The summer of 1998 was a wet one. Danes fled to the warmer latitudes to get some sun in their holidays. While they were away, the rain, though unsuitable for sunbathing, was collected in pots, pans, barrels and large storage tanks. Collected to help conserve dwindling drinking water resources.
In recent years, numerous reports have appeared in the media of the contamination of groundwater resources. Bore-wells after bore-wells have been shut down. Contamination with nitrates (from fertilisers), pesticide residues from agriculture and contaminants percolating from waste dump sites is to blame.
Large investments in water treatment plants along with heavy taxing on water consumption helped Danes to understand the seriousness of the problem. From 1987 to 1992, water consumption in Denmark fell by 14 per cent. Moreover, water supply authorities aim to save an additional 20 per cent in the years to come. "That will be a difficult task. But it is necessary if we are to have drinking water enough in the future," says Svend Madsen, head of the water saving department of Copenhagen's waterworks.
In 1990, a small rainwater collecting unit was installed in a house with eight families in the town of Arhus. This has become a popular way for environmentally conscious people to save water. A number of communities now harvest rainwater to flush toilets, wash clothes and cars and for spraying pitches of football stadiums. When not used directly, rainwater is often led from large buildings to small ponds. From here the water can percolate and recharge groundwater.
There are several examples now of catching rainwater in Denmark. Different people use it in different ways:
BO 90, a collective housing complex with 17 flats, collects rainwater in a 10-cubic metre storage facility in the cellar. The water is re-circulated through a separate pipe system for flushing toilets or gardening. The high-quality wastewater of the house - water from the kitchen sink and used bath water - are saved for a cleaning unit. Rainwater is used for washing clothes, points out Erik Jorgensen, a resident. The community was awarded a Scandinavian environmental prize in September 1998.
At a centre with 22 condominiums for elderly people, rainwater is used for toilets and washing clothes.
The 12 toilets at a boy scouts centre use rainwater for flushing toilets, which conserves 225,000 litres of drinking water a year.
The Danish stadium Parken, which hosts national and international soccer games, has since 1993 collected rainwater from the roofs of the stadium. The rainwater is lead to storage tanks that hold 50,000 litres. It is used to water the expensive , pitch of the stadium at night. "We save nearly us $200 each time we use the rainwater. We prefer rainwater to drinking water because the former is soft and poor on calcium, which is better for the grass," says Bent Jensen, technical manager at Parken.
At Rigshospitalet, the main hospital of Denmark, rain-water is used indirectly. Five ponds in central Copenhagen collect water. This is used for the cooling of the hospital's clinics and offices. This provided an alternative to the ozone-depleting chloroflourocarbons in the air-conditioning system.
A car wash facility at one of the major petrol stations along the highway to Copenhagen collects rainwater which is used to wash cars. When the 30,000-litre tank is full, it lasts to about 150 cars being washed in the hall, says Helge Voss of the Danish division of the petrol company Q8s.
Despite these efforts, government agencies and water supply authorities do not believe in these methods. The few rainwater harvesting installations do not have a significant influence on the water use, they claim, adding that the cost of installation does not correspond with the amount of water saved. So there is no support, financial or political. Except an exemption grant on normal wastewater removal and treatment charges.
Collecting rainwater is not the way we are going, says Tina Otterstrom of the Danish Environmental Protection Agency. There are a lot of problems. It requires downscaling of quality measures for water. Though concessions can be made on the quality of rainwater for use in toilets and washing, Otterstrom says that there is a need to ensure that rainwater is not in any way mixed with drinking water. This requires two sets of pipes.
Though the Copenhagen water supply authorities do not promote rainwater harvesting, they recognise that the method has its benefits. It reduces the amount of water coming through the sewers, saving energy use in the sewage treatment plants.
However, disregarding the lack of support from government or municipal authorities, grassroots organisations and communities of environmentally conscious people keep on establishing rainwater harvesting units.
They object to first class drinking water being used for flushing toilets in a world where drinking water is becoming increasingly scarce.
Harvesting rainwater breaches the immense gap between the rich provinces of southern China and the poor northern areas
China's huge water resources look very meagre when compared to its population. The country's per capita water availability is one-fourth of the world average. Moreover, these resources are unevenly distributed both in space and time. South and southwestern China has 81 per cent of the water resources, though it supports only 54.7 per cent of the country's population and merely 35.9 per cent of the land area. Northern China is not so lucky.
"What this means in real terms is that 300 out of 600 Chinese cities lack adequate water supply and 114 have serious water shortage," point out two researchers who have worked on "Rainwater Utilisation as Sustainable Development of Water Resources in China". Zhu Qiang of the Gansu Research Institute for Water Conservancy (GRIWAC), Lanzhou, and Liu Changming of the United Research Centre for Water Problems, Beijing (under the Chinese Academy of Sciences) say that quality of water is another concern. "Tests for the main river section (of the Huang He) indicate that 68 per cent of water samples did not measure up to the national specification of environmental water quality," they indicate.
The conventional way to solve the water crisis has been river valley projects or inter-river basin diversions. With many favourable sites for such projects already used, this is increasingly running into trouble, Zhu and Liu point out. Besides an increasing cost of construction, large projects cause social and environmental havoc, resulting in large-scale inundation of settlements and forests and a negative impact on the hydroiogical and hydro-ecological balances. Over-extraction has lowered the groundwater table considerably.
One ray of hope in this otherwise bleak scenario is rainwater catchment and utilisation in the loess plateau (loess is a special type of soil comprising pale-yellow sedimentary deposits). The plateau and the hilly areas in north and northwest China are the driest and the poorest areas of the country. Both groundwater and run-off are very scarce. The topographic conditions make it impossible to construct water conveyance systems and irrigation networks. Result: 9 out of 10 years are drought years. Poverty is rampant.
The only potential source of water is rainfall. However, rain in this semi-arid area is mostly "small rain", according to the researchers. "It cannot produce run-off on natural soil," they say. Moreover, the deeper soils of the loess are such that most rainfall infiltrates into the soil and then evaporates. This makes for an intriguing situation. Although the Chinese have captured rainwater for about 1,000 years, the harvesting efficiency is too low. But there arc seeds of hope.
Gansu is a very dry province in northwest China. An experiment-and-demonstration programme for catching rainwater has been carried out in the central and eastern parts of the province since 1988. The programme has met with success. About 1,000,000 people in the rural areas have bid farewell to shortages of drinking water after centuries of thirst.
Until recently, the GRIWAC, supported by the local government, carried out systematic experiments on 'rainwater catchment and utilisation' (KWCU). Numerous demonstration projects were set up, aimed at supplying water for drinking and courtyard irrigation.
The new RWCU system comprises a catchment field, water storage and irrigation facilities, Zhu explains. A special kind of cement tile on the roof or a concrete slab in the courtyard forms the catchment field, while an underground cellar stores the water. This has shown to increase rainwater collection efficiency ten-fold. The success of the project has led to the launching of the 1-2-1 programme. This envisages one catchment area feeding two underground storage tanks to support cash and fruit crops on one piece of land. By 1996, about 200,000 families (one million people) had solved their water problem. "The project not only solved the drinking water problem that has puzzled the local inhabitants for generations but also created a better living environment," says Zhu. An additional land area of 10,000 hectare (ha) was irrigated. Yields increases between 20 per cent and 100 per cent were reported.
A follow-up project to improve dry land farming by using rainwater has been carried out on a larger scale in Gansu. Similar projects were started in neighbouring areas such as Ningxia Hui and Inner Mongolia Autonomous Region. In Ningxia, in the autumn of 1995,16,000 water cellars were built to store rainwater for the spring. "In Inner Mongolia, from 1995 to 1996, the pilot projects included 1,584 water cellars built to irrigate 386 ha of land for 1,452 families in 32 villages," Zhu reveals. Water was harvested from highways, threshing yards and also from seepage-controlled fields.
This effort ensured an economical and thoughtful use of the invaluable resource. Land was prepared with furrows to collect more water. It was further covered with plastic sheets to minimise evaporation. An experiment carried out in Ningxia between 1984 and 1995 showed that supplemental irrigation for spring wheat can raise yield by 19 per cent to 29 per cent. Every cubic metre of w r harvested can enhance yield by 2.1 kg.
The city has realised the importance of harvesting rainwater to meet its water shortage. But regulations need to be implemented with greater care
Chennai, the ever-thirsty city notorious for its serpentine water queues, is rediscovering the merits of rainwater harvesting (RWH). It is planning to catch rain where it falls. It is also the first Indian city to include a provision for conserving rainwater in its civic laws. "All special buildings must contain rain water harvesting measures after January 1, 1994," announced the Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) in 1993. The Chennai Metro Development Authority (CMDA) suggested a new control rule that included rainwater conservation measures. "The purpose was to recharge the depleting aquifers by rainwater harvesting," says a CMDA official. It would avoid flooding of low-lying areas, a formidable problem in Chennai, he adds.
Water has always been scarce here, often requiring the Metro Water Board to control its supply severely to ensure optimum usage. In Chennai, surface water is drawn from three inter-connected reservoirs: Poondi, Cholavaram and Redhills (total capacity of 7.152 million cubic metres), white ground-water is tapped from 76 bore-wells located in six well fields of Araniar-Koratallaiyar Basin in the city's north-west.
Situated on India's eastern coast, Chennai has a flat terrain that slopes gradually to the sea. On an average, it receives about 1,200 mm of rainfall, 78 per cent of it during the northeastern monsoon from October to December. The rains are cyclonic - heavy rains in short spells. Most of the rainwater usually flows into the sea.
The 1993 drought paved the path towards RWH. It caused massive water crises all over Chennai. K R Gopinath, a modern-day RWH pioneer, talking about such crises, says, "Rainwater is the trump card for a water revolution, not the major water projects." There were official moves too. The chairperson and managing director (CMD) of the board, M S Srinivasan, suggested that all new building proposals should include a RWH plan. In 1994, the new CMD, Shantha Sheela Nair, took up the matter. Later, private builders became enthusiastic about RWH, and in 1997, a forum of builders met the CMD, and decided on the types of RWH methods to be adopted. The board also published a brochure, suggesting various RWH methods.
The concept of rainwater harvesting has been accepted by the builders and many have even improved on the existing methods. However, there are problems. R Kumar of Navin builders says, "Most of the builders are doing RWH, but the government is yet to implement the order in their own buildings." T K Ramkumar of Exnora International, non-governmental organisation (NGO), criticises the government for its soft approach. "There is no serious attempt to implement the decision. People don't seem to understand the potential of rainwater," he says. N V Fundarikanthan, former director, Central Water Resources, Anna University, Chennai, says, "Now that the issue of water conservation has been raised, the government should plan seriously and implement RWH in a big way." In the absence of a systemic approach, RWH move might soon lose steam, the experts fear.
The Rotary Club of Madras recently revived three temple tanks in their attempts to cure the city of its water scarcity. But it is not enough. Once Chennai could boast of 39 temple tanks or kulams, each with an area of one to seven acres. These not only trapped rainwater but acted as flood-control devices and recharged the groundwater sources as well. Urbanisation, however, made these tanks obsolete, almost reducing them to garbage dumps.
The Virubhaksheeswarar, Gangadeeshwarar and Rawees-warar tanks in Chennai suburbs were recently rejuvenated, thanks to the club, which had taken up the initiative in the early 1990s. R Benjamin Cherian, a rotarian, says, "We wanted to revive the tanks as they would recharge the ground water." The tanks are designed in an attractive, artistic manner. During some festivals, the idol of the temple deity is taken to the centre of the tanks.
Due to Chennai's topography - it slopes from west to east - major inlets have been built on the tanks' southwestern or northwestern corners. Further, they were interconnected to drain the overflow of one into the other.
However, maintaining these tanks is a problem. The Temple Authority is severely cash-strapped. So the Rotary Club came to the rescue again. Interacting with schools, the club would have groups of school children visit the tanks and clean them on every holiday. "People living in the neighbourhood have also come forward for the maintenance," says V Ganesan, who is involved with the project. The Rotarians are optimistic, and are planning to revive three more tanks this year.
R Jeyakumar promises 72 crore litres of water to Chennai annually. But he is neither a water-diviner, nor a magician. He is a builder. So how does he plan to quench Chennai's perpetual thirst? "Very simple," he says, "Catch the rain water." His method of collecting water from within house compounds can help solve Chennai's water problem.
A drain, dug along the compound wall, collects the run-off during the rains. The excess water that flows along the drain would be fed into a series of bore pits connected to the drain though pipes. The water then would reach groundwater aquifers, recharging them.
Jeyakumar's 44-year-old mind makes some quick calculations: Assuming, one bore pit fetches 600 litres a day, 10 pits per house would trap as much as 6000 litres. And assuming there are 60 days of rain annually, the total water conserved per house is a huge 3,60,000 litres per annum. Taking a target of 2,000 house, the total rainwater collected in Chennai would be 72 crore litres.
The substantial rain that this state receives runs off due to the hilly terrain. But the state government is realising the importance of catching this
Mizoram is blessed with a lot of rain, 2,500 mm per year. Yet this tiny north-eastern hill state invariably faces acute water crises in the dry season.
The reason is the topography - hills of sedimentary rocks comprising mostly of hard shales. The run-off disappears fast. Though this run-off gives rise to springs in the rainy season, they disappear soon. There has been a tradition of collecting rainwater to make nature's bounty last over the dry months.
Rainwater is harvested widely in the region. It is gaining popularity, especially in the rural areas, where piped water supply remains inadequate and expensive.
The towns of Mizoram are located on hill-tops or on the upper reaches of slopes. Water from rivers has to be lifted up to these towns. Aizwal, the state capital, has a public water supply system based on water from a perennial river called Tlawng. It is designed to supply water for a population of 80,000. However, the population of the city now exceeds 300,000. Rainwater harvesting has continued to play a very important role here.
Today, Aizwal meets most of its water needs from roof-top rainwater harvesting. Townsfolk try to meet their water needs without depending on municipal supply. And this entire effort was undertaken by the people themselves with no government support.
Mizo villages were established on hilltops to protect against marauding tribes. They used springs for their water needs. Rainwater percolating in the soil on the hill slopes comes out in springs at outcrops of rock layers during the rainy seasons and many weeks after rainfall.
Small catchment tanks were constructed with stone masonry or concrete masonry at convinient locations and the water collected in these catchment tanks was an important source of water supply. At some locations water from such catchments was available throughout the year.
However, spring water became inadequate as Aizwal grew. The springs also began to dry up, largely due to deforestation. Government had to haul up water from rivers and streams miles below the town. The cost was enormous, the supply scanty. Moreover, the water had chemicals and bacterial contamination.
History came to the rescue. In 1894, the British established the first administrative unit here. Water was supplied to the British post from a 5,455,200-litre underground rainwater reservoir. This was fed by a catchment of sloped roof with galvanised corrugated sheets around the reservoir.
Roofs of buildings in Aizwal are sloped keeping with the wet climate. Roof-top rainwater collection is thus the most convenient and economical form of water supply. Households slowly turned to roof-top rainwater harvesting without help from the government. Rainwater in Mizoram is quite pure, the region being virtually pollution-free.
Yet, roof-top harvesting is losing some of its mystique in the urban areas due to subsidised piped water supply. Further, the region has also witnessed a rise in the use of modern toilets and kitchens. Using rainwater in these is highly inconvenient.
However, the future of roof-top harvesting in the modern, urbanised areas is not overtly bleak. The government is slowly recognising the need for it, encouraging it by underwriting the cost of construction of rainwater harvesting units. In the rural areas, about 6,000 private systems have been set up owing to this effort.
Written by Anupama Kumarfrom reports by Makoto Murase and Nobua Kurokawa in japan, Hannah Buttner and Uwe Hoering in Germany, Gert Lynge Sorensen in Denmark, Zhu Qiang and Liu Changming in China, John Mbugua in Kenya, Jitendra Verma in Chennai and Dunglena in Mizoram