Abstract:
The major objective of this thesis work is to assess the water loss situation in the Baro
basin between Gambella and the outlet to Sudan. The whole basin between Gambella
and Burebiey (the final outlet to Sudan) was first considered as one reach. The thesis
has identified that there are significant water losses that occur in this basin. Tl_ie water
balance of the monthly mean flows indicate thatthere is an average annual water loss of
about 3366 million cubic meters, and the time series shows that overbank spills occur
when the monthly flows at Gambella exceed about 1 . 5 billion cubic meters and the
outflows through bifurcating channels start when flows at Gambella surpass one billion
cubic meters. In order to exactly know where the maximum amount of losses occurs,
the reach between Gambella and Burebiey was divided into three subreaches. After
extending the records at all stations ( 1929-2004), the total mean annual water loss
observed is about 3852 million cubic meters. In the first two subreaches minor losses
are observed, and the major losses which account about 60 % occur in the last subreach,
. between Jekow and Burebiey. About 92 % of these losses are due to outflow through offtaking channels and overbank spills. The paper also considered the potential
evapotranspiration loss in the whole basin between Gambella and Burebiey. These
losses were compared with the total water losses/spills, and it found that the former
losses exceeded the latter ones. It is concluded that if the flows at Gambella are
maintained .at a maximum of 1 . 5 billion cubic meters a month there would be no much
inundation in this basin and, hence, people could get permanent settlement, and their
properties could be secure from damage and wastage.
