Submitted to: Human and Ecological Risk Assessment
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/28/2014
Publication Date: 1/1/2015
Publication URL: http://handle.nal.usda.gov/10113/60222
Citation: Jayakody, P., Parajuli, P.B., Brooks, J.P. 2015. Assessing climate variability impact on thermotolerant coliform bacteria in surface water. Human and Ecological Risk Assessment. 21:691-706. Interpretive Summary: This study used a series of models to estimate the effect extreme climate change would have on transport of bacterial and nutrient contaminants. The models were applied to the Upper Pearl River Watershed in Mississippi, using bacterial data collected from the streams as well as historical nutrient and physicochemical characteristics from US Geological Survey water monitoring stations. The models were validated with real world data collected from other watershed streams in Mississippi. The models estimated that, given two potential scenarios, which predict moderate and extreme climate change, mid-century bacterial water levels could vary between a 54% reduction to a 1600% increase from baseline (current levels). Late-century bacterial levels could see as high as a 2000% increase from baseline. The studies demonstrated that climate change could have a strong effect on the presence of fecal coliform bacteria in surface water, which could compromise public health or pass water purification costs onto the consumer. That being said, bacterial levels will be dependent on the direction and intensity in which the climate changes and mitigation steps taken by the world’s population.
Technical Abstract: This study investigated the impacts of climate variability on fecal coliform bacteria (FCB) transport in the Upper Pearl River Watershed (UPRW) in Mississippi. The Soil and Water Assessment Tool (SWAT) was applied to the UPRW using observed flow and FCB concentrations. The SWAT hydrologic model was successfully calibrated and validated for daily time steps using both manual and automatic (SUFI-2) methods from Feb 2011 to June 2012 (NSE and R2 up to 0.79). Future climate variability was simulated with the LARS-WG, a stochastic weather generator, using the global climate model, CCSM3, which was developed by the U.S. National Center for Atmospheric Research (NCAR). The SRES (Special Report on Emissions Scenarios) A1B of the Intergovernmental Panel on Climate Change (IPCC) were simulated for the mid (2046-2065) and late (2080-2099) century. The FCB simulations showed acceptable model performances (R2 up to 0.59 and NSE up to 0.58). During the mid-century climate, bacterial levels varied between a 54% reduction to a 1,613% increase, while late-century FCB levels varied from a 56% reduction to a 2,175% increase.