AN ASSESSMENT OF THE IMPACTS OF HUMAN ACTIVITIES ON RIVER’S WATER QUALITY: A CASE STUDY OF CHIMVU RIVER

Human activities are recognized as major sources of environmental problems. Worldwide freshwater resources, which provide important ecosystem services to humans as well as aquatic organisms, are under threat from rapid population growth, urbanization, industrialization, agricultural activities as well as domestic activities. Therefore, there is a need to assess and monitor these resources so as to as how human activities are having an impact on them. In this context, the physical and chemical water quality of Chimvu River located in Thyolo district, close to Malawi University of science and Technology (MUST) was assessed with possible contamination from agriculture activities and sand mining. The chemical and physical parameters were assessed at seven sampling sites. In addition, a biomonitoring approach was used where by organism from the river were collected to estimate aquatic ecological condition of Chimvu River using South African Scoring System (SASS). The results showed that some of the measured parameters in some sampling stations did not conform to local as well as international standards of water quality. For example, concentration of dissolved oxygen (DO) in almost all sampling stations were below the recommended level of greater than 8mg/l. Turbidity was found to be at above an agreed value of 50 NTU at sampling point 2 where turbidity value was 63.5 NTU. This is attributed to agriculture activities and sand mining activities which happens along the river’s stretch. Biomonitoring assessment revealed that the river is dominated by pollution tolerant as well as semi-tolerant organisms which indicates that the river is polluted hence not suitable for pollution -sensitive organisms

The study therefore proposes the need for further monitoring of the river where the sampling period should be increased in order to cover the whole stretch of the river