Mauritius

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GEOGRAPHY, POPULATION AND WATER RESOURCES

Mauritius is an island country in the Indian Ocean with a total area of 2 040 km, consisting of the island of Mauritius itself (1 860 km), representing most of the country's territory; Rodriguez island (107 km); and the distant Cargados Carajos shoals and Agalaga islands.

TABLE 1
Basic statistics and population

Area of the country 1994 204 000 ha
Cultivable land   - ha
Cultivated land 1995 85 400 ha
Total population 1994 1 104 000 inhab.
Population density 1994 541 inhab./km
Rural population 1990 59 %
Water supply coverage    
Urban population 1990 100 %
Rural population 1990 100 %

Total population is about 1.1 million inhabitants (1994), of which 59% is rural. Average population density is 541/km.

Agriculture contributes 11 % to GDP, of which 65 % is from sugar cane, against 73 % in 1986.

Climate and water resources

The climate is of the tropical oceanic type in summer, and of the subtropical type in winter. There are two seasons: a hot one from November to April, and a cold one from May to October, with two transitional periods from April to June and from September to October. Cyclones occur, mostly during the hot season, and often cause serious damage to crops and buildings. The average annual rainfall is 2 180 mm, but varies from 700 mm in the western coastal zone to 4 000 mm/year on the highest parts of the central plateau.

There are 25 main river basins, and the largest are the Grand River Southeast and the Grand River Northwest. Discharge to the sea is estimated to be 0.5 km/year. Globally, renewable water resources are estimated at 2.2 km

There are ten man-made reservoirs, with a total capacity of 70.2 million m.

Total water withdrawal was estimated in 1974 at 360 million m (Figure 1), of which 277 million m for agriculture, which seems to be a considerable overestimate. Total water withdrawal was estimated at 566 million m/year in 1989. 40% of the people's water needs is met with groundwater (Figure 2). The total coverage in water supply is excellent in Mauritius, since it is estimated to be 100%.

Mauritius

TABLE 2
Water balance

Water resources:      
Average precipitation   2 180 mm/yr
    4.4 km/yr
Internal renewable water resources - total   2.2 km/yr
Internal renewable water resources - per caput 1994 1 993 m/yr
Global renewable water resources   2.2 km/yr
Dependency ratio   0 %
Total dam capacity   0.07 km
De-salinated water   - 10 6 m/yr
Water withdrawal:      
- Agricultural 1974 276.8 10 6 m/yr
- Domestic 1974 58.4 10 6 m/yr
- Industrial 1974 24.8 10 6 m/yr
Total   360.0 10 6 m/yr
per caput 1974 409 m/yr
as % of internal renewable water resources   16.4 %
Other withdrawal   - 10 6 m/yr
Wastewater:      
Produced   - 10 6 m/yr
Treated   - 10 6 m/yr
Re-used treated wastewater   - 10 6 m/yr

TABLE 3
Irrigation and drainage

Irrigation potential   - ha
Irrigation:      
1. Full or partial control Irrigation: equipped area 1995 17 500 ha
- surface irrigation 1995 1 500 ha
- sprinkler irrigation 1995 14 600 ha
- micro-irrigation 1995 1 400 ha
% of area irrigated from groundwater 1995 12 %
% of area irrigated from surface water 1995 88 %
% of the equipped area actually irrigated     %
2. Spate irrigation area   - ha
3. Equipped wetland and inland valley bottoms   - ha
4. Other cultivated wetland and inland valley bottoms   - ha
5. Flood recession cropping area   - ha
Total water managed area (1 +2+3+4+5) 1995 17 500 ha
- as % of cultivated area   - %
- increase over last 10 years 1995 11 %
- power irrigated area as % of water managed area 1995 40 %
Full or partial control schemes: Criteria      
Large schemes > 1 000 ha 1987 7 030 ha
Medium schemes 1987 5 080 ha
Small schemes < 500 ha 1987 4 610 ha
Total number of households in irrigation      
Irrigated crops:      
Total irrigated grain production   - t
as % of total grain production   - %
Harvested crops under irrigation   - ha
- sugar cane   - ha
-   - ha
Drainage - Environment:      
Drained area   - ha
as % of cultivated area   - %
Flood-protected area   - ha
Area salinized by irrigation   - ha

IRRIGATION DEVELOPMENT

The irrigation sector is primarily for sugar cane, which has in Mauritius one of the highest yields in the world. This crop is well adapted to the area, since it is resistant to the cyclones, which are frequent in the area.

In 1970, the full or partial control irrigated area was about 12 000 ha, all for sugar cane. In the late 1980s, half of the full or partial control area was irrigated by sprinkler. The full or partial control irrigated area was estimated to be 16 720 ha in 1987 (Figure 3) and 17 500 ha in 1995, mainly sugar cane irrigation on estates. Sprinkler irrigation is the major irrigation technique (83 %).

Formerly, groundwater was used to a large extent to irrigate the sugar cane plantations. This practice has now generally ceased. owing to the high cost of electricity which makes it quite unprofitable. In fact, pumped irrigation is used only during the planting of the sugar cane (once every 8 years), in order to guarantee the harvest. Irrigation is also used to a limit extent in market gardening.

INSTITUTIONAL ENVIRONMENT

The main institutions involved in the irrigation and water subsector are:

FIGURE 1: Water withdrawal (total: 0.36 km in 1974)

FIGURE 2: Groundwater withdrawal (Mauritius island; 1989)

FIGURE 3: Types of full or partial contra irrigation schemes (1987)

Under the Central Water Authority Act No. 20, the Central Water Authority is the only body authorized to supply water for domestic, commercial and industrial use. It is responsible, inter alia, for data collection, correlation and interpretation for all water resources studies, the inventory of water resources, and the preparation of a policy for the utilization and monitoring of water resources.

TRENDS IN WATER RESOURCES MANAGEMENT

The agricultural sector in Mauritius is currently undergoing fundamental changes. The new keywords of Mauritius agricultural development are not only diversification of crops by use of the interlines of sugar cane for growing food crops such as potatoes or onions, but also development of higher value-added crops such as fruits, vegetables and horticulture; increasing farm size; and introduction of more capital-intensive techniques.

In the irrigation subsector, more emphasis is being placed on water-saving techniques (drip, pivot, guns) and non-labour-intensive systems. Surface irrigation systems, having poor efficiency (less than 40%), are being replaced by drip or sprinkler. The concept of localized schemes from small impounding dams (capacity 0.1 to 0.3 million m) is being encouraged. Three projects funded by the World Bank are already in the pipeline.

MAIN SOURCE OF INFORMATION

World Bank. 1992. Mauritius: Expanding horizons.


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