Irrigation development is still at its low.
Ethiopia is the second most populous country in Africa (Awulachew et al. 2005). According to the Central Statistical Agency of Ethiopia projection (CSA 2005) from the 1994 census, the total projected population in Ethiopia for 2006 was estimated to be 75,067,000, about 85 percent of which lives in the rural areas depending on subsistence agriculture.
Ethiopia covers a land area of 1.13 million km2, of which 99.3 percent is a land area and the remaining 0.7 percent is covered with water bodies of lakes (MOWR 2002). It has an arable land area of 10.01 percent and permanent crops covered 0.65 percent while others covered 89.34 percent.
According to the World Bank, the per capita income in 2005 was $160 per year. The agricultural sector is the leading sector in the Ethiopian economy, 47.7 percent of the total GDP, as compared to 13.3 percent from industry and 39 percent from services (World Bank 2005).
Though agriculture is the dominant sector, most of Ethiopia’s cultivated land is under rainfed agriculture. Due to lack of water storage and large spatial and temporal variations in rainfall, there is not enough water for most farmers to produce more than one crop per year and hence there are frequent crop failures due to dry spells and droughts which has resulted in a chronic food shortage
Ethiopia has an extremely varied topography. The complex geological history that began millions of years ago and continues, accentuates the unevenness of the surface; a highland complex of mountains and bisected plateaux characterizes the landscape. Interspersed with the landscape are higher mountain ranges and cratered cones. According to some estimates about 50 percent of African mountains, about 371,432 km above 2,000 meters, are confined within Ethiopia (FAO 1984). Altitude ranges from 126 meters below sea level in the Dalol Depression on the northern border, to the highest mountain, Ras Dashen in the Semien Mountains north of Lake Tana rising
to 4,620 m.a.s.l. The plateau in the northern half of the country is bisected by the Ethiopian Rift Valley, which runs more than 600 km north–northeast of the Kenyan border to the Koka Dam on the Awash River south of Addis Ababa. The rift then descends to the northeast and its lateral escarpments begin to diverge from each other crossing the Afar Depression towards the Red Sea coast (Ayenew et al. 2005).
Based on Global Precipitation Climatology Centre (GPCC http://gpcc.dwd.de) data, we have derived climatological data. Accordingly, the mean annual rainfall is 812.4 mm, with a minimum of 91 mm and a maximum of 2,122 mm; with a highest rainfall ranging from 1,600–2,122 in the highlands of the western part of the country, and a lowest rainfall from 91-600 mm in the eastern lowlands of the country. The mean annual temperature is 22.2 degrees celcius. The lowest temperature ranges from 4-15 degrees celcius in the highlands, and the highest mean temperature is 31 degree celcuis in the lowlands at the Denakil Depression.
It is expected that through an optimal development of water resources, in conjunction with development of land and human resources, a sustainable growth of food production can be achieved.
Since the mid-1980s, the Ethiopian government has responded to drought and famine through promoting and construction of irrigation infrastructure aimed at increasing agriculture production.
These are traditional, small, medium and large-scale irrigation schemes performing at different levels.
Irrigation development has positive socio-economic and some negative environmental impacts. Formally accounted overall irrigation development is estimated at some 5 – 6 percent of the developable potential of 3.7 million ha.
The irrigation area in year 2002 was 197,000 hectares with a coverage distribution of 38 percent traditional, 20 percent modern communal, 4 percent modern private and 38 percent public schemes(MoWR 2002). The revised figure puts the total irrigated area at about 250,000 hectares (Awulachew
et al. 2005). This number gives a per capita irrigated area of about 30 m2. This value is very small compared to 450 m2 globally. The targeted growth expansion (according to the 2001 Water Sector Development Plan), is also not significant and not expected to bring a significant change and the much-needed economic growth. Considering the population growth as per table 1 and the targeted development of the 2002 water sector development strategy, the per capita irrigated area only reaches 45 m2 per head by the year 2015 and does not move the sector significantly. Therefore, given extreme meteorological and hydrological variability in Ethiopia, it is important that significant attention be given to enhance better water control, use and management of the water resources for agricultural production through irrigated agriculture. Corollary to this, the revised strategy, according to Plan for Accelerated and Sustained Development to End Poverty (PASDEP) (MOFED 2006), puts the large and medium-scale irrigation growth by year 2010 at an additional 493,000 hectares, which is an improved plan on previous strategy.
The project related to this paper known as “Impact of Irrigation on Poverty and Environment (IIPE)” is sponsored by the Austrian Government to be executed by the International Water Management Institute (IWMI) in collaboration with Austrian and Ethiopian Universities, Research Institutions and relevant ministries in Ethiopia. One of the expected outputs of the project is to establish a comprehensive data and information database on irrigation and drainage sub-sector.Often the availability of reliable and consistent data and information on surface and ground water is one of the basic requirements for development, use and management of water resource, in order for water managers to make well-informed decisions, as well as for researchers to make proper analysis and arrive at reasonably accurate conclusions.
In Ethiopia, the major problems associated with the generation of reliable data and information on water resources management consists of a lack of consolidated strategy, including institutional linkages, processes of collection, storage, analysis, and dissemination. A clear example of this is the lack of consistent and reliable figures on irrigated agriculture from various sources in Ethiopia.
Recognizing this fact and in an effort to contribute to the knowledge base of the water sector of the country, IWMI (together with other partners) has conducted a survey on existing small, medium and large-scale irrigation developments in Ethiopia and created a database in Geographic Information System (GIS). The creation of this database on irrigation and drainage is the first of its kind in putting together the existing data in an organized manner and make it available for end users.
The database contains spatial data of river basins, river networks and existing irrigation schemes (small, medium and large-scale) in each administrative region of Ethiopia; and the potential that can be realistically irrigated in each river basin. Although the already developed database is a very useful output, it is considered as an evolving working document which will be updated from time to time as additional information and recent developments emerge. The accompanying sections therefore discuss the general water resources information of Ethiopia and specifically discuss the potential and development of irrigation identified by regions and basins as well as aggregate values at national level. As much as possible, the irrigation potential and development are geo-referenced and mapped in GIS environment. The resulting Geospatial Database, maps and Microsoft Access database, which are already shared with regional government bureaus and federal ministries, can provide invaluable and harmonious information systems that can be updated from time to time, as new schemes are put in place.
Surface water resources: river basins
The country has 12 river basins. The total mean annual flow from all the 12 river basins is estimated to be 122 BMC (MoWR 1999). This could be further refined when data on recent master plan studies becomes available.
At present, surface water and meteorological data are collected and processed on a regular basis through existing hydro-meteorological networks.
The idea of a river basin, despite its physical or natural attributes, is more than an engineering concept and encompasses the magnitude and dynamics of a resource that must be harnessed for the common good (Molle 2006). It has often been advocated that the most logical unit for water resources planning and optimum utilization of available water resources is the river basin.
Accordingly, it is desirable that all major river basins in Ethiopia have an integrated development master plan study, and their potential in terms of economic development be known.
Surface Water Resources: Lakes and Reservoirs
Ethiopia has 11 fresh and 9 saline lakes, 4 crater lakes and over 12 major swamps or wetlands. Majority of the lakes are found in the Rift Valley Basin. The total surface area of these natural and artificial lakes in Ethiopia is about 7,500 km2. The majority of Ethiopian lakes are rich in fish.
Most of the lakes except Ziway, Tana, Langano, Abbaya and Chamo have no surface water outlets, i.e., they are endhoric. Lakes Shala and Abiyata have high concentrations of chemicals and Abiyata is currently exploited for production of soda ash.
( Source: working paper published by the international water management Institute, IWMI.)