Soil erosion and sediment dynamics in urban basins under land use and climate change

Rapid land use change in urban basins exposes cities to erosion problems that lead to severe impacts such as sedimentation of channels and reservoirs, degradation of water, and flooding. Climate change threatens the global society by intensifying soil erosion and hydrological extreme events. A changing climate has already increased runoff, reduced snowpacks and shifted precipitation regimes. On the other hand, the impacts of urbanization in a changing climate on the sediment dynamics in urban basins is poorly comprehended. The lack of studies in urban basins is due to challenges in collecting data, mainly in developing countries such as Brazil. Here, we assessed the effects of changes in land use and of climate change on soil erosion and sediment yield in two periods: historical (1985 to 2017) and future (2020 to 2050) in Bandeira river basin, Middle-West of Brazil. In that basin, there is a reservoir built for flooding control and sediment retention. To determine soil loss and sediment yield, we used the InVest model, which was calibrated by using sediment samples collected from the reservoir. This model estimated soil loss according to the Revised Universal Soil Loss Equation (RUSLE) for each pixel, and sediment yield is the product of soil loss and the sediment delivery ratio for each pixel. Future scenarios of land use were determined from the Dinamica EGO model. To incorporate the effect of climate change into the model, the USLE R-factor was calculated using two downscaled Global Circulations Models HadGEM2-ES and MICROC5 forced into two RCP scenarios, 8.5 and 4.5. Thereby, we expect to understand how land use change associated with climate change affects sediment yield and dynamics in urban basins. Understanding those changes is crucial to developing resilience to face critical events such as floods and water shortages, especially in developing countries.