Water is perhaps the most precious asset on earth. Indians have traditionally considered it as one of the five basic elements of nature. Fresh water is essential for human survival and rain is its predominant source on earth. The rainfall that is trapped in surface and groundwater sources is all that is available for human consumption. That is why Rainwater Harvesting (RWH) is so important. RWH is not an option or an alternative, but the only way to sustain surface and groundwater sources and is relevant in both rural and urban areas.
There are two important aspects of RWH: the collection of rainwater for immediate use and the natural or artificial recharge into the soil for sustaining and improving groundwater sources. In rural areas, where large amounts of open space are available, RWH is essentially the collection of rainwater in surface water bodies, such as ponds, lakes and irrigation tanks. That is the first aspect of RWH. Due to the shrinking of open spaces in cities and other urban areas, however, RWH is predominantly used there to artificially recharge aquifers to sustain over exploited groundwater sources. That is the second aspect.
Almost all urban areas in India, consisting of large- and medium-sized cities, face the twin problems of floods during the monsoon and shortage of fresh water during non-monsoon months. At times, floods and drought can be more serious than urban designers planned for. Both of these problems are of a more recent origin; they are primarily caused by a failure to harvest enough of the rainwater that falls in such areas. The solution to both of these problems lies in understanding the scenario and making determined attempts to harvest every drop of rainwater, either as collection for immediate use, aquifer recharge or both.
Chennai is a coastal city located in South India and is the capital city of the Federal state of Tamil Nadu. Until about thirty years ago, Chennai’s coastal suburbs possessed some of the best quality groundwater. That groundwater was available in large quantities, because the sandy soil allowed any amount of rain to percolate into the soil on its own (without human intervention). Indiscriminate paving, indulged in by the builders of condominiums, has prevented rainwater from percolating into the soil, resulting in groundwater depletion and saline ingress.
A few of us realised that there was a need to educate the residents about the importance of RWH. We set up the Rain Centre, a one-stop information and assistance centre for RWH in Chennai, which was inaugurated by the Honourable (late) Chief Minister, Ms. Jayaram Jayalalithaa, in August 2002. Besides working to create the much-needed awareness among various sections of the urban society, the centre also offers free advice to all those who want to implement RWH.
Tamil Nadu was the first state in the country to not only create awareness about the need and importance of RWH, but also to make RWH mandatory, as early as 2002-2003. It was to be implemented in both old and new buildings. Though the compliance rate was only 50 per cent, the impact was phenomenal; groundwater levels went up by six metres in some localities and eight metres in others. The quality of the water also improved.
Chennai is facing a severe water crisis – an unprecedented drought since April 2019. Piped water supply has been stopped for more than four months and groundwater levels are badly depleted. This has resulted in surface water sources and bore wells drying up, leaving the residents to depend on expensive outsourced water.
The reasons for the water crisis are both natural and manmade. In 2018, Chennai received just sixty per cent of its annual average rainfall of 1.4 metres. That is just one reason that can be attributed to nature.
On the other hand, the manmade reasons are many:
- A large majority of residents have still not taken RWH seriously and are only providing lip service to it.
- The state is also not giving RWH the importance that it deserves since the demise of the Chief Minister, Ms. Jayalalithaa. For example, it is indulging in the indiscriminate construction of storm water drains and dumping large quantities of rainwater into the ocean almost every year.
- Thousands of traditional water bodies that are located within the city’s extended area and in former agricultural districts are being encroached upon. They are being filled with solid waste and waste water. Chennai will only be able to protect itself from future water crises if these areas are maintained by periodic desilting and also protected from abuse.
This serious drought is a wakeup call; future droughts are going to be more severe than the present one. If we do not wake up now, we never will. We should value water and rain more highly and take steps to secure them for future generations.