Modeling River Sosiani's water quality to assess human impact on water resources at the catchment scale

To investigate the water quality status at catchment scale, the MIKE 11 modeling system (DHI) was used on the Sosiani, western Kenya. The river's catchment was delineated according to land-use practice into forested (Fz), agricultural (Az) and urban (Uz). Rainfall-runoff processes were modeled using NAM (DHI) and the hydrodynamic model was built using the MIKE 11 HD module. Water quality (WQ) modeling was limited to the oxygen cycle. Model calibration was done on the basis of available measured WQ data at Fz-Az; Az-Uz boundaries. Simulated data versus observed data show model efficiency of 0.70. The Uz contributes 75% of BOD flux in the catchment.