The impacts of land cover change on stream discharges in Luvuvhu River Catchment, Vhembe District, Limpopo Province, South Africa

Abstract

Luvuvhu River Catchment experiences floods resulting from heavy rainfall intensities exceeding 15 mm per hour. The generation of runoff is triggered by the rainfall intensity and soil moisture status. In this study, remote sensing and GIS techniques were used to analyse the hydrologic response to land cover changes. Runoff was calculated as a product of the net precipitation and a curve number coefficient. It was then routed using the Muskingum-Cunge method using a diffusive wave transfer model that enabled the calculation of response functions between start and end point. Flood frequency was determined using theoretical probability distributions. Spatial data on land cover was obtained from multi-temporal Landsat images while data on rainfall, soil type, runoff and stream discharges were obtained by direct measurements in the field, Department of Water Affairs and from the South African Weather Services. The results showed that land cover changes had impacted negatively on the hydrology of the catchment. Peak discharges in the catchment were noted to have increased by 17% over the study period while flood volumes were noted to have increased by 11% over the same period. The synergism between remotely sensed digital data and GIS for land surface analysis and modelling was realised, and it was therefore concluded that hydrologic modelling has potential for determining the influence of changes in land cover on the hydrologic response of the catchment.

Mapping Land-Use/Land-Cover Change in a Critical Biodiversity Area of South Africa

“…The area’s relief consists of undulating terrain with plains, hills and mountains that cover an area of approximately 67,000 hectares (ha). The climate is primarily influenced by the intertropical convergence zone [ 27 ]. Rainfall distribution in the area is classified as unimodal, with a rainy season predominantly between October and January [ 28 ].…”

Assessing the frequency of drought/flood severity in the Luvuvhu River catchment, Limpopo Province, South Africa

“…Excessive rainfall is regarded as the main parameter that causes floods and understanding the frequency and climatology of such extreme rainfall events is key in developing measures towards improving coping strategies in any region (Musyoki et al, 2016). Therefore, improving the knowledge of weather systems (tropical lows and cut-off lows) that influence rainfall patterns could help farmers to cope with the effects of extreme rainfall events (Singo et al, 2016). Previous research has revealed that farmers rely on different sources of weather information, such as agricultural extension officers, television or radio, newspapers, friends and cellphones, but poor understanding of the weather information and inaccurate weather forecasts decrease the reliability of forecasts, resulting in farmers being exposed to flood impacts (Armah et al, 2010).…”

“…The occurrence of drought and floods is common in the Luvuvhu River catchment (LRC), impacting negatively on crop production and agricultural income as a result of reduced crop sales, harvest failure and livestock mortality (Devereux, 2007;Mathivha et al, 2016). Rainfall variability can result in either drought or floods and affects agricultural production in especially rain-fed farming areas (Afifi et al, 2016;Kori et al, 2012;Murali and Afifi, 2014;Oseni and Masarirambi, 2011).…”

Ecosystem Service Valuation for a Critical Biodiversity Area: Case of the Mphaphuli Community, South Africa

“…The total area under study is approximately 67,000 ha, with an even distribution of hills, plains, and mountains. The area is characterised by unimodal rainfall distributions, where the rainy season is between October and January, with an average annual rainfall of between 200 and 400 mm [42][43][44]. The total area under study is approximately 67,000 ha, with an even distribution of hills, plains, and mountains.…”