| dc.description.abstract | The effect of changes in climate and land cover on watershed dynamics has been well established worldwide. The increasing sediment load in the Manafwa River Catchment has reduced both the capacity of the river Manafwa to support the previous flows as well as deteriorating the quality of water available for treatment as observed at the Manafwa Water Treatment Works. There are also fears of limited flows to support downstream agricultural activities such as at the Doho Irrigation Scheme.
This study was therefore undertaken to investigate and quantify the impact of both land use and climate change on the stream flow in river Manafwa. Remote sensing and GIS technology was used to detect and classify trends of land use change in the catchment from 2008 to 2013 to 2018, and the impact of these changes on the streamflow. HEC-HMS software was used to model river year 2068 using IPCC-predicted climate change scenarios.
It was found that the area covered by vegetation was 1057km2, 687km2and 306 km2 in 2008, 2013 and 2018, respectively. This implies a rapid decline in vegetation cover which is cleared to provide land for farmland and human settlements.
The USLE model was used to estimate the sediment loads in the streamflow. ArcGIS was used to derive the parameters for the USLE model. Sediment load values of 648,447, 2,146,848 and 2,988,378 tons for 2008, 2013 and 2018 respectively were obtained. This shows a significant increase in sediment load with decline in vegetation, in the Manafwa River Catchment.
The climate change projection and analysis were done using the A1B and A2 scenarios up to 2068. The analysis of the scenarios showed that there is a likelihood of reduced stream flows in river Manafwa. | en_US |
