Kenya, during its course through the different agricultural and industrial
areas of Gatundu, Gachororo and Juja farms, receives untreated industrial,
domestic and agricultural waste of point source discharges from coffee and tea
factories. During wet season the water is also polluted by non-point (diffuse)
sources created by runoff carrying soil, fertilizer and pesticide residues from
the catchment area. This study involved the calibration of water quality model
QUAL2K to predict the water quality of this segment of the river. The model was
calibrated and validated for flow discharge (Q), temperature (T°), flow
velocity (V), biochemical oxygen demand (BOD5), dissolved oxygen
(DO) and nitrate (NO3-N), using data collected and analyzed during
field and laboratory measurements done in July and November-December 2013.
The model was then used in simulation and its performance was evaluated using
statistical criteria based on correlation coefficient (R2) and
standard errors (SE) between the observed and simulated data. The model reflected
the field data quite well with minor exceptions. In spite of these minor differences
between the measured and simulated data set at some points, the calibration and
validation results are acceptable especially for developing countries where
the financial resources for frequent monitoring works and higher accuracy
data analysis are very limited. The water is being polluted by the human
activities in the catchment. There is need for proper control of wastewater by
various techniques, and preliminary treatment of waste discharges prior to
effluent disposal. Management of the watershed is necessary so as to protect
the river from the adverse impacts of agricultural activities and save it from
Cite this paper
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