Development and modelling of realistic retrofitted Nature-based Solution scenarios to reduce flood occurrence at the catchment scale

Open Access Publication in Special Issue Nature-based Solutions in River Landscapes in AMBIO (2021), Authors: Valerie Chen, Ricardo Bonilla, Fernando Chapa and Jochen Hack


The publication presents the development of Nature-based Solution scenarios in an urban watershed, taking into account spatial availability based on current land use. The scenarios are derived from field experience obtained in Costa Rica and focuses on the incorporation of multifunctional structures to reduce runoff volume in urban areas. Hydrological modelling of different Urban Green Infrastructure implementation strategies shows their potential impact on flood reduction.

Decentralized Nature-based Solutions such as Urban Green Infrastructures (UGI) are increasingly promoted to reduce flooding in urban areas. Many studies have shown the effectiveness of flood control of UGI at a plot or neighbourhood level. Modelling approaches that extrapolate their flood reducing impact to larger catchment scales are often based on a simplistic assumption of different percentages of UGI implementation. Additionally, such approaches typically do not consider the suitable space for UGI and potential implementation constraints. This study proposes a scenario development and modelling approach for a more realistic upscaling of UGI based on empirical insights from a representative neighbourhood. The results from this study, conducted in the metropolitan area of Costa Rica, show that upscaling the full potential for UGI could significantly reduce surface runoff, peak flows, and flood volumes. In particular, the permeable pavement has the highest potential for flood reducing in public space while cisterns perform best at the property level. These results can guide the formation of policies that promote UGI.

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