The Yamuna flows near Chandigarh. Photo: Shyamal/Wikimedia Commons, CC BY-SA 3.0
- Floodplains have both natural storage and natural recharge, so if we conserve and use floodplains wisely, we can have a perennial source of water.
- Floodplains are mainly recharged by (unpolluted) monsoon rain and by late-monsoon floods, when the pollution in rivers has been largely flushed out.
- Floodplains can sustainably water most of our river cities, towns and villages, providing a perennial, non-invasive solution for good-quality water.
- For this, floodplains have to be protected as water sanctuaries, and all farmland here must convert to farming that is not water-intensive and doesn’t use fertilisers.
There is a green lining in the 2022 Union budget in the form of natural agriculture on the borders of rivers, in particular the Ganga.
Natural agriculture must be understood as organic agriculture that will avoid sullying the river with fertiliser and pesticide runoff. The plan has now evolved into a blueprint for forestry plantations on the banks and catchments of 13 major rivers with an investment of Rs 19,000 crore over the next five years. There is tremendous potential to this idea and it can do volumes for our rivers and also help resolve our drinking water contingencies.
Rivers in India are now overdrawn, silted and polluted. They are a piteous spectacle, with hardly any flow except in the monsoons and so polluted that their water is unfit for any use or life.
There are several examples of reviving and cleansing rivers, like the Rhine in Germany, the Thames in the UK and the Hudson in the US. The obvious way has been to make sure that no industrial or toxic effluents are allowed into them and that all domestic sewage is treated (by sewage treatment plants) before they are discharged.
But does this mean that the river will regain its purity in a few years or decades? The Rhine, an icon of Europe, has been scrupulously protected from pollution by over 50 years of German discipline. But it is an unkept secret that nobody directly drinks the Rhine’s water even today as it is not potable.
I discovered this when I happened to sit by two German gentlemen who had come to a ‘Namami Gange’ meeting, to offer their services to clean the Ganga. “Is the Rhine clean today?” I asked. “Of course,” they said. “It is well known.” While waiting for the minister to arrive, I asked them if people drank directly from the Rhine, to which they replied: “Of course not.” Were they going to share this with the prospective client? “Of course not.”
So if we do start cleaning the Ganga and other rivers today, will we get potable water in a few years or even a decade? Of course not, it would seem. But we must clean them nonetheless: that is the only way the quality of their water will improve.
‘Har Nal Me Jal’
This brings us to the Indian government’s ‘Har Nal Me Jal’ mission (‘Water in every tap’), which aspires to provide piped drinking water to all households, drawn from rivers. We must realise that this grandiose scheme will provide water for all uses except direct consumption (drinking). The only way to do this will be after filtering the water through a reverse-osmosis (RO) setup.
‘Har Nal Me Jal’ doesn’t include this possibility, so it will only increase the cost of water and also produce non-recyclable waste, in the form of discarded RO apparatuses. In addition, RO doesn’t only filter pollutants but also minerals and nutrients out of the water. We must ask therefore if there could be a more wholesome answer to India’s drinking water problem.
Indian rivers are monsoon rivers. They have deep (50-100 m) and wide (several km) sandy floodplain aquifers that run for thousands of kilometres and serve as enormous natural stores of water. Sand is porous, which makes for wonderful aquifer material, and the floodplains hold a lot of water (35-40 % of their volume). They are recharged by monsoon rains and floods, and feed the groundwater aquifers in their environs.
Given the increasing scarcity of water, India’s rivers are likely to be one of its few perennial water resources in future. We must make the sustainability of all the ecological services a river provides a priority. We must also ensure we avoid injuring catchment areas, floodplains and the basin by overbuilding dams, canals and by discharging pollutants into the rivers. For this, the rivers need environmental flow 1.
The miracle is that floodplains have both natural storage and natural recharge, so if we conserve and use floodplains wisely, we will have to do little else to have a perennial source of water. This is nature’s bounty and gift – natural infrastructure – provided on the condition that we don’t use more than what can be replenished every year.
Most of our cities are river cities and have severe water problems – in terms of supply or quantity as well as quality. NITI Ayog and WaterAid have found that over 70% of all our surface waters – rivers and lakes – are badly contaminated. So we are hard-pressed to find a solution to avail good-quality in our cities. Since the river is always in contact with the floodplain, one would imagine that the floodplain water is also polluted, but this need not be the case.
Floodplains and subterranean forest aquifers are the two remaining water sources that are not polluted. Floodplains are mainly recharged by (unpolluted) monsoon rain and by late-monsoon floods, when the pollution in the river has been largely flushed out. Since rivers are polluted, particularly in the lean months (October-June ), we must ensure that contaminated river water never enters the floodplain, or we will lose it all.
Specifically, the gravity flow has to be one way – from the floodplain down to the river. The sacred condition that this translates to for the floodplain is that the level of groundwater in the floodplain must always be well above that of the river.
This is not a pie in the sky. The Delhi Palla floodplain project, over a tract of some 20 km of the northern end of the Yamuna, sustainably provides good-quality water for over a million people every year.
Floodplains can sustainably water most of our river cities, towns and villages – except for the megacities. This is a perennial, non-invasive solution for good water that is thankfully still available in these times of water shortage. Sustainability entails that a substantial fraction of the total recharge must be left to water the river itself. This is natural infrastructure that can be conserved and used. But the floodplains have to be protected as water sanctuaries: in particular, they must be protected with a 1-2 km wide tract on both sides of the river. All wilderness, wetlands and forest areas must be preserved as such.
On the other hand, all farmland on the floodplains must convert to growing organic food forests or fruit orchards, which are not water-intensive. Paddy, a water-guzzling crop, is the mainstay on our floodplains but it should be avoided to the extent possible – except in places that have a surfeit of rain.
If the land adjacent to the river belongs to farmers, they need to be amply compensated (Rs 40,000 per acre per year) and enjoy rights to the produce as well. This can be easily accommodated from the revenue, at present rates, of the water that goes to the city, leaving a large balance in reserve for the local government. This makes great economic sense and is the perfect solution for towns, farmers and river ecology. I and others have already suggested such a scheme.
This scheme will also help curb sand-mining and illegal water extraction, stop pollution by local agencies and industries, and encourage cities to be responsible in their waste management. Overall, this ‘conserve and use’ solution will be ingenious, of great benefit to everyone and generate a healthy profit.
There are numerous cities that can be completely watered by floodplain water. They include Mathura, Agra, Prayagraj, Benares and Bhubaneshwar, among others. For the peninsular rivers, the floodplains are not so deep, but this does not affect their recharge; all of them have ample scope for water recharge.
The ‘conserve and use’ scheme will also work well for water-short China, which has rivers with great floodplains – as well as for the Tigris and the Euphrates in Iraq.
A rough and conservative estimate of the sustainable water potential of the floodplains of India comes to more than 50 billion cubic metres every year. If we use half of this to provide water to towns and cities, we can provide good-quality water for three-quarters of a billion people at the rate of 100 litres per person per day.
In sum, protecting floodplains as water sanctuaries is a perennial solution that will conserve the floodplains in a non-invasive way for future generations. This will go a long way towards helping resolve the water scarcity that all our cities are facing, while also helping to maintain the ecological integrity of our rivers.
Vikram Soni is the author of Naturally: Tread Softly on the Planet (2015).
Minimum flow required to sustain ecosystems that depend on the river↩