Peak Water: the three peaks

“In the same way that peak oil has meant the end of cheap, easy-to-access sources of petroleum, peak water means we are going to have to go further, spend more, and expect less in the realm of freshwater. Peak water reminds us that water, which we used to think was widely available and inexpensive, can no longer be taken for granted.” Although the planet contains around 1.4 billion cubic km of water, nearly 97% of this is saltwater in the oceans. Most of the 35 million cubic km of freshwater, meanwhile, is locked up in glaciers in Antarctica and Greenland, in permanent snow cover, or in deep groundwater inaccessible to humans, write Palaniappan and colleague Peter Gleick in PNAS. But people are able to use freshwater from rivers, surface lakes, accessible groundwater, soil moisture and rainfall. “Obviously there are tremendous differences between oil and water, particularly that water is primarily a renewable resource, while oil is non-renewable,” said Palaniappan. “There is a certain fixed amount of water on the planet that has been here since the origins of the planet, while the amount of oil on the planet is constantly declining. But there are ways in which we can see a peak oil type effect in the water sector.” Palaniappan and Gleick have defined three types of peak water: peak renewable water, the total annual supply of water from sources such as rainfall, rivers, streams and groundwater basins that are recharged relatively quickly; peak non-renewable water, for aquifers containing fossil groundwater accumulated over many thousands of years and with a very slow recharge rate, or for groundwater systems that cannot be recharged when overpumped because the basin becomes compacted; and peak ecological water.

EnviromentResearchWeb