Potential of retrofitted urban green infrastructure to reduce runoff - A model implementation with site-specific constraints at neighborhood scale

Abstract

The urbanization has resulted in significant changes in the water balance. Urban Green Infrastructures (UGI) have become a promising method for reducing reoccurring floods whilst providing additional social and ecological benefits. However, there are several challenges to successfully implementing UGI in already developed areas, such as accounting for retrofitting UGI scenarios and pre-existing use of spaces. Accurate estimations of the potential of UGI in reducing flood-causing at the watershed scale are therefore important. This study investigates the influence of site-specific constraints on the effectiveness of UGI in reducing flood-causing runoff at the watershed scale. In particular, this study takes urban fabric characteristics in the development of UGI implementation strategies for different types of residential and industrial neighborhoods into account. Furthermore, it applies a hydrological simulation-based approach to estimate the runoff reduction potential of these strategies for a case study in the Metropolitan Area of San José, Costa Rica. The results indicate that UGI implementation potential depends on urban fabric characteristics and modelling different UGI implementation scenarios shows differing hydrological performance. In residential areas, either permeable pavement or infiltration trenches and street planters lead to the highest runoff reduction. In industrial areas, only permeable pavements lead to the highest runoff reduction. Overall, industrial areas enable more potential for UGI and reduce runoff generation. The findings of this study can guide the development of retrofitting UGI scenarios and upscaling strategies under heterogeneous settlement characteristics.