Publication Date:
2017-07-11
Description:
A simple grid cell based distributed hydrologic model was developed to provide spatial information on hydrologic components for determining hydrologically-based critical source areas. The model represents the critical process (soil moisture variation) to runoff generation accounting for both local and global water balance. In this way, it simulates both infiltration excess runoff and saturation excess runoff. The model was tested by multi-site and multi-variable evaluation on the 50 km 2 Little River Experimental Watershed I in Georgia, US, and two smaller nested sub-watersheds. Water balance, hydrograph, and soil moisture were simulated and compared to observed data. For streamflow calibration, the daily Nash-Sutcliffe coefficient was 0.78 at the watershed outlet and 0.56 and 0.75 at the two nested sub-watersheds. For the validation period, the Nash-Sutcliffe coefficients were 0.79 at the watershed outlet and 0.85 and 0.83 at the two sub-watersheds. The percent bias was less than 15% for all sites. For soil moisture, the model also predicted the rising and declining trends at four of the five measurement sites. The spatial distribution of surface runoff simulated by the model was mainly controlled by local characteristics (precipitation, soil properties, and land cover) on dry days, and by global watershed characteristics (relative position within the watershed and hydrologic connectivity) on wet days when saturation excess runoff was simulated. The spatial details of runoff generation and travel time along flow paths provided by the model are helpful for watershed managers to further identify critical source areas of non-point source pollution and develop best management practices.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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