Multi-scale analysis of climatic and anthropogenic factors on erosion and sediment yield in the Peruvian Andes

The Andean region is susceptible to soil erosion due to steep topography, prevalent rainfall and high probability of earthquakes and landslides. By its impressive length, continuity and height, the mountain ridges significantly disrupt the atmospheric circulation resulting in a wide variety of environmental conditions. The western flank draining to the Pacific Ocean is characterized by strong environmental gradients, rough topography with deeply incised canyons, and highly variable and extreme precipitation patterns. These environmental conditions pose particular challenges for erosion and sediment flux monitoring. The thesis presents new data on the sediment yield of Andean rivers draining to the Peruvian coast. The dataset is based on time series of river suspended load, discharge and turbidity, and sediment accumulation in reservoirs. About 55% of the observed variance can be explained by hydrometeorology and topography, while anthropogenic factors such as land use marginally improve the model predictions. The effect of climate variability on sediment transport was further studied in the Cañete catchment where the 240MW El Platanal hydropower plant is located. By calibrating a coupled hydrological-sediment transport model for the Cañete River, the effect of precipitation variability on sediment transport and reservoir sedimentation was assessed. Even under the most optimistic scenario, the lifespan of the reservoir is shorter that its officially expected functionality of 50 years. The geomorphic processes driving sediment production and transport were quantified using UAV-PPK-SfM techniques. The processing chain was optimized for 4D geomorphic monitoring in rough terrain by including co-registration techniques. By analyzing the spatial patterns in sediment yield along the western Andes, the thesis enhanced the knowledge base on sediment transport to the Peruvian coastal plain. Besides, it illustrated the vulnerability of hydroelectric facilities to climate variability, and showed the potential of drone mapping for 4D hazard monitoring and forecasting in rough and poorly accessible terrain.