Sustainable Stormwater Management: A Holistic Planning Approach for Water Sensitive Cities

The planning of sustainable stormwater infrastructures for future water-sensitive cities requires new holistic methods. In the Indo-German research project SMART&WISE, a structured approach was developed to improve the planning processes for water infrastructure systems. The developed approach attempts to map the entire decision-making process when planning suitable infrastructures. A basic distinction is made between retrofit and greenfield planning. Four analyses form the basis of the planning approach: (1) Flood Protection, (2) Water Balance, (3) Water Scarcity and (4) Heat Islands. An indexation of different analyses results enables to overlay and visualize the overall result. The approach was tested successfully in two pilot projects: An Indian pilot case in a semi-arid climate zone and a German pilot case in an arid climate zone. It could be shown that the approach is suitable to cope with heterogeneous population and settlement development, climate change and increasing resource scarcity. The approach can help to facilitate interdisciplinary collaborations (especially urban planners and engineers for urban drainage). Increase in evaporation and a decrease in heat is the decisive advantage of low impact development measures (LIDs) for a sustainable stormwater management. However, an increase in evapotranspiration is not recommended in semi-arid or arid regions, since it would further increase water stress. For regions at risk of water scarcity, a balance between water sources, storage, reuse and demand must be achieved.