Water Sensitive Urban Planning

Abstract

Sheetal Sharma

Extreme weather events responding to imbalances in natural and physical environment systems have been observed recently with floods, droughts, tsunamis etc, mostly in the urban areas of the world. Several studies carried out have modelled surface water runoff from land use and land cover with differential precipitation and found that surface runoff increases with the proportion of built up areas. Despite these facts, some urban catchments still reveal a better natural water cycle though built up is more in them as compared to others having less built up but facing disturbed natural hydrological cycle. Considering this, hypothesis can be made that only built up is not responsible for the runoff generation but some other factor like open spaces, planning, geology plays an important role in the behavior of runoff. The paper attempts to correlate land use, land cover, built up and resulting runoff for urban watersheds. It also finds out correlation between local bye laws and behavior of water cycle over it.

Considering runoff modification as prime effect of urbanization to the hydrological cycle in terms of behavior of surface water, the intention of the study is to contribute to a better understanding of the relation of the local hydrological parameters in urban areas to the physical transformation of land covers as impervious built ups and develop an understanding of the resulting effects of components of one system on other. This will help to predict and project the changes in hydrological cycles due to land use /land cover transformation and thus help urban planners in physical planning of new urban areas as well as development of an existing urban area to achieve a maximum sustainability in the city. Hence, water sensitive urban planning with combination of built up, open spaces and geology will help planners to cope with the unwanted increase in runoff leading to flash floods. For this purpose, 19 urban water catchments were studied for their development scenario byelaws, built up, runoff and water tables for past 30 years and above. Observations were used to correlate urban parameters like land cover, runoff, infiltration, and evaporation with hydrological ones and bring a model solution for balanced water cycle achievement during urbanization.

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