Sunday , 23 September 2018

When will we start river and water body rejuvenation?

 By Ranjay Sinha


In the present world scenario, due to the rapid urbanisation and industrialization human population have been increasing exponentially.  People are desperately in quest of the land and water resulting in heavy burden on the availability of the fresh water. It is well known fact in spite of 75 per cent of water bodies available in the world we are getting less than one per cent of fresh water for our use.

In India, the 2nd largest populated country is facing extensive crisis of water since last few decades. Findings of reports on the availability of water are alarming as 600 Indians face high to extreme water stress. India ranks 120th among 122 countries in water quality index. The government has been taking initiatives to get rid of acute crisis of fresh water but for fresh water we are fully dependent on south west and north east monsoon which is mostly irregular in nature. The Indian monsoon cycle is mostly irregular in pattern and many research papers has been published by distinguished scientists like Dr Rajiv Nigam, NIO, Goa, Dr N Khare, ministry of earth science, New Delhi on predicting the future behaviour of monsoon and climate.

During the tenure of  former Prime Minister, Atal Bihari Vajpayee, the planning to connect all the major rivers of India together was initiated but not implemented. The objectives of this valuable plan was to ensure water to each and every part of the country, prevent flooding and ensure adequate flow to those rivers which receive low rainfall and those falling in rain shadow areas.

Every year during the monsoon periods we are finding that some areas are over rained while some part are still facing draughts resulting in the over rained area gets flooded and the damage of life and properties to habitants. Similarly, rain deficit areas also face the famine situation. Afterwards, the farmer loses the crop due to irregular pattern of monsoon and fails to repay loans.

Now is the time to make a concrete program to recharge and conserve the fresh water. In a interview Rajendra Singh, water conservationist and Ramon Megsaysay award and Stockhholm Water prize winner revealed that, about 70 per cent of small rivers have died. He said that, water conservation efforts must involve people and not contractors.

Niti Aayog recently come out with a composite water management index to assess the performance in efficient management of water resources. But as per the Niti Aayog report, MGNREGA is not doing enough for river rejuvenation. The money was used for building roads, toilets, generating employment etc.

Every year during the monsoons, the main rivers and its tributaries carry million tons of rock debris, sand, silts and clay which they either dump in their banks or near the estuaries area. These silts and sands also gets deposited in the river basins and occupy a huge areas which in turns led to flooding even during a small amount of rain because these rivers do not have any more space to hold the water. Moreover, as the storage of water is very less it gets dried up even in the beginning of summer which results in water crisis along the nearby areas.

Moreover clay covers the maximum area of river bed and does not allow the underground water body to recharge as clay is highly impermeable. We are very much aware that as per hydrological cycle as well ground water recharging the presence of effective porosity and effective permeability must be there at the land surface, river basin etc. For rejuvenation of river, the river basin must be cleaned from impervious sediments and must be assure the presence of sandy soil, alluvial soil etc which allows water to move towards the ground water table.

Every year state governments float tenders for the dredging of sand from the river beds. The sands is mined by the contractors and supplied to the construction sites. But this practice is also not going smoothly as due to some illegal sand mining as well as the concern over adverse impact on flora and fauna. According to environmentalists cleaning of the river bed may destroy the breeding of turtles and some fishes so it must be stopped now.

Indian coastal areas receive heavy rain fall about 3000 mm per year but still these areas suffer severe water crisis. The reason is no proper management to restrict the surface run-off from intermixing with the seas. There must be sufficient amount of checked dam in and around plateaux areas of coastal region. The deep valleys can be identified surrounded by the plateaux and the passage to the sea must be stopped to restore the water. Moreover the thick lateritic caps (weathered and disintegrated products of basaltic trap rocks) along the western coast of India are not able to hold the fresh water run-off during monsoon and maximum water drains into sea.

The residents along the Konkan coast and Malabar coast are generally involved in the commercial plantation like Mango, Cashew etc. They face severe water crisis during the start of summer. In some regions there is little ground water but not sufficient as the water is found in the pockets termed as perched water body. These water bodies do not connect themselves with the aquifer and the reason is the presence of impermeable strata all along in its premises.

Hence; for rejuvenating the water bodies like aquifer the facilities of recharging and percolation must be there and also need to identify the impermeable wedge zone which will not allow the intermixing of ground water to the sea water.

Once these areas gets identified the ground water recharging can be done by covering areas with plantations as well as rain water harvesting systems. In order to rejuvenate water bodies like ponds and lakes the nearby surrounding area must be covered with the plantation because the roots of the plants can hold water and also help the surface water to percolate and rejuvenate the water bodies. These plants also help in slowing down the evaporation rate of fresh water bodies due to minimise the temperature of these areas.

In Chennai, the water crisis is very much severe and the state government has taken the steps that each and every residential complex, malls, markets lay out plans must include rain water harvesting scheme too.

*The writer is a senior geologist in the private sector

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