Assessing Climate Variability Impact on Thermotolerant Coliform Bacteria in Surface Water

ABSTRACT

This study investigated the impacts of climate variability on thermotolerant coliform bacteria (TCB) transport in the Upper Pearl River watershed (UPRW) in Mississippi. The Soil and Water Assessment Tool (SWAT) was applied using daily observed stream flows and TCB concentration data. The SWAT model was successfully calibrated and validated using both manual and automatic methods from February 2011 to June 2012 (NSE and R² up to 0.79). The Long Ashton Research Station Weather Generator (LARS-WG), a stochastic weather generator, with the global climate model, CCSM3, which was developed by the U.S. National Center for Atmospheric Research (NCAR) was used for future climate variability simulations. The Special Report on Emissions Scenarios (SRES) A1B of the Intergovernmental Panel on Climate Change (IPCC) was simulated for the mid (2046–2065) and late (2080–2099) 21st century. The SWAT model simulated TCB concentrations in surface water and demonstrated reasonable performances (R² up to 0.59 and NSE up to 0.58). During mid-century climate, average monthly TCB levels increase to 175%, while late-century average monthly TCB levels increase to 297% from the watershed. Although late-century climate variability impacts were determined more critical than mid-century climate impacts, appropriate watershed management practices are required to adapt to maintain and improve water quality.

Key Words:

• water quality
• bacteria
• watershed
• SWAT model
• climate change

ACKNOWLEDGMENTS

We acknowledge the contributions of the Special Research Initiatives at Mississippi Agricultural and Forestry Experiment Station at Mississippi State University; Ms. Dunita McCullum at the Mississippi Department of Environmental Quality; and Mr. Kurt Readus, State Conservationist, NRCS/MS. We would also like to acknowledge two anonymous reviewers and the editor of this journal, who helped us to improve the overall quality of this article.