Quantification of soil erosion in mountain catchment in the Himalaya using meteoric ¹⁰Be as a tracer tool

Soil erosion is one of the major global hazards threatening the food security of the world population. Soil erosion can be a result of both natural and anthropogenic processes. Field monitoring and models (numerical and physical) are commonly used to quantify soil erosion. However, field methods are time-consuming and the models inherently work with a level of uncertainty. Soil erosion studies in the Himalayas have been mostly carried out using modelling but there is a lack of sufficient field data to validate the results. We quantified soil erosion in a small catchment (Pranmati) in the Himalayas using the fallout meteoric ¹⁰Be nuclide for the first time. Based on the ¹⁰Be flux delivery rates determined from global circulation models (GCM), we calculated the rates of soil erosion at discrete points in the hilltop and mid-slope regions of hillslopes. The erosion rates vary between 17 mm kyr^-1 to 68 mm kyr^-1. These rates were determined in pristine areas that are unaffected by anthropogenic activities, thus, indicate the background erosion rates in the region. We established empirical relationships with estimated erosion rates and topographic parameters to assess the sediment dynamics in the hillslopes. It was observed that the sediment redistribution process operates differently in the mid-slope region compared to the hilltop region, due to increasing complexity of the active processes in the mid-slope region.