Sunday, August 31, 2003

Pilot study shows human water use significantly threatens freshwater ecosystems

A joint study by the International Water Management Institute (IWMI), the World Resources Institute (WRI), the Center for Environmental Systems Research of Kassel University (KU) and IUCN-The World Conservation Union warns that excessive use of water in the world's major river basins threatens the collapse of many local economies and communities, potentially affecting the lives of over 1.4 billion people who live in the river basins.

Another report, Groundwater and its Susceptibility to Degradation: assesses the problem of shrinking ground water supplies and options for management by the United Nations Environment Programme (UNEP). The report paints a worrying picture of this critical, hidden, natural resource, as growing and thirsty cities, industries and agriculture take their toll.

"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."

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.

The growing water crisis is an indication that the world is reaching its carrying limit for human civilization. And the problem is being aggravated by climate changes.

Drier than normal weather conditions in regions around the world - including near-record droughts in some countries - have sparked growing concern about the state of the world's drylands. Heavy use is stretching the limits of the world's drylands, which are home to more than 2 billion people, one-third of the earth's population.

"More than 40 percent of the world's poorest countries consist largely of drylands. Farming, raising livestock, and other means of making a living in these countries are often inextricably connected to the health of the land. But heavy demands on these lands are reducing their ability to support large populations. The United Nations estimates that the livelihoods of an estimated 1 billion people in 110 countries are threatened by drought and desertification.

A number of countries around the world are experiencing the worst droughts they have seen in decades, and drylands have been among the hardest regions hit. Parts of the United States are now seeing dust-bowl like conditions. Starvation is a threat for tens of thousands in drought-stricken southern Africa. Massive numbers of livestock are dying of thirst in dry regions in Asia and the Pacific."

We are entering an age of limits. One way or another we will spend this century learning to live in harmony with nature. The lessons may be hard.


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