Published: Saturday 31 May 2008

Complex phenomenon

The increasing pace of erosion at the Sunderban delta, as mentioned in your editorial Science drowns at lands end (April 30, 2008), is an interesting example of active earth processes like sea level rise, land erosion and land subsidence. It is, however, difficult to explain the mechanism or causative factor of such rapid erosion due to sea level rise, particularly in the prevailing context of climate change where sea level rise is a global phenomenon.

Studies carried out by scientists A S Unnikrishnan and D Shankar for the Indian Ocean, as noted in the article, show a very slow rate of sea level rise, which is insignificant due to obvious in-built errors. Though such erosions along the Indian coastline are ubiquitous, they are highly localized. In south Gujarat, for instance, the coastal tracks between Dandi and Daman have been experiencing rapid erosions, similar to that in the Sunderban delta, since 1986. The sea has engulfed a number of fishing hamlets along the coast.

Contrary to this, in other coastal areas of Gujarat, such as Hazira and Umbharat near Surat, the sea is moving away from the present-day high water line, releasing additional land, which gets submerged only by extreme high tides during rough weather conditions.

As per my understanding, such selective phenomena of erosion cannot be attributed only to rise in sea level due to climate change. The most plausible explanations to the problem can be ascribed to three factors:

Down to Earth Active tectonism in Indian sub-continent. We experienced a major tectonically-induced event, tsunami, in 2004, which resulted in massive subsidence of crustal mass. The Sunderban delta and nearby islands were equally affected by this.

Down to Earth Excessive soil erosion from the catchments of major river systems like the Ganga, the Padma and the Brahmaputra are ultimately dumped in the Bay of Bengal. Over the period, the bay has become a major depositional basin and is experiencing slow but continuous subsidence due to soil loading. This can also be ascribed to active geotectonic phenomena.

Down to Earth Anthropogenic factors, such as reclamation of inter-tidal regions for industrial and urban settlements, divert wave energy to other regions enhancing the rate of erosion. Back-bay reclamation at Nariman Point in Mumbai is a classic example of such land use modification that has created problem of excessive sand build-up and erosion in Varsova in North Mumbai.

The Maharaja Sayajirao University of Baroda, Vadodara

Down to Earth Your article holds vital information for me. Thanks.

National Geophysical Research Institute, Hyderabad

Down to Earth The erosion in Sunderbans is happening because of tidal waves and not because of the sea level rise. The sea level rise along Sunderbans coastal line is insignificant. Only green forest cover can check the erosion.


Down to Earth Your editorial offers a vivid description of Ghoramaras reality. In such a scenario, the West Bengal governments decision to set up a chemical hub in the state seems erroneous.

Recently, I came across a news report that quoted West Bengal Chief Minister Buddhadeb Bhattacharya as saying that a huge chemical hub, kicked out of Nandigram, will be built at Nayachar come what may. Amidst all the political din, it will be pertinent if your magazine can help build up a scientific opinion<>

Choking roads

Your article on congestion on roads, Planning in the air (April 15, 2008), reminded me about what John Diandas, the world-famous transport expert, had once told me: When roads get congested, people tend to widen the road to cope with congestion. But this does not happen. On the contrary, more cars come in to again choke off the widened road.

Rohan H Wickramasinghe
Institute for Tropical Environmental Studies, 41 Flower Road,
Colombo 7, Sri Lanka

Down to Earth Travelling to Bangalores new airport, which is on the city outskirts, can be a nightmare for many. But there are certain groups who are happy and stand to benefit from it. They are the real estate mafias. They have already started buying hectares of land in and around the Bengaluru international airport. Who cares for air pollution, poor infrastructure and wobbly administration in the city?

raj nair

Down to Earth You talk of promoting public transport. But I wonder if people possessing cars will agree to resort to bicycle or use the public transport to reduce the level of greenhouse gases in the atmosphere.

Before promoting public transport, we need to educate people about greenhouse gas emissions, its impact on the climate as well as on our health. The Department of Environmental Sciences should organize workshops to spread awareness among people about pollution-related problems. Meaningful environmental education should be made an integral part of the school curriculum.

Lopamudra Giri

Food security

Your cover story Food crunch (April 15, 2008) makes an interesting reading. In the face of climate change and its impact on agriculture, India needs to guard itself against economic squeezing by developed countries. India should be more concerned about achieving and sustaining food self-sufficiency, while insuring it against the decline in global food supply.

S Venkataraman

Down to Earth The cover story on food price has candidly exposed the United Progressive Alliance governments hidden political agenda in the budget 2007-2008.

The mega loan waiver to the tune of Rs 60,000 crore for farmers was politically motivated with an eye on the vote-bank. The soaring prices of essential commodities will not be compromised unless drastic steps are taken to check the spiralling inflation.

Instead of such political stunts, it would have been better if the government had overhauled procurement policies and invested heavily in the agriculture sector to boost production.

Tiruvannamalai, Tamilnadu


Consumer interest

Your cover story Pure myth (March 31, 2008), is informative. But I have a problem with upcoming water purifiers which claim to be using various scientific technologies.

They do not offer a reliable testalso convenient and easily accessible to consumersthat can help us know if the filtered water is actually free from harmful bacteria. Companies manufacturing water purifiers should also mention the expiry date of filters they use. As per my knowledge, none of the companies follow this.

For a common consumer like me, chlorination is the cheapest method for purifying water. Its reliability is also easy to test.

Karve Nagar, Pune


Non-violence or inaction?

The report Sikkim Struggle (April 30, 2008) states that there are proposals for 27 hydel projects in Sikkim, of which 14 are to come up in North Sikkim including seven in Dzongu, an area reserved for the dwindling Lepcha tribe. To get these projects scrapped the Affected Citizens of the Teesta (act) activists have gone on a hunger strike.

The non-violent protest launched by the act activists is appreciable.

However, their non-participation in the state government-formed committee to review the projects will not help the cause. It was necessary on the part of act to reconfirm the press statement issued by Sikkim Chief Minister Pawan Kumar Chamling saying that he has withdrawn six of the seven dams in Dzongu except the one in Panang. The Panang hydel project is said to be in an advanced stage of completion.

Instead of hunger strike, act could at least open a dialogue with the government. The path of confrontation, which act activists have now adopted, seems ill-advised.

Karma T Pempahishey

Free for farmers

Thanks for publishing an article on free and open source software (Foss time in India, April 30, 2008). I am a farmer from Kerala who is using the free software, which offers more facilities than Microsoft.

S Chandrasekharan Nair


The article Green rice (April 15, 2008) quotes Mahadeswara Swamy saying that Ninety per cent of the methane produced in the fields is absorbed by the roots. What he meant was Though methane is not produced by paddy, ninety per cent of methane produced in the fields is absorbed by the roots and transmitted to the atmosphere.

In the article Mahadeswara Swamy has been erroneously referred to as Indias national communication officer to the United Nations Framework Convention in Climate Change (unfcc).

Swamy is the principal investigator with one of the National Communication (ii) projects to unfcc on inventory of ghgs.

We regret the error.

Alternative measures

The overutilization of polythylene bags and plastic containers at shopping malls troubles me. I want to start an awareness camp and practical alternatives to polythene bags in the housing society where I live.

Any suggestions please?

Leena Dash

Down to Earth While discussing how to best use treated wastewater from industries (output from effluent treatment plant with secondary treatment), we thought of using it in the construction industry, particularly in ready-mix concrete. We discussed with few consultants who appreciated the idea saying that the measure will discourage industries to use scarce groundwater through bore-wells. However, considering the chemical-oxygen demand (COD) and total dissolved solids (TDS) content in the treated industrial wastewater, we are not sure if it will deteriorate the concrete quality. We hope for suggestions in this regard from research groups.

Amit Gupta
Mahindra & Mahindra
Kandivili (E), Mumbai


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