Prediction of climate change impacts on agricultural watersheds and the performance of winter cover crops: Case study of the upper region of the Choptank River Watershed

Abstract

Elevated C02 concentration, temperature, and change in precipitation patterns driven by climate change are expected to cause significant environmental effects in the Chesapeake Bay Watershed (CBW). Although the potential effects of climate change are widely reported, few studies have been conducted to understand implications for water quality and the response of agricultural watersheds to climate change. The objective of this study is to quantify changes in hydrological processes and nitrate cycling, as a result of climate variability, using the Soil and Water Assessment Tool (SWAT) model. Specifically we assessed the performance of winter cover crops (WCC) as a means of reducing nutrient loss in the realm of climate change and evaluate its impacts on water quality at the watershed scale. WCC planting has been emphasized as the most cost-effective means for water quality protection and widely adopted via federal and state cost-share programs. Climate change data were prepared by modifying current climate data using predicted mean temperature and precipitation change for the future periods (2070-2099) predicted by four global climate models. Current CO2 concentration, temperature, and precipitation increased by 850 ppm, 4.5 °C, and 23%, respectively. Although temperature increase reduced the water and nitrate loads, nitrate loads were found to increase by 40% under baseline land management and WCC were found to be less effective at reducing nitrate (nitrate increased by 4.6 kg/ha). Therefore agricultural conservation practices are likely to be even more important in the future, but acreage goals may need to be adjusted to maintain baseline effects.