Relevance and Importance of RWH in cities (urban areas) like Chennai
In cities like Chennai, or in general in urban areas, RWH is more relevant and important than in villages (rural areas) for the following reasons
Cities are mostly built up resulting in a heavy runoff of rainwater than infiltration into the soil, unlike villages where large areas remain unpaved.
Traditional waterbodies which would have existed till about a few decades back in urban areas have been largely converted into dwelling places resulting in floods. Only a few still remain in the extended areas of cities.
The above reasons put a severe constraint on RWH in that rain can be harvested only as groundwater.
While sources are shrinking in urban areas, demand for fresh water for domestic and industrial use has increased manifold, making harvesting more and more relevant.
If rainwater is not harvested in cities, they will run out of groundwater, which is an important supplementary source.
As mentioned above, in coastal cities like Chennai, what is not harvested runs off to the sea and gets wasted. Sea water is then converted into fresh water using desalination process, which is not a wise thing to do.
Why is RWH being talked about so much now than ever before?
Let us look at how Chennai was, say, 200 years back. Kings and rulers had created waterbodies and harvested rain in them, the water from which people used, to meet their fresh water demands. Community wells were also created for people to source water for their daily needs (some of these wells can be seen even now on public roads in the suburbs).
Whereas in the last 100 years, people bought their own piece of land, constructed a house within it and also dug an open well or a bore well to exploit groundwater for their daily needs. Therefore, responsibility of sustaining the groundwater source through RWH shifted from the kings and rulers to the individuals and is now everybody’s business.
In the last 50 years it has further shifted from individuals to builders (also architects), who buy a large piece of land, close the open well(s) in it, construct several apartments (condominiums) in them and also dig one or more bore wells, pumping out inferior quality water from them to cater to the daily water needs of the several hundred people living in these apartments. RWH has now ended up as the responsibility of the builders.
Role of NGOs in RWH
Role of NGOs and Citizen’s Organisations is very important in not only creating the much-needed awareness among various sections of the society about RWH but also offering help in designing a suitable RWH system and also implementing the same with the help of well-trained contractors.
This can best be achieved by setting up Rain Centres in towns and cities. Rain Centres, which are one-stop information and assistance centres for RWH, should be thought of as bridges connecting people with RWH. They are permanent exhibitions for RWH. Our Rain Centre, the first of its kind in the entire country, set up in Chennai in 2002 with the blessings of the T.N. Government can be a role model for this.
Since 2002, the Rain Centre has been not only creating awareness regarding RWH among various sections of society starting from school children to college students, builders, architects, planners, bureaucrats, etc, but also helping the residents of Chennai to implement RWH in their respective homes by offering free advice. Booklets on RWH in English and Tamil are also available.
Role of the state in the past and in future in RWH
We should feel happy and proud that Chennai and Tamil Nadu are the role models for urban and rural RWH for the entire country. The T.N. Government has been keen on popularizing and promoting RWH since the early nineties. It all started in 1994 when Chennai Metropolitan Development Authority (CMDA) issued a notification to all builders who submitted building proposals for approval, to incorporate RWH in the plan submitted along with the proposal. This was of course only for new constructions.
In October 2002, a law was enacted making RWH compulsory in all buildings – existing and new. Residents were given time till August 31, 2003 to set up a RWH system within their respective homes. During 2014-16, the Government wanted an audit to be carried out by an NGO on the compliance to, and impact of, RWH in Chennai Metropolitan Area. This was carried out by the Akash Ganga Trust and a report was submitted to the Government.
As mentioned earlier, RWH is the responsibility of both the state and the society. The state should in future get involved in the following:
Continue the activity of creating awareness about RWH among various sections of society. At present, not much effort is being shown by the state.
As RWH is compulsory for all new constructions, CMDA and Greater Chennai Corporation (GCC) which give building plan approvals, should ensure that RWH is carried out in all new constructions as per the guidelines mentioned in the Tamil Nadu Combined Development & Building Rules 2019 before giving completion certificates. This is lacking at present.
In fact, a recommendation was made by the trust, while carrying out the audit, that there should be third party monitoring of at least ten percent of all new projects.
Government should ensure that RWH has been carried out in an efficient manner in all their buildings (both old and new). This is also not happening at present.
The Greater Chennai Corporation is involved in the indiscriminate construction of storm water drains all over the city. These drains collect all the precious rainwater falling in public spaces and on the roads and dump it in the Bay of Bengal. This is suicidal and should be reconsidered. They should make all sincere attempts to harvest this urban runoff and the excess if any should be led into the sea. There are several ways of doing it.
Chennai city has grown from 174 sq.kms. to 426 sq.kms. In this extended area, there are several traditional waterbodies. To name a few, Ambattur, Korattur and Villivakkam in the west and Narayanapuram, Nanmangalam and Kovilambakkam in south. These are being used as garbage dump yards and abused in several other ways and encroached upon. These waterbodies will have to be recovered, revived, repaired, and rejuvenated and made fit for harvesting the rain so that they act as a source of freshwater. It is heartening to note from the media that Villivakkam ery has been renovated.
Last but not the least, there are more than 3,000 irrigations tanks (traditional erys) in the neighbouring districts of Chengalpattu, Kanchipuram and Thiruvallur, most of which have lost their agricultural relevance. These waterbodies can be repaired, rejuvenated and converted into reservoirs like Red Hills, Sholavaram and Chembarambakkam and used to supply water to the neighbourhood and if possible to the other areas of Chennai.
Role of the society/each citizen/resident
In each premises, whether it is an individual house or an apartment complex, it rains only on two places: the roof and all around the built-up area, which is also called the setback area which, in most cases will be the driveway. Rain falling on the roof is brought down by pipes, which will have to be interconnected and led to the sump through a simple filter for immediate use, if there is a need. The overflow from the sump could be diverted to an open well if there is one within the premises.
In the absence of an open well, it could be led to a recharge well (RCW), which is an empty baby well, constructed out of cement rings readily available in the market. The depth of the recharge well will be 15 feet and the diameter will vary from 3 to 5 feet depending on the quantity of rainwater that is likely to be injected into the RCW.
A large majority of Chennai residents have attempted to harvest only the rain falling on rooftops. No attempt has been made to harvest the rain falling on the setback area (driveway), which still runs off to the street and gets wasted. There are ways to harvest it by intercepting the runoff near the gate(s) and leading it to RCWs.
Every resident should ensure that not a drop of rain falling within the premises, goes either to the sewer or the street through the gate(s). We should all realise that RWH is a community effort and that unless the entire neighbourhood implements RWH, it would be difficult to get the full benefits. Therefore, each resident should make sincere attempts to harvest the rain falling within their premises and talk to their neighbours to harvest the rain falling in their premises. Everyone should become a changemaker.