Estimating soil erosion rates using ¹³⁷ Cs and ²¹⁰ Pb _ex on cultivated and forest areas in central‐western South Korea

Abstract Soil erosion reduces soil productivity and pollutes streams and reservoirs through sediment inflow. Daecheong Lake, South Korea and its surrounding area, including the study area, is designated as a water source protection zone and has been experiencing increased soil erosion due to climate change, leading to water quality degradation. In this study, 137 Cs and 210 Pb ex radionuclides were used to estimate the medium‐ to long‐term soil erosion rates in cultivated and forest areas typical of the Daecheong Lake region. The average erosion rates estimated using 137 Cs and 210 Pb ex were 4.73 and 1.10 t ha −1 yr −1 , respectively, for the forest area, and 75.61 and 124.70 t ha −1 yr −1 , respectively, for the cultivated area. For the forest area, these rates were similar to those estimated in previous studies, but the rates for the cultivated area were relatively high when compared to previously reported values. In addition, the relationship between erosion rate estimates based on 137 Cs and 210 Pb ex showed different patterns for cultivated and forest areas. This difference may be attributed to the different time scales associated with the 137 Cs and 210 Pb ex methods, enabling the spatiotemporal analysis of erosion that occurred in cultivated and forest areas. Therefore, we demonstrate the potential of using 137 Cs and 210 Pb ex to estimate erosion rates in Korea and suggest that these two distinct radionuclides can be useful tools for understanding the history of soil erosion in cultivated and forest areas through the interpretation of differences in estimated erosion rates.