Assessing and managing risks from climate change in drinking water supply sources - safeguarding raw water quality through improving catchment resilience

Abstract

Increasing temperatures and changes in precipitation patterns and amounts are expected to increase pressures on water resources and result in decreasing water quality and quantity. Water utilities face the challenge to anticipate and plan for deteriorations in the water quality of untreated abstraction sources (so-called raw water quality) and to manage consequent risks, a challenge exacerbated through deep uncertainty associated with climate change. This research proposes a framework how to integrate effects of climate change on raw water quality into risk assessment and to build capacity to anticipate and respond to change.

A national assessment of public water supply catchments in Scotland was used as a demonstration case for applying the framework. The analysis was conducted with data from 154 drinking water supply catchments from a period of 2011-2016. Empirical relationships between catchment characteristics and water quality were examined to understand overarching drivers, pressures, and underlying catchment sensitivities leading to impacts on raw water quality. Risk screenings were developed for two water quality indicators, colour and E. coli, and UKCP18-based climate and land use projections were used to identify and map catchments and areas with potential increases in risk.

The screenings identified crucial controls on water quality, high risk areas, areas of uncertainty, and allowed first suggestions for possible response options based on catchment vulnerabilities. They also provided a basis for a strategic review of and planning for the complete supply system, by providing a starting point for transferring results and insights from individual sites, and by allowing for a first appraisal of long-term sustainability of supply. By focusing on catchment integrity and resilience as a crucial part of climate change mitigation and adaptive management, this research emphasises an ecosystem-based approach as a frame for water service providers to achieve multiple objectives.

Date of Award	2023
Original language	English
Awarding Institution	University of Dundee
Sponsors	Scottish Government
Supervisor	John Rowan (Supervisor) & Iain Brown (Supervisor)