Effects of Land Use on Spring and Streamflow Water Quality in River Malaget Sub-Catchment, Kericho County, Kenya
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Various studies have shown that land use impacts on water quality are attributable to about 80 % of diseases in the developing world. The main objective of the study was to evaluate the effects of land use on water quality in River Malaget sub-catchment. The specific objectives were to: i) establish spring and streamflow water quality; ii) determine the water quality index of the selected sampling points and iii) evaluate the relationship between spring and streamflow water quality in River Malaget sub-catchment. Stratified and purposive sampling techniques were used to select 33 sampling points, i.e., 10 springs and 1 river point from each of the 3 agro-ecological zones. Maps of spatial distribution of the water quality parameters tested were developed. Additionally, MANOVA was used to compare the means from the three agro-ecological zones. Water samples from each sampling point were tested for 15 parameters. WQI for each sampling point and for the entire study area was determined. Parametric results revealed that all samples tested for temperature, electrical conductivity, DO, nitrites and total hardness were within the recommended levels. However, some of the samples tested for nitrates, ammonia, pH, turbidity, total dissolved and suspended solids, BOD, E.coli, fluorides, and phosphates were found to exceed the recommended levels. Pillai’s trace in MANOVA, revealed a significant variability in the distribution of the water quality parameters in relation to land use as the means of the three agro-ecological zones were significantly different, V =1.535, F(20, 44) =7.262, p <.05. Univariate ANOVAs on each of the variables revealed significant effect on temperature, F (2, 30) = 4.833, p > .05; electrical conductivity, F (2, 30) = 14.730, p > .05; turbidity, F (2, 30) = 3.600, p > .05; and nitrates, F (2, 30) = 5.879, p > .05. WQI values ranged from 12.22 to 237.86, i.e., from excellent to very poor water quality. Most of the samples had WQI values which were less than the threshold value of 100. More than half (57.58 %) of the samples were of excellent water quality, while 24.24 % were of good water quality, 9.09 % were of poor water quality and the remaining 9.09 % of the samples were of very poor water quality. The high levels of turbidity in the sub-catchment in all the samples, which exceeded the NEMA and WHO guideline values is largely responsible for the very high WQI values. Student’s independent T-test analysis showed a significant difference (p < 0.05) between streamflow and springs for TSS, total hardness and nitrates. In conclusion, indeed, land use has had an impact on streamflow and spring water quality in the study area, considering the spatial distribution of temperature, nitrates, electrical conductivity and turbidity. It is recommended that farming activities and waste disposal is done far from water sources, at least about 30 m away. Additionally, water should be boiled before drinking and all springs should be protected against contamination.