Assessment of the dynamics of surface hydrology and water quality of the Barotse floodplains, western Zambia.

The seasonal interactions among rivers, floodplains, vegetation and anthropogenic activities result in highly dynamic systems, which tend to exhibit distinctly different biogeochemical patterns
throughout the wet and dry seasons. An assessment and characterization of the spatial-temporal variability of water quality of the Barotse Floodplain, Western Zambia was based on three major components: biological, physical and chemical properties. Samples were collected and analysed for two successive years for both wet and dry seasons. Further, a hydrological model was developed using the Soil and Water Assessment Tool (SWAT) for predicting sediment yields into the floodplain. This was done to investigate for any heavy metal presence in water and sediments due to upstream mining activities, and nutrient transport mechanisms for the separate seasons. Results from bacteriological tests indicated that coliforms were highest on the Mongu-Senanga Transect (85.7%), which had Too-Numerous-To-Count (TNTC> 200 coliforms) readings on several points due to a number of human induced activities. Physio-chemical characteristics
generally showed a low pH (6.5-6.9) for the dry season as compared to the pH (6.9-7.5) for the wet season. The Luanginga River, at the confluence of the Zambezi River, had the highest turbidity (87.9 NTU), electrical conductivity (EC) and total dissolved solids (TDS). Results from the hydrological model gave sediment distribution in the floodplain with 0.609
tons/year/subbasin as the highest yield of sediments in the floodplain from the Luanginga River. The model calibrated and validated with its performance monitored by the P and R-factor. The
parameters read of: P-factor 0.5 to 0.75; and R-factor 0.56 to 1.36 respectively. In conclusion, this study shows that the Barotse Floodplain is still in a pristine state and therefore
results from this research may be used as baseline information for future work. Due to the upstream large scale copper mining and increased anthropogenic activities via the Luanginga River leading to high turbidly, a proxy to the high sedimentation observed, continuous monitoring is encouraged