Soil Erosion and Sedimentation Rate using Cesium-137 in the Sembrong Catchment
Abstract:
The use of Fallout Radionuclides (FRNs) as tracers for the study of soil erosion and sedimentation in catchment areas is still not very popular when compared to conventional methods in Peninsular Malaysia. However, this approach is gaining ground among researchers because various factors have been identified especially in small study areas in parallel with the time period of the study. In this study, Cesium-137 is used as a medium-term tracer to measure the rate of soil erosion in the Sembrong catchment area, Kluang as a study site for two different study seasons. The Sembrong catchment area is the main choice for this study and the area is not very large and is among the catchment areas that have the most important ecosystems in Peninsular Malaysia. It has a fresh water reservoir of 7.76 km2, with an estimated storage capacity of 24.84 million m3 and covers an entire catchment area of approximately 130 km2. Sediment core sampling is carried out in two different seasons, namely the rainy and dry seasons, using standard metal corers, involving sampling at several sampling stations that involve a variety of land uses. All the sediment samples taken were pre-sliced by 2cm and brought to the Radiochemistry and Environment Group (RAS), Nuclear Malaysia to undergo the sample preparation process such as drying, sieving and finally for analysis using a Gamma Spectrometry. The results of the analysis show that the rate of soil erosion and sedimentation for both seasons is variable where the dry season only gives the value of the soil erosion rate. Meanwhile, the rainy season has provided both soil erosion values and sedimentation rates for the overall results. This situation is shown in the dry season which has given the value of the soil erosion rate between 5.09 t/ha/y to 65.2 t/ha/y. Meanwhile, the value of soil erosion and sedimentation during the rainy season ranges from 8.02 t/ha/y to 39.78 t/ha/y and -4.81 t/ha/y to -50.81 t/ha/y, respectively. Rubber and oil palm plantations refer to Station 17 and station 4/6 which are located near Lake Semberong and Sungai Sembrong have the highest soil erosion and sedimentation rates at 51.03 t/ha/y and -50.81 t/ha/y respectively. In conclusion, 137Cs as a medium-term tracer has been successfully used to determine the rate of soil erosion and sedimentation in two different seasons for the Sembrong catchment area.
