A watershed fragility index for assessing the vulnerability of river ecosystems

Abstract

Accelerating impacts of climate change have heightened the vulnerability of ecosystems, posing critical challenges to biodiversity conservation. While current climate change vulnerability assessment frameworks provide valuable insights, they often fall short of fully integrating local stressors. This paper introduces the Watershed Fragility Index (WFI), an innovative tool designed to address these gaps by offering a more comprehensive evaluation of multiple stressors. The WFI leverages Geographic Information Systems (GIS) for spatial analysis, Fuzzy logic for handling ecological complexity and variation, and the Analytic Hierarchy Process (AHP) for prioritizing stressors. For a better comprehension of various exposures, 12 factors are assessed − flooding susceptibility, temperature change, wildfire potential, soil type, geology, distance from waterbodies, slope, altitude, land use and cover, distance from roads, watercourse barriers, and forest change. They are organized into different sub-indexes related to natural disturbances, environmental fragility, and anthropogenic stressors. The tool is demonstrated on the Humber River watershed in the province of Newfoundland and Labrador, in eastern Canada. The results indicate that certain stressors create vulnerable areas near important lakes. Overall, the watershed is classified predominantly as low fragility. However, the most vulnerable regions, characterized by moderate fragility, are mainly found in the Lower Humber area, which also contains a larger area with roads, watercourse barriers, and steeper slopes. The outputs offer crucial insights to aid environmental planning within the Humber River watershed and can serve as an evaluation tool for other regions. The WFI is a novel tool for policy development, enabling environmental managers and conservationists to create targeted and adaptive strategies that enhance habitat and species resilience through comprehensive and integrated assessment.