SEDIMENT AND PHOSPHORUS FLUXES ALONG OAK ORCHARD RIVER, NEW YORK STATE

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A hydrologic model (SWAT) was developed and calibrated for the Oak Orchard watershed to evaluate sources and sinks of sediment and phosphorus along the main channel. The model includes the most important anthropogenic features that impacted water flow and nonpoint source pollution. These features included reservoirs at the Iroquois National Wildlife Refuge (INWR), Waterport and Glendale dams; point sources such as the Erie Canal, US Gypsum, Allen Canning, wastewater treatment plants, and tiledrains at the muckland, an intensely farmed area that was drained to combat malaria in the 19^th century. The model uses 2005 landcover data and has realistic agricultural crop rotation, fertilizer and tillage management schedules developed from Cornell Extension crop guidelines. To achieve the proper water balance observed at the watershed, seasonal inputs of water had to be added from the Erie Canal and the Onondaga escarpment. This water came from outside of the watershed. The best simulation of phosphorus was obtained by reducing the area of farmland in the Muckland slightly and utilizing the acreage of harvested farmland from the agricultural census to specify total crop area. The resulting model has NS prediction efficiencies of 0.81 and 0.91 for monthly flow and total phosphorous respectively. The largest inputs of total phosphorus came from the Mucklands and the river between Glendale and Waterport dams. The model suggest that total phosphorus is not sequestered significantly along the channel system, however sediments are sequestered in the low gradient reach south of the harbor, Glendale Reservoir and the INWR water control structure. Seasonal flows from the Erie canal increased total phophorus by 7%, however this was believed to be due to its effects on water balance.