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Mathew Kurian

That Kerala reels under water shortage in the summer months, despite the copious rains, is worrying and probably typifies a trend sweeping the entire world.

NO ONE — not even governments, for that matter — remains complacent about a possible water scarcity that we may have to face — next season next year; may be in the next decade. The UN predicts acute and widespread water shortage the world over by 2030.

Drought has been stalking the country even if the preceding season had been bountiful. Kerala, with annual rainfall averaging 3,000 mm, remains routinely plagued with summer water shortages. This is despite the fact that never in the past 20 years has rainfall been than the stated average. This agro-climatic zone probably typifies — and demonstrates by magnifying it — a trend, sweeping the entire world.

The annual 3,000 mm rain is very high precipitation indeed. It means that the resultant water would stand to a height of 3,000 mm (3 meters) over every unit area where the precipitation is received. If the municipal requirement of water per day per individual is 50 litres, water from a column standing over just 6 sq m of surface would suffice to meet this need year round.

One of the most populous States, the population density in Kerala is 780. It means about eight persons on an average live on every hectare in that state. The water requirement calculated per hectare, on this basis, should be entirely met from the rain received on just 6x8 sq m of surface area. Water brought down in rains over the rest of the 9,952 sq m to every hectare, is in excess of the municipal water needs of the state. (What portion of this excess quantity accounts for the industrial or agricultural consumption of water in that State remains a moot question.) That the State reels under water shortage in the summer months, despite the potential source (over 2,200 per cent of municipal needs), is intriguing.

Senior citizens will readily agree that the water situation in Kerala was different even 50 years back. Not just the major rivers of the State — or at least those that go by that name there — even their subsidiaries to the third level, were perennial; they would not go dry even at the height of summer. Even perennial surface springs that served as community source could be, not infrequently, encountered.

Perennial surface springs, one does not anymore come across. Perennial open draw wells that go dry in the summer are on the increase. Even the major rivers have now turned seasonal; with flow interrupted at the height of summer, turning themselves into a series of dirty pools.

Clearly, the sub-terranian springs are getting depleted. But rains — the ultimate source for water on the earth — remain just the same now, as they were a century earlier and there are records to prove it.

Searching the environment for clues as to what may have caused this devastation, one meets with only one ubiquitous, catholic, universal change common to all tracts, regions and situations.

Doubtless, it is the extensive denudation of the forest cover, which one comes across anywhere where civilization and modern farming has reached. There is no other single common denominator where hydrographic deficiencies have happened.

Geographic compulsions have acutely limited land availability in Kerala, with the consequence that forests continue to be usurped and even the high-ranges are now under cultivation. The general principle in land use of reserving slopping lands with a gradient of more than 30 per cent, as forests, is observed more in its breach here.

Lands with a gradient of more than 50 per cent under cultivation, are indeed, very common. It is not unusual to find occasional patches of cultivated land having even a slope of 100 per cent; where the gradient is so acute that as one reckons a metre horizontally, the land falls away to an equal extent!

It is not as if the farmlands in Kerala remained unprotected without conservation measures being attempted. The idea of watershed-based conservation measures for whole tracts is gaining acceptance. Yet, alleviation of drought remains a far cry.

What has proved devastating to the land is the depletion of the organic content of the soil — a consequence of what we call clean cultivation. Before conventional farming obliterated it, the soil had its rich vegetative cover and the resultant copious litter of wastes immediately beneath it. The degradation of this litter incessantly added a wealth of `humus' to the surface soil. And, humus it is that bestows to the mere detritus — the proceeds of disintegration of parent rock — those attributes that transform it into productive soil. Humus, for one thing, is infinitely more porous and space-enclosing in its construction than soil and, consequently, is capable of absorbing into it quantities of water exceeding even its own volume. A generous presence of humus in the soil ensures that when rain occurs, water is quickly absorbed by it, as would perhaps happen with a sponge; leaving the soil (macro) pores largely open for further ingress of water. Water movement among mere soil particles, on the other hand, is much slower.

It takes about an hour for water to move 15 cm down, even in laterite soils, fairly open textured as it is. Because of this slow movement, the top layer tends to remain flooded; as the immediate aftermath of a rain. Water from a second rain following, say, in 5-10 minutes, meets with a situation, almost as if it had fallen on a sheet of water, with little of it being able to go into the soil. During the height of the monsoons, rains come in such quick successions that the flooded state of the top layer of soil turns most of it into surface run off. Continuous, heavy precipitation, which happens in the South-West monsoon on the west coast, need not necessarily result in enormous groundwater storages — the source for underground springs.

The loss of the vegetative cover contributes to surface run off in other ways too. The successive strata of leaves in a tropical forest help dissipate the momentum of falling rain, divesting it of its cutting power. From the leaves of ground-hugging vegetation, rain drips on the mulch underneath and then merely spreads on to the soil, without ever having to break up the soil crumbs. Rain slashing naked soil, on the other hand, proves damaging to the soil structure — incidentally, an important attribute of soil productivity.

The rain drop that must have been falling a km or more, rains into a soil crumb with considerable cutting force and throws the finer soil particles that went into its construction, asunder. These particles get carried about in the storm water, turning it muddy in the process. Some of them, carried by water down, get lodged in the soil pores, effectively sealing them and blocking further ingress of water and turning as much as much of it into surface run off.

Besides sponging rain water away and keeping open the soil pores for further water, organic debris help open up the soil in the physical sense also. A wide spectrum of live forms — thousands of species of them, both animals and plants, microscopic as well as yet larger sized, whose growth permeates the entire top soil and are involved in the degradation of organic debris — are sustained by the organic rich soil.

This bio-system in the soil is a very tangible presence and remains the key to soil productivity. Their combined body mass can be surprisingly large and the spatial needs for it, considerable. The waxing and waning of their life-phases, consequently, help open up the soil for water and air movement. So do their metabolites, to a degree never even dreamt by us.

The difference between a richly verdant patch and a barren soil that the foot senses, is all that makes the vital difference between a soil that is capable of drinking in water and one that is not — between one that promises flourishing of life and one in the process of dying and slowly turning into a desert. Even with urbanisation happening unprecedentedly, open space (farm lands) that receives natural precipitation still remains so vast that there is little choice than re-designing the farming strategies and ensuring that the vast riches of water of natural precipitation are efficiently led into sub-soil reserves.

But, strangely enough, just rain harvesting by guiding precipitation directly into storage alone continues to be the pet theme even of governments.

(The author is former Joint Director of Agriculture, Kerala.)

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