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Constructed wetlands

December 19, 2009

Ecological way to manage wastewater

While natural wetlands should never receive wastewater from urban runoff, constructed wetlands can pick the city’s storm water runoff and waste water and biologically treat it to acceptable standards


EYE-CAPTURING: Constructed wetlands to treat wastewater.

Wetlands are areas like swamps and marshes typically subject to soil saturation and flooding during parts or whole of the year.

They have a unique variety of flora and fauna which can withstand the occasional full submergence as well as full dry conditions and are often referred to as the nurseries of life.

Wetlands have long been recognised as potential zones capable of handling various pollutants and being capable of absorbing or transforming them.

Many of the ‘tank’ ecosystem of south India are wetlands in the sense that they can be submerged during parts of the year and be dry during other times.

With tanks in urban areas losing their original purpose of providing agricultural water, their conversion to constructed wetlands has the potential to treat urban wastewater in a decentralised fashion, absorb and mitigate the impact of urban floods as well as provide a bio-diversity spot for flora and fauna.

Constructed wetlands

Constructed wetlands are artificially built wetlands designed to mimic the natural wetlands. Wetlands are different from pools or lakes primarily with more vegetation coverage and less water at shallow depths.

It is possible to design and classify the constructed wetlands as fully submerged wetland where the water is in contact with air and a subsurface horizontal flow constructed wetland where the water flows in a stone or brick bat medium and is not in contact with the air.

Constructed wetlands are typically shallow structures which are kept to depths of 1 meter or less. The bottom of the wetland is usually lined to prevent water from percolating down into the aquifer.

Constructed wetlands have shown tremendous potential of assisting in the biological digestion of human wastewater flows. The plant species can be of the variety that float on the surface, are completely submerged or are rooted at the bottom of the wetland.

Each plant species has a different role to play in the wetland by itself and also as host to other organisms such as bacteria.

In the home: A small constructed wetland can come up at the household level itself. Many sites and homes in the city’s periphery come up in places where there is no underground drainage facility. Here a modified septic tank called a baffled reactor can be built.

The wastewater from the home both from the kitchen and the bathroom is allowed to predigest in the baffled reactor and then allowed to flow into a constructed wetland.

This further treats the waste water as also allows a uniquely bio-diverse area spring up close to the home.

Bringing in a landscape feature

The Rajans have a house far away from the city and many homes in the layout had to take recourse to a septic tank and a leaching system for taking care of their waste water.

The Rajans chose to go for a baffle reactor and a constructed wetland instead and have therefore not only been able to treat wastewater well but also obtain a beautiful landscape feature on their plot

In layouts and apartments: Constructed wetlands can be designed to handle large volumes of wastewater and storm water emerging from these developments. Again a certain form of pre-treatment or pre-digestion of waste water is needed before the constructed wetlands take over and treat the water further.

By integrating it with parks and open spaces, walkways can be created with a palate of plants to enhance the visual appeal of the landscape while providing the functionality of treating wastewater.

At the city level: Constructed wetlands have treated wastewater flowing in canals in the city of Fuzhou,China.

Formerly a stinking 80 km network of flowing wastewater is now a lush green walkway around the city with no smell an with a clarity level in the canals which is much higher. The system was designed by John Todd and Ocean Arks international.

While natural wetlands should never receive wastewater from urban runoff, constructed wetlands can pick the city’s storm water runoff and waste water and biologically treat it to acceptable standards reducing turbidity levels, reducing bacteria , removing nutrients and increasing oxygen level of water while enhancing bio diversity.

Water wisdom calls for using nature and its bio-diversity as an ally in maintaining and enhancing the quality of life in our cities and homes.

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Water Bills- What they tell you.

December 17, 2009

WATERWISE

Water-bills- What they tell you

S.Vishwanath

www.rainwaterclub.org

zenrainman@gmail.com

080-23644690

A bill for water may seem a dull and uninteresting document. It can however be made quite interesting and informative.. In Bengaluru if you are connected to the Bangalore Water Supply and Sewerage Board mainline, you should receive a water bill every month.

Apart from the Subdivision name, Bill number, consumer i.d and type, one important item is the Last date of payment.  A small note is appended at the bottom of the bill which indicates that ‘If payment is not made before the due date steps for disconnection of supply will be initiated’. It is understood that not a single disconnection for domestic connections has been carried out so far. The penalty for late payment is also not indicated on the bill. A sign however urges you to pay on time and help BWSSB serve you better. The 24/7 kiosks of BWSSB for collection is however a global best practice which does not find mention in the bill.

Then comes the information on consumption. A ‘present reading’ in litres and a ‘previous reading’ in litres and the difference between the two indicates the consumption.  Sydney waters, when it gives a bill, compares it to the average consumption across the city and lets the household know whether they are above or below average. It also lets the household know how it is doing vis-à-vis standards by flagging a red or a green signal.

Next set of items is on Water charges. This has to be read with the back page of the bill which indicates the Increasing Block Tariff. The first slab of 0-8000 litres is charged at Rs 6 a kilo-litre and the next slab 8-25,000 litres  at Rs 9 per kilo-litre. That means if you have consumed 25,000 litres you pay 8 x 6 + 17 x 9 = Rs 201/- . The bill does not indicate the production cost of water which the BWSSB claims is around Rs 18 /- a kilo-litre. This would mean that the actual production cost of the 25,000 litres by the family would be Rs. 450/- and since the family pays Rs 201/- it receives a subsidy of Rs 249/- in that month. The vital information is important to let the consumer know actual costs and then to push for full cost recovery.

The next item is meter charges. Since the meter is paid for by the consumer during installation it is not clear what this meter charge is. Most probably it is the meter reading charge and if so must be clearly indicated.  Sanitary charges follow and read with the back page, it indicates a flat Rs 15/- for a domestic consumption up-to 25,000 litres . The actual cost of collection and treatment is not indicated. Once this is done it would be clear as to how much a family is subsidised for sewage collection and treatment. One estimate for collection puts it at Rs 600/- or Rs 24/- a kilo-litre. This means that the household gets a subsidy of Rs 585/- every month.

The interesting item is S.C for bore-well. This a Sanitary Charge for the water consumed from the bore-well and let into the sewage lines, which then the BWSSB has to treat. This is unique to any city in India. The back page of the bill indicates a flat rate of Rs 50/- per month per individual house and  for apartments also. If the BWSSB moves towards metering bore-wells it could then rationally charge on a volumetric basis incentivising less abstraction from groundwater.

Lessons: Institutions such as BWSSB and individual consumers could learn a lot from devising a communicative bill. Since a bill reaches the consumer every month it is a great communication tool for the BWSSB. Water wisdom demands that a water bill can be made interesting and a knowledge creator rather than a drab financial document.  Can we move towards water wisdom then?

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A turnaround in groundwater in a smart industrial area

December 12, 2009

WATER WISE

Managing water in an industrial unit

S. VISHWANATH

Thanks to a 10-year master plan, a water-scarce area sees a change of fortune


Proven method: Drip irrigation systems deliver water directly to the root zone of plants and reduce consumption

Located in a semi-arid area, the industrial unit spread over 343 acres depended solely on groundwater for its requirements. Borewells to a depth of 450 feet supplied the five lakh litres of water needed daily. In the year 2000, a disastrous year of rainfall, all the groundwater sources dried up and water had to be rationed. The plant had to shut operations and it became difficult to even supply water to the factory workers and their families resident in the colony.

The industrial unit resolved to consult experts from the ground water and forestry departments and came up with a comprehensive 10-year water management master plan involving watershed planning, rainwater harvesting, groundwater recharge and large-scale tree plantation.

Work began in right earnest that year itself with constant monitoring. More than 1,10,000 saplings of native trees which required little water were planted on campus. Percolation tank areas were identified and dug, recharge pits made and channels dug to link catchments to dried open wells.

A demand management strategy reduced water consumption to its optimum. Drip irrigation system was introduced to deliver water directly to the root zone of trees and reduce consumption.

Gradual change

A gradual change came over the area. Due to the recharge efforts the groundwater table rose by 250 feet and groundwater is now available in open wells also. Though the daily demand has gone up to eight lakh litres, a combination of reducing demand, recycling and reusing waste water and recharging groundwater has ensured that sustainable water is available right through the year.

Due to the rise in groundwater table, pumping costs have decreased and water is available at around Rs. 7 per kilo-litre. Energy costs and carbon emissions too have declined since the head to which water has to be pumped has reduced. The trees are fully grown, reducing ambient temperature by 2 degrees Celsius. Birds are flying in and biodiversity has increased and the industrial unit has become a bird-watchers’ paradise. Fruits from the mango, coconut, chikku, pomegranate and gooseberry trees fetch nearly Rs. 2 lakh a year. The entire ecosystem has been transformed and regenerated.

What began as a work to tackle water shortage has resulted in bio-diversity enhancement, a carbon footprint neutral plant, and an energy-efficient and water-efficient plant.

Award

The Mahindra and Mahindra unit at Zaheerabad won the excellent water management unit award and the innovative projects award for this remarkable work at the recent National Award for Excellence in Water Management 2009 organised by the CII at the CII-Sohrabji Godrej Green Building Centre in Hyderabad.

Industries like M & M Zaheerabad show that a dedicated team effort to overcome water adversity, combined with leadership, scientific planning, implementation and monitoring can transform a water-scarce region to a water-positive region. Since industrial demand for water is fast rising in India, solutions which show ‘water positivity’ are the need of the hour. That is water wisdom.

www.rainwaterclub.org

zenrainman@gmail.com

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Water management in apartments – a checklist

December 6, 2009

Ensuring water supply in apartments

A checklist of the factors apartment owners have to take note of

Apartments are the new reality of urban living. One of the key challenges is to meet the water supply demand to keep all the amenities working.

Here is a small checklist that apartment owners, associations and builders need to keep in mind so that the taps in the flats do not run dry

* Since multiple sourcing will be the order of the day, make sure that the sustainability of sources is kept in mind when connecting systems.

In simple terms, will water continue to come from the main pipelines? Will the borewells continue to give good quality of water for the next 20 years?

Is the apartment designed well for water tankers to come in and empty their loads systematically without disturbing the residents or the neighbourhood?

* Is there individual metering for each flat? Nobody likes to pay for the consumption of others. Individual metering to each flat rewards water conservation and punishes excess use. This should become the rule rather than the exception.

* Are the landscapes designed to be water efficient? The beautiful lawns and the exotic flowers are a delight to watch but can be huge water guzzlers. Is the landscape designed for water efficiency and less water consumption? Is treated wastewater of the right quality available for the landscape at all times?

* Is there a good leak detection system in the distribution network? Leaks can be surprisingly large and if undetected can cause huge water losses. Is there a system of metering and measuring at wholesale and retail levels to ensure that leaks are detected and fixed at regular intervals?

Facility manager

* Is there a good facility manager who is trained in water and wastewater management systems? Unless the right skills are available it will be impossible to manage the swimming pool, the landscape, the fire-fighting systems, the wastewater treatment and reuse systems et al. In short, without a well trained set-up, the system will collapse over time.

* Is there a good wastewater treatment and reuse system which is easy to operate, easy to repair and which reuses the bulk of wastewater for non-potable purposes such as toilet flushing and landscape demands?

* Is the rainwater and stormwater harvesting system designed well and in compliance with the law? Do they turn around the entire apartment block to a ‘zero runoff’ area and harvest every drop of rain?

* Are the borewells metered and monitored for quality and quantity? Is there a maintenance system for the borewells? Is a detailed hydro-geological data and the borewell log sheet available with the water facility manager?

* Is the water treatment system designed for BIS 10500, the drinking water standard for India?

Right devices

* Are all the devices in the bathroom, kitchen and other areas the most water-efficient in the business? Are all taps, showers, flushes, WCs of high quality and water efficient?

* Is the entire water and energy system well understood by the maintenance people? Are all pumps optimised for energy use and water delivery?

* Does the community meet often to discuss the water report card and become water and environment literate? Only by building the right communities and transferring the right knowledge through practice to the younger generation will we build a resilient and just society.

www.rainwaterclub.org

www.arghyam.org

e-mail:rainwaterclub@gmail.com

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Groundwater in Bangalore

December 6, 2009

WATER WISE

Understanding groundwater

S. VISHWANATH

There is no comprehensive legal or institutional framework for managing groundwater and prevent the digging of borewells in the city


Out of control: Borewells are being sunk without any restrictions

Borewells are everywhere in India and have become the lifeline for water. In Bangalore alone, the Bangalore Water Supply and Sewerage Board records the presence of about 100,000 borewells. Other estimates suggest that the city may have 400,000 borewells pumping out water to the tune of 100 million litres to 400 million litres per day. In any case new borewells are being dug by the hundreds every year all over the country.

New technologies for drilling are constantly emerging and borewells can now be dug to depths of 1,500 feet. The diameter of the drill also ranges from four-and-a-half inches 10 inches. Hydraulic drilling rigs make it possible to drill very fast and a drilling job can be completed in 10 to 12 hours’ time. Installing a pump usually requires two to four hours.

Typically a yield test should be done to optimise the selection of the appropriate pump and a water and energy-efficient pump which is maintenance free should be selected.

There is no comprehensive legal or institutional framework for managing groundwater in our city. Since the BWSSB manages piped water for the city and levies a Rs. 50 monthly sanitary cess on borewells, it is best placed to become the regulatory authority for groundwater. It can begin by insisting that all borewells in the city should be registered with it, not only those where it has given a water or sanitary connection. It can then begin a process of metering groundwater and charging on a volumetric basis rather than a flat rate. This will enable a better understanding of the volume of water being drawn from the aquifers.

No stipulation

There is no law currently which prevents the digging of borewells anywhere in the city. There is also currently no stipulation of any minimum distance between borewells. There is no law against the noise pollution created by borewells and their drilling at any time of night or day. The understanding of structural or other damage to adjacent buildings is limited. We need to insure from these risks in a comprehensive manner.

Maintaining a log of the successful and unsuccessful borewells, metering and measuring drawal on a monthly basis, keeping a log of the energy consumed per kilo-litre of water drawn, drawing up a maintenance schedule for the pumps, keeping regular track of water quality and ensuring recharge commensurate with drawal is the best way to go for apartments and layouts. A social ban on individual borewells, metered supply of water through common borewells, a tariff collection regime to ensure rainwater harvesting and recharge throughout the campus to ensure zero runoff of storm water is part of the best practices recommended for borewells.

www.rainwaterclub.org

www.arghyam.org

E-mail: zenrainman@gmail.com

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Monsoon

August 4, 2009

Monsoon
August 4 2009
It’s finally fully here. Mausim – season, monsoon – rains and you find it in the breeze today. Distinctly from the South West sending the clouds scurrying across the sky the sound and light show follows and the mosquitoes are blown away. This is not the season of the sun, disappearing of course behind the clouds. Termites take wing and fly , snakes appear on the landscape, power cuts are the norm with even a little bit of rain and vodka is at its tastiest. The constant whirr of the crickets , the flying insects inside the house and clothes refusing to dry. Rainwater in my tank and my open well brimmeth over. Season to plant trees and offset carbon, i go for the pongaemia. Red earth on my shoes and Chyna – the dog- needs a blanket now to sleep upon, the floor is damp and cold. The rains are upon us and all is well with the world,for now.

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Chitra Vishwanath

March 27, 2009

http://www.livemint.com/2008/08/14010747/Chitra-Vishwanath.html

Chitra Vishwanath works only with sustainable technologies and has built a couple of hundred mud buildings in and around Bangalore
I think
In a time of environmental crisis, it is criminal to use any material for building other than what is available on your own site. Mud is one such material, especially in Bangalore.
(For a discussion on sustainable architecture with Chitra Vishwanath click below)
The local mud makes for good stabilized mud blocks for walls and roofs.
We can
All you need to do is introduce a basement into the design, digging for which will provide all the mud.
You must, of course, provide adequate overhangs (roof projections) to prevent running water hitting and flowing on the surface of the wall, and a high plinth.
The blocks must be adequately stabilized (with cement or other binders), and should have a specified weight per unit of density. Any good mason can then build with these mud blocks.
Mud can be in used in several other ways, too—cob, rammed earth, and wattle-and-daub walls, for instance—depending on considerations of desired aesthetic, available skill sets and local climate.

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Chitra Vishwanath Architect

March 27, 2009

Women we love
Nirmala Ravindran
February 27, 2009

CHITRA VISHWANATH

chitra
Architect Chitra Vishwanath, would rather show you her work than talk about it. Environmentally-sound and cost-effective are the key words that describe her work.

A pioneer in the field long before these phrases became fashionable, her own house stands on 1500 sq ft of land on the outskirts of Bangalore as a model of her beliefs. Her home does not use air conditioning, or even fans, the walls are unplastered and made of mud bricks created on the site.

Chitra Vishwanath built a home that is environmentally sound and cost-effective—with no ACs, no fans and unplastered walls made of mud bricks. Built on various levels, it has a 1,000 sq ft vegetable garden.
With a multitude of skylights and open passages, the airy house is the perfect example of energy conservation. “We’ve done a lot of things to our home—things we cannot do in a client’s house. It’s nice to be able to show the possibilities.”

Eco-friendliness cannot be a fashion statement, she believes. It has to be a way of life. Along with her husband, Vishwanath, who is a civil engineer and rainwater harvesting expert, Chitra has created much-lauded homes and buildings across the country. Putting the money where their mouth is, the Vishwanaths have constantly worked at their home, making it a laboratory of change, and ensuring that the aesthetics are in place.

The composite pit in the compound handles the organic waste and garbage from the house. Solar panels to heat water, water harvesting takes care of more than 70 per cent of the water requirements of the house and Chitra uses solar cookers to make her rice and dal.

In addition, she says, “We have a toilet that separates the solid and liquid matter, and the water can be recycled into the ground.” Chitra has ensured that most, if not all, of their needs are met by optimum utilisation.

But nothing prepares you for the surprise of seeing vegetables and rice being grown on the terrace, proving that a little thought and ideology can work wonders. “It’s not a project that we can finish. We are constantly looking for new ways to improve our own thinking and ideas and hopefully help in the larger plan of conservation.”

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Mani shankar Aiyar

March 7, 2009

Source: http://www.indianexpress.com/story/29112._.html

‘I was always Leftist. Economic reforms made me completely Marxist’
Mani Shankar Aiyar
A few weeks ago the newspapers reported that the number of Indian billionaires had exceeded the number of billionaires in Japan, and there was a considerable amount of self-congratulation on this. I understand from P. Sainath that we rank eighth in the world in the number of our millionaires. And we stand 126th on the Human Development Index. I am glad to report that last year we were 127th.

At this very fast rate of growth that we are now showing, we moved up from 127th to 126th position. This is the paradigm of our development process. In a democracy, every five years the masses determine who will rule this country. And they showed dramatically in the last elections that they knew how to keep their counsel and show who they wanted. We, my party and I, were the beneficiaries and we formed the government. Every five years, it is the masses who determine who will form the government. And in between those five years the classes determine what that government will do.

In determining what that government will do, the CII has played an extremely important role. I am not surprised, as that is its job. It represents industry, and therefore it argues for the interests of the industry. Industry has been enormously benefited by the processes of economic reform that we have seen in this country over the last 15 years or so. But the benefits of these reforms have gone so disproportionately to those who are the most passionate advocates of reforms that every five years we are given a slap in the face for having done what the CII regards as self-evidently the right thing for this country.

It is a sustainable economic proposition, because our numbers are so vast, that there are perhaps 10 million Indians who are just as rich as the richest equivalent segment anywhere in the world or in any group of countries. There are about fifty million Indians who really are extraordinarily well off. That’s the population of the UK.

But if you look at the 700 million Indians who are either not in the market or barely in the market, then the impact of the economic reforms process, which is so lauded by the CII, makes virtually no difference to their lives. That is why there is a complete disjunct between what the democratic processes are trying for in the short run and what those who have made an enormous success of our achievements in the last fifteen years deem to be, at least in the short run, their own requirements.

So when you talk of a nine point two per cent growth rate, it becomes a statistical abstraction: 0.2 per cent of our people are growing at 9.92 per cent per annum. But there is a very large number, I don’t know how many, whose growth rate is perhaps down to 0.2 per cent. But certainly, the number of those who are at the lower end of the growth sector is very much larger than those who are at the higher end.

Yet what happens when you have the budget? As an absolute ritual every finance minister (my colleague Chidambaram is no exception) will devote the first four or five pages of his budget speech to the bulk of India and there will then be several pages, including whole of part B, which deals perhaps with one or two per cent of our population. Almost the entire discussion that takes place at CII or CII-like forums, will be about Part B rather than Part A.

There are comfort levels that you get from statistics — for instance, suddenly Arun Shourie, announcing in the NDA government that our poverty rates have fallen from 35 per cent to 22 per cent. He did it by changing the basis on which you estimate poverty. You cannot compare apples and oranges. The next national sample survey has shown that our poverty levels have actually increased. Are we going to be mesmerised by these statistics or understand that 700 million of our people are poor?

So we have an Indira Awaas Yojana which will ensure that there will be a ‘jhuggi’ for every Indian round about the year 2200. We have the PM Gram Sadak Yojana which was supposed to complete all the gram sadak in seven years — we are in the eighth year. And where we are told that the education of 1000 may be covered, who knows only the education of 500 will be covered. And if you happen to be a tribal in Arunachal, you are told that because of your social custom you are to live in one hut atop a hill, we can’t provide you a road.

I was always something of a leftist. But I became a complete Marxist only after the economic reforms. Because I see the extent to which the most important conception of Marx — that the relationship of any given class with the means of production determines the superstructure — holds.

This ugly choice is placed before the government. An unequal choice, because you have organised yourself to say what you want to say but the others are only able to organise themselves and that too without speaking to each other in the fifth year when the elections take place. That is why this expression anti-incumbency, although the Oxford Dictionary says that it is a word belonging to the English language, is a peculiarly Indian phenomenon. Because everything that goes in the name of good governance like the economic reforms either does not touch the life of people or affect them at all.

We have seen what happened at Nandigram, we have seen what was happening at Singur and we have these propositions that say that SEZs are going to come and lakhs of hectares are going to be utilised for the good of the country. For what’s the syndrome in all this, it’s still ‘do bigha zameen’. The chap says that I want my one bigha of zameen to be reinstated, but you offer double the compensation and “baad mein dekha jayega”. You go to Hirakud, which is where Jawaharlal Nehru actually used the expression modern temples of India, and you ask what happened to the tribals who were driven out of there. Absolutely nobody knows.

Coming to the cabinet, you see what happens. The minute suggestions are made as to what would perhaps benefit the people and what would benefit the classes, the tendency is to say that our great achievement is 9.2 per cent growth. Our great achievement is that Indian industrialists are buying Arcelor and Corus. That Time magazine thinks we are a great power.

In these circumstances, when a proposal came before the government to spend Rs 648 crore on the Gram Nyaya department, we were solemnly informed by one of the most influential ministers in the government to remember that we are a poor country. I was delighted when the next day he was with me in a group of ministers and I reminded him of his remark and said in that case can we stop spending the Rs 7000 crore on the Commonwealth Games and he said, “No, no, that is an international commitment and a matter of national pride.” This national pride will of course blow up if you spend Rs 7000 crore on the Commonwealth Games. We will be on the cover of Time and Newsweek.

I have always wondered why this rate of growth and economic reforms process is dated to Manmohan Singh. Because actually it should be dated to L.K. Jha’s book Economic Strategy for the 80s. It is the decade in which we quickly recovered from agricultural depression and registered a double digit growth. At the beginning of the decade our biggest import was crude oil and after that it was edible oil. By the end of the decade we were exporters of several kinds of edible oil.

Why is it that Nehru became successful with his Hindu rate of growth? The reason is that the Hindu rate of growth was five times what our pre-Hindu rate of growth was. From 1914 to 1947, the figures of which are available, the rate of growth of the Indian economy was 0.72 per cent. And we got the Hindu rate of growth which was five times that and it made a difference to the people. The minute you had solid land reforms, the people had their ‘zameen’. That is what Mother India was all about. People felt that they were involved in the process. All the political talk was: gareeb ke liye ham kya kar sakte hain. Indira Gandhi matched it beautifully when the entire political spectrum joined hands against her by saying, “Woh kehte hain Indira hatao, hum kehte hain Garibi hatao.”

There is nobody so marginal in a government as the minister of Panchayati Raj. I count for nothing. Nothing! When I was the minister of petroleum, I used to walk surrounded by this media. I kept on telling them that petrol prices can do only three things — go up, go down or remain where they are. And it was all over the place. But try and get them to write two words about the 700 million Indians — absolutely impossible. And now with terrestrial television it is even worse. You have to be quarreling with your mother-in-law or hitting your daughter-in-law to be able to hit the headlines. It is impossible to get particularly the pink papers to focus on issues that affect the bulk of the people. And it is so easy to get them to focus on issues that are of high relevance to only one or two per cent of the people.

I believe the CII, if it is serious about the issue, should not be restricting itself to 25 minutes discussion before lunch but hold discussions for ten days and maybe something will come out of it.
Edited extracts from a speech at the CII Northern Region annual meeting 2006-07, New Delhi, April 4

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Climate change and Asian monsoon

January 6, 2009

http://www.scidev.net/en/news/climate-change-linked-to-decline-in-asian-monsoon.html

Climate change linked to decline in Asian monsoon

Wu Chong

29 December 2008 | EN | 中文

Stalagmite_Flickr_Lyubov.jpg

Cave deposits can yield clues to climate change and monsoon strength

Flickr_Lyubov

Evidence that human-induced climate change may be affecting the Asian monsoon cycle has been published by a Chinese-US team.

Zhang Pingzhong, of Lanzhou University in China, analysed a 1,800-year-old stalagmite recovered from the Wanxiang Cave in West China’s Gansu Province, which lies on the current path of the Asian summer monsoon.

The team measured levels of the elements uranium and thorium throughout the stalagmite and analysed its oxygen isotope ratios — different forms of oxygen whose levels are linked to rainfall and thus provide a record of the climate at the time.

Records show that, before 1960, warmer years were associated with stronger monsoons, and the temperature decreased when the monsoon weakened. But the study found a reversed association after this date.

“The rising temperature now leads to less precipitation, which is not a natural pattern,” said Larry Edwards, geologist at the University of Minnesota and co-author of the paper, which was published in Science (November).

“So we came to an important conclusion that the monsoon had started to be affected by man-made causes.”

Using the literature, the researchers linked the changes to human-induced greenhouse gases and aerosols.

Their finding corresponds with previous work by Ding Yihui, a leading Chinese climatologist, on changes in China’s rainfall pattern in the late 1960s.

The fact that recent Asian monsoon decline has taken place in the global warming period rather than in cold periods,” was an important finding, Ding told SciDev.Net.

But he said that more investigations were needed into its causes.

Ding said he is soon to publish another study in Science predicting Asian monsoon activity over the next 100 years.

The team also discovered that weak summer monsoons were highly correlated with the demise of major Chinese dynasties in the past four centuries.

Using the results from the stalagmite analyses, the team was able to match the amount of rainfall to the dates that China’s Tang, Yuan and Ming dynasties rose and fell.

For example, the researchers detected weak summer monsoon periods between 850 and 940 AD. This coincided with the last six decades of the Tang Dynasty. Decreased monsoon strength reduced the rainfall and led to a poorer harvest, which may have sparked unrest and led to the downfall of Tang.