Abstract:
One of the famous and universally applied drought index known as Palmer
Drought Severity Index (PDSI) was used to examine the drought parameters of
the basin. This method used precipitation, evapotranspiration, soil moisture
recharge and soil moisture loss as an actual and potential values as input data.
To study the drought situation of the basin, 34 years rainfall and mean
temperature data were collected from 18 stations which located in side the
basin and also the soil types derived from soil map was also collected from
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Ministry of Agriculture, Ethiopia,
t The analysis shows that PDSI can be positive (moisture surplus) or it can be
negative (moisture stress or drought) condition. By using the result of PDSI
values of each station, SDF graph of the basin were developed.
Accordingly, the 5 year return periods of drought shows 8% of the basin was a
drought duration less than 5 months, 74% of the basin was a drought duration
of 5 to 6 months, 16% of the basin was a drought duration of 6 to 7 months and
2% of the basin was a drought duration of 7 to 8 months whereas a 10 year
return periods shows 2% of the basin was a drought duration less than 9
months, 6% of the basin was a drought duration of 9 to 10 months and 92% of
the basin was a drought duration of 10 to 17 months.
Finally the severity, duration and frequency of occurrences of the drought were
regionalized by interpolating the value of SDF at each station by help of
Arc View GIS environment.
