A conceptual approach for evaluating the multiple benefits of urban flood management practices

Abstract

This paper focuses on the spatial distribution of the dominant and relevant benefits of urban flood management based on context-and location-specific evaluations. We explore the conceptual rationale and describe a detailed methodology for assessing the benefit profile, benefit intensity, and comment on benefit dependencies arising from urban flood management practices that utilise green infrastructure. A case study is described which demonstrates the application of the concepts in Portland, Oregon, USA. A Geographic Information System approach is developed to evaluate some of the multiple benefits of the East Lents Floodplain Restoration Project. Results are presented in the form of a comparative benefit profile, and a spatially distributed benefit intensity. The paper concludes with the implications of the methodology for future multiple benefit evaluation of urban drainage and flood management systems.

Evaluating the multiple benefits of a sustainable drainage scheme in Newcastle, UK

“…The multiple benefits GIS toolbox demonstrates the spatial distribution of the benefits (and disbenefits) of BGI and how their intensity changes with distance from the infrastructure, illustrating how benefits may radiate out from the site of intervention (Hoang et al, 2016;Morgan and Fenner, 2017 location-specific evaluations of the spatial extent of benefits that are dependent on the pre-existing environmental conditions. For instance, the benefits of a BGI project in a densely residential area with limited current greenspace will generate a different benefit profile and spatial distribution to the same project in an area with abundant greenspace.…”

“…While many multiple benefits have been reported in the literature Ellis, 2013;Jose et al, 2015), they are often valued notionally and so difficult to include in funding proposals and thus implement widely (Ashley et al, 2015;O'Donnell et al, 2017;Thorne et al, 2015). To address this need, new tools and methodologies have been developed to evaluate BGI and SuDS, for example lifecycle assessment (Casal-Campos et al, 2015), geographic information system (GIS) evaluation (Hoang et al, 2016;Morgan and Fenner, 2017;Norton et al, 2015) and spreadsheet monetisation (CIRIA, 2015).…”

Managing urban flood risk in Blue‐Green cities: The Clean Water for All initiative

“…They are by no means definitive, and in future research, determining the pollutant trapping rate of, for example, NOx and particulates could provide a more comprehensive evaluation of the ability of BGI to trap airborne pollutants. Hoang et al () conclude that, in addition to providing flood storage during a flood event (its primary function), the East Lents project contributes positively beyond the project area by improving landscape connectivity, amenity accessibility, and habitat accessibility when it is not flooded. Carbon sequestration and noise reduction were found to have declined immediately following construction of the project; however, these are expected to be temporary impacts due to removal of vegetation during the restoration works.…”

Spatial Evaluation of Multiple Benefits to Encourage Multi-Functional Design of Sustainable Drainage in Blue-Green Cities

“…It is clear from many studies that not all benefits occur simultaneously, and some benefits may preclude the establishment of others [14,20]. For example, in a flood plain restoration scheme in the Johnson Creek watershed in Portland Oregon, recreational benefits were found to be in direct conflict with habitat and biodiversity benefits [21].…”

“…The grid square resolution over which the calculations are performed can vary from 1 m × 1 m to 30 m × 30 m, depending on the purpose and scope of the analysis. These tools have been used to generate benefit intensities and benefit profiles arising from flood mitigation interventions in a number of cities including Portland, USA [20] and Newcastle, UK [37]. In the latter location, six benefit categories were modelled to demonstrate the approach, including access to greenspace, air pollution trapping (PM10), carbon sequestration, flood damage avoided, habitat size and noise attenuation.…”