Letters

Scope of water harvesting

Shamjibhai Antala's contribution to the Saurashtra region is appreciable ('Miracle man' Down To Earth, Vol 8, No 11; October 31). However, the article wants us to believe that construction of water harvesting structures all over the country will be adequate to meet water requirements and no big dams are needed. This can only happen if certain wild assumptions are made. These would imply that:

l It rains everywhere, every year in the country and all one has to do is erect a small barrier to arrest water at each place;

l Everywhere the terrain is such that water will infiltrate quickly, irrespective of the intensity of rainfall, topography or geology;

l All the water, which precipitates during 25 to 30 rainy days in the whole year, can be arrested this way to satisfy all our present and future needs, even with the population reaching 165 crore in 2050;

l The quality of water infiltrating saline and other unsuitable soils will remain unaffected and hence these areas would not require any external supply of water;

l There is enough energy available in the country to pump out all the infiltrated water;

l Large surface areas are available, without reducing cultivable lands, to store water in shallow surface ponds. These ponds will not evaporate, though they will occupy large surface areas relative to the volume stored;

l These ponds will not be silted and will be dependable even during periods of drought;

l No hydropower will be required by the country and all its energy needs can be met from local and imported fossil fuels. Also, there will be adequate foreign exchange for imports; and

l Pollution caused by all such power sources will be more acceptable and preferable to hydel storages.

Many more such implied assumptions can be listed. Every person opposed to big dams has been citing Alwar, Ralegan Siddhi and Sukhomajri without explaining why these have not been replicated even in areas only a few kilometres away. If it was possible to apply this solution everywhere, they would not have waited so long to adopt such measures.

This is not to deny the importance of water harvesting structures. They are essential to supplement the big storage systems but they cannot be substitutes for big dams. Both have to be developed to complement each other. The latest studies of the Central Water Commission reveal that the rate of sedimentation in reservoirs drops drastically after the initial years. Even the deposited silt densifies and reduces in volume considerably. India has been constructing dams for over a century but, so far, no dam has been discarded solely due to siltation. Siltation can be drastically reduced through appropriate catchment area treatment. Waterlogging and salinity are the results of improper water management, which is not related to 'bigness' or 'smallness' of a storage.

Water management should surely be improved even without stopping large dams. Water that does not reach the farmer does not necessarily get wasted forever -- most of it infiltrates into the soil and serves the same purpose as that of the water recharged by harvesting structures. Canals bring this water from far away places even to areas where rain is inadequate. New irrigation systems with lined canals and improved water management have high irrigation efficiencies. One should not harp on unpleasant experiences of old systems.

MAHENDRA U PUROHIT
Received on email

The editor replies:
I agree that small water harvesting systems are no substitute for big dams. But you should speak to the country's water managers for not considering small water harvesting systems. It is not correct to say that the experiences of Alwar, Ralegan Siddhi and Sukhomajri have not spread. The concept of Sukhomajri has been adopted in about 200 villages around it. Taking a leaf f.

Water harvesting for Olympics

Water harvesting is catching up the worldover. During my recent trip to Australia, I saw that at the Olympic village in Sydney, they are collecting rainwater and using it to water the lawns and also for flush systems for which a separate line has been laid at various places. Rainwater from the roofs of the various stadiums is also collected by a pipe system and carried underground for the above uses. They are also using solar energy to a significant degree....

A matter of facts

This is with reference to the article 'Beware! Fluorosis is zeroing in on you' ( Down To Earth , Vol 8, No 6; August 15). The author, R N Athavale, states that "the number of people affected by fluorosis in India is estimated at 2.5-3 million." Whereas, unicef reported in 1995 that "the number of people in India affected by fluorosis which causes dental problems, gastro-enteritis and crippling is estimated at an appalling 25 million".

At the 5th International Conference on the Biogeochemistry of Trace Elements (July 11-15, 1999, Vienna, Austria), the Fluorosis Research and Rural Foundation, Delhi, reported that "an estimated 62 million people have been adversely affected due to consuming fluoride-contaminated water, of which six million are children below the age of 14".

I would request the authors to check the difference in the three estimates and make their comments.

DIPANKAR CHAKRABORTI
Director and head,
School of Environmental Studies
Jadavpur University
Calcutta

R N Athavale replies:
The statistics given in the article are based on notes taken by me during a lecture delivered by A K Susheela, director, fluorosis management programme of the Fluorosis Research and Rural Development Foundation, at the national workshop on "Control of Fluoride in Drinking Water". It was held at the National Environmental Engineering Research Institute, Nagpur, in February 1999.

We need to make a distinction between the number of persons drinking water having excess fluoride and those afflicted by the "fluorosis" disease. Not everyone who drinks excess fluoride is afflicted by fluorosis. The latter depends on other factors, such as the amount in excess over the safe limit, period of ingestion, genetics and diet....

Lessons from Tokyo

This is with reference to the special report on the Japanese government's fight against diesel pollution in Tokyo ( Down to Earth, Vol 8, No 9; September 30). I visited Japan in 1997. I was amazed at the fact that there was almost no air or noise pollution. But while the authorities and the people in Tokyo are taking preventive measures, in India there are no stringent norms against pollution. I hope India will learn from Japan.

HARESH L KUNDAL
Rajkot...

Humans first

It is heartening to see the zeal with which Down To Earth is investigating issues that are fundamental to the life and livelihood of the poorest of the poor. We ought to highlight the fact that violations of environmental law also results in depriving the common people of their basic resources....

The importance of insects

The article on the insect man Georges Bossard ('Beetles for breakfast', Down To Earth , Vol 8, No 11; October 31) made interesting reading. His statement on the extent we depend on insects is fascinating. It is also illustrated in a book, Dust, by Charles Pellegrino. This book presents the grim scenario of the world coming to an end as a result of the total elimination of insects. Though a work of fiction, this book will make us think twice before we use the bug spray.

ROM WHITAKER
Mamallapuram, Tamil Nadu...

The right unit

In the article 'Plagued by deformities' ( Down To Earth, Vol 8, No 11; October 31), the presence of fluoride in water was mentioned as eight per cent. This would be a fatal dose.

SAHAB DASS
Agra...

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