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Title:   Author  item
                                            Collick, Amyitem
                                            FUKA, DANIEL - Virginia Polytechnic Institution & State Universityitem
                                            EASTON, ZACHARY - Virginia Polytechnic Institution & State Universityitem
                                            Buda, Anthonyitem
                                            WELD, JENNIFER - Pennsylvania State Universityitem
                                            White, Michaelitem
                                            Veith, Tameria

                                                         - *Tamie*item
                                            Bryant, Rayitem
                                            Bolster, Carlitem
                                            Kleinman, Peter
  Submitted to: Hydrological Processes
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 2/18/2014
                                    Publication  Date: 3/11/2014
                                    Citation: Collick, A.S., Fuka, D.R., Easton, Z.M., Buda, A.R., Weld, J.L., White, M.J., Veith, T.L., Bryant, R.B., Bolster, C.H., Kleinman, P.J. 2014. Predicting phosphorus dynamics in complex terrains using a variable source area hydrology model. Hydrological Processes. 29(4):588-601. doi: 10.1002/hyp.10178.Interpretive Summary: Excess phosphorus (P) loss from agricultural areas leads to a decline in water quality and upsets the ecological balance of major water bodies, such as the Chesapeake Bay.   Reducing the loss from agricultural fields requires a good understanding of the particular sources of P loss and the means by which it is transported to waterways.  Water quality models are expected to predict the timing and quantity of P loss so that watershed managers and planners are able to implement appropriate techniques to reduce the loss of nutrients from the fields.  This study evaluates two versions of the Soil and Water Assessment Tool (SWAT) in a Pennsylvania watershed in order to determine which one is more effective in predicting and locating P loss.  Our work shows that correctly modeling the hydrological processes as well as the nutrient transport processes is critical to accurately predicting runoff and P loss.
                                Technical Abstract: Prediction of phosphorus (P) loss from agricultural watersheds depends on accurately representing the processes governing P loss from agricultural watersheds and the particular transport factors facilitating loss.  The Soil and Water Assessment Tool (SWAT), a model commonly used to predict runoff and P transport, traditionally simulates runoff employing the curve number (CN) method, which assumes infiltration excess runoff, although shallow soils with shallow restricting layers or perched water tables generate zones (variable source areas) of saturation excess runoff.  In this study, we compare traditional SWAT to a re-conceptualized version, SWAT-VSA, which represents variable source hydrology, in a complex agricultural watershed in south central Pennsylvania.  SWAT and SWAT-VSA simulated hydrology similarly (0.69 and 0.65, respectively), but SWAT-VSA outperformed SWAT in predicting P loss from the watershed after incorporating detailed farm field management in both models.  Although SWAT generalized P loss (soluble P loss: 0.01 - 0.02 kg ha-1) across the agricultural fields, SWAT-VSA was able to pinpoint those fields generating higher levels of runoff as well as receiving heavier amounts of P fertilizer applications ultimately resulting in greater P loss (0.01 - 0.20 kg ha-1).  This latest work with SWAT-VSA broadens its use into complex landscapes, illustrates its usefulness as a tool in nutrient management, and continues to advertise the push towards integrating hydrologic modeling with phosphorus management.


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