Abstract:
Soil erosion is one of the most important factors affecting water quality of catchment, it is important to assess the effect of soil erosion on water quality in a catchment, the transported sediments from soil erosion are deposited in catchment which lead to the increased pollutants in water treatment plant intake and reduce the performance of water treatment plant, the main objective of this study is to assess the impacts of soil erosion on water quality and its implications on the performance of Kadahokwa water treatment plant, to achieve this assignment, Kadahokwa water treatment plant and intake were visited to get primary data through informal and structural interviews on soil erosion status in the area, ArcGIS software was used to delineate the catchment and for mapping all USLE model factors, to assess the impact of Kadahokwa river sediment load on Kadahokwa water treatment plant, raw water samples were collected in Kadahokwa river during rain and dry seasons, laboratory tests of escherichia coli, turbidity, total suspended solid(TSS) ,sieve analysis and soil water content for bed load sediment were conducted.
Fifty respondents interviewed during this research, showed that the main causes of soil erosion in Kadahokwa catchment are mostly heavy rainfall (60%) and steep slope (30%),the results of laboratory experiment also revealed that turbidity of raw water and total suspended solid are too high during rainy season than dry season and it was contaminated by Escherichia coli, sieve analysis results showed that the soil of Kadahokwa catchment is sandy clay loam with high proportion of sand (84.74%) and the remaining one are silt and clay (15,26%) which cause the damage of valves and taps, filters blockages, fills of tanks and pipes with mud, silt and it can also be causing the delay in water treatment process, the effect of high turbidity of raw water is the increase of sulfate used in water treatment processes, the actual average annual soil loss by using USLE model is 56.69tons/ha/year, after application of various proposed soil erosion control measures, the annual average soil loss is diminished from 56.69 tons/ha/year to 12.23 tons/ha/year, by concluding, soil erosion control measures including soft and hard best management practices (BMPs )are proposed and recommended to be implemented in Kadahokwa catchment.
