The fight to conserve the Delhi Ridge is well known and documented. It was Professor Vikram Soni, now Emeritus Professor at Jawaharlal Nehru University and Jamia Millia Islamia, Delhi, who directed this effort. He then moved from pure conservation to building “conserve and use” models which are profitable and beneficial to all stakeholders while also being kind to the planet. Prof. Soni explains how these models — if they gain traction with State governments — could spur eco-sensitive development and service India’s cities, from Delhi to Tamil Nadu. Excerpts:
You have been working on a project to extract water from the flood plains of the Yamuna for Delhi’s water needs. How did you go about this?
We found out using scientific methods how much water was in the flood plains and how deep these flood plains are — they are almost 100 m deep and almost 5-6 km wide. And they run for nearly 48 km in Delhi. We experimented and researched to find that they had a lot of water (nearly 40% of this entire volume). In 2009, we made a presentation to the Prime Minister’s secretariat, where members of the Central Water Commission, Ministry of Water Resources, Central Ground Water Board and [Delhi] Jal Board were present.
Could this area provide a perennial and non-invasive water supply for Delhi? We found that you cannot use most of this water, but you can use some of this… about 200-250 million cubic metres (MCM) per year. This would be sufficient for over three million people.
But half of the river course was already encroached. Finally, the project we did was north of a place called Wazirabad, close to Delhi University, up to a place called Palla. The potential of the whole project was such that it could give a perennial water supply of about 100 MCM per year.
This water is naturally stored in the sandy aquifer of the flood plain. There was no problem when water was withdrawn from a tube well using motors that ran at 0.3 million cubic gallons per day (MGD). It is a porous and extensive aquifer and the rest of the aquifer compensates for any local withdrawal.
We checked the water in the flood plain and found to our surprise that all the water was pretty good. This had to be understood — why was the water in the aquifer not communicating with the water in the river which was very polluted? This is partly because the flood plain is fed by water from rain and the monsoon flood, which comes late in the monsoon when the pollution has been flushed out. During the remaining nine months, when there is little rain, the water from the aquifer very slowly percolates into the river. So long as you are about 200-300 metres away from the river, the water continues to be good.
So how do you go about extracting this water? How far can you go without destroying it?
The water stored in the flood plains of Himalayan rivers is 20 times as much as the water in the rivers themselves. It is a continuous resource. But we have to be very careful not to take out more than is being replenished [by the monsoons]. And, finally, only field trials would show the exact allowed ecological withdrawal each year. But 100 MCM over about 15 km of river course was a figure we came to after looking at it from many different points of view.
Finally, field trials have to be done every year, with sensors and piezometers, to monitor groundwater levels, to make sure the levels do not come down more than about 4 or 4.5 metres. Right now what is happening is that they are withdrawing about 50 MCM a year, because the pipeline cannot handle more than that.
We will have sensors to monitor the quality of the water. The electrical conductivity of the water measures the salinity and one has to make sure it does not cross 700 parts per million. The salinity can last for over a thousand years, so you have to be very careful you don’t overexploit the aquifer.
Can you reverse the salinity if it should mix with the river water?
If you overexploit it, the aquifer would be finished forever. Such a thing has happened before because of the lack of research and understanding, in the Yamuna flood plain in Noida. For 25 or 30 years it provided water for close to a million people.
This can also happen from sand mining on the flood plain. All these schemes have to have very strict rules and legislations, and this should be built into the software that regulates the pumping.
After your experience with the Delhi Ridge you did not go back to conservation itself, isn’t it?
Well, I never left conservation. All I did as a reality check was to move on to “conserve and use”. Conservation by itself does not seem to work anywhere in the world, but if you can show it has value, it will work better.
A 100 MCM a year of water withdrawn from the Yamuna flood plains in Delhi is worth ₹400 crore per year at the DJB’s standard water tariff. Priced at the highest commercial tariff, it can get ₹700 crore a year.
The philosophy behind all our projects is non-invasive, perennial and local whilst the cost to set them up is minimal.
Is there a similar situation in Tamil Nadu?
Tamil Nadu has many rivers. In southern Tamil Nadu, most of the rivers come from the Western Ghats. There are many cities on rivers with flood plains. Even if the river is not flowing throughout the year, the flood plains store the water. Some of this water can be used, but the Western Ghats, which are the source of these rivers, need to be preserved. There are some other resources in Tamil Nadu, such as wetlands, a lot of which were destroyed in the last 20-30 years for real estate projects that came up here — some of these can be revived.
We are also working on a non-invasive scheme for a regulated supply of local mineral drinking water for cities. The supply will be sourced from natural storage in a subterranean aquifer underlying a local forested hill. When rain falls on this forest, it slowly percolates into the ground whilst picking up minerals and nutrients from the forest leaf cover, seeping through these crevices in the mineral rock and finds its way to the bottom to create aquifers. We have tested this water in Delhi to find that it is similar in its constitution to mineral water sourced from a mountain spring.
Tamil Nadu, and even those States that don’t have rivers, can use these projects. Even Rajasthan has the Aravallis running through the State — Rajasthan could become a provider of mineral water!
You have come up with a plan for building Amaravati as a “natural city” and sent it to the Andhra Pradesh Chief Minister. How did this come about?
These things follow in sequence. We had already looked at river flood plains and mineral water; and Amaravati is on the Krishna river. It is going to be built as a new city. First, we looked at the flood plains of the Krishna river. They not only contain a lot of water, but they are also the most fertile areas — perhaps in the whole country. A single farmer there can have an income of ₹10 lakh an acre!
When we saw the city’s plan and saw that the flood plain was going to [have] casinos, resorts, [the] secretariat and so on, we were surprised. The flood plain is about 35 sq. km in the total area of 216 sq. km planned to be used for the phase I and phase II of the city. It can provide not just water but organic vegetables and fruit for the entire city — half a kilo per person, for a million people.
We suggested that the entire flood plain be preserved as a source of water and organically grown vegetables. We worked with Romi Khosla, architect and urban planner, and decided to use a chessboard pattern for the entire city. Imagine the black squares form the green area of the city and the white squares the built-up area. Such a city can have three times the green area of a green city like Delhi.
In summer, the ambient temperature can go as high as 45°C in Vijayawada and also in Amaravati. When the temperature rises, the air expands and rises, then the cool air from the neighbouring green areas will flow in, cooling the built up areas again. Also, the river there is always full, so cool air from the river will flow in. It would give a drop of about 5°C. The in-house temperature can be reduced by another 5°C using architecturally well-designed features, like a four-inch wall with a gap, reflecting roofs, etc. Without air conditioning you can bring down the temperature by 10°C, saving a lot of energy.
You mentioned that you approached the government with this plan…
This plan is really a bid to improve the character of cities. Instead of building a world-class city which will be high on consumption of energy, and ruin the river flood plains which are the ultimate source of water, a city like this which is self-sustaining will really be a pioneer among cities. Instead of being world-class, it would be in a class of its own. If it succeeds, it could become the prototype for building cities in this template.
We made a booklet of this plan and sent it about six months back to the Chief Minister of Andhra Pradesh both by post and through people. We are hoping that he will get us to meet with the urban developers.
How can science help in other problems of this kind?
Too many of our scientists are working on abstract subjects that don’t go out of the box of the scientific journal.
For example, Delhi has about four lakh students doing projects in college. They should be working on such things, not just sitting in a closed library and referring to journals and the Internet. The projects they do should be grounded on the ideas we have discussed.
Science in the public interest is very important. It’s multidisciplinary. While we have great dreams of unravelling the secrets of the universe, the living earth beneath our feet is disappearing.
Science has a role to play, to be the change.
