Evaluating the influence of climate change on the fate and transport of fecal coliform bacteria using the modified SWAT model

Authors: JEON, DONG JIN - Gwangju Institute Of Science And Technology; LIGARAY, MAYZONEE - Ulsan National Institute Of Science And Technology (UNIST); KIM, MINJEONG - Ulsan National Institute Of Science And Technology (UNIST); KIM, GAYOUNG - Ulsan National Institute Of Science And Technology (UNIST); LEE, GIL - Ulsan National Institute Of Science And Technology (UNIST); Pachepsky, Yakov; CHA, DONG-HYUN - Ulsan National Institute Of Science And Technology (UNIST); CHO, KYUNG HWA - Ulsan National Institute Of Science And Technology (UNIST)

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2018
Publication Date: 12/29/2018
Citation: Jeon, D., Ligaray, M., Kim, M., Kim, G., Lee, G., Pachepsky, Y.A., Cha, D., Cho, K. 2018. Evaluating the influence of climate change on the fate and transport of fecal coliform bacteria using the modified SWAT model. Science of the Total Environment. 658:753-762.

Interpretive Summary: Considerations and projections of global change must include microbial water quality issues. Elevated temperature can change growth and survival of microorganisms, and elevated rainfall will change the transport of microbes to water sources with the overland flow. These changes in microbial fate and transport can be estimated with the water quality models provided the responses of microbes to changes in weather are simulated correctly. Recently we improved the microbial module in the USDA-ARS model SWAT by including new information about the microbial responses on the land and in water to temperature and season. In this work, we used this improved SWAT model to assess the effect of the projected changed in weather on the water quality characterized by the bacteria E. coli concentrations. We found that the levels of E. coli will increase both in soil and in stream water for the range of global change scenarios. Results of this work can be used by water management professionals responsible for water use in recreation, irrigation, aquaculture, and other fields affecting food safety and public health.

Technical Abstract: Fecal coliform bacteria (FCB) contamination of natural waters is a serious public health issue. Therefore, understanding and anticipating the fate and transport of FCB are important for reducing the risk of contracting diseases. The objective of this study was to analyze the impacts of climate change on the fate and transport of FCB. We modified both the soil and the in-stream bacteria modules in the soil and water assessment tool (SWAT) model and verified the prediction accuracy of seasonal variability of FCB loads using observations. Forty bias-correcting GCM-RCM projections were applied in the modified SWAT model to examine various future climate conditions at the end of this century (2076–2100). Lastly, we also compared the variability of FCB loads under current and future weather conditions using multi-model ensemble simulations (MMES). The modified SWAT model yielded a satisfactory performance with regard to the seasonal variability of FCB amounts in the soil and FCB loading to water bodies). The modified SWAT model presented substantial proliferation of FCB in the soil (30.1%–147.5%) due to an increase in temperature (25.1%). Also, increase in precipitation (53.3%) led to an increase in FCB loads (96.0%–115.5%) from the soil to water body. In the in-stream environment, resuspension from the stream bed was the dominant process affecting the amount of FCB in stream. Therefore, the final FCB loads increased by 71.2% because of the growing peak channel velocity and volume of water used due to an increase in precipitation. Based on the results of MMES, we concluded that the level of FCB would increase simultaneously in the soil as well as in stream by the end of this century. This study will aid in understanding the future variability of FCB loads as well as in preparing an effective management plan for FCB levels in natural waters.