Posts Tagged ‘water quality’

h1

Urban floods in Bengaluru

September 6, 2008

The problem is in the planning

Water, water everywhere…planners, institutions and individuals can take several steps to mitigate the physical and economic impact of urban flooding, says S. VISHWANATH

— Photo: K. Murali Kumar

The deluge: The state of affairs in an upmarket villa after a lake breached on the Whitefield-Hoskote Road.

A series of flooding events across Bengaluru has brought into sharp focus the need for better management of rain. Though nothing on the scale of the Kosi floods yet, it has caused severe economic and physical damage to the city and left many psychologically scarred. The coming of the rains is looked at with trepidation and newer areas of the city seem to be affected every time it rains.

Several interesting facts emerge around urban floods. In Bengaluru, it is clear that it is rain which causes the floods unlike, say, a city like Patna where rain could cause the Ganga to swell and flood the city. Surprisingly, recent evidence suggests that it rains more in the city and slightly downwind than in the regional rural periphery.

This is according to a study by NASA scientist Marshal Shepherd. The urban heat island effect, where cities are warmer than their surroundings and which causes the build-up of rain clouds on the city; pollution, which allows rain to coalesce around dust and oil particles; and the wind-break effect of cities, which causes the clouds to discharge on the cities, all seem to contribute to this phenomena. Bengaluru needs to prepare for more rain than average and higher intensity rains at the same time.

Cities also increase runoff as more and more soft agricultural and fallow areas get built upon or paved. From a small well-mulched site, hardly 10 per cent of the rain falling will runoff as storm water. However, build a house on the same site and pretty much 90 per cent of the rain falling will runoff as storm water. Buildings increase runoff tremendously in the Bengaluru context and the storm water drains have to cope with this increase.

Waste management

Solid waste management is crucial to flood management since most of the uncollected garbage will end up in the lowest area, usually the storm water drains, choking them and reducing their ability to carry storm water out.

Tanks and lakes which collected surplus water and recharged the groundwater or dissipated it slowly are on the decline. These are built up, like the ISRO headquarters built on an old tank bed. They then become prone to flooding or transfer the flood problem downstream.

The network of tanks and the valleys and drains connecting them are in a bad state of management with encroachments on several of them. With no institutional approach to manage the tanks and the valleys, little is done except during the flood event itself to ensure that the channels flow freely and that the tanks are not encroached upon. Traditional storm water management techniques simply collect the rain water and funnel it across the city downstream. Newer methods combine traditional approaches with new ones such as Sustainable Drainage Systems (SUDS). It employs a range of natural processes to purify urban runoff. Removal of sediment, bio-filtration, biodegradation and water uptake by plants all help to remove pollutants. Vulnerability maps of areas prone to flooding need to be prepared for citizens to become aware of the choice they make for where they live.

Rainwater harvesting

Even as the Government is working towards making RWH mandatory in the coming days for the city, the system has one of the best potentials to replenish ground water, improve its quality, provide supplementary water for domestic requirements and mitigate flooding. If every building in Bengaluru can store or recharge 60 mm of rain in a single day it should be possible to mitigate the effect of almost every flood except the rare. This means that a 100 square metre roof area will need to store or recharge 6,000 litres of water. Zones with the best possible recharge and zones with the best possible storage need to be identified in the city and steps taken to encourage people to go in for rainwater harvesting.

A recharge well of 3 feet diameter and about 20 feet depth can send in up to 12,000 litres of water into the ground in a single day, provided lithological conditions are favourable. The city needs many such recharge wells in the catchment area of critical flood zones to detain flood waters and top up the aquifers instead of surface flow flooding.

At the broader scale, tanks and lakes need to be networked and managed as retention and detention structures. With rainfall prediction accuracy being developed, tanks have to be linked to catchments and kept ready to hold the maximum water to dampen peak storm events. A deslited tank in Bengaluru can recharge up to 11 mm of water every day while an undesilted one can recharge hardly 1 mm. Desilted tanks can recharge aquifers quickly, lower the surface water levels and be in a position to function as flood mitigators. Full tanks are not good at dampening floods.

Flood insurance

In Europe, urban flood research has been driven by insurance companies who want to understand risks associated with floods and plan premiums accordingly. This sector has yet to mature in India but taking flood insurance is a wise step especially if your car has been found floating in the basement after a rain. Good advice comes from ICICI-Lombard on its website on what to do after a flood. It starts by saying that you should not return home till the authorities declare it safe to go back. Then the steps recommended are: turn off electricity and gas, make sure the water and food you consume are safe, stay healthy, call your insurance agent, take photographs and videographs of the damage caused and finally take care of yourself and family. Wise words, indeed, and this is water wisdom when it relates to urban floods.

Send your responses to:

zenrainman@gmail.com

080-23641690

www.rainwaterclub.org

www.arghyam.org

Advertisements
h1

Ka- Sanskrit root meaning water

May 6, 2008

WATER WISE

Preserve the lifeline S. VISHWANATH

The Sanskrit ‘Ka’ meaning ‘water’ is the language root for both the Arkavathy and the Cauvery

— Photo: M. Moorthy

Save it: The Cauvery in all its splendour at sunset. The Jamuna for Delhi, the Manjira and Krishna for Hyderabad, the Cauvery and the Krishna for Chennai and the Arkavathy and the Cauvery for Bangalore — rivers are the lifeline for our cities.

The Sanskrit ‘Ka’ meaning water is the language root for both the Arkavathy and the Cauvery. It is important therefore for us to treat our rivers with respect. Each individual’s action counts…be it consuming less water, ensurin g wastewater treatment, managing garbage correctly and planting and taking care of trees and forests in the catchment of our rivers.

Primary source

It rains on the land and rain is the primary source of water. The forests hold the water and release it slowly, ensuring that the soil does not run off and erode and also choke up water bodies. The rivers run from the waters they receive from the surface of the land, but very importantly from the waters that they receive from the base flows below the ground and which appear as springs or feed the channels directly. We take the water from the rivers for our use but we need to return it in the same quality at which we took it.

How would it be if every city were to release its wastewater upstream and draw its fresh water requirement downstream of the release point of wastewater? Would we be more ecologically responsible?

It is time for all of us to ensure that the precious resource called water is well understood, distributed equally to all and taken care of as a precious gift of nature. For that we need to become water literate. And water literacy — knowing where the water we use comes from and taking responsibility for its wise use and release back to nature after use — is the first step towards water wisdom.

h1

Bangalore- Urban water issues for the poor

March 11, 2008

Near the Byatrayanpura zonal office of the Bangalore Corporation,is this ‘mini water supply scheme’ as a bore well connected to a cistern is called in this part of the country. People in the suburbs, especially in the low income bracket, get water once in two days near their house. Tis water is apparently not good for drinking or cooking. The dal (lentils) does not get cooked according to this lady. So they collect good water from this cistern. That means queuing up with their plastic pots at 4.00 a.m. in the morning for everybody’s quota of 2 pots of good water for drinking and cooking. Again the process is repeated at 12.00 noon but this time for water which comes in the evening.

Fights and disagreements are regular as is jumping the queue and stealing of pots too. The pots themselves are made of low grade plastic and are not fit for potable water purpose. They crack in the sunlight and need to be replaced ever so often.

Shiva, who helped bring Ganga down from the heavens, taking her force on his matted locks also looks on benignly. The very God’s seem powerless in this day of water shortage.

Question is will not 24/7 water supply help these people? Will they not spend less time and money even if water is privatized as some people claim it will be or already is? For 2 pots of water the lady spends at least 6 hours of her time daily. Even at Rs 5 /- an hour as opportunity cost this translates to Rs 30/- for 30 litres or Rs 1 /- a litre.

Per kilolitre the cost would be Rs 1000/- . Nowhere has this cost been imposed on people by private sector, but this is the cost imposed by the State here with its sheer inefficiency of delivery of goods low quality and even less quantity and no accountability.

Can we not change the system with even private participants who are held accountable for their actions? When shall we do that? When the human right to water is legislated perhaps and when governments are open and transparent in their dealings. On the one hand we have an insensitive state and on the other a passive community not willing to demand what is their right.

h1

Requiem for our rivers

March 10, 2008

This is a column I have in The Hindu. It appears every Saturday in the supplement called Property Plus. This is last weeks article.

WATER WISE

Requiem for our rivers S. VISHWANATH

Price of development: Copious flows in the Arkavathi is a thing of the past. This is a requiem for the Arkavathi and most of our peninsular rivers. The Arkavathi is a tributary of the Cauvery. Rising in the Nandi Hills to the north of Bangalore it passes through most of Bangalore Rural district and joins the Cauvery at Sangama in Kanakapura district. It flows for 190 kilometres and in hydrological parlance is called a second order stream, meaning it is a tributary of the Cauvery which joins the sea. The Cauvery is a first order stream flowing into the sea, its major tributaries are second order streams and the Vrishbhavathi which joins the Arkavathi is a third order stream. The catchment area from where the water collects in the river is more than 4000 square kilometres. Yet the Arkavathi is dead and barely flows during heavy rains. Why is that so? This is a sorry tale of the death of a river.When Bangalore first ran out of water from within its boundaries in 1894 it was decided that a reservoir at Arkavathi would need to be built to ensure that enough water was available to the city. The Hessarghatta reservoir, about 24 km from the city, was built on the Arkavathi and continued to supply water till about 1934 when the second reservoir on the Arkavathi called the Thippagondanahalli or the Chamaraja Sagara Reservoir was constructed to bring in more water for the increasing thirst of Bangalore.

Both reservoirs were built on the Arkavathi for The Gazetteer of Bangalore Rural says the Arkavathi “is not exactly a seasonal stream, in the summer months it presents the usual aspect of a sandy bed with a small current of water flowing at one side.” In short it was a perennial river. Large tanks such as the Madhure and the Dodballapur ere also constructed on the river and would usually fill up. The town of Dodballapur depended on the Arkavathi for its drinking water requirement as did the town of Ramanagara.

Groundwater was available at 1 to 3 metres below ground level in the Arkavathi basin. Wells ranging from 2 to 10 metres in diameter and depths of between 3 to 12 metres provided up to 60,000 litres of water per day. In summer, well water would fall at best to 4 metres. Wells provided drinking water for all villages as well as agricultural water for irrigation. More than 30,000 wells were present in the Arkavathi basin. This was the situation till the 1980s.

Pressure What killed the Arkavathi? A combination of the natural phenomena of drought and pressure on the catchment of the river. From 1980 to 1987, six out of the eight years were drought years with below normal rainfall. Wells dried up and were replaced by deep tubewells and borewells. Over-pumping resulted in a steep fall in the water table with most wells drying up and a competitive deeper drilling of borewells resulting in depths of nearly 300 metres being reached. With the fall in the groundwater table there was no base flow into the river. It first dried up in summer but then was unable to flow in the rainy season except for a few days. The tanks and the channels leading to the tanks were encroached upon or mismanaged and the links of surface water flows to the river stopped. All the tanks dried up and the Hessarghatta was abandoned as a reliable source of water to the city. The same fate awaits the Thippagondanahalli in a few years when it too will cease to be a reliable source for storage. The Nagarakere or the Dodballapur tank was long since given up as a source and the drinking water situation there is perilous with most water coming from private tankers. Villages struggle for drinking water in the basin especially in summer as borewells go dry.

The change of land use to predominantly agricultural activities resulted in the levelling of land and the construction of field bunds. Ploughing of land was a natural corollary to farming activities. Runoff from the land became zero. Sand mining and granite quarrying disrupted rivers badly and added to the problem.

Then came the industries with their huge water demand. The apparel park set up in Dodballapur in the Arkavathi basin will need water from the Cauvery and so will the international airport in the Dakshina Pinakini basin. The second order streams are dead and the first order Cauvery is the only reliable source. The question is for how long?

What does it mean for property? In the absence of any river basin- level institution even at the second order stream level, who will be responsible for the planning of the rivers and waters both above the ground and below the ground? Who will plan, invest and manage the waters of our rivers and who will be held accountable for failures?

With the coming up of the international airport a property boom is on in Dodballapur. Land prices have skyrocketed and housing colonies, resorts, restaurants and apartments are seeking to locate themselves there. But where is the water for this development?

Unless we create the right institutions at the right river basin level and arm them with the ability to plan and act on the plan, water shortages will be the order of the day and will hinder livelihoods and economic growth. Agencies such as the Bangalore Water Supply and Sewerage Board are woefully inadequate to manage sources and to provide water for all.

This is true of ALL our second order streams and it is a matter of time that climate change hits us and starts affecting first order rivers.

Water wisdom lies in recognising problems at the scales at which they occur and taking remedial action at that scale legally, institutionally and financially so that the problems are overcome.

Economic development and poverty reduction will be hit unless ecological resources are taken care of and that is the responsibility of ALL of us as citizens of the country. Recognise the river basin you are in and take action to revive it.

Water wisdom is leaving things better for the future generations than what we inherited.

h1

Rainwater harvesting – Vastu certified

March 10, 2008

Tis neighbour of ours is a senior citizen. He obviously has his belief which one respects and therefore ‘Vastu’ proofing his house apparently called for this fluoroscent colours of bright yellow and orange . These are all over the city now and no it is not some post modern fetish sweeping the city it is an old ancient one called Vastu (Indian Feng Shui to those uninitiated).

But the nice part for rainwater harvesting is that he read about it in the newspapers and came a visiting our house alongwith his plumber. They figured out the best way to do rooftop rainwater harvesting. Collect it into a sump tank but if opportunity arises to lead the rain into a small well that he already had. The filter was the key and the blue drum filter of ours was right. He had some difficulty in sourcing the Male threaded adapter and the female threaded adapter (MTA and FTA) something to note for the Rainwter Club and so we were pleased to give this to him.

They now have a full fledged system at work and you can see the result

We expect the water quality in the well to improve and him to get about 150,000 litres of water every year of average rain.

h1

Rainwater and multi-purpose storage tanks for water- 24/7 water for women

March 3, 2008

When water comes intermittently this single women household has a great deal of trouble in accessing water. As this lady explains, the rainwater and multi purpose storage tank can hold about 140 pots x 15 litres per pot = 2100 litres of water. She fills it up whenever she finds the time during the day and it lasts her 15 to 20 days. She now can wash clothes and provide water for her cows right near the house. The happiness on her face is worth all the efforts for promoting rainwater harvesting in multi purpose storage tanks. The representative of the funding agency for this project is also happy to see the tank work.

She promises to whitewash the tank on the outside to keep it from cracks and to keep the water inside cool.

This is an ideal solution in fluoride affected villages and in arsenic affected villages. Also where there is a shortage of water in summer or intermittent supplies, water tankers can come and fill the tank up providing the 55 litres per person per day promised to every inividual in rural Karnataka by the government in its State Water Policy.

This is village Arjunabettahalli near Nelamangala in Bangalore Rural district. The bore well gives water unable to be drunk because of the high salinity. A nature cure resort nearby called Shreyas has come to the aid of the people by providing them support for the rainwater multipurpose tanks. Now we try and find funding for toilets, to clean the waste water in the village and to improve the village pond. Some people can afford the rainwater tank on their own and have built it so but others like this woman needs help.

Now you would know why this work is challenging ,rewarding and nice.It puts a smile on the ladies face.

h1

The Persian Wheel revisited- Araghatta

February 23, 2008

The ‘ara-ghatta’ or rope-pot system of lifting water from open wells was probably invented in erstwhile India of the past. With its use in Iran and perhaps its discovery there it came to be called the Persian wheel.

The araghatta itself became the Rahat or reghat or gharat in North India. Ubiquitous everywhere in India it has all but disappeared with the lowering of the water table in many parts of India and the coming of the diesel and electric pump. As a device it is my surmise that the pulley which became the wheel was first discovered around water. The well itself is a remarkable discovery. A hole in the ground which yields water allowed mankind to ‘conquer’ the open spaces and unyoke itself from the tyranny of being tied to rivers and lakes. The Persian wheel still exists in some parts of remote India and with its disappearance will go a water culture and history. Here Avinash plays the Araghattikka , the person working the Araghatta. Usually bullocks, elephants or camels did the job of moving in circles to lift water.

The biggest confusion amongst authors and people is between the Water wheel and the Persian wheel. The water wheel-the noria- is perhaps an Egyptian invention and is stream or river based water lifting device and a water mill at times.

In the above the Noria or the water wheel is a water mill and not a water lifting device. It uses the strength of the current to move and to translate that to a grinding action.

The Persian wheel is the saqia and is a land based water lifting device from wells, more in the nature of a pump. In fact in parts of Kolar in Karnataka it is called a ‘bucket pump’.

As ground water levels decline in India Persian Wheels cannot reach the water to draw them out from open wells. One such Persian wheel stands forlorn and frustrated as the water table has dipped in Kolar Karnataka India. This wheel has worked for the last 80 years and 2007 was the first time that the water table fell so low that the wheel could not work for day. A nearby open well which draws copious water with an electric pump is suspected of causing the dip. The Rainwater Club works with farmers to ensure efficient use of water and allow the Persian wheel- a symbol of sustainable and carbon free water use- to continue its existence as a living, century old water culture of India.

Ananda K Coomaraswamy argues in his monograph The Persian Wheel argues that it is not justified to draw its origins to Persia. Its mention in the Panchatantra and the Rajatarangini as the cakka-vattakka or the ghati yantra.

The FAO document on water lifting devices is an excellent one to compare the efficiencies of various lifting devices for water

”’ http://www.fao.org/docrep/010/ah810e/AH810E08.htm#Fig.%2026 As it states

The Persian wheel, is a great improvement on the mohte, as its chain of buckets imposes an almost constant load on the drive shaft to the wheel. Persian wheels are usually driven by some form of right angle drive. The first is the most common, where the drive shaft from the secondary gear is buried and the animals walk over it; this has the advantage of keeping the Persian wheel as low as possible to minimise the head through which water is lifted. The second example is a traditional wooden Persian wheel mechanism where the animal passes under the horizontal shaft. The sweep of a Persian wheel carries an almost constant load and therefore the animal can establish a steady comfortable pace and needs little supervision.”

Noria and Saqiya: 

Needham, in Science and Civilisation, Vol. IV(2), gave a clear definition of the two forms, the noria having the containers fixed to the rim of the wheel, and the saqiya on the rope or chain flung over the wheel (p. 356). Having done so, he was able to follow up the evidence gathered by Coomaraswamy and Laufer, and argue that the earliest water-wheel in India was the noria, and that, moreover, India was probably the country of origin of this device. The reasons Needham adduced for this conclusion were two-fold: first of all, the noria was in the Hellenistic world in the first century BC and in China in the second century AD, and this proximity of date in such distant civilisations suggested an intermediate source of diffusion. Secondly, he located the earliest recorded reference (derived presumably from Coomaraswamy) to the noria in the term cakkavattaka (turning wheel) used in the Cullavagga Nikaya (assigned to ca. 350 BC) for one of the three permissible models of water-lift.  Source: D.P.Agarwal Needham on Early Indian Inventions of Hydraulics, Cotton-Gins and Alcohol Distillation