Nature-based solutions for flood mitigation in informal settlements in Bangkok, Thailand

Abstract

Nature-based solutions (NbS), such as green roofs or pervious pavements, are systems promoting stormwater retention and they are increasingly being recognized as effective means of mitigating floods and enhancing climate resilience. However, there is limited research on the use of NbS in informal settlements. This study aimed to address this gap by exploring the potential of NbS in mitigating floods in Bangkok’s Baan Mankong (BMK) informal settlements. Using the PCSWMM hydrological software, this study compared the effectiveness of different NbS retrofitting scenarios in reducing floods in three BMK sites in Bangkok: Sirin and Friends, Chatuchak Community, and Pracha Ruamjai. It found that retrofitting the sites with pervious pavements was the most effective method for flood reduction, while green roofs only reduced outflow during low rainfall events, and rain gardens were only effective if large enough and placed downstream. In addition to retrofitting existing settlements, this study also explored the potential for future BMK site designs that incorporate more green spaces to reduce outflow. The findings suggest that designing future BMK sites with more green spaces could be a viable solution for creating more flood-proof settlements. Overall, this study provides insights into the appropriate NbS for retrofitting existing BMK settlements and offers possibilities for future BMK site designs that are more resilient to flooding.