Delhi’s Invisible Treasure: The Yamuna Palla floodplains
If we use less water than is recharged every year by rainfall and late-season floods, and not tamper with the reserve built over millions of years, then this precious resource would last forever.
The sandy aquifers on the floodplains of our rivers naturally store and recharge a lot of monsoon water that can be used as a local, sustainable and perennial quality water source for cities. If we use less water than is recharged every year by rainfall and late-season floods, and not tamper with the reserve built over millions of years, then this precious resource would last forever. I had initiated the first sustainable, floodplain project in the world through the Prime Minister’s secretariat in 2009. The realisation of this unique idea, known as the Palla floodplain project, was taken up by the Delhi government and is now providing water to nearly a million people in Delhi.
The Palla floodplain project runs over 20-25 odd kilometres of river length, north of Wazirabad. This floodplain was rigorously researched and was found to have a replenishable yield of between 80 -100 million cubic meters (MCM)/ year (50- 60 million gallons per day(MGD)). The project has been running at less than half its potential due to old and leaky pipelines. We established an ecological ‘Conserve and Use’ plan to augment this to its full potential of 100 MCM/year (60 MGD) . At the median rate of domestic water charged by the Jal Board for the consumer, this will provide a revenue of about ₹400 crore per year for the water utility.
The Delhi government in a public release in 2016 had announced the ‘Palla project as an original, ‘Conserve and Use’’ ecological, non-invasive and perennial water project — the first such project in the world’. Such floodplain projects can be used to sustainably water over 500 river towns in India. Not to forget, floodplain aquifers are perhaps the only unpolluted perennial water sources left in the country. The project is of global importance and has been lauded by South Australian Water. Delhi can be the flagship of this water scheme.
But we found that the entire water resource of the aquifer is in immediate danger of being lost due to a lack of protection and misuse. Foremost, intensive wheat and flower cultivation that uses about 30 cm of raw water, and another minimum of 30 cm or so for a second annual crop (even basmati rice) over the summer and monsoon months, has taken over the floodplain. About 4-5 kilometres wide and 20-25 kilometers long , this 80-100 sq km of area is drawing over 60 MCM/ year(~35 - 40MGD) of water. This is depleting the aquifer, leaving a balance of less than 40 MCM/year for Delhi’s water supply.
I had already suggested in an article that farmers on the floodplain can plant and harvest food forests or fruit forests on the floodplain, which are water lean and be given an assured income of ₹30,000 per acre per year for providing water to citizens of Delhi. According to reports, the Delhi government has done just that, which is a very welcome step, as the water intensive agriculture is depriving Delhi of water for well over a million citizens .
But the Delhi government has been overzealous in announcing that they would create a medley of lakes on the floodplain to trap monsoon floodwaters. Since the floodplain is already a porous sandy aquifer and absorbs most of the floodwater, such an intrusion may not be optimal. The floodplain itself is like an invisible underground lake. I would like to suggest that organic agriculture, for example, planting of food forest or fruit forests on the floodplain, would be a better option than carving out lakes, where vast quantities of sand would have to be transported out affecting the wetland ecology of the floodplains — very much akin to sand mining, . Furthermore, in any case, the floodplains are designated as a protected Zone O in the master plan and declared a biodiversity zone. Also, open lakes would lose a very large amount of water — nearly 3 metres depth of water — in a year from evaporation.
Further, villages are routing their sewage into nearby depressions on the floodplains and contaminating this vital resource. If this is not stopped forthwith, the floodplain will terminally lose quality water. Also, the Delhi government had earlier announced a scheme of creating 70 more borewells and Ranney wells in this area .This would exceed the maximum withdrawal that is sustainable and bring the groundwater levels in the floodplain down to below the river water levels in the lean season, allowing gravity flow from the polluted river into the unpolluted floodplain . Noida had a sustainable and perennial water source from its Yamuna floodplain aquifer, which provided it with good quality water for over 30 years till about four years ago. It was thoughtlessly over-exploited and with sand mining on the banks of the Yamuna on one side and the Hindon on the other, polluted water entered, terminally destroying the aquifer. This is permanent loss of a vital water resource for future generations.
Most importantly, the water levels of the floodplain need to be monitored very scrupulously to be well above the polluted river water level to avoid contamination. Once contaminated, the aquifer cannot be restored. It must be urgently protected as a water sanctuary for Delhi.
Vikram Soni, Emeritus Professor, Jamia Millia and JNU & PI Sci Foundation (Science in Public Interest)