Rain Water Harvesting in Chennai: A Model for other Indian Cities
By Santha Sheela Nair
All over the world metropolitan water supply system managers have valued using more water per capita from increasingly distant sources, leading to crises. The inefficient design of systems unmindful of urban resources and constraints has aggravated drought-flood cycles. Harnessing rainwater and floodwater using urban space as a catchment is a striking example of environmentally sustainable service provision that is both a drought- proofing and flood- mitigation plan. Chennai, the fourth largest metropolis and capital of Tamil Nadu, covers 76sq.km of extremely flat coastal plains and has an average annual rainfall of around 1250mm, with more than 75 per cent falling during October-December. Averaged out, drinking-water sources consisted half of surface water and half of groundwater which in a normal monsoon year, 80 per cent came from surface-water reservoirs and 20 per cent from groundwater reserves.
The increasing drinking-water crisis in the growing city led to access water from rivers through canals or pipes running long distances that required interstate agreements. Increasing demand and ever-decreasing per capita availability led to excessive dependence on groundwater by enterprises, individuals, households and the civic authorities. As mining and selling water increased alarmingly, ground water aquifers became saline and depleted fresh-water aquifers. Recurring droughts, meant considering evacuation of urban areas.
The answer was tapping the potential of rainfall which the city received in a period of four months, invariably leading to inundation and floods, disrupting regular water supplies and sewerage systems. Drainage was impeded further throughout monsoons by rising tides and high sea levels.
In 2003, rainwater harvesting was made compulsory by law, throughout Tamil Nadu, in all buildings, not only new but also existing ones. The fulcrum of the Rain Water Harvesting (RWH) programme of the state was the political commitment shown by the Hon’ble Chief Minister Ms. J.Jayalalitha. In 2001, at the time of the elections in the party manifesto itself, the party committed to make Rain Water Harvesting mandatory and once in power it backed it by a strong political will. Efforts by the State for dissemination of information and promotion ensured sustainability both in monetary as well as environmental terms in the provision of drinking water.
In Chennai, the decentralized availability of drinking water saw the paradigm shift from a system wholly controlled by engineers and the Chennai Metropolitan Water Supply and Sewerage Board to a level of co-management. Households’ accessing simple water supply systems was an innovative intervention in drinking water management, while authorities maintained large professionally controlled and formal water supply systems. The success of these measures depended on unrelated but concerted actions implementing the process ‘in letter, spirit and functionality of the law’ The campaign was strengthened by a discreet but effective message that non-adoption was punishable. The design paradigm adopted by Chennai decentralized water supply systems for a more conservative, personalized water supply systems to suit the households and the community led to less wastage of water but also savings in energy otherwise needed for water and sewage treatment. Decentralized water collection and usage is more democratic as well as more ecologically sustainable than conventional centralized water supply systems.
Providing such services with people’s participation is a model for all large urban cities to consider in the planning and managing of their drinking water. Chennai serves as a precedent and model for other similarly challenged cities. A city that was infamous for its acute scarcity of drinking water and exploitation of ground water started moving towards water security achieved by application of affordable and environmentally sustainable solutions created in situ and with social benefits.
Impact of the improvements in rain water harvesting structure.
The lessons for the other Indian cities are to shift the base for securitizing drinking water availability to citizens and households. Average rainfall in the other Metros is Delhi with 714 mm, Bengaluru with 978 mm, Mumbai with 2012 mm and Kolkata with 1800 mm and these are cities that could emulate Chennai to bring into force a decentralized water supply with the democratization of its management in an urban context. The most important lesson learnt from the Chennai experience is that Rain water is an important untapped resource for all water managers and can be collected and used personally for all uses and simultaneously diverted to ground for recharge depleting aquifers. RWH contributes sufficient quantity of water however; brief the spell of rain may be both for improved surface and ground water management. Urban built up areas serves as an excellent catchment as it can contribute to collection of good quality water not affected by run offs in fields and open spaces. RWH has the additional advantage of improving surface and ground water, and this in turn contributes to overall improvement of the urban space. It is necessary to make water security became a people’s movement with involvement of engineers, builders, architects, planners, environment activists, scientists, hydro-geologists, politicians, administrators and households as stakeholders in a metropolitan city water supply system.
The strong political will at the highest level in the entire political cadre, matched with committed executive skill at all levels, made the RWH campaign a phenomenal success and a model for the country.
By Santha Sheela Nair
All over the world metropolitan water supply system managers have valued using more water per capita from increasingly distant sources, leading to crises. The inefficient design of systems unmindful of urban resources and constraints has aggravated drought-flood cycles. Harnessing rainwater and floodwater using urban space as a catchment is a striking example of environmentally sustainable service provision that is both a drought- proofing and flood- mitigation plan. Chennai, the fourth largest metropolis and capital of Tamil Nadu, covers 76sq.km of extremely flat coastal plains and has an average annual rainfall of around 1250mm, with more than 75 per cent falling during October-December. Averaged out, drinking-water sources consisted half of surface water and half of groundwater which in a normal monsoon year, 80 per cent came from surface-water reservoirs and 20 per cent from groundwater reserves.
The increasing drinking-water crisis in the growing city led to access water from rivers through canals or pipes running long distances that required interstate agreements. Increasing demand and ever-decreasing per capita availability led to excessive dependence on groundwater by enterprises, individuals, households and the civic authorities. As mining and selling water increased alarmingly, ground water aquifers became saline and depleted fresh-water aquifers. Recurring droughts, meant considering evacuation of urban areas.
The answer was tapping the potential of rainfall which the city received in a period of four months, invariably leading to inundation and floods, disrupting regular water supplies and sewerage systems. Drainage was impeded further throughout monsoons by rising tides and high sea levels.
In 2003, rainwater harvesting was made compulsory by law, throughout Tamil Nadu, in all buildings, not only new but also existing ones. The fulcrum of the Rain Water Harvesting (RWH) programme of the state was the political commitment shown by the Hon’ble Chief Minister Ms. J.Jayalalitha. In 2001, at the time of the elections in the party manifesto itself, the party committed to make Rain Water Harvesting mandatory and once in power it backed it by a strong political will. Efforts by the State for dissemination of information and promotion ensured sustainability both in monetary as well as environmental terms in the provision of drinking water.
In Chennai, the decentralized availability of drinking water saw the paradigm shift from a system wholly controlled by engineers and the Chennai Metropolitan Water Supply and Sewerage Board to a level of co-management. Households’ accessing simple water supply systems was an innovative intervention in drinking water management, while authorities maintained large professionally controlled and formal water supply systems. The success of these measures depended on unrelated but concerted actions implementing the process ‘in letter, spirit and functionality of the law’ The campaign was strengthened by a discreet but effective message that non-adoption was punishable. The design paradigm adopted by Chennai decentralized water supply systems for a more conservative, personalized water supply systems to suit the households and the community led to less wastage of water but also savings in energy otherwise needed for water and sewage treatment. Decentralized water collection and usage is more democratic as well as more ecologically sustainable than conventional centralized water supply systems.
Providing such services with people’s participation is a model for all large urban cities to consider in the planning and managing of their drinking water. Chennai serves as a precedent and model for other similarly challenged cities. A city that was infamous for its acute scarcity of drinking water and exploitation of ground water started moving towards water security achieved by application of affordable and environmentally sustainable solutions created in situ and with social benefits.
Impact of the improvements in rain water harvesting structure.
The lessons for the other Indian cities are to shift the base for securitizing drinking water availability to citizens and households. Average rainfall in the other Metros is Delhi with 714 mm, Bengaluru with 978 mm, Mumbai with 2012 mm and Kolkata with 1800 mm and these are cities that could emulate Chennai to bring into force a decentralized water supply with the democratization of its management in an urban context. The most important lesson learnt from the Chennai experience is that Rain water is an important untapped resource for all water managers and can be collected and used personally for all uses and simultaneously diverted to ground for recharge depleting aquifers. RWH contributes sufficient quantity of water however; brief the spell of rain may be both for improved surface and ground water management. Urban built up areas serves as an excellent catchment as it can contribute to collection of good quality water not affected by run offs in fields and open spaces. RWH has the additional advantage of improving surface and ground water, and this in turn contributes to overall improvement of the urban space. It is necessary to make water security became a people’s movement with involvement of engineers, builders, architects, planners, environment activists, scientists, hydro-geologists, politicians, administrators and households as stakeholders in a metropolitan city water supply system.
The strong political will at the highest level in the entire political cadre, matched with committed executive skill at all levels, made the RWH campaign a phenomenal success and a model for the country.
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