Water sensitive planning and design as an ecologically inspired approach to delivering flood resilient urban environment in Sri Lanka

The paper draws on Colombo, Sri Lanka as the case study for developing Water Sensitive Planning and Design (WSPD) to deliver a flood resilient urban environment. Digital data and documentary data were evaluated to analyse water sensitive characteristics, potentials and constraints within the catchment. Spatial analysis tools in ArcGIS were used when analysing issues in the landscape mosaic. Evaluation of the landscape mosaic clearly identifies urban form and its significant issues in creating ecological links and patches, such as, marshes, streams, roads and shrubs that can create potential opportunities during stormwater management. Geographically, the low-lying area plays an important role as the natural detention/retention basin for stormwater of the urban catchment during intensive rainfall. In addition, increased impervious surfaces created by high-density urban development and the limited availability of space have created challenges for retrofitting additional stormwater infrastructure. The study identifies the important role that urban planning can play in safeguarding strategies to deal with urban water related issues in more compromising and accommodating ways when situating stormwater infrastructure to optimise the connectivity and corridors. The study demonstrated the importance of street layouts in the urban landscape to support the development of WSPD. This approach provides sustainable ecological protection and outcomes to achieve a flood resilient environment in the catchment.