Spatial and Seasonal Dynamics of Total Suspended Sediment, Total Dissolved Solids and Turbidity of a Lacustrine Reservoir in the Magoye Catchment, Southern Zambia

Abstract

Dissolved and suspended sediment that form part of the Total Sediment Load (TSL) affects the quality of water making it unsuitable for selected aquatic invertebrates and livestock. The study aimed at determining spatial and seasonal dynamics in the concentration levels and distribution of selected physical parameters in a small lacustrine system whose main problem was punctuated by rapid deposition of clastic and none-clastic sediment. Water sampling was done during the rainy and cool-dry seasons across the reservoir using sampling bottles and DGPS. Laboratory analysis was done to determine variations in concentration levels of the parameters over time and space. Distributions of selected parameters across the reservoir were analysed using 3D Spatial Analysts Tool, Inverse Distance Weighted (IDW) in ArcGIS 10.2. Using paired T-Test at 0.05 level of significance, the study found statistically significant differences (p<0.001) in the concentration of TDS, TSS, and turbidity between the rainy season and cool-dry season. With exception of TDS, TSS and turbidity were higher in the rainy season than in the cool-dry season. Rainfall was the main control variable regarding seasonality influence on TDS, TSS, and turbidity. The study concluded that although lacustrine reservoirs may be closed systems, they still experience variations spatially and temporally in terms of concentration of TDS, TSS and turbidity. The study recommends implementation of integrated catchment-wide management of anthropogenic activities so as to minimize excess generation, transportation and deposition of sediment, which punctuate elevated levels of TDS, TSS and turbidity.