Stormwater best management practices: Factors influencing resident adoption and catchment-scale effects on runoff quantity and quality

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2022-12
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Marmur, Breanna L.
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Thompson, Jan
Kaleita, Amy
Tyndall, John
Wolter, Peter
Zhou, Yuyu
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Natural Resource Ecology and Management
Abstract
Stormwater best management practices (BMPs) can restore more natural hydrologic cycles in cities and reduce impacts of urbanization and climate change by decreasing surface runoff and pollutant transport. Distribution of such practices throughout the landscape, including private properties, requires participation of a variety of stakeholders. This dissertation is focused on four studies related to residential stormwater BMP retrofits. In the first study literature about resident BMP adoption was reviewed to investigate how decisions to adopt BMPs are influenced by experiences with water-related and stormwater issues, interactions with other people, and participation in education and outreach. This review indicated residents are strongly influenced by experiences with local water-related and stormwater issues and by social norms and interactions in their communities. Outreach programs could thus be improved by directly addressing local stormwater issues and how BMPs can mitigate for them, and by highlighting instances of local BMP adoption to increase desirability of these practices. The second study reports on analyses of four homeowner surveys and investigated the effects of outreach on resident knowledge and opinions about water quality, stormwater management and BMP implementation. Overall, community education and outreach programs increased resident knowledge about local water quality issues and BMPs and led to increased practice adoption. Intensive education efforts (direct communication including regular mail and e-mail and personal invitations to events) were even more effective. This points to the potential effectiveness of targeting efforts to encourage more residents to implement BMPs through direct communication aimed at increasing their awareness of stormwater and stormwater management practices. The third study was focused on a before-after-control-treatment paired watershed project designed to investigate the impacts of 25 small-scale BMP retrofits on runoff quantity and quality in residential catchments in central Iowa. BMPs installed in the treatment watershed reduced effective impervious area (EIA) by 2% (1,600 m2). Peak discharge decreased immediately following BMP installation but increased during the subsequent period. Total event flow volume also decreased soon after practice implementation but then increased such that no change was detectable at the end of the project. No change in water quality metrics were measurable. More strategic placement of BMPs to treat EIA (rather than non-connected impervious surfaces) and proper practice maintenance are likely to improve performance of BMPs at a landscape scale. In the fourth study the Storm Water Management Model (SWMM) was used to investigate a set of BMP retrofit scenarios under current and future climate conditions. This included assessment of the accuracy of SWMM tools (the LID Controls) for simulating clustered BMPs. The model simulated runoff adequately but underestimated peak and total flow volumes for small storm events. The effect of specific BMPs was also modeled and indicated implementation of a variety of practices enhanced overall effectiveness at the catchment scale. A final set of simulations examined performance of BMPs for potential future climate conditions (warmer and wetter). This indicated that properly maintained BMPs could mitigate for anticipated effects of climate change and that even impaired BMPs could mitigate some of those effects. Overall, work presented in this dissertation demonstrates stormwater management in residential catchments can mitigate negative water quantity and quality effects associated with both urbanization and climate change and provides insights to improve outreach programs.
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