Exploring soil erosion and reservoir sedimentation through the RUSLE model and bathymetric survey

The aim of the paper was to compare the soil erosion in a river catchment with the sediment volume accumulated at the river mouth. Firstly, the sediment yield was estimated in GIS based on the soil loss according to the RUSLE model, and then further integrated into the sediment production equation. Following this, we estimated the sediment volume accumulated at the river mouth based on the diachronic overlap of topographic and bathymetric data. This methodology was validated for the Eselnita catchment exiting into the Iron Gates I Reservoir. The LS factor has an average value of 4, with lower values for the forest cover. The C factor has an average value of 0.057 being statistically correlated with the RUSLE result. The average soil loss was estimated at approximately 1.89 t ha⁻¹ yr ⁻¹, a value that is validated by previous studies as a low risk of erosion at national scale. The sediment transfer model indicates a distribution of cells sediment production strongly correlated with the time travel to the discharge channels. Overall, the sediment volume obtained by using the RUSLE model corresponds to about 70% of the sediment volume accumulated at the river mouth during 53 years (1970–2022). The difference in sedimentation may be due to human activities along the river mouth's banks to extend the built-up area and to enjoy the waterscape. This paper is relevant for the topic of reservoir sedimentation and recommends the use of the RUSLE model to predict the sediment contribution, especially for small ungauged catchments.