Browsing by Author "Malembeka, Fredrick"

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    Assessment of agricultural drought using long-term simulated soil moisture in Simiyu river catchment
    (University of Dar es Salaam, 2007) Malembeka, Fredrick
    Earlier studies in Simiyu river catchment using physics based distributed hydrological model SWAT, suggested that rainfall was not catchment representative, hence attempt was made to interpolate rainfall using rainfall interpolation was also intended to acquire a long-term dry year which would be used in the assessment of agricultural drought using maize as a reference crop. Missing values prevented classification of rainfall years into dry, normal and wet years. Model efficiency criteria were reduced from annual to seasonal models; and as a results models for smaller time scales of monthly, weekly and daily models were not anticipated. SWAT was used to predict soil moisture based on rainfall-runoff transformation in which two outlets were used. Ndagalu outlet gave model efficiency criterion of 0.58 and 0.41 in calibration 91976/77) and validation periods (1980/81) respectively; and as a results, Sayaga outlet was not used in the sequent assessment of agricultural drought due to poor agreement between observed and simulated hydrographs. Furthermore, upon modification it could also be used to compute spatial drought indices and may be used to draw estimated irrigation scheduling margins for different crops in other catchments.