Evolution of the Limpopo River Basin in Botswana based on morphometric and morphotectonic features from selected rivers using GIS techniques

Abstract

ABSTRACT This study used morphometric techniques to generate new information describing the evolution and hydrogeological behaviour of the Limpopo River Basin in Botswana, based on the analysis of drainage surface features, form, and size. Drainage basins provide basic information on their evolution, which, when quantified, yield information on the interaction between tectonics, climatic, and surface processes. Drainage networks were extracted from the Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) (90 m × 90 m), and subsequently, morphometry indices were computed using ArcGIS 10.5. Drainage network extraction was performed using the Arc Hydro extension in ArcGIS 10.5. ArcGIS 10.5 image processing technique was used to extract lineaments and create rose diagrams. The results showed that the Limpopo sub-basins in Botswana were drained by fourth- and fifth-order streams, with a total drainage area of 107, 871 km2. Additionally, the basin asymmetry and mean bifurcation ratios showed tilting in the sub-basins, suggesting tectonic instability and structural control in a low – to-moderate active tectonic zone. The sub-basins also had a coarse texture, indicating a high infiltration capacity. These results are essential for planning and managing watershed systems, flood risk assessment, and potential groundwater assessment for the different sub-basins of the Limpopo River Basin in Botswana.