As a water conservation measure, Government has given an unprecedented thought to proposals such as RainWater Harvesting. Keeping this in view, CMWSSB has decided to embark upon popularising the RWH techniques among the residents of Chennai city, as also in the neighbouring areas.
Considering the importance of Rainwater harvesting in conserving the precious ground water resource, the Board has taken initiative to constitute a fully dedicated "Rain Water Harvesting Cell". The main objective of the Cell is to create awareness and to offer technical assistance free of cost to the residents and also to provide to the citizens 'cost effective solutions'. CMWSSB has created several models, detailed designs etc., which are available in the form of brochures, booklets and are being distributed to the public. In the recent past, we have also tried to disseminate related information through electronic and print media quite vigorously. An Information Centre on RWH was opened from 10.8.2001 onwards at the CMWSS Board Head Office.
Efforts were taken to convert the Rain Water Harvesting campaign launched by the Government as people's movement. A number of seminars/ workshops and exhibitions were organised involving various Government agencies, NGOs and private individuals. As a result of this intensive campaign the Rain Water Harvesting has become popular in Chennai city and the people are adopting it on their own.
Realizing the importance on regulatory mechanism for providing rainwater harvesting CMWSSB has made the installation of Rain Water Harvesting structures as a compulsory pre-requisite for providing water and sewer connections for all the new buildings.
Regular training programme are being conducted at the Metrowater Resources Centre for the benefit of public, private engineers and building workers.
A list of Resource Persons has been prepared and made available. Details on RWH have also been put up on the Metrowater website.
The initiatives taken by CMWSSB can be categorised into macro level and micro level initiatives. At macro level the Board has constructed a number of check dams to recharge ground water in wellfield area and also have constructed injection wells to arrest saline water intrusion in one of its wellfield close to coast.
At micro level, this Board have taken a no. of steps to popularise RWH at individual house hold level in Chennai city. This Board has also implemented RWH in the public buildings such as Raj Bhavan, Children's Park, Egmore Museum, Presidency College, Stanley Hospital, Nochikuppam slum and Lady Willingdon Higher Secondary School to create models for demonstration. In Chennai city, a total no.of 38,218 RWH structures have been constructed by individuals and in Government Buildings.
Macro Level Groundwater System:
Water level depletion and low yield
Though it was estimated that a total quantity of 180 mld (39.5 mgd) of ground water could be extracted from all the six Wellfields, in A.K.Basin the actual yield become reduced year by year and during the year 1990, it become only 50% of the original estimate.
This is due to the fast rate of depletion of water level caused by continuous extraction mainly by farmers,low rainfall and frequent drought periods. During the same time it was observed that sea water intrusion upto 9 km inland took place into the Minjur aquifer which is located very near to the coast (Bay of Bengal).
Construction of Checkdams and Injection wells
Implementation of Groundwater Regulation Act
On the basis of clear evidence of sea water intrusion into the Minjur aquifer, the Tamilnadu Government realised the necessity of saving the coastal aquifers and other ground water potential zones in and around the city and enacted legislation to regulate and control the extraction, use or transportation of ground water.
The Act which came into force with effect from 15.2.88 has been named as "The Chennai Metropolitan Area Groundwater (Regulation) Act, 27 of 1987". A total number of 243 revenue villages of the neighbouring two districts and the city of Chennai are included in the scheduled areas of the Act. The competent authorities to implement the Act are (i) CMWSS Board for Chennai city and (ii) the respective Revenue Divisional Officers/Sub-Collectors for the other revenue villages.
The Act envisages (i) Registration of existing wells (ii) Regulation of sinking new wells (iii) Issue of licences to extract ground water for non-domestic purpose and (iv) Issue of licences for transportation through goods vehicles. Licences were issued by the Revenue officials on payment of prescribed fees after getting technical clearance from CMWSSB.
Impact of macro level initiatives
In order to reassess the ground water potential in the Arani-Koratalaiyar river basin a detailed restudy of the entire river basin has to be taken up by the Board with the assistance of the World Bank.
- To create public awareness on the importance of RWH among the public.
- To popularise simple and cost effective RWH methods in order to attract larger participation of the public.
- To offer technical guidance/assistance about the methods to be adopted based on the local geological formations and site conditions.
- To monitor water level and water level quality in the Rainwater Harvested areas and wells (both existing and proposed areas/wells).
- To assure proper maintenance of the RWH structures after installation.
- To do and undertake anything which would promote RWH (both in individual houses and public places).