Tools for Climate Change Vulnerability Assessments for Watersheds
It is expected that the impacts of climate change on Canada’s water resources will be significant. Climate induced changes in precipitation and air temperature will lead to earlier timing of peak flows, greater frequency of flooding, and more extreme drought conditions. Changes in climate and the related impacts on terrestrial and freshwater environments will also affect nutrient cycling, stream temperatures, the distribution, concentration, and timing of contaminants, as well as the transport and concentrations of sediments in watercourses. Such changes are consequential to human communities and freshwater ecosystems and as a result social-ecological systems in Canada are “vulnerable” to the effects of climate change.
This compendium of tools was prepared for use by technical experts, adaptation planners and resource managers to develop climate change vulnerability assessments of water quantity and water quality at a watershed scale.
Drawing guidance from the Intergovernmental Panel on Climate Change (IPCC) this compendium defines vulnerability assessment as a process for assessing, measuring, and/or characterizing the exposure, sensitivity, and adaptive capacity of watersheds to climate change. The purpose of a vulnerability assessment is to generate knowledge that improves understanding of the implications of climate change. The knowledge generated by a vulnerability assessment can inform allocation of resources for climate change planning and adaptation.
The range of approaches available for assessing vulnerability include an “impact assessment” (focusing on exposure to future climate and sensitivity of the system to that change), a “first order vulnerability assessment” (focusing on exposure and sensitivity to both biophysical and socio-economic impacts), and a “second order vulnerability assessment” (a first order assessment that includes a consideration of adaptive capacity). These approaches represent “top- down” methods of assessing local impacts on human communities and ecosystems. “Bottom-up” or participatory approaches represent distinct though complementary approaches which draw upon the perspectives and knowledge of communities to understand current and future vulnerabilities. The selected approach will largely depend on the available knowledge, data, technical abilities, and capacity (people, time, and money).
To identify tools relevant to the Canadian context, Canadian and international case studies of watershed-scale vulnerability assessments were used. Tools were selected to be representative of a broad range of water resource issues, data needs, and technical capabilities.
The tools in this compendium are varied and diverse. They range from indicator-based approaches to sophisticated hydrological models that calculate exposure to flood events under future projections of climate change. They also range from qualitative to quantitative approaches that address a broad range of characteristics of social-ecological systems.
This compendium describes tools in a variety of ways. First, an “at a glance” overview summarizes the full suite of tools that are described in more detail. For each tool, a summary is provided describing the approach, inputs/outputs, user considerations, and citations where readers can go for more information. Next, a framework for classifying tools according to the dimensions, components, and elements of vulnerability is also provided. The purpose of this classification is to represent the full range of considerations and commonalities across all vulnerability assessments and related tools. Lastly, more tools were identified than are described here and as a result the reference list includes more citations than are referenced in the report so it can be used as a searchable resource.