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Title: Development of a soil moisture-based distributed hydrologic model for determining hydrologically based critical source areas

Author
item LI, SISI - Chinese Academy Of Sciences
item GITAU, MARGARET - Purdue University
item Bosch, David
item ENGEL, BERNARD - Purdue University
item ZHANG, LIANG - Chinese Academy Of Sciences
item DU, YUN - Chinese Academy Of Sciences

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2017
Publication Date: 8/29/2017
Citation: Li, S., Gitau, M., Bosch, D.D., Engel, B., Zhang, L., Du, Y. 2017. Development of a soil moisture-based distributed hydrologic model for determining hydrologically based critical source areas. Hydrological Processes. Pp 1-15. https://doi.org.10.1002/hyp.11276.
DOI: https://doi.org/10.1002/hyp.11276

Interpretive Summary: Precise and cost-effective watershed management requires spatial and temporal details of hydrologic characteristics, such as runoff generation areas and flow pathways that can be provided by distributed hydrologic models. However, there is a gap between the complexity of hydrologic processes at field or hillslope scales and the simplicity of operational models at the watershed scale. A spatially explicit watershed model was developed to reduce this gap. The model uses empirical equations and limited parameters to represent the most critical hydrologic processes, soil moisture and surface runoff. The model was tested on three watersheds in the Coastal Plain region of the US. Results indicate good agreement between observed and simulated soil moisture and streamflow.

Technical Abstract: A distributed hydrologic model was developed to provide spatial and temporal information on hydrologic components for watershed management. The model used empirical equations and limited parameters to represent the most critical processes, i.e. soil moisture variation and surface runoff routing. The model was tested on three coastal watersheds, the 22.1 km2 watershed J, the 16.8 km2 watershed K, and the 50 km2 watershed I of the Little River Experimental Watershed in Georgia, US. Water balance, hydrograph, and soil moisture were simulated and compared to observed data. For streamflow calibration, the daily Nash-Sutcliffe coefficient was 0.79 for the watershed outlet and 0.50 and 0.79 at the two sub-watersheds. For the validation period, the Nash-Sutcliffe coefficients were 0.72 at the watershed outlet and 0.52 and 0.73 at the two sub-watersheds. The percent bias was less than 25% for all sites. For soil moisture, the model also predicted the trends well at all five gauges, with a coefficient of determination greater than 0.5. The spatial distribution of surface runoff simulated by the model was controlled by both local characteristics (precipitation, soil properties, and land cover) and global watershed characteristics (relative position within the watershed and hydrologic connectivity), indicating both infiltration-excess runoff and saturation-excess runoff were well represented by the model.