DISTRIBUTION OF RAINFALL
Ethiopia is located in the tropics and variations in altitude have produced a variety of microclimates. Mean annual rainfall ranges from 2000-mm over some pocket areas in the southwest highlands, and less than 250-mm in the lowlands. In general, annual precipitation ranges from 800 to 2200-mm in the highlands (>1500 meters) and varies from less than 200 to 800-mm in the lowlands (<1500 meters). Rainfall also decreases northwards and eastwards from the high rainfall pocket area in the southwest. Ethiopia’s varied topography has created three climatic zones , which have been known since antiquity as the dega, the weina dega, and the kolla . The dega (also known as the coolzone) occupies the central sections of the western and eastern parts of the northwestern plateau. The elevation of this region is mostly above 2400 m, and daily temperatures range from near freezing to 16 ° C . The weina dega or the temperate zone ranges between 1500 m and 2400 m in elevation,and consists of parts of the central plateau. It has daily highs between 16 and 30 ° C . The kolla or hot zone generally comprises areas lower than 1500 m in elevation, the Denakil Depression,and the tropical valleys of the Blue NileWithin each climatic zone, seasonal variations and atmospheric pressure systems contribute to the creation of three seasons, which are known as the Kiremt, Belg,and Bega. The Kiremt season is the main rainy season and usually lasts from June to September, covering all of Ethiopia except the southern and southeastern parts. The Belg season is the light rainy season and usually lasts from March to May; it is the main source of rainfall for the water-deficient southern and southeastern parts of Ethiopia . The Bega season is the dry season and usually lasts from October to February, during which the entire country is dry, with the exception of occasional rainfall that is received in the central sections The major relief regions of the country influencing the climatic conditions are Western Highlands, Eastern Highlands, the Rift Valley and the Western & Eastern Lowlands. The Western Highlands lie at altitudes between 2,400-3,700 meters with the highest mountain Ras Dashen (4620 meters) above sea level, while the Eastern Highlands are found in the eastern part of the country.The Rift Valley is found between these two massifs.
Three Rainfall Regimes
Parts of Ethiopia have unimodal and bimodal rainfall patterns which can be generalized into the three rainfall regimes with two, three, or four seasons.
Three Major Rainfall Regimes for Ethiopia
Two Seasons: The western half of Ethiopia has two distinct seasons (wet from June-September and dry from November-February), with the rainfall peak occurring from July to August.
Three Seasons: The central and most of the eastern part of the country have two rainy periods and one dry period. These season are known locally as the mainKiremt rains (June –September), small Belg rains, (February-May), and dry Bega season (October-January).
· Kirmet rainfall is very important because 90-95 percent of the food is produced during this main meher crop season. Drought during kiremt may lead to food insecurity because this is when most parts of the country receive 60-90 percent of their rainfall.
· The belg harvest accounts for only 5 to 10 percent of the total annual grain production of the country, but it may provide up to 50 percent of the yearly food supply in the some highland areas, such as Wollo and Shewa regions (all belg regions and the north-central belg region).
Four Seasons: The south and southeastern parts of Ethiopia have two distinct dry periods (December-February and July-August) and two rain seasons (March-June and September-November). The main rain season is referred to as the belg rains because it occurs from March-June (belg map).
Three Seasons in Highlands (two rainy seasons and one dry season)
Big “kiremt” rains
Long and heavy rains from mid-June to mid-September are called the big rain or kiremt, which correspond to the main “meher” growing season. Violent thunderstorms in the highlands are common in late June.Small “belg” rains
Short and moderate rains from February to May are known as the little rains or belg, and correspond to the Ethiopia’s secondary harvest season for the northern highland areas. These rains are very important to:
- Plant short-cycle crops such as wheat, barley, teff, and pulses which are harvested in June or July.
- Plant long-cycle cereal crops such as corn, sorghum and millet which are harvested during the meher season.
The belg rains are also the main annual rains for the pastoral and agro-pastoral areas of southern and southeastern Ethiopia. The planting period for the belg rains in the south starts in March and harvesting takes place in June or July. The belg rains are also critical in assuring pasture and water for livestock in the south.
In farming regions where the belg rains do not produce an extra harvest, the rains are still crucial for:
- Seed-bed preparation for short and long-cycle meher crops.
- Formation and development of the inflorescence of coffee crop;
- Maintaining livestock conditions, including plow oxen that are crucial for agriculture and ruminants that are important economic assets.
"Bega” dry season (October-January)
A short period of hot dry weather from October-January, known locally as “bega”, occurs between the two rainy seasons. During the Bega, most of the highland Ethiopia is sunny during the day and cold during the night and morning, which includes frost in December and January. Farmers harvest their meher crops during this dry period.
Group Name R.NO
- A/wehab Temam 5
- Awel Siraj 14
- Gezahegn Nigusse 23
- Lilina Tedla 32
- Tizazu Ejigu 41
