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GEOGRAPHY, POPULATION AND WATER RESOURCES
The United Republic of Tanzania is located on the southeastern coast of Africa and comprises the mainland and two islands (Zanzibar and Pemba). Its total area is about 945 090 km². The cultivable area is about 40 million ha, or 42% of the total land area. The cultivated area is 6.3 million ha, which is 7% of the total area and 16% of the cultivable area.
Total population is estimated to be about 29 million (1994), of which 22% is urban. Average population density is 31/km², but almost two-thirds of the people live in areas that together form only about 10% of the total area. Annual population growth is 3.0%.
Basic statistics and population
|Area of the country||1993||94 509 000 ha|
|Cultivable land||1993||40 000 000 ha|
|Cultivated land||1993||6 300 000 ha|
|Total population||1994||28 846 000 inhab.|
|Population density||1994||31 inhab./km²|
|Rural population||1988||78 %|
|Water supply coverage|
|Urban population||1991||65 %|
|Rural population||1991||65 %|
The agricultural sector accounts for about 50% of the GDP, employs close to 90% of the labour force and generates more than 80 % of export earnings.
Climate and water resources
Average precipitation is 937 mm per year, but 50% of the country receives less than 750 mm and 80% receives less than 1 000 mm. Rainy seasons on the coast are from March to May and from November to December. Total rainfall decreases from north to south. Around Lake Victoria it is well distributed throughout the year with a peak between March and May. In the south there is a dry season from May-June to September-October. The mean temperature is high, especially in the coastal area (30°C).
Tanzanian renewable water resources amount to about 80 km³/year, of which 30 km³ is groundwater. These water resources are grossly under-utilized, primarily because much of the unused land either does not have good soils or is distant to a source of water. Tanzania does not receive water from neighbouring countries, but shares three major lakes (Victoria, Tanganyika and Malawi) as well as the Rovuma River at the border with Mozambique.
Water withdrawal for agricultural, domestic and industrial purposes was estimated to be 1. 17 km³ in 1994 (Figure 1).
|Internal renewable water resources - total||80||km³/yr|
|internal renewable water resources - per caput||1994||2 773||m³/yr|
|Global renewable water resources||89||km³/yr|
|Total dam capacity||-||km³|
|De-salinated water||-||10 6 m³/yr|
|- Agricultural||1994||1 040||10 6 m³/yr|
|- Domestic||1970||101||10 6 m³/yr|
|- Industrial||1970||24||10 6 m³/yr|
|Total||1 165||10 6 m³/yr|
|per caput 1994||40||m³/yr|
|as a % of internal renewable water resources||1.5||%|
|Other withdrawal||-||10 6 m³/yr|
|Produced||-||10 6 m³/yr|
|Treated||-||10 6 m³/yr|
|Re-used treated wastewater||-||10 6 m³/yr|
Irrigation and drainage
|Irrigation potential||1993||828 000||ha|
|1. Full or partial control Irrigation: equipped area||1993||150 000||ha|
|- surface irrigation||-||ha|
|- sprinkler irrigation||-||ha|
|% of area irrigated from groundwater||-||%|
|% of area irrigated from surface water||-||%|
|% of 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)||1993||150 000||ha|
|- as a percentage of cultivated area||1993||2.4||%|
|- increase over last 10 years||-||%|
|- power irrigated area as % of water managed area||-||%|
|Full or partial control schemes: Criteria|
|Large schemes > 400 ha||1993||30 000||ha|
|Small schemes < 400 ha||1993||120 000||ha|
|Total number of households in irrigation|
|Total irrigated grain production||-||t|
|as a % of total grain production||%|
|Harvested crops under irrigation||-||ha|
|- sugar cane||1993||10 600||ha|
|Drainage - Environment:|
|as a % of cultivated area||-||%|
|Area salinized by irrigation||-||ha|
The potential for irrigation development is estimated to be 828 000 ha based on soil and water availability - that is 2% of the cultivable area.
Exact figures about the Total water managed area are not known. It is estimated to be somewhere between 120 000 and 200 000 ha (between 14 and 24% of the potential). Most of this is in traditional, small-holder schemes, with size estimates again ranging from 106 000 to 150 000 ha. Medium to large schemes make up the balance, ranging from 20 000 to 50 000 ha (Figure 2).
Almost all irrigation water on the mainland is surface water coming from rivers, streams and springs. In only a few cases, storage reservoirs have been constructed. Sprinkler irrigation is used on some large-scale projects, but it is rather expensive. In the semi-arid central lowlands, with annual rainfall below 500 mm, various forms of water harvesting, micro-catchments and other techniques are used to try to control and concentrate rainfall runoff.
The main crop in large scale irrigation projects is rice. Sugar cane occupies about 10 000 ha of the irrigated area. In small-scale projects, most of the irrigated area is occupied by rice. In some limited areas, maize is cultivated, and there are some trials with vegetables and horticulture under irrigation.
The cost of irrigation development varies according to the type. For large-scale projects, the cost varies between $US 10 000 and 15 000/ha. For small-scale development, figures between $US 6 000 and 15 000/ha are given.
FIGURE 1: Water withdrawal (total: 1.17 km³ in 1992)
FIGURE 2: Types of full or partial control irrigation schemes (1993)
Institutions directly involved in water and irrigation development are:
- Water Division, responsible for design, construction, equipment, maintenance and operation of laboratories, water planning, water supply, water research, sewerage and sanitation; and the
- Central Water Board, which is the principal advisory body to the government on all matters relating to the utilization of water resources, including the appointment of national water supplies and the allocation of water rights. It also has the power to control and regulate water pollution;
- Fisheries Division, to advise the government and the local fisheries administrations on all fisheries matters and to regulate fishing; and
- National Environment Management Council (NEMC), the advisory body to the government on environmental matters, particularly charged with the formulation of policy and legislation on environmental issues.
The present Water Law was enacted in 1974 and amended in 1981. Water Regulations adopted in 1975 have a broad scope of application, covering various aspects of utilization, management, conservation and administration of both surface and groundwater resources. Under the law, all land, whether occupied or unoccupied, belongs to the State. The president is empowered to grant rights of occupancy not exceeding 99 years.
The legislation does not explicitly consider water resources planning, construction, operation and maintenance of irrigation systems, or the management of wetlands.
TRENDS IN WATER RESOURCES MANAGEMENT
A National Irrigation Development Master Plan was prepared with the assistance of a UNDP/FAO project.
Until recently, the irrigation sector in Tanzania has been marked by poor performance - in terms of both implementation efficiency and scheme operation; high expenditure levels on unadapted schemes; and ineffective national coordination and planning. Recent policy changes, the new liberalized trading environment in Tanzania, and priorities for developing the irrigation subsector are starting to show an impact, mainly on smallholder irrigation. Furthermore, the recent redefinition of institutional responsibilities and a better-trained staff in the State Irrigation Services have resulted in a more efficient service to the irrigation subsector. It is expected that if the recently drafted National Irrigation Development Master Plan is approved, donors and Government initiatives will be coordinated into a general programme, and commercialization of specific activities of the State Irrigation Service will take place.
MAIN SOURCES OF INFORMATION
Bureau of Statistics, Dar-es-Salaam. 1993. Statistical Abstract 1991.
FAO. 1993. National Action Programme for the United Republic of Tanzania. FAO/IAP WASAD. Rome.
FAO. 1993. Draft National Irrigation Development Plan. Report prepared under UNDP/FAO project URT/90/016.
Statistics Unit, Planning and Marketing Division. Various dates. Basic Data: Agricultural & Livestock Sector - Mainland 1986/87-1991/92
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