minimppv.gif (940 bytes)minimtoc.gif (878 bytes)minimpnx.gif (858 bytes)

Yemen


GEOGRAPHY AND POPULATION

Yemen, with a total area estimated at 527 970 km, is located on the south-western edge of the Arabian Peninsula. Apart from the mainland it includes many islands, the largest of which are Socotra in the Arabian Sea to the far east of the country and Kamaran in the Red Sea. The country is bordered by Saudi Arabia in the north, Oman in the east, the Arabian Sea and the Gulf of Aden in the south, and the Red Sea in the west. A large part of the boundary between Yemen and Saudi Arabia has not yet been defined officially.

The present Republic of Yemen was born in 1990, as a result of the unification of the former Yemen Arab Republic (YAR) and the People's Democratic Republic of Yemen (PDRY). These two parts are sometimes still referred to respectively as the northern and southern part of the country. For administration purposes, the country is divided into 17 governorates.

TABLE 1 - Basic statistics and population

Physical areas:
Area of the country 1995 57797000 ha
Cultivable area 1994 3 617 753 ha
Cultivated area 1994 1 052 786 ha
- annual crops 1994 852 786 ha
- permanent crops 1994 200 000 ha
Population:
Total population 1995 14501000 inhabitants
Population density 1995 27 inhab./km
Rural population 1995 66 %
Water supply coverage:
Urban population 1990 65 %
Rural population 1990 48 %

The cultivable land is estimated at about 3.62 million ha, which is 7% of the total area. In 1994, the total cultivated area was 1.05 million ha, or 29% of the cultivable area, of which 0.85 million ha consisted of annual crops and 0.20 million ha consisted of permanent crops.

The total population is 14.5 million (1995), of which 66 % is rural. The average population density is about 27 inhabitants/km2, but in the western part of the country the density can reach up to 300 inhabitants/km (lbb province) while in the three eastern provinces of the country the density is less than 5 inhabitants/km. This is closely related to the physical environment. By far the largest part of the population lives in the Yemen Mountain area in the western part of the country, where rainfall is still significant, although not high in many locations. The hostile environment of the desert and eastern upland areas is reflected by low population density. The average demographic growth rate is estimated at 3.7%, which is very high. In 1990, agriculture accounted for 20% of the country's GDP and employed 62% of the labour force.

CLIMATE AND WATER RESOURCES

Climate

Yemen has a predominantly semi-arid to arid climate, with rainy seasons during spring and summer, and high temperatures prevail throughout the year in low-altitude zones.

TABLE 2 - Water: sources and use

Renewable water resources:
Average precipitation   170 mm/yr
    89.8 km/yr
Internal renewable water resources   4.1 km/yr
Total (actual! renewable water resources 1995 4.1 km/yr
Dependency ratio 1995 0 %
Total (actual) renewable water resources per inhabitant 1995 283 m/yr
Total dam capacity 1995 180 106 m
Water withdrawal:
- agricultural 1990 2 700 106 m/yr
- domestic 1990 201 106 m/yr
- industrial 1990 31 106 m/yr
Total water withdrawal   2 932 106 m/yr
per inhabitant 1990 251 m/yr
as % of total (actual! renewable water resources   71.5 %
Other water withdrawal   - 106 m/yr
Average groundwater depletion 1994 700 106 m/yr
Wastewater - Non-conventional water sources:
Wastewater:      
- produced wastewater 1992 37 106 m/yr
- treated wastewater 1990 20 106 m/yr
- reused treated wastewater   - 106 m/yr
Desalinated water 1989 10 106 m/yr

In Aden mean figures of 25C (January) to 32C (June) occur, but maximun temperatures over 38C are quite common, combined with a very high relative air humidity. Mean annual precipitation on the mainland gives a volume of 93.6 km. The average annual rainfall ranges from less than 50 mm in the coastal areas and the deserts to 200-400 mm on the slopes of the highlands and more than 1 000 mm on the western slopes of the mountains.

The many different landscapes of Yemen can be grouped into five main geographical/ climatological regions:

TABLE 3 - Irrigation and drainage

Irrigation potential   - ha
Irrigation:
1. Full or partial control irrigation: equipped area 1994 383 200 ha
- surface irrigation 1994 382 450 ha
- sprinkler irrigation 1994 350 ha
- micro-irrigation 1994 400 ha
% of area irrigated from groundwater 1994 100 %
% of area irrigated from surface water 1994 0 %
% of area irrigated from non-conventional sources 1994 0 %
% of equipped area actually irrigated   - %
2. Spate irrigation area 1994 98 320 ha
3. Equipped wetland and inland valley bottoms (i.v.b.)   - ha
Total irrigation (1+2+3) 1994 481 520 ha
- as % of cultivated area   46 %
4. Flood recession cropping area   - ha
Total water managed area (1 + 2 + 3 + 4) 1994 481 520 ha
- as % of cultivated area   46 %
- increase over last 10 years   - %
- power irrigated area as % of water managed area   - %
Full or partial control irrigation schemes: Criteria
Large-scale schemes > 5 ha   - ha
Medium-scale schemes   - ha
Small-scale schemes < 2 ha   - ha
Total number of households in irrigation      
Irrigated crops:
Total irrigated grain production 1994 156 000 tons
as % of total grain production 1994 20 %
Harvested crops under irrigation (full or partial control)   - ha
- permanent crops: mainly qat   - ha
- annual crops: total   - ha
. cereals (sorghum, maize, wheat, barley) 1994 49 110 ha
. vegetables   - ha
. pulses 1994 26 230 ha
. sesame 1994 20 410 ha
. other annual crops   - ha
Drainage - Environment:
Drained area   - ha
as % of cultivated area   - %
- drained areas in full or partial control irrigated areas   - ha
- drained areas in equipped wetland and i.v.b   - ha
- other drained areas   - ha
- total drained area with subsurface drains   - ha
- total drained area with surface drains   - ha
Flood-protected area 1994 70 000 ha
Area salinized by irrigation   - ha
Population affected by water-borne diseases   - inhabitants

Water resources

Yemen can be subdivided into four major drainage basins, regrouping numerous smaller wadis:

The floods of the wadis in Yemen are generally characterized by abruptly rising peaks that rapidly recede. In between the irregular floods the wadis are either dry or carry only minor base flows.

Surface water resources have been estimated at 2 000 million m/year, but this quantity corresponds to the runoff from major rivers and does not include the runoff produced within the smaller catchments. Renewable groundwater resources have been estimated at l 525 million m/year, a large part probably coming from infiltration in the river beds. A major groundwater aquifer was recently discovered in the eastern part of the country with an estimated storage of 10 km. This aquifer is still under study and it is not known whether the groundwater is rechargeable or whether it is all fossil water.

The surface runoff to the sea measured in some major wadis is estimated at 270 million m/year, the groundwater outflow to the sea at 280 million m/year. There might be some groundwater flowing into Saudi Arabia, but no data are available. The existence of surface drainage crossing into Saudi Arabia suggests that some sharing of surface flows could be possible, but details are not known.

Dams

The total dam capacity is estimated at 0.18 km. In general, the dams are built for irrigation and domestic purposes, but at the same time they contribute to groundwater recharge. There are also many flood control dams which are not intended to store water, but to divert the spate floods immediately to the adjacent irrigation network (spate irrigation).

Figure 1 - Water withdrawal {total: 2 932 million m in 1990)

Water withdrawal

In 1990 total water withdrawal was estimated at 2 932 million m/year, of which over 90% for agricultural purposes (Figure l). Most of the water used was groundwater (from wells and springs), resulting in groundwater depletion as withdrawal exceeds the annual groundwater recharge. The rates of decline of the groundwater levels is alarmingly high in many zones, especially in the Yemen Highlands, where decline of between 2 and 6 m/year is commonly observed. In coastal zones this leads to the incidence of salt water intrusion. Spring-fed irrigation has reduced significantly as groundwater tables have dropped. The quantity of desalinated water was estimated at 10 million m/year in 1989, contributing to the water supply of Aden.

IRRIGATION AND DRAINAGE DEVELOPMENT

In 1994, the total water managed area was estimated at 481 520 ha. A global figure for irrigation potential is not available. About 48 000 ha have been identified for further irrigation development, mostly in the coastal plains and in Wadi Hadramaut.

Figure 2 - Distribution of the water managed areas total: 481 520 ha in 1994)

Figure 3 Origin of irrigation water f/p (total: 383 200 ha in 1994)

Two main types of water management can be distinguished (Figure 2):

On the remaining cultivated area of 571 266 ha, water harvesting is practiced, based on collecting and retaining overland flow in zones where soils permit agriculture. The receiving zone is always smaller than the zone where overland flow is produced, thus a multiplier effect is produced which permits agricultural production in low precipitation zones. The numerous constructed mountain terraces, also called 'the hanging gardens of Yemen', collect and retain rain and overland flow in a similar way.

Overall irrigation efficiency low, between 35 and 45%, depending on field levelling and the water conveyance system used. Sprinkler irrigation and micro-irrigation are found on a limited number of farms and in pilot projects, using water from tubewells and springs. Almost all irrigation is surface irrigation (Figure 4). It is thought that efficiency could be increased to 60% by lining the canals and installing pipe distribution for surface irrigation, and to over 80% by adopting sprinkler irrigation and micro-irrigation techniques.

Figure 4 - Irrigation techniques f/p (total: 383 200 ha in 1994)

Farm size, including both rainfed and irrigated agriculture, is very small in general: 37% of the farms have less than 0.5 ha, 72% of the farms less than 2 ha, while only 4% of the farms have more than 10 ha.

Very rough estimates of the cost of irrigation development using groundwater from tubewells lead to figures between $US 250/ha for large schemes (10 ha) and $US 450/ha for small schemes (2 ha) in the lowlands, while in the highlands the cost might vary between $US 575/ha and $US 1 300/ha respectively. The differences in cost between the lowlands and the highlands are mainly due to differences in the characteristics of the aquifers. Operation and maintenance costs vary between $US 175/ha per year in the lowlands and $US 350/ha per year in the highlands.

According to the Constitution, flowing and underground water are defined as 'res communis'. However, a landowner has 'precedence' for water taken from a well on his land. In spring-irrigated areas water can be attached to land in the form of 'turns', which give rights to divert the canal into the field for a fixed period of time. The 'turn' can however be detached from the land and sold or rented separately. This landowner 'precedence' has permitted the private development of deep tubewell extraction, which is in some ways in conflict with Islamic principles. Islamic and customary law has no precedent for dealing with a new technology that allows landowners to extract (and sell) unlimited quantities of water from deep aquifers, and modern law has not yet regulated it either.

The major irrigated cash crops are cotton (12 270 ha), coffee (8 060 ha), sesame (20 410 ha), tobacco and qat. As far as the production of qat. is concerned, no official figures are available, but there have been estimates that at least one-fourth of the irrigated land is under qat production. Main cereal crops are sorghum, maize, wheat and barley, with a total irrigated area estimated at 49 110 ha. Production of vegetables, potatoes and fruits have increased significantly. Pulses also retain an important place. However, no figures on the area covered by all irrigated crops are available for the country as a whole. In 1994, the yield of irrigated wheat was 3.75 tons/ha as against 0.71 to 1.70 tons/ha for rainfed wheat. The yield of irrigated barley was 4.84 tons/ha as against 0.77 to 1.30 ton/ha for rainfed barley.

The flood protection area has been estimated at between 70 000 and 80 000 ha. Salinization due to irrigation exists in several regions, but no figures are available. No drainage systems are reported to exist.

INSTITUTIONAL ENVIRONMENT

The Ministry of Agriculture and Water Resources (MAWR) is responsible for formulating policies for water resources, for food security and for crops, livestock and forestry production, and for coordinating public investment and services in the sector. The General Directorate of Water Resources is located within the Ministry with four general departments: water resources; irrigation and maintenance of water installations; farm mechanization and land reclamation; irrigation studies. Most field services are provided to farmers through decentralized Regional Development Agencies (RDA), supported by technical services at national level. However, the division of responsibility between MAWR, the Agricultural Research and Extension Authority (AREA) and the RDAs with respect to water management is unclear.

Responsibility for coordinating rural water supplies lies within the Water Supply Department of the Ministry of Water and Electricity (MWE).

The General Department of Hydrology is located within the Ministry of Oil and Mineral Resources (MOMR).

TRENDS IN WATER RESOURCES MANAGEMENT

The successful and sustainable exploitation of the water resources in Yemen is threatened. The most serious and obvious problem is the rapid depletion of groundwater resources. Almost all the important groundwater systems in Yemen are being over-exploited at an alarming rate. The socioeconomic consequences of groundwater resources depletion are dramatic since groundwater will become too expensive for use in agriculture and, as a result, regional agricultural economies based on groundwater irrigation are doomed to collapse if the water resources are not adequately controlled. The groundwater stocks may be further reduced by groundwater salinization (in coastal areas) and groundwater pollution (in urban areas and areas of intensive agriculture). Environmental degradation occurs, for example in areas where springs have dried up. The scarcity of water leads to ever-increasing competition which, if uncontrolled, might lead to socio-economic problems.

There is an increasing awareness in Yemen of groundwater depletion. The Government of Yemen has committed itself to a sustainable use of the water resources, which was reiterated in an official statement issued at the UN Conference on Environment and Development of 1992 in Rio de Janeiro.

Water resources management in the country suffers because there is no unified central decisionmaking organization. Several authorities are dealing with water related affairs with minimum integration and coordination. To solve this problem, a Presidential Decree for the establishment of the National Water Resources Authority (NWRA) was issued in October 1995, providing for the merger of the General Directorate of Water Resources of MAWR, the General Department of Hydrology of MOMR and the Technical Secretariat of the previously existing High Water Council. The main duties of the authority will be:

Measures to be implemented at field level may include the introduction of water-saving techniques (improving irrigation efficiencies, imposing a water tariff, etc.), groundwater licensing and enforcement of pollution control regulations.

MAIN SOURCES OF INFORMATION

Central Statistics Office. 1995. Population and housing census, December 1994. Ministry of Planning and Development.

Consulting Engineering Services Private Ltd. 1991. Land and water resources and irrigation development study. New Delhi, India.

General Department of Agricultural Statistics. Agricultural Statistics Yearbooks 1988-1992. Ministry of Agriculture and Water Resources.

General Department of Agricultural Statistics. 1995. Agricultural Statistics Pamphlet 1994. Ministry of Agriculture and Water Resources.

Ministry of Oil and Mineral Resources & TNO Institute of Applied Geoscience (Netherlands). 1995. The water resources of Yemen: a summary and digest of available information. Report compiled by Van der Gun, J.A.M. and Abdul Aziz Ahmed.

Noman, Abdullah Ahmed. 1989. Issues and problems of agricultural development/agricultural holdings. Al Farabi, Beirut.

TS/HWC-UNDP/DESD. 1995. Final reports. Volume III: Surface water resources; Volume IV: Groundwater resources; Volume VI: Water supply, wastewater and sanitation.

World Bank. 1993. Republic of Yemen, Agricultural sector study: Strategy for sustainable agricultural production. Report No 11126-YEM.

Zarina, M., Ismail, F., Abdullah, M., Alshab, M., Shasan. 1991. The first national population policy conference. Central Statistics Office, Ministry of Planning and Development.


minimppv.gif (940 bytes)minimtoc.gif (878 bytes)minimpnx.gif (858 bytes)