Challenges and considerations of applying nature-based solutions for future mega-cities: Implications for Karachi as a Sponge City

Rapid urbanization contributes to impervious surface areas resulting in higher vulnerability to flooding and loss of green spaces. Recently, sustainable methods like nature-based solutions (NBS) are effectively being used to build resilient cities. These are practices derived from nature by emulating and regulating ecosystem services. Specifically, the adaptation of sponge city (SC) concept as part of NBS is being extensively used in growing cities to help mitigate impacts of development. This study focuses on difficulties encountered by Karachi, such as extreme weather occurrences and flooding. It examines the feasibility of implementing SC methods drawing inspiration from successfully implemented examples of China and Saudi Arabia. The outcomes indicate significance of incorporating NBS and adoption of SC elements in urban planning to provide remedies for Karachi's environmental challenges.