Sensitivity of streamflow and microbial water quality to future climate and land use change in the West of Ireland

This study applied catchment modeling to examine the potential effects of climate change and future land management variations on streamflow and microbial transport sensitivities for two locations in the west of Ireland (Black River and Fergus River). Simulations focused on plausible combined scenarios of climate, population and agricultural production variations for the 2041–2060 period and compares resultant impacts to a baseline existing period (1994–2007). The variations in monthly, seasonal and annual streamflow, and the daily microbial load (for E. coli) were used to assess sensitivities. Results indicate that possible future changes in microbial load for both the Fergus and Black catchments typically follow projected seasonal fluctuations in precipitation and streamflow. Increased winter rainfall (intensity and frequency) will cause significant impacts on microbial transport, representing a period of increased risk. An increase in microbial source loads to land, concomitantly with projected changes in climate is likely to exert greater microbial pollutant pressures on surface waters. The simulated scenarios, and resultant microbial load changes, suggest that future variations in land use/management may be as important as the effects of climate change on in-stream microbial pollutant loads. Outcomes from this study can prove useful for informing water resource managers and other decision makers about potential impacts. This information can instigate the development of adaptation measures needed to alleviate increased catchment pollution from microbial contaminants (and other pollutants) in future years.