SWAT Circumstances Studies
SWAT is a watershed-scale model that applies empirical and physically based approaches to determine runoff responses to differences in land management. The model is primarily intended for application to agricultural watersheds and can simulate a wide variety of agricultural management practices and crop rotations under varying climate scenarios (Arnold et al. 1998 ; Arnold and Fohrer 2005 ; Gassman et al. 2010 ). The key inputs are soils, land cover, and topography (slope), which were intersected to generate Hydrologic Response Units (HRUs): the basic computational unit of the model. Land cover data are based on the 2008 Cropland Data Layer (National Agricultural Statistics Service, U.S. Department of Agriculture 2012 ; Han et al. 2014 ), which includes data for major and minor crop types as well as nonagricultural land classes. Pixel resolution for the 2008 Cropland Data Layer is 30 m. We reclassified some data classes (<0.25% of the original Cropland Data Layer) into available similar classes to simplify the spatial data and reduce the number of model HRUs. For example, sweet corn (0.17%) was reclassified as corn. Topography data are based on a digital elevation model (pixel size = 30 m) from the National Elevation Dataset (U.S. Geological Survey 2016 ), whereas soils data are from the county-level Soil Survey Geographic (SSURGO) database downloaded from the Web Soil Survey (Soil Survey Staff et al. 2019 ). SSURGO data for the study watershed had a minimum map unit size of 684 m 2 (excluding edge polygons). The model extent was the 12-digit watershed for headwater streams Rock and Pratt Creek, and the entire drainage area for Wolf Creek (10-digit HUC 0708020508) and Miller Creek (0708020509) (Figure 1). The final number of model HRUs ranged from 1,684 (Rock Creek) to 7,528 (Wolf Creek).
SWAT requires every single day weather enters off precipitation, heat, cousin humidity, wind-speed, and you may solar power radiation. Weather enter in data was indeed based on 2nd age bracket weather radar (NEXRAD) investigation to own rain and you may Environment Forecast Program Reanalysis (CFSR) (Fuka ainsi que al. 2014 ) to possess kept weather studies. New spatial climate study (NEXRAD and CSFR) try represented on the model because the a vinyl system arranged on a good grid (NEXRAD: 4km spacing; CSFR: about 29 km spacing). SWAT automatically chooses determine items that was near the centroid out of model subbasins. Having NEXRAD research, the amount of artificial gauges receive in watershed line varied out-of 6 (Material Creek) so you’re able to forty two (Wolf Creek). (suite…)