Introduction

Water is essential for human health, socioeconomic development, and the provision of long-term environmental services. Natural processes (e.g. precipitation, infiltration, evapotranspiration, condensation, etc.) sustain a large cycle in nature, which is disrupted by urbanization and man-made water systems. As a result, water has been forced into the linear model of “take-make-consume-dispose,” which is economically unsustainable and results in a gradual degradation of water quality as it passes through the system. The move to circular water systems necessitates a rethinking of water infrastructure, the application of cutting-edge technology, and the integration of nature-based ecosystems into grey infrastructure (i.e. hybrid infrastructure). Nature-based solutions (NBS) can be thought of as a catch-all term for addressing the above-mentioned challenges in a more sustainable way, compared to conventional hard engineering. NBS are systemic initiatives that bring more and more diversified natural characteristics and processes into the environment. They solve a single problem (i.e. societal challenge) or a set of problems (i.e. multiple challenges) while also providing environmental, social, and economic advantages, such as biodiversity, climate change mitigation and adaptation, resilience, human well-being, and so on.