Current ability of 137Cs radionuclear fallout method for erosion assessment in Indonesia

Abstract

Soil erosion is one of the most important natural resource management problems in watershed zone that affects soil quality, reduce soil nutrient content and further may harms food resilience. Erosion produced sediment is the biggest pollutant of surface water, contributes further to eutrophication and affecting water quality. Radionuclide Fallout (RNF) have been developed by Unesco to measure erosion qualitatively using isotope trace found in soils surface originated nuclear bomb test. This method has been applied in the Region of Sembalun at Lombok island and Kertasari at Greater Bandung in 2017. Grasslands of Mt Rinjani and Mt. Papandayan have been chosen as the reference sites. Kertasari area possess steeper slopes and receive more rainfall than Sembalun Area. The soil profiles at the expected reference on Mt. Papandayan contain less 137Cs radioactivity than those of Mt. Rinjani. Both study area represents locations where the activity of 137Cs was undetected due to the topsoil removal by high rate of erosion process. Undetected 137Cs radiation is more widespread in Kertasari than in Sembalun area. 137Cs RNF methods for quantitative assessments of erosion seems possess the limitation for the utilization in the steeply sloping region with high soil erodibility due to the presence of undetected radiation area. The method will still useful to be applied in a more flat area for both erosion and sedimentation study.