Rethinking water resources management in a context of environmental change

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Healthy water resources are key to the wealth and well-being of Canadians. Benefits to society, industry, and ecosystems are dependent on our ability to maintain water quality at acceptable levels as well as maintain an adequate temporal distribution of water quantity. A major challenge arises because both water quantity and quality are threatened by stressors including intensive agriculture, increased water demand, land use shifts, and climate change. And, the trend is expected to continue. The applicant has been working on the projection of the main stressors to water quality and quantity (climate change and land use), on the improvement of downscaling techniques, and the development of improved water management routines in hydro-ecological models. In the proposed research program, he aims to build on his previous work by developing methodologies and tools that can streamline projected changes into adaptation decisions. The problem is not new, and several researchers (including the applicant) have already tried to tackle the problem using a top-down approach, which essentially consists of using of a limited set of climate change scenarios to discover future risks. However, recent research has identified critical limitations in that approach. For instance, it has emerged that even when multi-model, multi-scenario projections are used, not all possible conditions are covered and, therefore, plausible risks may be overlooked. There is also no established way to evaluate the credibility of given projection scenarios, making it a challenge to include them in a decision or design framework. The bottom-up approach, which consists of identifying risky situations using stochastically generated climate states and then using projections to evaluate their likelihood in the future, was recently proposed to address the limitations of the top-down approach (Brown et al. 2011; Brown and Wilby 2012; Prudhomme et al. 2010), but several issues remain unaddressed. The objective of this five-year research program is to contribute toward issues that are yet to be adequately addressed in the bottom-up approach. Projected activities include the development and testing of a novel stochastic method that would clone and perturb an initial set of climate change scenarios derived from climate models and generate new ones that would cover the range of variability observed on the historical period; the exploration of new ways of evaluating the adequacy of a given weather generator for risk discovery in the bottom-up framework; the development of criteria to assess the value of a combination of climate models and downscaling technique in the bottom-up framework; and a case study to showcase the improvements in the South Nation watershed. Although the application will be centered in one pilot watershed, the methodology will be of interest for Canada and beyond.