Urban stormwater harvesting for domestic water supply: a water evaluation and planning approach

Abstract

Renewable groundwater and surface water supplies are insufficient for the existing urban population all over the world as water demand is increasing rapidly. Usage per capita in urban areas transcends 160 liters per day. Climate change is projected to increase water demand even more. Sources of surface water obtained by stormwater runoff can be well used to fulfill this requirement. The main objective of this work is to assess the water supply and demand in the dry condition in the Coimbatore region, Tamil Nadu, India, and to use the Water Evaluation and Planning method to create a model for supply and demand in the future. There are more than three dozen of surface water bodies in and around the metropolitan center. Most sources are heavily encroached upon. By linking stormwater runoff from its respective elevation to the accessible surface water bodies, an additional water supply source can be obtained. By using the Water Evaluation and Planning framework as a guide, models were developed to determine potential needs, compare demand and supply, water usage, lack of water use, and population coverage. The enhanced stormwater drainage system for Coimbatore city was also designed in such a way that the corporation's various roads were connected to the major water bodies. The domestic water demand in the future is predicted to be around 27 Million Cubic Feet(MCFT). Meanwhile, the possible amount of stormwater collection in the selected water bodies is predicted to be 50 Million Cubic Meter (MCM) to 320MCM. Thus, the study concluded that 100% of urban domestic water demand can be met if the urban stormwater is utilized by harvesting and storing in surface water bodies.