Assessment Erosion 3D Hazard with USLE and Surfer Tool: A Case Study of Sumani Watershed in West Sumatra Indonesia

Abstract

Quantitative evaluation of soil erosion rate is an important basic to investigate and improve land use system, which has not been sufficiently conducted in Indonesia. The Universal Soil Loss Equation (USLE) and Erosion Three Dimension (E3D) in Surfer were used to identify characteristic of dominant erosion factors in Sumani Watershed in West Sumatra, Indonesia using data soil survey and monitoring sediment yield in outlet watershed. Climatology data from three stations were used to calculate Rainfall erosivity (R) factor. As many as101 sampling sites were used to investigate soil erodibility (K-factor) with physico-chemical laboratory analysis. Digital elevation model (DEM) of Sumani Watershed was used to calculate slope length and Steepness (LS-factor). Landsat TM imagery and field survey were used to determine crop management (C-factor) and conservation practices (P-factor). Calculating soil loss and map of USLE factor were determined by Kriging method in Surfer 9. Sumani Watershed had erosion hazard in criteria as: severe to extreme severe (26.23%), moderate (24.59%) and very low to low (49.18%). Annual average soil loss for Sumani watershed was 76.70 Mg ha-1 y-1 in 2011. Upland area was designated as having a severe to extreme severe erosion hazard compared to lowland which was designated as having very less to moderate. On the other land, soil eroded from upland were deposited in lowland. These results were verified by comparing one year’s sediment yield observation on the outlet of the watershed. Land use (C-factor), rainfall erosivity (R- factor), soil erodibility (K-factor), slope length and steepness (LS-factor) were dominant factors that affected soil erosion. Traditional soil conservation practices were applied by farmer for a long time such as terrace in Sawah. The USLE model in Surfer was used to identify specific regions susceptible to soil erosion by water and was also applied to identify suitable sites to conduct soil conservation planning in Sumani Watershed.[How to Cite : Aflizar, R Afrizal, T Masunaga. 2013. Assessment Erosion 3D Hazard with USLE and Surfer Tool: A Case Study of Sumani Watershed in West Sumatra Indonesia. J Trop Soils, 18 (1): 81-92. doi: 10.5400/jts.2013.18.1.81][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.1.81]

The Influence of Soil Characteristic Changes on Erosion Rates Based on the Universal Soil Loss Equation (USLE) Method

“…High values of LS factor contribute to the increase of surface runoff velocity, intensify the amount of splashed soil particles, and increase water transport energy. Aflizar et al (2013) stated that during soil erosion prediction using the USLE model at a regional landscape scale, there are challenges in obtaining LS factors. To address this, LS factor calculations are grounded on raster resolution and DEM unit area.…”

Effect of soil erosion and topography on distribution of cadmium (Cd) in Sumani watershed, west Sumatra, Indonesia

“…Typic eutropept is derived from colluvial deposits of lava are distributed only in S3. The different geologic and soil families will affect the Cd in agricultural soils [8,23].…”

“…We collect land use maps, soil maps, and topographic maps to support this research. Estimates of Soil erosion has been calculated by the USLE model in previous studies [8] and for Mapping soil erosion and Cadmium in 3D map were conducted in Surfer® 9 [27] dealing with data from factors soil surveys, topographic maps and geology map…”

“…In detail, the distribution of erosion in Sumani watershed is as much as 51% in severe to moderate criteria found common in upland areas and 49% in low criteria found in lowland and flat areas. At other sites, it was found that the eroded soil from the high plains was predominantly deposited in the lowlands [8]. However, heavy metals have not been analyzed.…”

“…To measure soil erosion on a watershed where there are methodological limitations, estimation based on a model approach tailored to the research objectives should be adopted for accurately measuring erosion on small plot experiments [6]. Universal soil loss equation, USLE [7], which requires only few and tested input parameters can be used as a tool to make land and water conservation plans which have been used throughout Indonesia with little adjustment in factor values in relation to case at hand [1,2,8].…”