Gateway to Land and Water Information: Yemen national report

This report was compiled by Abdul Maged A. Al Hemiary
Technical Director of Renewable Natural Resources Research Centre
Agricultural Research and Extension Authority - Dhamar

Overview (Geography | Socio-economy | Climate)

Land resources

Water resources (AQUASTAT)

Plant nutrient resources

Hot spots

Bright spots

Challenges and viewpoints

References / Related internet links

1.1 Geography and administrative units

Yemen is located on the south of the Arabian Peninsula, between latitude 12 and 20 north and longitude 41 and 54east, with a total area estimated at 555000 km² excluding the Empty Quarter. Apart from the mainland it includes more than 112 islands, the largest of which are Soqatra in the Arabian Sea to the Far East of the country with total area of 3650 km² 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 (Map 1.1.1 PDF 32kb).

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). For administration purposes, the country is divided into 19 governorates in addition to the capital city of Sana'a. Governorates are in turn divided into 2864 districts comprising 2082 sub-districts (uzlah).(Map 1.1.2 PDF 71kb).

1.2 Socio-economic features

The total population is 17.1 million (MPD, 1998), of which 74.4 % is rural (Table 1.2.1). The average population density is about 31 inhabitants/km², but in the western part of the country the density can reach up to 300 inhabitants/km² (Ibb province) while in the three eastern provinces of the country the density is less than 5 inhabitants/km². 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 3.5%, which is very high.

Agriculture contributes 21% to the Gross Domestic Product (GDP) in Yemen, employs 60% of the population, and provides livelihood for rural residents who constitute about 76%of the total population. Agriculture is characterised by low and uncertain crop yields due to drought, insufficient and erratic rainfall, declining soil productivity due to soil erosion and poor crop management practices, and crop losses due to damage by insects and diseases, and malnutrition resulting from inadequate supply of feed.

The main agricultural products are fruit (mango, grape, citrus, banana, papaya and date.), vegetables (tomatoes, potatoes, watermelon, sweet melon, onion and cucumber.), Qat, and Cereals (maize, wheat, sorghum and barley).

The Yemeni economy has primarily depended on agriculture. Agriculture contributed 25% of the GDP in 1990 (Chart 1.2.1). Oil has been a main activity in the Yemeni economic. In 1999, Yemeni's oil production reached 143 million barrels at a total value of 412 billion Yemeni Riyals (around 68% of total state revenues).

Cultivated land has expanded from 1.21 thousand hectares in 1990 to 1.28 thousand hectares in 1999, an increase of14% of land for cereals crops, vegetables, fruit, cash crops and animal food.

Cultivated area for vegetable has also increased from 52,000 hectares to 62,000 hectares during the period (Chart 1.2.2). Production increased from 696,000 to 766,000 tons in 1999. Fruit cultivated area has doubled and production has increased to 588,000 tons in 1999. Farmers have turned to cotton plantation as a cash crop following its price liberalisation. Therefore, cotton cultivated area increased from 57,000 hectares to 91,000 hectares.

There is a close linkage between the poverty incidence among the population and the fluctuation in productivity from year to year.

The contribution of the agriculture sector in realising food security in Yemen is clarified in the following percentage of production vis-à-vis population needs:

Overall, local production covers a third of the need of the national economy of food.

1.3 Climate

Yemen has predominantly semi-arid to arid climate. Rainy seasons occur during the spring and summer (Table 1.3.1). The climate of Yemen is strongly influenced by the mountainous nature of the country (Bruggeman, 1997). Rainfall rises from less than 50mm along the Red Sea and Gulf of Aden coasts to a maximum of 500-800mm in the western highlands and decreases steadily to below 50mm inland (Map 1.3.1 PDF 29kb).

The rainfall depends on two main mechanisms, the Red Sea Convergence and the Monsoonal Inter tropical Convergence Zone. The former influence is most noticeable in the west of the country, this is active from March to May and to some extent in autumn, while the latter reaches the country in July-September, moving north and then south again so that its influence lasts longer in the south. Seaward exposed escarpments such as the western and southern slopes receive more rainfall than the zones facing the interior. The average temperature decreases more or less linearly with the latitude. Some of the climatic characteristics are shown in (Table 1.3.2).

The growing period is the period of the year when both moisture and temperature conditions are suitable for crop production under rainfed conditions. In Yemen with rainfall during spring and summer, temperatures are not limiting crop production in those periods with sufficient moisture for crop growth under rainfed conditions. The length of the growing period (LGP) analysis is based on historic data for individual years.

The (LGP) is define as the period during the year when prevailing temperature are conductive to crop growth (T mean>=c) and precipitation plus moisture stored in the soil profile exceed half the potential evapotranspiration (PET). Four types of growing period can be differentiated in Yemen (Bruggeman, 1997) (Map 1.3.2 PDF 40kb)

P exceeds PET for part of the year. The ratio P/PET for the duration of the growing period generally exceeds 0.7 (Chart 1.3.1).

P does not normal exceeds PET, but exceeds 0.5 PET for part of year. The ratio P/PET for the duration of the growing period generally exceeds 0.5 (Chart 1.3.2).

P exceeds 0.5 PET during short periods of the year. During the growing period frequent short dry spells occur (Chart 1.3.3).

Average temperatures are dominantly controlled by elevation. There is an approximately linear relation, this relation is disturbed by the proximity of the sea in the coastal areas. Mean annual temperature range from less than 12.5ºC in the central highland to 30ºC in the coastal plains. However, the winter temperatures may decrease to freezing the highlands.

The difference between the average temperatures of the warmest and the coolest month of the year in not constant over the zones. In the coastal areas and the western and southern slopes it is generally less than 100C, but in the interior it increases to about 150C. The average daily range (the difference between minimum and maximum temperature) in modest near the coast (less than 100C), but may exceed 200C at higher elevation and in the arid interior. (Map 1.3.3 PDF 45kb) shows the annual mean temperature.

2.0 Introduction

Yemen is among the oldest countries in the world where land and water resources practices have been developed. Terraces erection, rainwater harvesting and dam irrigation techniques were developed since many countries ware trackless waste.

The cultivable land is estimated at about 1.67 million ha, which is 3% of the total area (Table 2.0.1). In 1998, the total cultivated area was 1.28 million ha, or 68% of the cultivable area, of which 0.87 million ha consisted of annual crops and 0.41 million ha consisted of permanent crops. About 32 million ha is estimated as desert and rock outcrops, while range land are estimated to occupy 16 million ha including those areas which are covered by shrubs, perennial vegetation and grass. Only 1.5 million ha of the total area is considered as a forest and woodlands. (MAI, 2000)

2.1 Physiography

Topography of Yemen is dominated by the mountain ranges running parallel to the Red Sea coast through Sana'a towards Aden, with three ridges interspersed by upland plain (Map 2.1.1 PDF 32kb). These mountains merge with ranges rise from sea level to over 3700m within 100km from the Red Sea coast, running to the coast of the Gulf of Aden, which reach altitudes of about 2000m a.s.l.

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

The Coastal Plains:
The Plains are located in the west and south-west and are flat to slightly sloping with maximum elevations of only a few hundred meters above sea level. They have a hot climate with generally low to very low rainfall (< 50 mm/year). Nevertheless, the Plains contain important agricultural zones, due to the numerous wadis that drain the adjoining mountainous and hilly hinterland.

The Yemen Mountain Massif:
This massif constitutes a high zone of very irregular and dissected topography, with elevations ranging from a few hundred metres to 3 760 m above sea level. Accordingly, the climate varies from hot at lower elevations to cool at the highest altitudes. The western and southern slopes are the steepest and enjoy moderate to rather high rainfall, on average 300-500 mm/year, but in some places even more than 1000 mm/year. The eastern slopes show a comparatively smoother topography and average rainfall decreases rapidly from west to east.

The Eastern Plateau Region:
This region covers the eastern half of the country. Elevations decrease from 1 200 - 1 800 m at the major watershed lines to 900 m on the northern desert border and to sea level on the coast. The climate in general is hot and dry, with average annual rainfall below 100 mm, except in the higher parts. Nevertheless, floods following rare rainfall may be devastating.

The Desert:
Between the Yemen Mountain Massif and the Eastern Plateau lies the Ramlat As Sabatayn, a sand desert. Rainfall and vegetation are nearly absent, except along its margins where rivers bring water from adjacent mountain and upland zones. In the north lies the Rub Al Khali desert, which extends far into Saudi Arabia and is approximately 500 000 km² in area. This sand desert is one of the most desolate parts of the world.

The Islands:
The most important of all the islands is Soqatra, where more exuberant flora and fauna can be found than in any other region in Yemen.

2.2 Soils

Since early seventies numerous soil surveys have been carried out in scattered areas of Yemen. Table 2.2.1 (PDF 82kb) provides an overview of all major soil surveys hitherto conducted in the country.

These surveys, carried by various foreign bodies, often through bilateral aid, were undertaken at different levels of intensity and according to different classification systems. As they were in variably carried out within the framework of agricultural and rural development, the main purpose of these soil surveys was to provide the necessary information required for assessing the land potential for crop production. Consequently more effort went into the characterisation and mapping of soils for land capability evaluation, and relatively little attention was paid to the classification and correlation of soils, which in some instances was totally neglected. This is might have been due to the following factors:

Within the soil surveys carried out so far, hundreds of profiles have been described. These profiles have either been classified according to one or both of the two most common soil classification systems (i. e. USDA Soil Taxonomy (ST) or FAO-Unesco Soil Map of the Word Legend), or were classification according to local criteria.

For the western governorate soil map 1:500 000 (Map 2.2.1 PDF 184kb), which covers approximately 0.36% of the total land have attained in 1983. The map identifies the predominant soils and presents them at the sub-group level according to the USDA Soil Taxonomy. With the result that 60% of the mapped area is dominated by soil of the Entisol order with sub-order of Orthents, Fluvents, and Psamments. The incidence of the sub-order Orthents, can be associated with steep slopes; fluvents, with plains and wadis; and psamments, with sandstone mountain or sand dune plains. Greater groups of these sub-orders are classified as ustic or torric type. Other orders include Aridisols (8.7%), Mollisols (2.6%), Inceptisols (4.3%) and for a limited extent, Vertisols and Alfisols. Aridisols are either calsic or gypsic groups of the orthid sub-order. Mollisols are present in the most cool and moist areas of the country. Most of the Mollisols are buried in the mountain plains, whereas on the mountain slopes, they have shallow-lithic contact (Bamatraf A., 1987).

The country's soils are generally sandy to silty and loamy in the coastal plains, silty to loamy and clay loamy in the mountainous area, and low in nitrogen, phosphorus, and organic matter, In many areas, shallow soils limit the amount of water available for rainfed crops. Soil erosion caused by runoff and/or winds is often serious. Sand and dust storms, which generally blast across the lowlands and highlands, promote soil erosion (ISNAR, 1993). (Table 2.2.2 (PDF 66kb) briefly describes soil types and other Agroecological characteristics.).

2.3 Agroecological systems

Yemen is characterised by varieties of environmental zones. Since early 80s there were many attempts to classify the agroecological zones, occasionally by using the physiographic features and time to time by using landforms and climatological characteristics. The predominant distinction has given by Bamatraf A. M., 1994 as follows:

Recent demarcation of Agroecological zones in Yemen is not comprehensive, but the country could be divided into three major zones (Map 2.3.1 PDF 63kb) derived from the five Physical division reported in (2.1) these are:

The Coastal Region:
This region includes the low coastal plains facing the Red Sea, the Gulf Aden and the Arabian Sea. Its is makes a coastal strip extending to the Omani border in the east towards the southwest to Bab al Mandab, and north wards to the Saudi border. It starches over an area 2000km long and 20-60km wide, with an altitude ranges 0-500m a. m. l. Many seasonally flowing wadis dissect the region. An arid sub-tropical climate dominates the region with average annual rainfall in the range of 50-300 mm. The climate becomes semi-arid subtropical in areas adjacent to the foothills of the western escarpment.

The Mountainous Region:
This region includes the most complicated landscapes of the country. It is very irregular and dissected topography, with elevation varies from 500m at the foothills of its western and southern escarpments up to 3700m in the western peaks, then down to 1200m at its north-eastern escarpment. Due to this extreme physiographic diversity, differences in slope and location relative to the Red Sea, Gulf of Aden and Al Rub al-Khali, rainfall varies considerably within the region, with annual averages ranging from less than 300 mm to more than 1000mm. This region is divided into three main catchments, the western slopping towards the Red Sea, the southern towards the Gulf of Aden and the north-eastern towards the empty quarter ( Al Rub al-Khali). The climate is characteristic of the semi-arid tropics, with limited areas of dry temperate intermountain plains at altitudes above 2000m.

Eastern plateau:
This region is bordered by the mountains zone to the west, the southern coastal plains to the south and the empty quarter to the north. It covers vast expanses of sand desert and dissected plateau with elevation ranging from 500m on its northern and southern sides, to about 2400m on its western side. The average rainfall in this region is generally below 200mm, an arid sub-tropical climate dominates its major agricultural lands.

2.4 Wetlands, mangroves and inland valley bottoms

2.5 Inundation Land Types

2.6 Natural hazards

Due to the physiographic characteristics of the country, most of the arable lands are located within watersheds entities. The accelerating degradation of watershed basins of Yemen has serious economic, ecological, environmental and social implications

Insufficient information, however, is currently available on the magnitude of resources degradation, on the extent of soil erosion and sand encroachment. Most arable and watershed areas are subject to extensive soil erosion and desertification. Sand encroachment on agricultural land areas in the south (around Aden), west (specially Wadi Mawr and southern Tihama) and east ( specially around Marib and wadi Al Jawf) probably represents the most immediate and serious environmental threat in Yemen at present.

Erosion from the steep basins has resulted in talus fans with coarse gravel and silt along the foothills and gently sloping areas of fine silt along the alluvial plains below the outfalls of wadis in the coastal and interior plains.

Flooding occurs during monsoon season leading to loss of productive agricultural lands along the wadis, increasing sedimentation and significant widening of down stream wadi bed.

The natural vegetation of acacia scrub in the foothills has been degraded by the search for firewood. Natural forests have almost diapered due overcutting for construction, fuelwood, and fodder.

Currently, there is no innovatory of national forest resources. In addition, there is no detailed data on desertification (e. g. location and extension of sand dunes, movement, and patterns) trends in the degradation of terraces (e.g. ownership, size, impact and magnitude of soil erosion).

2.7 Land cover

2.8 Land use

There is inventory of national land cover or land use, except for western northern governorate and of limited scattered areas. There is no clear boundary between land use and land cover in Yemen.

Agricultural land consisting of arable land and land under permanent crops forms about 3%(of which about 450,000ha of mountain terraces is rainfed, 650,000 ha of relatively flatland in the inter-mountain region). Irrigated lands occupy some489, 000 ha distributed as 98,000 ha spate irrigation, 28,000 ha spring irrigation and 363,000 ha well irrigation.

The land use in upland areas of Yemen, particularly in the north, is based on the unique practice of bunding and terracing which permits reliance on rainfed agriculture. This is impeding the immediate runoff and erosion which the topography would otherwise allow, and ensuring the recharge of soil moisture and local groundwater. This terracing is extremely ancient and highly labour-intensive, with entire hillsides covered with stone bunds and earth banks interspersed with terrace areas, which may be as narrow as one meter in steep catchments. It is noteworthy that runoff is delayed during intense storms, with the terraces flooded as though with surface irrigation, and this allows the cultivation of cereal and vegetables on areas of steep slopes and sporadic storms.

2.9 Land use change

2.10 Land Productivity

2.11 Environmental Impact of land uses

3.1 Hydrography

Yemen's country information on water resources is available at AQUASTAT (Select from the list.)

Rainfall is the major source of all water in country. During the last decades, Yemen has been facing the pressing problem of providing water demands for a population growing rapidly. The agriculture sector is by far the major consumer of water and will continue will to be so in the future. The pressing need to increase agricultural products, people's domestic needs and industrial uses has lead to the available water resources depletion.

The total water requirements for the country for the base year 1990 and future in year 2010 are given in Table 3.1.1.

Water shortage is a serious problem in Yemen where the current estimated water use are by far exceeding (almost 30%) the renewable water resources (Chart 3.1.1)

Rainfall is the main source for surface water in the country. Most all the wadis are ephemeral, only a few have minor bas flows that may seasonal or permanent, but only in a limited part of their channels. The wadi beds are dry most of the time, and infrequent runoff peaks quickly occur and disappear. Flood peaks are often quick and infrequent because of sparse vegetation and mostly impermeable nature of the soil in the catchment areas.

Numerous wadis systems and related catchment areas cover the domain of Yemen. For simplicity, the country has divided into four major drainage basins, regrouping numerous smaller wadis (Map 3.1.1 PDF 41kb):

Surface water resources have been estimated at 2.1 billion m³/year, but this quantity corresponds to the runoff from major wadis and does not include the runoff produced within the smaller catchments. Water use was estimated at about 2.8 billion m³/year (Fara M. M., 1998). The country thus overdrew its resources by 0.7 billion m³/year. In general, all surface water sources in Yemen are harnessed and exploited.

Most surface water flows are intermittent, they usually carry water at and after short heavy rains. A number of floods on a periodicity of rains and it varies from 50 in wadis of the western slope to 3 - 4 in wadis with upstream in the southern slopes. Table 3.1.2 (PDF 101kb) lists annual runoff volumes, estimated annual rainfall and the size of the catchments.

[Table 3.1.2: Annual runoff volumes, Estimated annual rainfall and the Size of the catchments]

PDF 101kb

These estimates show that approximately 40 % of the runoff were comes from the western slopes. Whereas, The Gulf of Aden, Arabian Sea and Al Rub Alkhali contribute of 30 %, 25 % and 5 % respectively. Annual precipitation is approximately 65 billion m³. The surface runoff to the sea measured in some major wadis is estimated at 1430 million m³/year. (Al Hemiary, 1999).

During the last 20 years, groundwater resources in Yemen have been subject to sever exploitation to meet a continuously increasing water demand for irrigation and domestic use. Thousands of new bore holes were drilled and many existing dug wells were deepened, when they became dry because of over abstraction. This rapid and uncontrolled ground water development did not run parallel with a proper ground water management. Therefore, ground water resources have not been adequately quantified (Bamatraf, 1994).

Direct recharge of ground water in generally very low in Yemen. This is a logical consequence of the prevailing rainfall regimes.

Renewable groundwater resources have been estimated at l 525 million m³/year (FAO, 1997), a large part probably coming from infiltration in the wadi beds. A major groundwater aquifer was recently discovered in the eastern part of the country with an estimated storage of 360 billion m³. This aquifer is still under study and it is not known whether the groundwater is rechargeable or whether it is all fossil water.

Except for the reservoir behind the Ma'rib dam with a capacity of 400 million m³., which provides water irrigation for an area of 10 000 hectare, there are no large bodies of surface water in the country (Bamatraf, 1994).

Small dams existed in Yemen throughout history, as a means of improving water control, breaking spate or enhancing ground water infiltration. Over the last five years, government has embarked on an ambitious "small dam" program as a response to gravity water storage in the country. The program at present provides for construction or rehabilitation many hydraulic structures.

A total number of these structures is estimated to be about 547, out of which 173 are dams, 145 reservoirs, 195 weirs and 34 unclassified category. The hydraulic structure which have been completed are 132 (51 dams, 34 reservoirs, 41wiers and 6 unclassified) MAI, 2000. The total dam capacity is estimated at 0.18 km³.

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).

In 1990 total water withdrawal was estimated at 2 932 million m³/year, of which over 90% for agricultural purposes (Chart 3.1.2). 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 m³/year in 1989, contributing to the water supply of Aden.

Data in this issue is very limited. A brief study carried by the university of Sana'a 1995 shows that the total sewerage flows for the seven major cities in Yemen were estimated in 1995 as 43550m3/day =16million m3/year. The flow for the seven cities is expected to reach in the year 2005 a rates of 105895 m³/day or=39 m³/year.

The sewage treated water quantity is small but it has a strong impact on environment. It is used in agriculture without restrictions. It does not match with the standards and causes pollution to groundwater and deteriorates the soil structure.

There are many entities, which deal with irrigation water in the country. They can be grouped into the following:

Government has been trying three times to pass laws related to water since 1990. The traditional and customary roles are prevailing. These are mostly taken from the Islamic law (al-Sharia'a) and practiced to allocate, distribute water and solve dispute on water. These roles confirm that water is free for drinking and the priority for use is those who first reach water and develop it. Traditional roles are not enough to face the water needed by local communities for different purposes (Industry, Tourism), and the presentation of new crops.

3.2 Irrigation and drainage

4.1 Plant nutrient use and nutrient balance

4.2 Fertilizer production and costs

5.0 Overview

5.1 Land-related constraints to sustainable agriculture

Agriculturally important soils in Yemen are often of recent alluvial or colluvial origin. The textual composition of such soils can be highly variable, as they may made up of a number of sedimentary layers. However, sharply contrasting textures may occur in one of the layers, which can have a direct or indirect effect on crop growth and crop production.

Due to the intricate nature of the soil pattern, some mapping units consist of complexes. The soils identified belong to the Entisol and Aridisol orders ( Torripsamments, Torrifluvents, Torriorthents and Calciortheds) these together developed in medium textured loss deposits, were considered as the most suitable Agricultural soils along the middle and upper reaches of wadis. Alluvial soils (Torrifluvents) are considered, on account of their water holding capacity, as suitable for agriculture only with supplemental irrigation. Outwashed and redistributed loess deposits, which are widely cultivated along all wadis, have sometimes strongly been affected by wind erosion.

Because of breakdown of the bush fallow system due to population pressure on the land, soils are not adequately rested and their fertility is declining. Small-scale farmers especially those farming the uplands, extract more nutrients from the soil than they put in (nutrient mining).

Soil erosion by water is a major constraint to sustainable crop production. Most of the land areas are in the steep and rugged highlands, and increasingly vulnerable to erosion.

5.2 Water-related constraints to sustainable agriculture

5.3 Plant Nutrition-related constraints to sustainable agriculture

5.4 Other constraints to sustainable agriculture

Due to lack of effective government controls on resources population pressure and the predominant focus on tubewell irrigation expansion, the delicate balance between land and water resources is being endangered. The key issues include:

6.0 Overview: society's response to ameliorate the situation

6.1 Land-related response indicators

6.2 Water-related response indicators

6.3 Plant Nutrition-related response indicators

6.4 Other response indicators

8.1 References

Achouri Moujahed. 1998. Participatory Watershed Management Towards Integrated Water Resources Management.

Al-Hemiary A. Maged. 1999. Yemeni Experience in the Watershed Management. YEM/97/200. Sana'a ROY.

Bamatraf A. M, 1987. Supplemental Irrigation in Yemen Arab Republic; pp561-598, In: "supplemental Irrigation in the Near East and North Africa", Eds. E. R. Perrier & A. B. Salkini. Publ. Kluwer Academic, London.

Bamatraf A. M. 1994. Water Harvesting and Conservation System in Yemen; pp 169-188, In:" Water Harvesting for Improved Agricultural Production". FAO Expert consultation Cairo 21-25 Nov. 1993. FAO. Rome.

Bruggeman H.Y. 1997. Agro-climatic Resources of Yemen. Part 1. Agro-climatic Inventory. FAO proj. GCP/YEM/021/NET, Field doc. 11. Ministry of Agri. & Irrigation., Agri. Res. & extension Authority, Dhamar, Yemen.

Food and Agriculture Organization of the United Nations Rome, 1997.Irrigation in the near east region in figures

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

International Service for Agricultural Research (ISNAR). 1993. A Review of the Agricultural Research System in the Republic of Yemen. ISNAR, The Netherlands.

Ministry of Agriculture and Irrigation (MAI). 2001. Agricultural statistics year- book 2000. MAI, Sana'a, ROY.

Ministry o planning and Development (MPD). Statistics year-book 1998. Central Stat. Organisation. Sana'a, Yemen.

Mohamed Fara M. 1998. The water Resources of Yemen. Paper presented to environmental Information System for Natural Resources Conservation and use. Dec.1998., Sana'a ROY.

Richard Tutwiler. 1990. Agricultural labour and Technological Change in the Yemen Arab Republic; pp 229-251 In: Labor and Rainfed Agriculture in West Asia and North Africa., Eds., Dennis Tully. Publ. Kluwer Academic, London.

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

8.2 Related internet links

Country in general

Land resources

Water resources

Environment and Biodiversity

Bright spots - Land resources

Bright spots - Water resources

Yemen

1. Country overview