The Begasheka catchment is some 90 km west of Mekelle, 10km west of Adi
Abi. It is an area where REST have conducted many activities, including
building large water harvesting dams for irrigation.
The catchment is confusing and awkward to define from the ground, since
it is made up a close series of hills a result of river erosion of a peniplain.
There is no view point from which to get an overall view of the catchment.
The total area of the watershed is 1035 ha. Of the total watershed area,
52% is farmland the rest of the land is 29% area enclosure, 13% open grazing
land and 13% homestead. There is extensive terracing throughout the area
and some places are enclosed to prevent grazing.
Topography and Geology
The catchment is a high plateau surrounded by lower ground and within
the catchment there are a close series of hills of similar height. The
elevation of the watershed varies from 1750m at the outlet to 1891m at
the upper most of the watershed. The underlying geology is a grey shaly
metamorphosed limestone, perhaps turbidite, interbedded with sandstone;
sands and gravels fill the valleys.
This watershed is classified as Dry Weina Dega agro climatic zone. According
to the 5 years rainfall data measured at the nursery site in the watershed
(Figure 10), the mean annual rainfall of the watershed is 741 mm. Similarly,
the mean annual temperature and the mean annual potential evapo-transpiration
are 22.90C and 1837mm respectively.
Monthly rainfall for the nursery raingauge
There are many surface water features, dry gulleys cut through the river
valleys and at the exit of the catchment there is permanent surface water
which is used by the local population for drinking and washing. Numerous
check dams have been constructed as well as water harvesting ponds in
the largest tributaries. Groundwater is present in the valleys, 3-4 m
below ground level, which is
collected from hand dug wells, and sealed wells with India mark 2 handpumps
donated by UNICEF.
The rainfall in Begasheka ranged from 680-700mm for the period June 2004
-Feb 2005. Farmers had been recording rainfall until the rains stopped
in Nov 2004. Most of the rain fell in the 2 months July and August. An
early rainfall event of 30mm caused a flood which demolished a water harvesting
pond which had just been completed by REST.