Thanos Papanicolaou
IIHR - Hydroscience & Engineering, The University of Iowa

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Application Note: Watershed Studies
 
Watershed modeling: Watershed related processes are non-linear in nature due to complex interactions in pedology, geology, biology and hydrology and remain all-together a challenging problem with several societal implications.  Some of the perplex questions associated with watershed processes are the effects of scale in monitoring and modeling, the integration of all phases (i.e., surface and subsurface) in monitoring and modeling, and the development of economic and environmental indicators for alternative scenarios and modeling assessment purposes.  Recognizing the critical need for developing an integrated and scientifically sound framework in watershed research, interdisciplinary groups began to emerge, beyond traditional discipline, some innovative concepts for watershed modeling.
   
Modeling the Upper South Amana sub-watershed: Water Erosion Prediction Project (WEPP), upland erosion model to predict sediment erosion rates, was used to model the Upper South Amana sub-watershed (SAW) of the Clear Creek Watershed.  WEPP is a process-based, event-based, distributed parameter, water flow driven erosion prediction model. Climatic data and Digital Elevation Models (DEM) are also incorporated in the model along with the biogeochemical properties of the soils. Biogeochemical analyses were performed to characterize soil properties (e.g. organic matter, clay%, sand%, CEC, pH, etc.) in the Upper South Amana area.  These soil properties were used to calibrate WEPP and to perform a sensitivity analysis to identify the governing parameters of upland erosion in the Upper South Amana Area.  Simulations of sediment erosion and contaminant transport in the SAW via WEPP reveal that for high energetic runoff events, terrain heterogeneity plays a more central role than land use coverage heterogeneity.  Conversely, for low energetic runoff events, the effects of land use coverage heterogeneity become more pronounced and perhaps equal to the effects of terrain.