Hydrological and Water Quality Characteristics of Rivers Feeding into Small Earth Dams for Rural Water Supply: A Case Study of Traditional Authority Kalolo in Lilongwe District
The obligation to ensure adequate and clean water supply to everyone, has necessitated the development of small earth dams for rural water supply in developing countries. In Malawi, there are approximately 750 small and medium dams most of which are used multiple purposes. However, in most cases, the sustainability of these dams is challenged by gross catchment mismanagement and improper designs and set up. In this study, FDC analysis, in conjunction with water quality assessment, was used to evaluate the reliability of rivers flows that supply small earth dams designed for rural water supply in Malawi, using Kalolo area in Lilongwe district as a case study. FDC analysis showed that over 80% of the time, all rivers in the study area would not meet the target community’s water demand, without the dams in place. Water quality assessments show biological contamination as the major water quality problem. Significant seasonal variation in water quality is evident, with the dry season having generally better biological water quality. Further, the study categorized the catchments areas as moderately to largely modified using rapid ecological assessment method. Therefore, the low biological water quality may be attributed to uncontrolled anthropogenic activities in the catchment, arising from lack of proper catchment management. It is then recommended that construction of such small earth dams should be preceded by thorough scientific design through appropriate engineering and environmental studies, encompassing hydrological, geological, ecological and socio-economic factors, if the small earth dams are to result into long term outputs.
Keywords: River flow; small earth dams; flow duration curve; water quality; rural water supply.