Modelling potential climate change impacts on sediment yield in the Tsitsa River catchment, South Africa

Abstract

The effects of climate change on water resources could be numerous and widespread, affecting water quality and water security across the globe. Variations in rainfall erosivity and temporal patterns, along with changes in biomass and land use, are some of the impacts climate change is projected to have on soil erosion. Sedimentation of watercourses and reservoirs, especially in water-stressed regions such as sub-Saharan Africa, may hamper climate change resilience. Modelling sediment yield under various climate change scenarios is vital to develop mitigation strategies which offset the negative effects of erosion and ensure infrastructure remains sustainable under future climate change. This study investigated the relative change in sediment yield with projected climate change using the Soil and Water Assessment Tool (SWAT) for a rural catchment in South Africa for the period 2015–2100. Data from six downscaled Coupled Global Climate Models (CGCM) were divided into three shorter time periods, namely, 2015–2034, 2045–2064 and 2081–2100. Results were then compared with a control scenario using observed data for the period 2002–2017. The results show that, if left unmanaged, climate change will likely lead to greater sediment yield, of up to 10% more per annum. Peak sediment yield will also increase almost three-fold throughout the century. The study shows that projected climate change will have multiple negative effects on soil erosion and emphasised the need for changes in climate to be considered when embarking on water resource developments.

Simulation of the climate variability effects on sediment production in a river basin using the Erosion Potential Method model integrated with climate models

“…The strong positive correlation between the average annual precipitation and the average annual production of sediments justi es the increase in the production of sediments in all periods of the ETA- (Fontolan, 2019). However, several studies show that extreme precipitation events increase surface runoff, sediment production and reservoir sedimentation (Msadala et al, 2010;Mullan, 2013), so it is worth noting that advances in monitoring and modeling of soil erosion in relation to climate variability include the best representation of these events and the integration and distinction of different types of erosion (Theron et al, 2021).…”

“…However, it is worth noting that to assess the effects of variability climate, the integrated use of models may have limitations in simulating absolute rates of soil loss using averages annual reports of the climatic elements. In addition, the issue of omitting variations of static and dynamic factors can bring uncertainty due to the need to create new assumptions (Theron et al, 2021).…”

“…new assumptions(Theron et al, 2021) -it is important to note that when considering only annual precipitation data for the calculations, the effects of seasonality and extreme precipitation events may be omitted.…”

Evaluation of Wanggu Watershed Carrying Capacity on Water System Indicators in Southeast Sulawesi, Indonesia

“…Sedimentation in a watershed is influenced by several factors including the amount and intensity of rainfall, erosion that occurs, soil type, topography, rock formations, sediment types, and river channel characteristics (Gunawan et al, 2019). The effect of climate change, especially rainfall, causes erosion and sedimentation in a watershed, which is a very important assessment in relation to sediment loads and sediment yields (Bannatyne et al, 2022;Theron et al, 2021). High amounts of erosion also contribute to high sediment loads (Gwapedza et al, 2021), and also have negative effects on land and livelihoods, aquatic ecosystems, water availability, and power generation infrastructure (Bannatyne et al, 2022;Vercruysse et al, 2017).…”