Mauritania

GEOGRAPHY AND POPULATION

Mauritania, located in the north-west of the African continent, has a total area of about 1 million km². It is bordered in the north-west by Western Sahara, in the north-east by Algeria, in the east and south-east by Mali, in the south-west by Senegal and in the west by the Atlantic Ocean.

The cultivable area has been estimated at about 20 million ha, or almost 20% of the total area. In 1989, the total cultivated area was 204 000 ha, of which 199 000 ha consisted of annual crops and about 5 000 ha consisted of permanent crops.

The total population is about 2.3 million (1995), of which 46% is rural. The population density is about 2 inhabitants/km², but this figure varies from 0.1 in Tiris Zemrnour to 18.5 in the Gorgol region. The annual demographic growth rate is about 2.7%. Agriculture, including livestock, accounts for 20% of GDP.

TABLE 1 - Basic statistics and population

CLIMATE AND WATER RESOURCES

Climate

Average annual rainfall is 99 mm, but this varies from less than 20 mm in the north to more than 500 mm in the south-east (Sélibaby). The rainy season lasts only 3 months. Average minimum and maximum temperature vary from 16°C in January (Bir Mougrein) to 36°C in June (Kiffa).

Water resources

The total (actual) renewable surface water resources are estimated at 11.1 km³/year and the internal renewable surface water resources at 0.1 km³/year. The hydrographic system is dominated by the Senegal river which runs along the southern border and its tributaries on the right bank downstream of Bakel. There are some wadis with sporadic flows during the rainy season. Total groundwater resources have been estimated at 3.7 km³, which refers to the continuous aquifers only. The yields of the alluvial groundwater in the wadis and the intermittent aquifer systems have not yet been quantified. Internal renewable groundwater resources are estimated at 0.3 km³/year.

TABLE 2 - Water: sources and use

Figure 1 - Water withdrawal (total: 1.63 km³ in 1985)

Figure 2 - Distribution of the water managed areas (total: 113 200 ha in 1994)

In 1985, total water withdrawal was 1.63 km³, of which 92 % for agricultural purposes (figure 1).

It is estimated, that in the year 2000 about 3 750 water points will be needed to supply drinking water to the rural population, while at present 2 118 water points have been constructed.

IRRIGATION AND DRAINAGE DEVELOPMENT

Irrigation potential, considering soil resources, has been estimated at 257 000 ha, of which 110000 ha for flood recession cropping. Considering the available water resources as well, the irrigation potential in the Senegal basin is estimated at 165 000 ha, of which 125 000 ha along the main Senegal river and 40 000 ha in the Gorgol and Karakoro tributary areas. In addition, there are around 5 000 ha of oases.

TABLE 3 - Irrigation and drainage

In 1994, the water managed area was evaluated at 113 200 ha, of which 49 200 ha consisted of full or partial control irrigation schemes. Flood recession cropping covered the remaining 64 000 ha (Figure 2).

The area equipped for full or partial control irrigation consists mainly of small schemes, with an area of less than 50 ha each (Figure 3). The total area can be divided into 4 571 ha of oases and 44 629 ha of schemes in the provinces of the valley of the Senegal river and its tributaries (Figure 4)

Figure 3 - Typology of f/p control irrigation schemes (total: 49 200 ha in 1994)

Figure 4 - Distribution of the f/p control irrigation schemes (total: 49 200 ha in 1994)

Figure 5 - Methods of groundwater extraction in the oases (total: 4 751 ha in 1993)

Figure 6 - Typology of oases (total: 4 751 ha in 1993)

• In total there are 218 oases, irrigated by groundwater. There are 31 400 wells in the oases, in the majority of which the water is extracted manually (Figure 5). About 400 000 people live in the oases, but only 14 700 families possess the 4 751 ha of palm trees (more than one million productive palm trees) and cultivate around 244 ha of annual crops under the palm trees. The oases are very small, more than 46 % being less than 10 ha (Figure 6). The whole area equipped for irrigation is irrigated all year round.
• The schemes in the valley of the Senegal river and its tributaries are only partly irrigated each year (22 000 ha only in 1994). Large areas need rehabilitation, as almost 38 000 ha are considered to be in a quite bad or bad state, according to a recent survey. All these schemes are irrigated by surface water, mainly through pumping from the river (figure 7).

Figure 7 - Origin of irrigation water f/p (total: 49 200 ha in 1994)

Figure 8 - Typology of flood recession cropping (total: 64 000 ha in 1988)

Figure 9 - Irrigated crops (total: 134 899 ha in 1993)

The main irrigation technique used in the full or partial control irrigation schemes is surface irrigation. The average cost of irrigation development varies between $US 2 200/ha for small schemes to about $US 12 500/ha for large schemes.

Different types of flood recession cropping can be distinguished (Figure 8):

• the oualo in the major bed of the Senegal and Gorgol river valleys. The areas vary between 20 000 ha and 40 000 ha depending on the year, with an average of 30 000 ha;
• flood recession cropping around the large dams, with a total area of 10 000 ha, of which 4 000 ha in Lake Rkiz, 3 500 ha in Achram and 2 500 ha in Foum Gleita;
• flood recession cropping in the beds of the wadis on areas of less than 1 000 ha, with a total area varying between 16 000 and 20 000 ha;
• topographic depressions inundated by surface runoff water (6 000 ha). Estimates on the total area vary between 2 000 and 10 000 ha.

The major irrigated crops are sorghum, vegetables and rice. Palm trees grow in the oases. Mixed farming, with vegetable growing is important in the flood recession zones (Figure 9).

INSTITUTIONAL ENVIRONMENT

The public institutions intervening in hydraulic and agricultural development are:

The Ministry of Rural Development and Environment:

• Société rationale de développement rural (SONADER) (rural development);
• Direction de l'environnement et de l'aménagement rural (DEAR) (environment and rural management);
• Direction du développement des ressources agro-pastorales (DRAP) (agri-pastoral resources development;
• Cellule de planification (Planning Unit).

The Ministry of Hydraulics:

• Direction de l'hydraulique (Hydraulics Department);
• Cellule rationale de l'Office de mise en valeur du Senegal (OMVS) (National Desk of the Senegal River Development Office).

Decree No 90020 of 19 January 1990 establishes the clauses of the reorganization of the land properties, putting the accent on the individualization of land tenure, in three phases: authorization to cultivate, provisional concession and permanent concession.

TRENDS IN WATER RESOURCES MANAGEMENT

The major constraints to the exploitation of the water resources and the development of irrigation in Mauritania can be summarized as follows:

• high costs of irrigation development and especially of earth structures;
• accessibility (river and oases);
• weak support given to the private sector with insufficient investment to sustain the productive capital;
• marketing problems;
• inadequate organization of the operation of the schemes, especially of the communal schemes;
• high costs of extraction of the groundwater resources;
• salinization of the soils (delta and lower river);
• high evapotranspiration (2 000 to 3 000 mm/year from south to north);
• insufficient and irregular rainfall and surface flow in the wadis.

MAIN SOURCES OF INFORMATION

Cellule de planification, Ministère du développement rural et de ltenvironnement. 1994. Le développement rural en chiffres.

FAO/DDC. 1988. Programme national de construction des barrages en terre.

FAO/DDC. 1990. Projet de développement intégré de la vallée du fleuve Senegal. Document de travail (voles irrigation).

GERSAR. 1994. Etudes d'application des schémas directeurs du fleuve Sénégal et du Delta.

Ministère du développement rural et de l'environnement. 1993. Annuaire statistique des oasis.

PNUD. 1990. Schema directeur pour la mise en valeur des ressources en eau. Rapport du projet PNUD/DTCD/MAU/87/008.

SONADER. 1993. Enquête périmètres irrigués.

SONADER. 1994. Rapport d'activités 1993.