Estimation of Erosion and Sediment using Gavrilović Method in Krueng Jreu Sub-basin, Aceh Province, Indonesia

Abstract

Erosion and sediment in a basin can be estimated by calculating and forecasting using various methods. This study aims to assess erosion and sedimentation in the Krueng Jreu sub-basin in the province of Aceh, Indonesia, using the Gavrilović method. This research was carried out by analyzing secondary data for the last ten years, from 2012 to 2021. Data include geology, slope, land use, and river channel networks. The observed parameters include the coefficient of intensity of erosion, temperature coefficient, and sedimentation coefficient, which are used to analyze the erosion volume, spatial sediment rate, and total sediment rate in the Krueng Jreu sub-basin area. The results of calculations using the Gavrilović method show that four main parameters of the biophysical characteristics of the sub-basin, including (1) sensitivity of soil and local geological conditions to erosion, (2) land use, (3) erosion type, and (4) slope of land, have been shown to affect the occurrence of erosion and annual sediment rates. Geological conditions and land use provide a high level of sensitivity to the results of the coefficient of intensity of erosion. Temperature and rainfall are directly proportional to the annual erosion volume and the spatial sediment rate. The lowest yearly erosion volume and spatial sediment rate in 2019 were 64965.41 m3km-2year-1 and 58206.18 m3km-2year-1. Meanwhile, the highest annual erosion volume and spatial sediment rate will occur in 2021, 101500.71 m3km-2year-1 and 90940.21 m3km-2year-1. Fluctuations in the annual volume of erosion are caused by rainfall, affecting the spatial sediment rate and the total sediment rate.