Global Warming Effects on Faecal Coliform Bacterium Watershed Impairments in Portugal

Abstract

Impairment of surface water quality by faecal coliform bacteria is an issue of great importance across the globe. A water quality model, Hydrological Simulation Program FORTRAN, was used to predict the impacts of farming and climate change on faecal coliform loads and concentrations in streams of the Lis River watershed, in the Leiria region, Portugal. The calibrated faecal coliform model simulated well the patterns and range of observed faecal coliform concentrations. The accuracy of the model was evaluated by the per cent bias coefficient and the coefficient of determination. The results indicate a general deterioration of the water quality regarding faecal contamination in Lis River. Maximum daily loads were calculated for each of the impaired streams; an average of 77% reduction in the current faecal coliform load from the watershed is necessary to achieve the established water quality goals by the Council Directive 75/440/EEC (1975). Climate change scenarios (increments on temperature and precipitation) were assumed to predict the behaviour of faecal coliform bacteria in the watershed. The simulated results showed that an increase of 1 degrees C in air daily temperature results in an increase of water temperature of 1.1 degrees C and a 1.5% decrease on faecal coliform bacteria in stream concentration. The combined effect of air temperature (+1 degrees C) and precipitation (+7%) increment leads to an increase of similar to 2% in bacteria inflow to the basin. Copyright (c) 2014 John Wiley & Sons, Ltd.