Identifying the potential of ground water recharging zones in Chennai Metropolitan Area during flash floods

Water is an essential component of life on Earth. Increases in population and exploitation of ground water may worsen the situation of living on Earth. Additionally, due to climatic changes, two extreme events such as floods and droughts make the scenario tougher. India, the second largely populated country with 17.7% of the total world population, has around 30% of its population living in urban areas like Chennai, India’s 6th largest city. Chennai, the capital of Tamil Nadu state, is a metropolitan city with the population density of 11 million inhabitants and is expanding its boundary due to urban sprawl. It is also losing all of its resources to meet the inhabitant’s day-to-day needs. The Chennai city requires 10 million litres of water per day to hydrate its population. With an average of 1400mm of yearly rainfall and with four major reservoirs having capacity of 11.5 thousand million cubic feet, Chennai ran out of water between 2015 and 2019. NITI Aayog report of India have projected that by 2030 the water demand will be twice its availability which will push many cities to “Day Zero’ scenario. This study focused on identifying the potential of ground water recharging zones in Chennai Metropolitan Area (CMA) using GIS. These zones were overlaid in the drought-prone zones and flash flood zones of CMA maps. The study also focused on built-up and open space ratio on the above mentioned maps along with the soil maps. The final results was the overlay analysis of all the maps that were collected and illustrate the possible recharging zones that could be used to save water during flash flood periods and the same can be used to overcome the summer droughts. This study concluded by suggesting the zones where further flash flood and drought mitigation plans can be executed. This study can be extended by providing solutions to the zones identified to overcome the water stress that happens due to the urban sprawl in Chennai.