- Peak Renewable - - Water limits that are the total renewable flows in a watershed. Many of the world's major rivers are already approaching this threshold - - when evaporation and consumption surpass natural replenishment from precipitation and other sources.
- Peak Nonrenewable - - Water limits where human use of water exceeds the natural recharge rates, such as in fossil groundwater basins of the Great Plains, Libya, India, northern China and parts of California's Central Valley. In these basins, as increase in extraction is followed by leveling off and then reduction, as the costs and amount of effort needed to acquire the dwindling resource rise - - a concept similar to peak oil.
- Peak Ecological - - Water in this context is the idea that for any hydrological system, increasing withdrawls eventually reach the point where any additional economic benefit of taking the water is outweighed by the additional ecological destruction that it causes. Although it is difficult to quantity this point accurately, we have clearly passed the point of peak ecological water in many basins around the world where huge damage has occurred , including the Aral Sea, the Everglades, the Sacramento-San Joaquin Valley and many watersheds in China.
Technology and innovation play the same role in Peak Water as they do in Peak Oil. Whereas Peak Oil utilizes technology and innovation to find and maximizes the discovery and extraction of oil - - Peak Water utilizes technology and innovation to conserve water. Better irrigation technology, alternative forms of energy that need less water, and water efficient appliances all play an important role in water sustainability.
Read more in the April 2010 issue of Scientific American - - "Solutions To Environmental Threats."