Ghana

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GEOGRAPHY, POPULATION AND WATER RESOURCES

Ghana, located in western Africa, has a total area of 238 540 km The cultivable area is about 100 000 km which is 42% of the total area. The cultivated area is about 11 400 km which is 4.8% of the total area and 11.4% of the cultivable area.

The population is estimated to be almost 17 million (1994), of which 66% is rural. The average population density is 71/km, but ranges from 20/km in the Northern Province to 575/km in the Greater Accra province. The population growth rate was estimated at 3.5% per year during the period 1984 to 1991.

TABLE 1
Basic statistics and population

Area of the country 1994 23 854 000 ha
Cultivable land 1990 10 000 000 ha
Cultivated land 1990 1 140 000 ha
Total population 1994 16 944 000 inhab.
Population density 1994 71 inhab./km
Rural population 1990 66 %
Water supply coverage    
Urban population 1990 90 %
Rural population 1990 29 %

Agriculture contributed 44.7 % to the GDP in 1994.

Water resources

Average rainfall is about 1 264 mm/ year, but ranges from 890 mm/year in the coastal zone near Accra to 2 030 mm/year in the southwestern rainforests. The rainfall is bi-modal in the southwestern forest zone, giving a major and a minor growing season; elsewhere, a uni-modal distribution gives a single growing season from May to October. Except for the southwestern zone, the reliability of the rainfall, particularly after crop germination, is a major factor affecting crop growth.

Global water resources are estimated at 53.2 km per year, consisting of 30.3 km/year, of internally produced water resources and 22.9 km/year, of runoff from other countries.

The drainage network of Ghana is divided into three main systems: the Volta river system, the southwestern river basins, and the coastal rivers.

Ghana

TABLE 2
Water balance

Water resources:      
Average precipitation   1 264 mm/yr
    301.7 km/yr
Internal renewable water resources - total   30.3 km/yr
Internal renewable water resources - per caput 1994 1 788 m/yr
Global renewable water resources   53.2 km/yr
Dependency ratio   43.0 %
Total dam capacity 1994 148.5 km
De-salinated water   - 10 6 m/yr
Water withdrawal:      
- Agricultural 1970 156 10 6 m/yr
- Domestic 1970 105 10 6 m/yr
- Industrial 1970 39 10 6 m/yr
Total   300 10 6 m/yr
per caput 1970 35 m/yr
as % of internal renewable water resources   1.0 %
Other withdrawal   - 10 6 m/yr
Wastewater:      
Produced   - 10 6 m/yr
Treated   - 10 6 m/yr
Re-used treated wastewater   - 105 m/yr

TABLE 3
Irrigation and drainage

Irrigation potential 1994 1 900 000 ha
Irrigation:      
1. Full or partial control Irrigation: equipped area 1994 6 374 ha
- surface irrigation 1994 5 794 ha
- sprinkler irrigation 1994 580 ha
- micro-irrigation 1994 0 ha
% of area irrigated from groundwater 1994 0 %
% of area irrigated from surface water 1994 100 %
% of equipped area actually irrigated 1994 61 %
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) 1994 6 374 ha
- as a % of cultivated area 1994 0.6 %
- increase over last 10 years   - %
- power irrigated area as % of water managed area 1994 57.6 %
Full or partial control schemes: Criteria      
Large schemes > 500 ha 1994 4 720 ha
Medium schemes 1994 1 204 ha
Small schemes < 100 ha 1994 450 ha
Total number of households in irrigation      
Irrigated crops:      
Total irrigated grain production   - t
as % of total grain production   - %
Harvested crops under irrigation   - ha
- rice   - ha
- vegetables   - ha
- maize   - ha
Drainage - Environment:      
Drained area   - ha
as % of cultivated area   - %
Flood-protected area   - ha
Area salinized by irrigation 1992 1 480 ha

In the urban areas, 90 % of the population has access to piped drinking water, while only 29 % of the rural population has access to safe drinking water. Total water withdrawal was estimated at 0.3 km in 1970 (Figure 1).

IRRIGATION DEVELOPMENT

The potential for irrigated rice production in the Inland Valley Swamps (IVS) and river flood plains is about at 1.9 million ha in Ghana, according to the World Bank's estimate. The potential for full control irrigation development, based on soil and water availability, is estimated at 346 000 ha.

The Total water managed area is about 6 374 ha. In fact, this area corresponds to the full or partial control irrigated area, as there are no data relative to the existing wetlands and IVS. On the major part (5 794 ha), surface irrigation is practiced, while sprinkler irrigation is used on 580 ha (Figure 2). Large-scale irrigation schemes (> 500 ha) cover 4 720 ha; medium-scale irrigation schemes (100-500 ha) cover 1 204 ha, while small-scale schemes (< 100 ha) cover 450 ha (Figure 3). The developed area is solely irrigated by surface water (Figure 4), through gravity, pumping or a combination. The area actually irrigated is only 3 920 ha, as a large part of the equipped area is not currently in use.

Average yield for irrigated rice is 5 to 6.5 t/ha, compared with yields of between 1.0 and 1.5 t/ha under uncontrolled conditions. The major irrigated crop is rice, followed by tomato, okra, pepper, aubergine, cowpea and maize.

FIGURE 1: Water withdrawal (total: 0.3 km in 1970)

FIGURE 2: Irrigation techniques, full or partial control (1994)

FIGURE 3: Types of full or partial control irrigation schemes (1994)

Costs of irrigation development vary widely -from about $US 5 000 to 50 000/ha, while the threshold level for irrigation investment should not be more than $US 6 200/ha based on 1989 rice prices. Projects such as Ashaiman, Afife, yea, Aveyima and Weija cost between $US 5 000 and 14 000/ha, whilst costs for Tono and Bantanga were between $US 40 000 and 50 000/ha due to the lie of the land. Typical costs are about $US 2 500/ha for water conservation projects, and between $US 4 000 and 6 500/ha for small schemes of about 100 ha that use pumps.

INSTITUTIONAL ENVIRONMENT

Ghanaian irrigation development is dominated by the public sector. The Ghana Irrigation Development Authority (GIDA) was, until recently, the sole agency involved in the management of the schemes. GIDA provided all agricultural inputs and extension services. It operated and maintained the system, delivered the water to the farmer's fields and secured credit. The comprehensive involvement of GIDA has been cited by the World Bank as one of the causes of poor performance in the majority of the irrigation projects. Therefore, GIDA is testing the concept of fully involving the beneficiary groups in project identification, construction and management, through the establishment of Cooperative Societies. In the future, communities wishing to have new irrigation projects must form Cooperative Societies to show their commitment. GIDA will train the farmers, and the extension staff of the Ministry of Food and Agriculture will be based in the project, which approach should ensure sustainability following the departure of GIDA after 3-4 years. However, GIDA may provide backstopping when necessary.

TRENDS IN WATER RESOURCES MANAGEMENT

The utilization of the irrigation potential and improvement in irrigation output are constrained by the following obstacles:

FIGURE 4: Origin of irrigation water, full or partial control (1994)

The nature of the land and surface water resources makes the potential for further development of large-scale irrigation schemes costly. A cheaper alternative could be development of small-scale IVS projects (fadamas) and river flood plains. These areas are suitable for rice cultivation and irrigable by shallow groundwater or controlled flooding. However, the accelerated sedimentation that would be generated from these areas by natural processes and by agricultural activities due to the introduction of irrigation will need to be controlled, inter alia, by improved tillage systems. If this is not done, then the intensive development of inland valley bottoms and river flood plains could lead to rapid siltation of the water channels and dams.

MAIN SOURCES OF INFORMATION

Ministry of Agriculture. 1991. Agriculture in Ghana, Facts and figures.

Rural Water Supply Ghana. 1991. Rural water supply and sanitation section strategy.

Statistical Service. 1984. Population census of Ghana: Demographic and Economic.

Water Resources Research Institute/FAO. 1993. Survey on water use for agricultural and rural development.

World Bank. 1990. Ghana Medium-term Agricultural Development Programme.


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