The impact of deforestation and precipitation regimes on sediment yield in a Peruvian catchment with hydropower operations

Soil erosion is a challenge for the operation and storage capacity of the Chimay Hydroelectric Central (Peru), which produces siltation on its reservoir. An improved understanding of the relationship between recent changes in Land Use and Land Cover (LULC), precipitation, surface runoff and other hydrological processes’ temporal and spatial dynamics, and sediment yield, are imperative for better decision-making regarding sediment management in the catchment. In this study, downscaling of the Global Precipitation Measurement product was performed to better represent precipitation in the temporal and spatial scale in the catchment as ground station-based data is scarce. The downscaled precipitation dataset was used as an input for the SWAT+ model, which later was applied to estimate different variables, including streamflow and sediment yield. The model achieved a satisfactory agreement between observation and simulations in monthly streamflow with Nash Sutcliff Efficiency values greater than 0.80 and yearly sediment yield with a Percent Bias of 10%. The model was applied to different LULC scenarios that depict different levels of deforestation. The simulation results showed that there is a positive relationship between sediment yield and deforestation, while there is also a strong relationship between streamflow and sediment yield, with wet years showing higher sediment yield values. However, other dynamics influence this erosion-prone watershed, such as the intrinsic properties of the soil, and spatial dynamics of the Andean Tussock Grassland vegetation, the predominant land cover class in the catchment