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The UNEP paints a worrying picture of this critical, hidden, natural resource. In rural India, 50% of irrigation water and 80% of drinking water is pumped up from underground sources by 3 million hand-pumped wells
The theme for World Environment Day (June 5) this year is `Water: Two billion people are dying for it'. Indeed, many of the world's natural underground reservoirs, upon which two billion people depend for drinking water and irrigation, are under increasing stress, says a new report. The report, Groundwater and its Susceptibility to Degradation: A global assessment of the problem and options for management by the United Nations Environment Programme (UNEP), paints a worrying picture of this critical, hidden, natural resource, as growing and thirsty cities, industries and agriculture take their toll. It cites cases from across the world to highlight the global threat, whilst also outlining a range of options to help secure and conserve supplies. In Arizona, United States, 400 million cubic metres of groundwater is being removed annually, which is about double the amount being replaced by recharge from rainfall. Almost a fifth of the water in storage in the huge Ogalla/High Plains Aquifer of the Midwest of the United States has been removed. In recent decades, the water table there has fallen by an average of 3 metres, and upto 30 metres in some places. Other countries highlighted include Mexico, where the number of aquifers considered over-exploited has jumped from 32 in 1975 to nearly 130 by the 1990s, says the report. Impacts include contamination by salt as seawater seeps in to replace the freshwater loss and contamination from the surface caused by pumping. Land subsidence causing damage to property and infrastructure has been recorded in several states including Mexico City, Queretaro and Celaya, as a result of the falling water table. In Spain, more than half of the nearly 100 aquifers are over-exploited. "In the important Segura river basin of eastern Spain, the ratio of groundwater storage depletion to available renewable water resources has increased from less than 20% in the mid-1980s to 130% by 1995." Ironically, some cities in very dry and arid regions like the Arabian Gulf suffer a form of flooding known as `waterlogging' because of a heavy dependence on desalinated water from the coast which is leaking and becoming trapped in the ground. A typical Arabian Gulf coast city may be losing as much as a third of its water supplies to leaky mains, and even more from over-watering of parks and gardens. This heavy reliance on treated seawater is, in some cases, partly due to these cities having polluted their own underground water making it unfit for human consumption. The report, which is being released at World Environment Day celebrations in Lebanon, is also being launched at several key locations around the world. Klaus Toepfer, UNEP's executive director, said: "Some two billion people and as much as 40% of agriculture is at least partly reliant on these hidden stores. Groundwater also supplements river flows, springs and wetlands vital for rural and urban communities and wildlife. Indeed, most of the world's liquid freshwaters are found not in rivers and lakes, but below the ground." "We are here in Lebanon for World Environment Day, the first time the event has been held in the Arab world. This report will have particular resonance in a region where it is estimated that in some areas over 90% of the population could be suffering severe water stress by 2032," he said. Toepfer said the past 50 years had been marked by dramatic increases in the use of groundwater as populations have grown, demand for food has climbed and industrialisation has expanded in the developed and into the developing world. "This report is both cause for hope and concern. It shows that many underground supplies are proving quite resilient to chemical and other kinds of pollutants because slow passage through the rocks above them helps reduce or even eliminate health-hazardous substances before they reach supplies," he added. "However, they appear more vulnerable to neglect or over-use. If a lake, river or reservoir becomes depleted or dries up, the event is highly visible. There is public outcry and often action taken. I hope that this report will serve as a wakeup call concerning the human, social and economic consequences of squandering our vital underground water supplies. Hopefully its findings will ensure that underground water supplies are no longer `out of sight and thus out of mind', but quite rightly conserved for current and future generations," said Toepfer. The UN's Millennium Development Goals and the water component of the World Summit on Sustainable Development's (WSSD) Plan of Implementation will be almost impossible to achieve without improvements in water efficiency in agriculture, industry and households which should, in turn, conserve freshwater above and below the ground. Martin Walshe, senior water adviser at the UK Department for International Development (DFID), said: "The importance of water and its fundamental contribution to sustainable development is now recognised, but the contribution of water to poverty reduction will only be realised if it is set in the broader context of social and economic development and environmental improvement. At a regional level, groundwater is of huge importance in Africa, Asia and Central and South America. Nationally, countries from Palestine to Denmark are dependent on groundwater and examples of local reliance can be drawn from Mexico City to Ethiopia." "In a rural context, groundwater provides the mainstay for agricultural irrigation and will be the key to providing additional resources for food security. However, concerns are growing over the sustainability of individual water sources, and there is a growing need for management strategies that recognise the complex linkages that exist between groundwater supplies, urban land use and effluent disposal," he said. Brian Morris, principal hydrogeologist at the British Geological Survey in the United Kingdom, which has been involved in the report, said: "The difficulty in managing groundwater lies in the fact that it is often easy and relatively cheap to tap for large numbers of users. What is needed is pragmatic management such as increasing public and government awareness, properly resourcing the agencies that manage groundwater, supporting community management and encouraging the use of incentives and disincentives particularly in poorer countries and rural areas. It is vital we give groundwater value like any other scarce resource." Key findings of the report Falling water tables The UNEP report, compiled in conjunction with the British Geological Survey and funding from the UK Department for International Development and Belgian Development Cooperation, links the fate of many of the world's growing cities with the prudent management of their underground water supplies. It lists 12 megacities, ones whose populations exceed 10 million, that are dependent on groundwater. These are Bangkok, Beijing, Buenos Aires, Cairo, Calcutta, Dhaka, Jakarta, London, Manila, Mexico City, Shanghai and Tehran. Rural areas can also be heavily dependent on groundwater. The report highlights rural India where 50% of irrigation water and 80% of drinking water, much of which is brought to the surface by a network of 3 million hand-pumped wells, comes from underground sources. Some countries are heavily dependent on aquifers for agriculture. Saudi Arabia's agriculture is almost exclusively dependent on aquifers, with 96% of its water for irrigation coming from underground. This is followed by Bangladesh, 69%; Tunisia, 61%; Syria, 60% India, 53% and Pakistan, 34%. Certain arid parts of the world have identified vast reserves of ancient groundwater, called palaeowater, formed thousands of years ago in a wetter climatic period. Libya, for example, is taking 7 million litres of water a minute from over 1,000 borewells that tap aquifer systems below remote areas in the southern Sahara. The water is transported in pipes, the `Great Man-Made River', to the Mediterranean coast 500-900 km away. Dhaka, Bangladesh, is an example of how heavy tapping from urban aquifers can have a profound impact. There are now an estimated 1,300 borewells drawing underground water for the city and its suburbs. In some areas the water table has fallen by as much as 40 metres. As a result, new borewells are producing a third less than ones dug in the 1970s, surveys show. In Lima, Peru, deeper and more expensive borewells have to be dug to meet demand, and the energy costs of water production have risen by a quarter. The risks of over-exploitation can be catastrophic in economic terms, especially in rural areas dependent on irrigation. Freshwater can become contaminated with salt making it unfit for human consumption and most agriculture. Removing the salt is costly and energy-intensive, making it too expensive for many developing countries to consider. Rising water tables Paradoxically, in some very dry parts of the world, water levels are rising with striking effects. In Riyadh, Saudi Arabia, the population has soared from 20,000 in 1920 to over 1.2 million. Piped water is being pumped from the coast from desalination plants, which remove salt from seawater to meet a high demand of more than 600 litres per person per day. An estimated one-third of the piped water is lost to leaks from the city's mains. At the same time, there are losses from underground storage tanks. Over-irrigation of lawns, roadside verges and parks means that a great deal of water is now leaking into the ground. The geology under Riyadh is such that the water cannot easily seep away. Basements and pipes have been damaged and deformed. The city has been forced to deploy expensive pumping equipment to tackle the problem. The UNEP report cites Kuwait and Doha, Qatar, as suffering similar problems. It says that, here, additional impacts are being felt. The desalinised water percolating through the ground is dissolving naturally-occurring salts that, in turn, attack and corrode concrete and the steel-reinforcing of foundations and other infrastructure. Fixing leaky pipes, metering, pricing reform, incentives for drip irrigation and hosepipe bans are among a range of measures that might reduce losses and the phenomenon of `water-logging' being witnessed in some areas of the Arabian Gulf.
Pollution
Worldwide, the ground is used for the disposal of all kinds of wastes. Fortunately, many toxic wastes are absorbed and broken down by natural processes such as bacteria. However, not everything is easily degraded. In some cases, so much waste is entering the ground that its natural ability to break down pollutants is exceeded. Meanwhile, not all the rock strata are the same -- some are less efficient at neutralising pollutants. This can also threaten the viability of local underground supplies. Merida, Mexico, highlights this concern. Concentrations of sewage-linked bacteria can, in some groundwater, be several thousand times higher than that allowed under international health standards.
Elsewhere, other potentially damaging pollution includes pesticides, fertilisers and industrial chemicals and wastes. Research from Barbados, where the weed-killers atrazine and ametryn are widely applied, has revealed pesticide contamination in borewells as high as three micrograms per litre, or 50% higher than World Health Organisation (WHO) guidelines. On Gran Canaria in the Canary Islands, levels of fertiliser-linked nitrates have been detected in underground water sources at levels as high as 170 milligrams per litre. The contamination, which is 120 milligrams higher than the WHO guideline limit, is related to banana production. Solving the problems The report makes numerous suggestions on how groundwater can be conserved and sustainably managed. But it concedes that many potential improvements and remedies are politically and socially difficult unless long-term goals are adopted. Those managing water supplies, such as water agencies and government water departments, need to manage groundwater in tandem with rivers, lakes and reservoirs -- a so-called integrated water management approach. Economic actions, not directly related to groundwater, may have a big impact on water use. Promoting alternative rural livelihoods, such as brick-making and textiles which are less water intensive than agriculture, may help diversify the economy away from heavy reliance on irrigation. Indeed, economic development generally can give a country and its communities `greater options' leading to less reliance on ground and surface waters as a whole. Diversifying rural economies may require investments in training and the availability of credit to get small, alternative businesses up and running. The report says this may require new thinking among traditional water agencies involving alliances with departments of industry, commerce and education. In many developing countries, including ones in Africa, a chronic lack of hard facts on the condition of their groundwater makes it difficult to draw up action plans. Making these hard facts publicly available is even more crucial and vital to build trust when aquifers are shared between one or more countries. A monitoring and early-warning project, coordinated by the UNEP and the United Nations Education, Science and Cultural Organisation (UNESCO), in seven West African cities, including Abidjan, Niamey and Dakar, has helped by pinpointing `pollution hot spots' and threats to aquifers. The scheme has
been extended to three countries in Eastern Africa -- Ethiopia, Kenya and Zambia. The report Groundwater and its Susceptibility to Degradation: A global assessment of the problem and options for management is available at Earthprint www.earthprint.com Source: UNEP, June 5, 2003
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