Asian Urban Information Center of Kobe
Mr. Shiv Das Meena
Joint Commissioner (Education), Chennai Corporation, India
Drinking water is one of the essentials for human existence. Surface and the ground water are the two major sources of drinking water. Drinking water supply in urban areas is mostly centralized and is primarily from surface sources such as natural or impounded reservoirs. As the population density and usage levels are relatively high in urban areas, water agencies construct, operate and maintain huge surface water dams and reservoirs for meeting their water demands. However individual households in urban areas also have their own bore wells/open wells to cater to needs other than potable water.
Chennai city depends on a few surface reservoirs outside the city limit which are fed by rainwater. However, on one hand due to poor monsoon rains these reservoirs rarely receives sufficient inflows resulting in water scarcity, and on the other hand the city is fast growing. Therefore, due to excessive pressure on ground water, the ground water table is fast depleting, and in some cases saline water intrusion is also taking place.
The concept of rainwater harvesting lies in tapping the rainwater where it falls. The rainwater collected can be stored for direct use or can be recharged into the ground water. A major portion of the rainwater that falls on the earth’s surface, runs-off in streams to rivers and finally to the sea. On an average only 8 to 10 % of the total rainfall recharges the ground water aquifer and most of the remaining rainfall is wasted in the form of surface runoff or evaporation. Chennai, on an average, receives rainfall for only 300 hours throughout the year. The characteristics of this rainfall demands not only that the city conserve large quantities of rainwater during these few days but also that it stores water whenever it rains preferably for direct use and alternatively to recharge ground water.
Rainwater can be stored either in containers (water tanks) above or below ground level or it can be charged into ground.
Chennai city faced severe water scarcity during the year 2001 and that acted as a major stimulus for rainwater harvesting. A special campaign was launched as a people’s movement during July 2001 to popularize rainwater harvesting by the institutions as well as individual households. Simultaneously steps were also taken to provide rainwater harvesting in public buildings. Technical assistance cells were established in various organizations such as the City Corporation office, city water agency’s office etc. A campaign was launched through mass media, seminars, exhibitions, rallies, mobile publicity vans, etc.
Rainwater harvesting was made mandatory by promulgating an ordinance during July 2003. All the citizens were directed through this ordinance to provide Rainwater Harvesting structure in all the buildings.
Today Chennai city is a rainwater friendly city. All the buildings, commercial as well as residential, are provided with rainwater harvesting structures. This has helped in improving the ground water table as well as in improving the quality of ground water. Moreover, during rainy season the dependence on the municipal water agency has come down.
Editor’s Note: This article was contributed by Mr. Shiv Das Meena specially to this newsletter to provide more detailed information on the Chennai’s water harvesting practice.
Hopefully South Africa will follow in India’s footsteps and start ‘forcing’ people to harvest rainwater. All the facts are on the table – let’s just hope we don’t wait until it’s too late…. Please conserve water.