Geographical Situation
Ethiopia is located between 3 and 18 N latitudes and 33 E and 48 E longitudes. It is the hinterland for all the costline of Eritrea on the Red Sea, and of Djibouti and Somalia on the Gulf of Aden and the Indian Ocean. It also shares borders with Sudan and Kenya and has become land-locked following the declaration of independence by Eritrea in 1993.
With a total land area of 111,811,000 hectares, Ethiopia is the seventh largest country in Africa. Altitudes range from around 100 meters below sea-level in the Afar Depression to a number of mountain peaks, of which Ras Dashen, the highest peak, is 4620 meters above sea level. Two-thirds of the land area is highland with a general elevation of 1,500 to 3,000 meters. The remaining one-thirds, is a lowland surrounding the central highlands. Most of the highland plateaus are interspersed by deep gorges, steep-sided valleys and numerous streams which feed major rivers including the Abay (Blue Nile), Tekeze, Awash, Omo, Wabe Shebele, Baro and Akobo. The southern half of the country is bisected by the Great Rift Valley, which has a range of 40 to 60 Km width and whose floor is occupied by several lakes.
The plateau surfaces are generally covered by thick deposits of tertiary lavas. The deep gorges, protected from widening by the hard lava cap, have often cut down through Cretaceous, Jurassic and Triassic sediment aries to the pre-cambrian basement. In the north, the tertiary lavas have been removed by erosion, exposing limestones and sandstones.
There are two types of soils in the highlands. Areas with relatively good drainage have red to reddish-brown clay-loam that hold moisture well and are fairly well supplied with minerals except phosphorous. The flat plateaus and valley-bottoms are poorly drained and have brownish to grey and black soils with high clay content. The arid lowlands are sandy desert soils with limited plant nutrients.
The wide range of altitude and soils, together with the proximity to the equator, has given rise to considerable climatic variations and settlement patterns in Ethiopia. In general, three major climatic zones are identified. These are the cool temperate (dega) with altitude of over 2,300 meters above sea level and annual average temperatures of less than 16 C, the hot lowlands (Kola) with less than 1500 meters above sea level and over 29 C, and the intermediate frost-free (Woina-dega) zone with altitude of 1500 to 2300 meters and temperature of 16 to 29.
The annual rainfall in the dega and woina dega zones ranges from 950 to 1,500 mm. The hot areas and coastal lowlands have an erratic and smaller amount of rainfall. The rainy seasons are generally classified into two: the main one in June - September, and the small one in April - May.