State Water Resources Research Institute Program

Project ID: 2011VT59B
Title: Advanced and Integrative Model of Phosphorus Loading from High Runoff Events
Project Type: Research
Start Date: 3/01/2012
End Date: 2/28/2013
Congressional District: Vermont-at-Large
Focus Categories: Non Point Pollution, Hydrology, Nutrients
Keywords: Topography, sediment, nutrient, phosphorus
Principal Investigators: Bomblies, Arne; Hill, Jane
Federal Funds: $ 24,750
Non-Federal Matching Funds: $ 63,912
Abstract: Lake Champlain Basin (LCB) non-point pollution control factors heavily into the environmental health of the lake, because excessive nutrient loading has resulted in a number of harmful algal blooms. Agricultural activity within the watershed is largely responsible for the phosphorus (P) and nitrogen (N) pollution, which originates in farmed fields within the LCB. Critical source areas (CSAs) have been defined as nonpoint phosphorous sources that contribute disproportionally higher amounts of P to the watershed (Ghebremichael, 2010). The high P loss stemming from CSAs has been attributed to unusually high P concentration within a CSA resulting from soil types and management practices (Pote et al., 1996, 1999; Sharpley, 1995; Sharpley et al., 1996), and areas susceptible to high volumes of runoff and erosion (Pionke et al., 1997; Gburek and Sharpley, 1998). P source areas are locally controlled, but transport in the watershed depends on hydrological processes. In the LCB, studies have looked at P transport within the watershed using the curve-number based SWAT model (e.g. Gebremichael 2010). Since sediment-bound P transport plays a major role in nutrient transport, and because runoff generation processes are variable in time and space in a watershed, a process-based model representing sediment mobilization from individual fields may be better suited to simulate the changes expected from alterations of management of those fields that are small components of subwatersheds. Moreover, because much sediment transport occurs during discrete high precipitation events, a process-based model should be better suited to simulate the impacts of changes in the precipitation regime expected from climatic change on LCB nutrient loading, as well as anomalously high loading stemming from spring flush events and other extreme hydrological events. In synergy with the recent Vermont EPSCoR grant that aims to model regional adaptation to climate change within the LCB, we propose to explore the utility of process-based models to determine CSAs, both present and future, from hydrological characteristics including intrafield topographic variability. The performance of these models will be critically evaluated using a comparison to frequently-applied lumped parameter models such as SWAT.

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