Rain water harvesting catching on, but slowly

NEW DELHI: Some facts:
Delhi’s ground water levels are fast depleting;
Some areas are ‘vulnerable’, with water levels having dropped by over 8 metres
About 60-70 per cent of Delhi is ‘vulnerable’. These include south, southwest, central, west and New Delhi districts.
During 1960-2000, water levels dropped by about 10 metres in Najafgarh, 20 metres in Mehrauli.
The list of casualties could go on. And this is the city’s chance to make a turnaround. According to the meteorological department, the monsoon is progressing normally and should hit Delhi by June 29, bringing a rainfall of about 65 cm, the average the city has recorded over the years. This means that one has all of two weeks to get one’s act together and reap a liquid harvest.
Especially, if the city is to recover lost ground. This season’s first rainfall of 13 cm could have generated enough water to run over 1,000 tubewells for 100 days. The Central Ground Water Authority (CGWA) says this amount of rain could have recharged ground water levels by a whopping 1,930 crore litres.
Curiously, the government has no centralised data on how much rain water the city will be able to harvest this monsoon. Several government departments, hotels, group housing societies and individuals have made inquiries, sought design plans and put rain water harvesting systems in place. ‘‘We have been asking people who use our designs to tell us when they are operational. Some do get back, but there is no system to get every information seeker to report back on whether the systems are in place or not,’’ said a senior official of the Central Ground Water Board (CGWB).
So, at best, we can only get a rough estimate. The CGWB alone — by March this year — had provided assistance and plans to 520 locations, including some institutions such as the Delhi Development Authority (DDA), Central Public Works Department (CPWD), New Delhi Municipal Council (NDMC), Delhi Cantonment, Military Engineering Services, group housing societies, educational establishments and hotels. ‘‘Since then, we have received another 200 to 300 requests for assistance. Now, each of our plans are designed to accommodate one hour’s rainfall at a time. Going by an estimate of about 619 mm of rainfall this season, each structure can harvest about 400 cubic metres of water. If 800 of our structures are in place by the rainy season, we can harvest about 32 crore litres of water this year,’’ a CGWB official said.
The Delhi Jal Board (DJB) has 155 structures in place. ‘‘We have about eight lakh square metres of roof surfaces for harvesting. We hope to harvest about 45 crore litres of water this year,’’ said Kawaljeet Singh, superintending engineer, in charge of DJB’s rain water harvesting project.
Singh, however, is not very hopeful that all the 150-odd inquiries that the DJB receives every day will be converted into concrete water harvesting systems. ‘‘Only about half the number of inquiries actually move a step forward to collect data and plans. Many people back out as soon as they realise that the DJB will not fund the project. In fact, when we visited some fairly well-to-do colonies, out of the 300 houses just 10 residents were willing to contribute towards a water harvesting project,’’ he said.
This calls for greater credit to residential colonies like Panchshila Park, Vasant Vihar and Karol Bagh who have put up rain water harvesting systems.
The Central Pollution Control Board, too has installed a rooftop harvesting system at its Parivesh Bhavan headquarters. With a catchment area of 1,400 square metres, the building can harvest up to 960 cubic metres of water every year. The Centre for Science and Environment (CSE) also has been inundated with calls for plans. In the last one month it has firmed up over 30 plans for various individuals and institutions. Of these, approximately 50 per cent have actually implemented the plans.
‘‘We are also developing seven model projects in the city for people to follow,’’ said Ekalavya Prasad, CSE’s networking executive for rain water harvesting projects.
‘‘We have been harvesting water in our office in Tughlakabad Institutional Area since 1999. About 50 per cent of the rain water is harvested through the rooftops and paved area, which is about 3.5 lakh litres every season. Despite the heavy construction on in the area — which depends largely on ground water reserves — we have been able to sustain the ground water levels here,’’ he said.
A CGWB official sums it up: ‘‘We have been able to build a consciousness among people about the need to harvest water. What we now need to do is make water harvesting fashionable.’’