Investigation of Low Impact Development Potential for a Densely Populated Area in a Semi-arid Climate

Abstract:

Cities of future are built around sustainable development by maximizing the efficiency of food, water and energy use meanwhile minimising resource depletion, waste production and environmental pollution, known as eco-cities. In water centric eco-cities, urbanization approach towards stormwater is to create alternative water resources by increasing the percentage of permeable areas by applying low impact development (LID) strategies such as rain gardens, green roofs, daylighting streams and rainwater harvesting. Moreover, this leads water resources to be a part of city life that improve the ecological situation of the environment, prevent floods and urban stormwater pollution. In the absence of such an approach, casualties and unfortunate events are likely to occur. For example, the city of Ankara, capital of Turkey, has been faced with several floods resulted from unplanned urbanization. This study aims to assess LID application potential to mitigate the flood risk for a densely populated urban area with 3 km² in Ankara located in a semi-arid climate where combined sewer overflows (CSOs) occurs during heavy rainstorms. Two sides of the selected region are surrounded with valleys. However, the rivers were channelized and buried. Valley is used for recreational purposes. Hydrological surveys are carried out on the basis of SRTM database, Google Earth image and on-site investigations. Suitability of practices have been discussed in accordance with hydrological surveys and runoff types because of the difference in their pollution loads. Roof runoff is considered as water resources with the application of pre-treatment for public use. Street runoff is discharged to the nearest green land and collected in a pond. The study also conducts the effects of environmental improvement for society. The implementation of LID strategies is a challenging task to apply for a highly populated site. On the other hand, every possible sustainable stormwater management application must be considered for improving the environment. The overall effects of practices help to feed groundwater, improve the ecology and detain a certain amount of runoff which is resulted in flooding events. The study can be used as a guide for sustainable stormwater management for eco-cities.