Watershed Management

WATERSHED MANAGEMENT: AUGMENTING GROUNDWATER RECHARGE

By K.C. Agamudai Nambi

The term ‘watershed’ is used to denote an area from which the run off of rainwater flows through a particular drainage point. The ‘drainage point’ may represent a pond, a lake, a dam or a river. There is not much difference between a watershed and a catchment area. We consider here watershed management with particular reference to the augmentation of the groundwater recharge.

Land and water are interdependent. If the soil is fertile and porous, it will facilitate the rainwater to infiltrate easily into it without any restriction for recharging groundwater. And if there is sufficient water source available to an area of land, the soil will naturally be fertile. The combination of soil and water will give birth to dense vegetation and as a result, the soil will become more fertile by the addition of the biomass. And as a matter of fact, the conservation of soil and its fertility is a prerequisite for augmenting the groundwater recharge. Here comes the necessity of the agronomical measures of soil conservation like contour cultivation and providing contour hedges by growing grasses like vettiver in three to five lines across the slope of the land.

Our forefathers had divided the landmass into five categories – Kurinji, Mullai, Marudham, Neithal and Palai comprising the mountain ranges, forest areas, areas for agriculture and cultivation, sea and its adjoining areas and deserts respectively. Kurinji and Mullai are meant only for natural vegetation and forest, Marudham for agriculture, Neithal for fishery and Palai for the miscellaneous utilities like installation of factories and industries. This division of lands comes under the Land Use Classification as Nature dictates.

But we have violated this natural classification. We have denuded the mountains of their natural vegetation for cultivation of cash crops and for constructing roads and buildings. Deforestation is going on without any restriction. Cultivable lands are bought from the poor farmers by the real estate promoters. Government on their part acquire agricultural lands and allot them for the so-called Special Economic Zones which results in the elimination of the ponds and tanks thereon. Seas are polluted and the adjoining lands are encroached for buildings. And because of these indiscriminate violations of the natural land use classification by the modern democracy, groundwater has been depleted causing the scarcity of water everywhere. And quarrying of sand in the river beds is antithetical to conservation of water. And the critical scarcity of groundwater together with global warming has caused the desertification of Mullai and Marudham, thereby expanding the last category of Palai.

This is the present situation in India. For conserving soil and water there are appropriate measures like laying of contour bunds in the dry lands, construction of contour stonewalls across the sloping sides of the mountains, provision of bench terraces in the mountain tracts wherever soil deposits are in plenty, digging of contour trenches where there is no top soil left, construction of check dams and percolation ponds across the gullies. And growing of trees in lines across the direction of the forceful wind will act as windbreaks or shelter belts for arresting wind erosion.

Afforestation is an important measure in watershed management. The trees conserve water and soil. The humus formed by the admixture of the leaves being fallen down after drying up, and the soil will act as a thick bed of sponge which will absorb the rainwater whenever it rains, kepp it within and ooze out little by little. A forest of millions of trees acts like a sponge reservoir oozing out the rain water throughout its length and breadth on the downstream side. This will facilitate the flow of water in the adjoining river throughout the year. This process through the forest will augment the groundwater recharge enormously.

The roots of the trees interlock the soil and hold it intact and thereby the trees protect the soil against soil erosion by flash floods of torrential rain and hurricane. Thus the trees conserve both the soil and water effectively. Forests are the protection for trees in the country. But we are removing them for converting the area for agriculture, constructing giant dams, highway roads, urbanisation and for other modern activities. Thiruvalluvar, the great poet, emphatically says that the wise won’t proceed with any project which will consume the capital itself with the hope of future gain (Kural: 463). But we are doing only this sort of destructive work. Deforestation is still going on in the name of development.

For maintaining the ecological balance in a country there should be forest reserves in not less than one-third of the total landmass (33 1/3%). At the time of independence, India had forests in about 40% of the total area. But, at present only in about 15% do we have left the forest to survive. This foolishness of ours is one of the main reasons for the scarcity of water we are now encountering.

We must find ways and means to make good as far as possible this deficiency of forest areas. It is suggested that the farmers may be motivated to grow trees at the rate of 20 trees per acre along with their dry cultivation. This small number of trees will not reduce much their annual income from their dry land cultivation. Twenty trees per acre, say neem trees, will fetch not less than Rs. 1.00 lakh after 20 years. That is to say, the farmer will be getting an additional income of Rs. 5000 per acre per year by growing trees in their dry lands.

We are lamenting on the non-availability of ground water, but we are not serious enough to carry out the water conservation measures as discussed below:

Laying of contour bunds is the cheapest measure for recharging ground water. But the Tamil Nadu Government has withheld its permission to carry out this work for the past 15 years. There is no technical reason or any justification for the stoppage of this work. The Government has to be apprised properly to obtain their consent to continue this work.

All the existing lakes and reservoirs have been silted up resulting in the reduction of their water holding capacity by not less than 30% of their original capacity. It has to be remembered that about 20% of the total storage will reach the underground water reserve. The government is not serious enough to carry out the desilting work. The silt that is excavated can be arranged to be applied to the agricultural fields surrounding the respective tanks at a nominal rate per tractor load bearable by the landowners. By this arrangement the cost of desilting can be recouped substantially. And at the same time the hardened soil in the agricultural fields, hardened due to the application of chemical fertilizers and pesticides in the course of the so-called green revolution will be reclaimed to some extent. The reclaimed soil with its improved porosity will facilitate more infiltration of rainwater downwards, thus augmenting the groundwater recharge.

Now let us take it for granted that all the existing tanks are restored to their original water holding capacities by pucca desilting work. This means that we will be relieved from the stress of water scarcity to a great extent.

For urbanization the water bodies are filled up with earth and utilized for various buildings. In the case of the city of Chennai alone more than 200 irrigation tanks have so far been abolished. Now let us just imagine that Chennai City had been planned in such a way that all the tanks were kept intact with appropriate arrangements for rainwater harvesting in order to store water in the tanks during rainy seasons as occurred before urbanization. Then the problem of water scarcity will not be so severe in Chennai as at present.

If we take into account all the tanks and ponds that have been filled up and made part and parcel of all the cities and towns in the whole of India, can we quantify the amount of destruction that we have done with respect to the groundwater recharge, the ecological balance, the degradation of the environment and to the abolition of inland aquaculture? The damage done by our modern democracy cannot be justified by any logical arguments.

Of course, we can do nothing to reinstate the innumerable tanks already swallowed by the urbanisation. But we can organize a movement of intellectuals and naturalists to apprise the government not to eliminate any more water bodies in future for urbanization or for any other purposes. The micro and macro watersheds should not be fatally disturbed on any account.

In order to make good substantially the enormous loss of the water bodies through urbanisation, the government may take steps to construct as many check dams and percolation ponds and also farm ponds throughout the country. Millions of such small structures, if constructed, will definitely augment the groundwater reserves. The problem of water scarcity can thus be eased out substantially.

Recently, Oliver De Chutter, the United Nations Special Rapporteur on food said that the only long- term way to resolve the food crisis would be to shift to ways of growing food that do not depend on pesticides or heavy machinery. After the advent of tractors in the rural areas the farmers stopped possessing bullocks for ploughing and other agricultural purposes. And, instead of applying farm yard manure to their fields they switched over to the application of chemical fertilizers. This is not a backward movement, but the rectification of the damage done to the farm lands by the wrong practices in the name of green revolution.

The government may offer some attractive incentives to the farmers for buying and maintaining bullocks as domestic animals and for ploughing with bullock-drawn ploughs instead of tractor ploughing. Only by this way the government can undo the damage done to the lands by the inorganic farming practices.

In conclusion...

Thiruvalluvar has depicted the close relationship between the farmer and his farmland thus:

“If the land owner stays away from his land

The land will sulk like his angry wife

And yield him no pleasure.” (Kural: 1039)

The landowner will have to be in close touch with his land just like with his wife. If he keeps himself away from his housewife she will turn to be resentful and avoid his embrace. Similarly, his land will sulk with him if he acts indifferently with her. Such an animated relationship prevailed between the tiller and his tilled land.

Until the nineteenth century the farmer had been in the apex of the social pyramid. The ploughmen were the linchpin of the world community as Thiruvalluvar puts it. In those days he himself would take care of the land against erosion or any other degradation.

As long as the farmlands and the farmers were revered with due respect in society, all the micro and macro watersheds were kept intact. Village ponds and irrigation tanks were desilted by them and the tank silt was applied to their lands. Thus they themselves maintained their water bodies.

But in the present days, due to the modern trend of globalisation and liberalisation, the farmlands and the farmers are looked down upon. The poor farmers are easily lured to sell their lands by the real estate promoters. They are badly exploited by the middlemen. There arise innumerable ways of easy earning in the urban areas. Hence the farmers, after selling out their lands, migrate into the cities and towns to live as wage earners. The percentage of the rural population is being reduced day by day.

This trend should be arrested by all means, if we are serious enough to maintain the watersheds, to maintain the eco system of the country, to augment groundwater recharge and keep self-sufficiency in food and our livelihood.

(Source: Sarvodaya Talisman, Nov.-Dec. 2010, pp. 43-46)