Selecting Adequate Spatial Resolution to Estimate Water Flow by Using SWAT Model

Abstract:When we studying hydrological runoff and nutrient cycle of watershed, SWAT(Soil Water Assessment Tool) model is very useful model. SWAT model can be driven delicately with many other data and it has many research case and users. Therefore, SWAT model is important model for studying hydrology. SWAT model is driven with spatial data, which are DEM(Digital Elevation Model), land cover map, soil map and so on, and it simulates water yield, ET(actual evapotranspiration), PET(potential evapotranspiration), sed yield and so on. In study which require spatial data, spatial resolution must be carefully considered. Low resolution might express imprecise and uncertain result, high resolution might express skewed result. Therefore, selecting adequate spatial resolution is important for study which treats spatial data.This study is practiced for selecting adequate spatial resolution to simulating water yield result of SWAT model. Adequate spatial resolution can be different according to Area size and topographic characteristics of target area. This study chooses Taehwa river, South Korea as target area. A high percentage of mountains are located in Korea and Korea also has a lot of steep slope area which can affect to results. SWAT model is driven according to 4 different spatial resolution(30m, 50m, 100m, 300m), and Simulated results are compared with observed results. Target period is set from 2008 to 2013. First 2 years are stabilization duration and 2010 2013 are verification period. According to watershed area size, simulated water yields per spatial resolutions are compared with other results and adequate spatial resolution will be selected.20 50m and 100m 800m resolution are expected to be accurate with observed results according to other studies. It is expected that watershed area size is directly propotional to spatial resolution. Keywords: SWAT, spatial resolution, water yield, river flow Acknowledge : This work was funded by "Development of satellite based ocean carbon flux model for seas around Korea" provided by Korean Ministry of Ocean and Fisheries