ferme reservoir is located in the village of Bambous and the district of Black River. The reservoir is mainly fed through Trianon Grosses Roches Feeder Canal, La Fenetre Feeder Canals and local catchment. The construction of the reservoir started in 1914 and was completed in 1918.

Salient Features of the Dam:


    •           Year of Construction : 1914
  •           Catchment Area : 19.61 km2
  •           Annual Regulated Yield : 17 Mm3
  •           Reservoir Capacity : 11.52 Mm3
  •           Dead Storage : 0.2 Mm3
  •           Full Reservoir Level : 146.0 m (amsl)
  •           Type of Dam : Earth cum masonry
  •           Length of Dam : 1526.54 m
  •          Type of spillway : Ungated masonry with concrete hearting Width of Spillway : 145.26 m

 

 

Midlands Dam

Purpose: storage of water for potable use and irrigation purposes.

The Midlands Dam site was chosen at the beginning of the twentieth century to create a reservoir. Works started in 1926 but were stopped in 1931. . The dam was finally constructed in December 2002 on Grand River South East near Midlands Village for the purpose of serving as buffer storage to the Nicoliere reservoir with a view to meeting an increasing water demand in the northern part of the island.

Salient features of the dam:


  •           Year of Construction : December 2002
  •           Catchment Area : 17.2 km2
  •           Regulated Annual Yield : 41 Mm3
  •           Reservoir Capacity : 25.5 Mm3
  •           Full Reservoir Level : 395.00 m (amsl)
  •           Maximum Reservoir Level : 398.24 m (amsl)
  •           Dam Crest Level : 399.00 m (amsl)
  •           Type of Dam : Rockfill with upstream asphalt concrete surface sealing and cutoff wall Maximum height : 19.5 m above ground level 30.0 m above foundation level
  •           Length of Dam : 2449 m including spillway
  •           Type of Spillway : Ungated concrete ogee shaped spillway
  •           Height of Spillway above foundation: 30 m

 

 

Bagatelle Dam

Purpose: storage of water for potable use

The Bagatelle dam was constructed to mobilize additional water resources and meet the increasing water demand of the district of Port Louis and the lower parts of the Plaines Wilhems district namely, QuatreBornes, Rose Hill, Stanley, Beau Bassin and Coromandel.

The construction of the dam started in 2012 and was completed in 2017. It is mainly fed from River Terre Rouge and River Cascade

Salient features of the dam:


  •           Catchment Area : 28.85Km2
  •           Regulated Annual Yield : 25.3 Mm3
  •           Reservoir Capacity : 14 Mm3
  •           Normal Reservoir Level : 396.5 m (amsl)
  •           Maximum Reservoir Level (PMF) : 399 m (amsl)
  •           Dam Crest Level : 400.00 m (amsl)
  •           Type of Dam : Rockfilland Earthfill
  •           Height : 48 m above ground level (rockfill) and 27 m (earthfill) above foundation level 
  •           Length of Dam : 2,550 m including spillway
  •           Type of Spillway : Morning Glory spillway
  •           Height of Spillway above foundation: 39.5 m