Many cities have trouble getting rid of surface water collecting during heavy rains and flooding. New thinking is being developed – and practiced: the natural habitat has ways of doing this that are sustainable.
Plants, the soil and water have natural characteristics that can help clean the air, lower temperatures by cooling, remove particles, suck up carbon dioxide by photosynthesis, make plants grow and so suck water. Plants and soil can absorb emissions, clean water and keep water in place for a long time.
The trick is to increase the number of plants, use permeable surfaces, cleaning ponds, open up rivers/streams or build rainbeds for plants. Making roofs green will absorb water and make it use longer time to reach the drains. The amount of water flowing into the drainage system can be dramatically reduced in this way, 20-70 % depending on conditions.
Water cycle landscaping is a term used for large scale planning and integration of resources, including evaluation of energyuse in buildings.
The cities are ecological systems and must be treated as such. Broad systems/ecological urban planning will get us there and natural processes will be part of the design.