Catchment process affecting drinking water quality, including the significance of rainfall events, using factor analysis and event mean concentrations

Abstract

To ensure the protection of drinking water an understanding of the catchment processes which can affect water quality is important as it enables targeted catchment management actions to be implemented. In this study factor analysis (FA) and comparing event mean concentrations (EMCs) with baseline values were techniques used to asses the relationships between water quality parameters and linking those parameters to processes within an agricultural drinking water catchment. FA found that 55% of the variance in the water quality data could be explained by the first factor, which was dominated by parameters usually associated with erosion. Inclusion of pathogenic indicators in an additional FA showed that Enterococcus and Clostridium perfringens (C. perfringens) were also related to the erosion factor. Analysis of the EMCs found that most parameters were significantly higher during periods of rainfall runoff. This study shows that the most dominant processes in an agricultural catchment are surface runoff and erosion. It also shows that it is these processes which mobilise pathogenic indicators and are therefore most likely to influence the transport of pathogens. Catchment management efforts need to focus on reducing the effect of these processes on water quality.

Integrated climate-chemical indicators of diffuse pollution from land to water

“…The expectation on improving water quality at larger scales may, however, be hindered by the i) changes in agricultural practices and intensity ( e.g . increased livestock density) 8 , 9 , and effective levels of actions implemented, ii) temporal chemical patterns (concentration and its variability) in stream water, in relation to monitoring periods and catchment response times 10 , iii) knowledge of catchment-related processes driving water quality 11 and associated hydrological time lags (months to years) and biogeochemical (years to decades) time lags 12 , degradation and recovery, including human activities 13 , and iv) changes in weather 14 . The four parameters are clearly linked 2 and have consequences within review frameworks.…”