data on storage reservoirs

DATA ON STORAGE RESERVOIRS

Presently, there are 11 man-made reservoirs in Mauritius, out of which, Dagotière and Valetta reservoirs are privately owned. The locations and the salient features of the impounding reservoirs are given in Fig.5.1 and Table 5.1.

Fig 5.1 Location of Impounding Reservoirs

RESERVOIRS CAPACITY

(Mm3)

MAXIMUM SURFACE

AREA (Km2)

PURPOSE

Mare aux Vacoas 25.89 5.60 Domestic Midlands 25.50 2.98 Domestic, Irrigation

Mare Longue 6.28 1.05 Hydropower, IrrigationLa Ferme 11.52 2.28 Irrigation

Piton du Milieu 2.99 0.76 Domestic Nicoliere 5.26 1.02 Domestic, Irrigation

Tamarind Falls 2.30 1.68 Hydropower, IrrigationEau Bleue 4.10 0.75 Hydropower Cascade 4.30 0.43 Hydropower

Dagotiere 0.60 - Mill, Irrigation Valetta 2.00 - Mill, Irrigation

Table 5.1 Salient Features of Impounding Reservoirs

Fig. 5.2 to 5.6 show the daily and normal* storage variation, the monthly outflow, the schematic diagrams and feeder characteristics of the 5 important storage reservoirs. Fig 5.7 shows the daily storage variation and the schematic diagrams and feeder characteristics of the Midlands Dam. *period 1985 to 1995

La Ferme

Tamarind Falls

Midlands

Nicoliere

Eau BleueMare aux Vacoas

Dagotiere

Valetta

Piton du Milieu

Cascade Diamamouve

Mare Longue

Grand Ruisseau

Ruiseau Gros Cerf

Gros Ruisseau & others

Tatamaka 2.0 du Poste (South) 4.25

Parc-aux-Cerfs 3.2 Citron(South) 9.5

Pradier 4.1Des Anguilles & tributaries Feeder Leckraz

2.63

Location :

Year of Construction :

Catchment Area : 19.50 km2

Mean Annual Rainfall : 3330 mmRegulated Yield : 33 Mm3 year approx.Reservoir Capacity : 25.89 Mm3 after hydrographic survey of 1996Maximum water spread area : 5.6 km2

Full Reservoir Level : 566.35 m amslFeeder Canals : (i) Tatamaka canal (1922), capacity 4.25 m3/s

(ii) Parc aux Cerfs Canal (1971), capacity 9.5 m3/s(iii) Pradier Canal (2002), capacity 2.63 m3/s

Feeders in local catchment (iv) Ruisseau Gros Cerfs

Type of Dam :

Maximum height of dam : - Cogliano : 10 m;- Tamarin : 11 m;

- Mare Soulier : 6 m; and- Second Spillway dam : 3.5 m

Length of Dam : 2948.50 mWidth of Spillway : 1063.5 mPurpose : Potable Water Supply

Cogliano and Tamarin dams are homogenous earthen embankments Mare Soulier Spillway and Second Spillway dams are of masonry

In 1928, with the contribution of the Tatamaka Feeder Canal, the reservoir capacity was further raised to 16.15 Mm3, and finally in 1961 to27.63 Mm3 with a water spread area of 5.6 km2.

In 1922, Tatamaka feeder canal was constructed to divert water from Riviere du Poste into the MAV reservoir. The carrying capacity of thecanal is presently 4.25 m3/s and the annual contribution is of the order of 15 Mm3.

In 1971, Parc aux Cerf Feeder Canal was constructed to divert flow from the upper catchment area of River Citron and North East part of thelocal catchment. The average annual contribution of the canal is 1.75 Mm3.

In 2002, the Pradier Canal was constructed to increase the inflow into MAV reservoir. Its annual contribution is estimated as 4 to 5 Mm3.

Contribution of local reservoir catchment is estimated as 11 Mm3/year.

(vi) Grand Ruisseau(v) Gros Ruisseau

The dam was comprehensively rehabilitated in the year 2000.

Salient features of MAV Dam

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

Across marshy area, called Mare aux Vacoas in the district of Plaines Wilhems and about 25 kmsSouth of Port Louis

In 1885, height and capacity increased in stages (in 1892, 1915, 1922, 1928, 1941) and finally in1961

History Notes

In 1892, the level of the dam was raised to an elevation of 558.54 m (amsl) and the capacity of the reservoir to 2.58 Mm3. In 1915, after aprolonged drought, the level of the dam was raised to an elevation of 560.06 m and the storage capacity to 5.27 Mm3.

The purpose of the dam was to store water for domestic water supply. That was how the Mare aux Vacoas Dam has come into existence.

In 1885, a masonry dam of one metre height was built across Riviere du Tamarin in the marshy land at Mare aux Vacoas draining an area of 13km2.

FEEDER CANAL LENGTH (Km) RIVER

DESIGN CAPACITY

m3/s

MARE AUX VACOAS RESERVOIR

NATURAL STREAMS :

FEEDERS SCHEMATIC DIAGRAM

Gros Ruisseau

Rui. Gros Cerf

Parc Aux Cerfs

Spills into Riv. Du Poste Pradier

Canal

Tatamaka Feeder

Grand Ruisseau

Release to Tamarind Falls Res.

La Marie ConduitRelease to La Ferme Res. Abandoned

MAREAUX

VACOAS

Gros Ruisseau

Rui. Gros Cerf

Parc Aux Cerfs

Spills into Riv. Du Poste Pradier

Canal

Tatamaka Feeder

Grand Ruisseau

Release to Tamarind Falls Res.

La Marie ConduitRelease to La Ferme Res. Abandoned

MAREAUX

VACOAS

Fig. 5.2 Daily and Normal Storage Variation for Mare Aux Vacoas

DAILY STORAGE VARIATION

MARE AUX VACOAS RESERVOIR

YEAR : 2000

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Riv. Du Rempart (North)11 Springs

FEEDER CANALS/ RIVER DIVERSIONS LENGTH (Km)

DESIGN CAPACITY

(m3/s)L.N.F.C 27 4.25

CHEVRETTES Div * 0.47 CHEVRETTES & GONTRAN 0.67

VACOAS Div * 0.47 1.68FRANCOISE Div * 4.1 0.42

Location :

Year of Construction :Catchment Area :Reservoir Capacity :Maximum water spread area :Full Reservoir Level :Type of Dam :Maximum height of dam :Length of Dam :

Type of spillway :

Width of Spillway :

Purpose :Feeders :

Regulated Annual Yield :

LA NICOLIERE RESERVOIRFEEDERS SCHEMATIC DIAGRAM

NATURAL STREAMS :

History Notes

La Nicolière Reservoir , constructed in the year 1929 across River du Rempart, near Grande Rosalie, is oneof the main sources of water supply to the northern districts of Mauritius and part of Port Louis. Its water isused for domestic, industrial and irrigation.

The reservoir has a storage capacity of 5.26 Mm3. The annual average regulated yield from the reservoir ofthe order of 30 Mm3 has increased by about 41 Mm3 after the contrustion of Midlands Dam in December2002. It is fed by the La Nicolière Feeder Canal (LNFC), River du Rempart and eleven small streams.

RIVER

G.R.S.E And R. Rempart

FRANCOISE

* diverted to La Nicolière Feeder Canal

VACOAS

On River du Rempart (North), in the district of Pamplemousses about 5 kms North East of Port Louis.

In December 2002, the Midlands Dam was constructed to serve as a buffer reservoir to La NicolièreReservoir.

(i) La Nicolière Feeder Canal from GRSE, designed capacity of 4.25 m3/s and of length 27 km

7.75 km21929

Salient features of La Nicolière Reservoir

5.26 Mm3 after hydrographic survey of 1996

Homogenous Earthen Embankment13.5 m above ground level

Ungated ogee shaped concrete spillway

1.08 km2

30 Mm3 prior to Midlands dam and 71 Mm3 after Midlands Dam.

(ii) River du Rempart

819.08 m

249.02 m (amsl)

(iii) Streams in local catchment

Potable, industrial and irrigation water supply

36.58 m (2 bays of 18.29 m each)

Nicoliere Feeder Canal from G.R.S.E Catchment

Spills into Riv. Du

Rempart

Riv. Du Rempart

(North)

11 No. Small Streams

A03E008c

CWA Filter PlantBassin Mercier

M1 Pipeline

LA NICOLIERE

Nicoliere Feeder Canal from G.R.S.E Catchment

Spills into Riv. Du

Rempart

Riv. Du Rempart

(North)

NP5

11 Small Streams

A03E008c

CWA Filter Plant

Bassin Mercier

M1 Pipeline

LA NICOLIERE

Fig. 5.3 Daily and Normal Storage Variation for La Nicoliere


LA NICOLIERE RESERVOIR

YEAR : 2000

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2

3

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5

6


STO

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(Mm

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utflo

w(M

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Salient features of Piton du Milieu Reservoir

Location :

Year of Construction : 1952


Mean Annual Rainfall : 3529 mm

Feeders : River Vacoas

River Bateau

Seasonal Streams

Regulated Annual Yield : 8.3 Mm3

Reservoir Capacity : 2.99 Mm3 after hydrographic survey of 1996

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 :

Purpose : Domestic Water Supply

363.12 m (2 spillways)

PITON DU MILIEU RESERVOIR

NATURAL STREAMS

River Bateau

River Vacoas

Piton du Milieu Reservoir is situated in the district of Moka. It is fed mainly from River Vacoas and Bateau. It serves water for domestic use in the East District Water Supply system.

Piton du Milieu in Moka district, about 20 kms South East of Port Louis

History Notes


Riv. Bateau

Riv. Vacoas

Filter PLant

Spills into

Riv. Vacoas

PITONDU

MILIEU

Riv. Bateau

Riv. Vacoas

Filter PLant

Spills into

Riv. Vacoas

PITONDU

MILIEU

Fig. 5.4 Daily and Normal Storage Variation for Piton du Milieu


PITON DU MILIEU RESERVOIR

YEAR : 2000

0.0

1.0

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Salient features of La Ferme Reservoir

Location : Near Bambous village in the Black River district about 15 kms South West of Port Louis.Year of Construction : 1914



Feeders : (i) Trianon Grosses Roches Feeder Canal.

(ii) La Fenêtre Feeder Canal

Annual Regulated Yield : 17 Mm3

Reservoir Capacity : 11.52 Mm3 after hydrographic survey of 1996

Dead Storage : 0.2 Mm3

Full Reservoir Level : 146.0 m (amsl)Type of Dam : Earth cum masonryMaximum height of dam : (i) above ground level - Earth dam = 8 m

= 8.62 m- Earth dam = 10 m

= 12.1 m

Length of Dam : 1526.54 mType of spillway : Ungated masonry with concrete heartingWidth of Spillway : 145.26 mPurpose : Irrigation

2.40

DESIGN CAPACITY

m3/s

4.5 Rempart (west) & Papayes

Plaines Wilhems

2.83 La Fenetre

LENGTH (Km) RIVER

LA FERME RESERVOIR

SCHEMATIC DIAGRAMFEEDERS

NATURAL STREAMS : River Belle Isle

Trianon Grosses Roches 8.0

FEEDERS CANALS

Masonry dam

History Notes

Constructed in 1914, with the sole purpose to supply water for irrigation to the western coast of the island. It is located inthe district of Black River near Bambous village and about 15 kms South West of Port Louis.

(ii) above foundation level Masonry dam

Trianon Grosses Roches Feeder

W018b

la Fenetre

Feeder

T008b

Spill from Pierrefonds

Spills into Riv. Belle Isle

U0

La Ferme Outlet

LA FERME

Trianon Grosses Roches Feeder

W018b

la Fenetre

Feeder

T008b

Spill from Pierrefonds TunnelSpills into Riv. Belle

Isle

U0

La Ferme Outlet

LA FERME

Fig. 5.5 Daily and Normal Storage Variation for La Ferme


LA FERME RESERVOIR

YEAR : 2000

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Salient features of Mare Longue Reservoir

Location :

Year of Construction : 1948



Annual Regulated Yield : 9.7 Mm3

Reservoir Capacity : 6.28 Mm3

Full Reservoir Level :

Feeders :

Type of Dam :

Maximum height of dam : 13 m

Length of Dam : 768 m

Type of spillway :

Width of Spillway :

Purpose :

Mare Longue Reservoir was constructed in the year 1948. Located in the district of Plaine Wilhems, about 30 kms South West of Port Louis. It receives water from three feeders, the main one being River des Aigrettes.

The storage water is used for hydro power generation at Tamarind and Magenta power stations and thereafter for irrigation.

Mare Longue, in the district of Plaines Wilhems about 30 kms South Westof Port Louis

Hydropower generation at Tamarind and Magenta power stations andthereafter for irrigation

Ungated semi circular concrete crest slab

River des Aigrettes feeder1; feeder 2; feeder 3

Homogeneous earthen embankment

Circumferential length - 152.4 mDownstream channel - 11.35 m

576.91 m amsl

History Notes


MARE LONGUE RESERVOIR

Riv.Des Aigrettes :

NATURAL STREAMS:FEEDER No. 1

FEEDER No. 2

FEEDER No. 3

Riv. Des AigrettesFeeder No.1

Feeder No.2

Feeder No.3

Riv. Des Aigrettes

Release to Tamarind

Falls Reservoir

Spills into Riv. Bambous

MARE LONGUE Riv. Des AigrettesFeeder No.1

Feeder No.2

Feeder No.3

Riv. Des Aigrettes

Release to Tamarind

Falls Reservoir

Spills into Riv. Bambous

MARE LONGUE

Fig. 5.6 Daily and Normal Storage Variation for Mare Longue


MARE LONGUE RESERVOIR

YEAR : 2000

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YEAR : 2004

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YEAR NORMAL Outflow

Location :

Year of Construction : December 2002



Feeders :

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

Purpose : Potable and Irrigation Water Supply

MIDLANDS RESERVOIR

NATURAL STREAMS

GRSE

Riv. Twinam

GRSE, River Twinam

History Notes


Midlands in the district of Moka, on Grand River South East

The Midlands Dam site was chosen at the beginning of the twentieth century to create a reservoir. Works started in1926 but were stopped in 1931 due to scarcity of funds.

Due to an increase in water requirement, the Government commissioned a study in 1991 with a view to finding anoptimal solution to meet the water demand of the northern districts of Mauritius. The dam was finally constructed inDecember 2002 on Grand River South East near Midlands Village.

Salient features of Midlands Dam

Release and Spills into G.R.S.EMidlands

Reservoir

G.R.S.E

Twinam

Release and Spills into G.R.S.EMidlands

Reservoir

G.R.S.E

Twinam

MIDLANDS RESERVOIR

Fig. 5.7 Daily Storage Variation for Midlands


YEAR : 2003

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data on storage reservoirs

Documents