A critical aspect of climate change is the increasing frequency and severity of extreme weather events. Climate change is expected to change the frequency and intensity of rainfall, triggering more frequent flooding. Many Indian cities, particularly coastal cities, are already facing frequent flooding causing extensive damage to society and city infrastructure.  In addition, urban development increases flood risk in cities due to local changes in hydrological conditions. The increase of impermeable surfaces in cities reduces the infiltration of rainwater and increases surface runoff resulting in urban flooding. Both climate change and urbanization exacerbate the flood risks in many coastal cities and strain existing urban infrastructure systems.

In this scenario, the development of nature-based solutions such as Blue-Green Infrastructure  (BGI) is recommended as a solution.  BGI refers to the strategically planned network of natural and semi-natural areas with other environmental features designed to provide water resource management by introducing the natural water cycle into urban environments. BGI provides effective measures to manage urban flooding, water supply, and quality regulation while delivering a wide range of ecosystem services. BGI includes elements such as urban forests, parks, playgrounds, retention and detention waterbodies, bio-swales, urban open space, permeable surfaces, green roads, and green roofs etc. BGI can be implemented at regional, neighbourhood and site scales. 

Due to the variety of BGI components and spatial heterogeneity of cities, regional characteristics influence the development of BGI components for a city and, subsequently, the benefits derived from it. Thus, cities in each region need to develop the layout and design of BGI components that are appropriate to the topography, and climate, particularly precipitation patterns.  BGI Toolkits are crucial for cities for equipping local agencies with the resources needed to support the realization of climate resilience through the development of Blue-Green Infrastructure.