Status: this preprint has been withdrawn by the authors.
Empirical Estimation of the Spatial Sediment Transport Capacity Coefficient Using the Rain Erosivity Factor and SWAT Model Results in the Han River Basin, South Korea
Chung-Gil Jung,Won-Jin Jang,and Seong-Joon Kim
Abstract. The ratio of sediment delivery is a critical and uncertain factor in model-based assessments of the total sediment yield of watersheds that results from the transport of sediment produced by soil erosion. This study estimates the watershed-scale distribution of sediment yield at a spatial resolution of 1 km by 1 km through evaluating the rain erosivity (R) factor of the Revised Universal Soil Loss Equation (RUSLE) in the Han River basin (34,148 km2) of South Korea over 14 years (2000~2013) using 1-minute data from 16 rainfall gauging stations. For this study, the Water and Tillage Erosion Model/Sediment Delivery Model (WATEM/SEDEM) sediment delivery algorithm is adopted. This algorithm is based on R, the soil erodibility factor K, the length-slope factors LS of RUSLE, and the transport capacity coefficient KTC. The average 1-minute value of R for the basin is estimated to be 3,812 MJ/ha · mm/year. To determine the 1-km grid-based transport capacity coefficient (KTC; generally given from 0.01 to 100) for the transport capacity (TC) equation used in the estimation of sediment transport with WATEM/SEDEM algorithm, the TC results from 181 subwatersheds ranging in area from 75.4 km2 to 281.5 km2 obtained using the Modified Universal Soil Loss Equation (MUSLE) implemented in the Soil Water Assessment Tool (SWAT) are used. A comparison of the suspended solids (SS) simulated using SWAT with the observed values at 7 locations yields an average coefficient of determination R2 of 0.72. Using the SWAT TC, the spatial KTC is determined in each subwatershed. These values range from 0.16 to 112.58, and the average value for the whole basin is 12.58. To permit general estimation of KTC values, multiple regressions are performed using the characteristic watershed factors of watershed slope, watershed area, the K factor of MUSLE, upland crop area (%), and paddy field area (%). A multiple regression equation of KTC with watershed area, K factor, and upland crop area (%) is derived. This equation yields an R2 of 0.76 when compared to the KTC values evaluated using SWAT. The KTC can be determined using information on watershed scale, soil and land use.
This paper is a resubmission of hess-2016-649. We corrected all comments.
Research highlits:
1) In South Korea, the TC in WATEM/SEDEM soil erosion mechanism was first proposed.
2) The notable scientific accomplishments of this study involve the implementation of the TC model and the subsequent derivation of a relationship between the KTC values and the watershed characteristics.
3) We tried to attempt to build models based on fundamental hydrologic and hydraulic processes.
This paper is a resubmission of hess-2016-649. We corrected all comments.
Research highlits:...
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