Cumulative Effects Assessment in Community Watersheds at Different Spatial Scales: A Review of Indicators

Abstract

Cumulative effect assessments (CEA) for water systems are becoming more necessary as pressures from multiple stressors impact communities, watersheds, and basins. CEA is an important tool for shifting from fragmented to holistic, integrated management as per the Integrated Water Resources Management (IWRM) paradigm. Through a review of scientific literature, this study analyzed the patterns and use of indicators for upstream-downstream linkages. This study found that five categories of spatial scale approaches are used: the national/regional scale, basin scale, watershed scale, local scale, and the specially defined multi-scale approach. It was found that CEA has been applied using a high-level, qualitative approach for national, regional, and multi-scale studies – these undertakings inform strategic planning and sustainable decision-making. Basin, watershed, and local scale CEA studies have focused on quantitative modeling of environmental and human systems. These assessments emphasized the interconnectedness of water systems, as well as the role of policy development and stakeholders in improving system outcomes. Four indicator categories were found to span all five spatial scales: water quality (occurred in 64% of the literature), water quantity (53%), land use (56%), and landscape characteristics (67%). These indicator categories provide a common foundation for understanding stressor interactions, impact response, and upstream-downstream linkages. However, further research is needed on temporal scales and the integration of time into CEA for watersheds. This review found that CEA, a tool which is useful for a variety of scales, can help find a balance between present and future needs and further community sustainability using a holistic and integrated approach.