Climate and land-use change impact on faecal indicator bacteria in a temperate maritime catchment (the River Conwy, Wales)

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  • Gianbussi Bussi
    University of Oxford
  • Paul Whitehead
    University of Oxford
  • Amy Thomas
    Bangor University
  • Dario Masante
    Bangor University
  • Laurence Jones
    Bangor University
  • Jack Cosby
    Bangor University
  • Bridget Emmett
  • Shelagh Malham
  • Christel Prudhomme
    Loughborough University
  • Harvard Prosser
    Cardiff University
Water-borne pathogen contamination from untreated sewage effluent and runoff from farms is a serious threat to the use of river water for drinking and commercial purposes, such as downstream estuarine shellfish industries. In this study, the impact of climate change and land-use change on the presence of faecal indicator bacteria in freshwater was evaluated, through the use of a recentlydeveloped catchment-scale pathogen model. The River Conwy in Wales has been used as a case-study, because of the large presence of livestock in the catchment and the importance of the shellfish harvesting activities in its estuary. The INCA-Pathogens catchment model has been calibrated through the use of a Monte-Carlo-based technique, based on faecal indicator bacteria measurements, and then driven by an ensemble of climate projections obtained from the HadRM3-PPE model (Future Flow Climate) plus four land-use scenarios (current land use, managed ecosystem, abandonment and agricultural intensification). The results show that climate change is not expected to have a very large impact on average river flow, although it might alter its seasonality. The abundance of faecal indicator bacteria is expected to decrease in response to climate change, especially during the summer months, due to reduced precipitation, causing reduced runoff, and increased temperature, which
enhances the bacterial die-off processes. Land-use change can also have a potentially large impact on pathogens. The “managed ecosystems” scenario proposed in this study can cause a reduction of 15% in average water faecal indicator bacteria and up to 30% in the 90th percentile of water faecal
indicator bacteria, mainly due to the conversion of pasture land into grassland and the expansion of forest land. This study provides an example of how to assess the impacts of human interventions on the landscape, and what may be the extent of their effects, for other catchments where the human use of the natural resources in the uplands can jeopardise the use of natural resources downstream.

Keywords

  • Pathogens; Water quality modelling; River Conwy; Climate change; Land-use change
Original languageEnglish
Pages (from-to)248-261
JournalJournal of Hydrology
Volume553
Early online date10 Aug 2017
DOIs
StatePublished - Oct 2017

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