|The Environment as a Consumer|
Experts have started constructing models based on the growing recognition that water must be set aside for environmental health. This means that water from the hydrologic cycle must be set aside for the environment to “use” in maintaining the health of its ecosystems, so that it can fill aquifers, rivers, and lakes as it did for millions of years before humans began to tap it. One intended result is the preservation of wetlands and coastal marshes so that they can do their part in cleaning and storing water, and can strengthen the resilience and flexibility of natural ecosystems on which the health of the hydrologic cycle depends.
As an example of the challenges which are faced by society on this issue, the World Economic Forum estimates that a minimum of one-quarter of the flow of the Yellow River in China is needed to maintain the environment; human withdrawals of water currently leave less than 10% in the natural system. Restoring the necessary balance to this system will be complex; it will require reversing centuries of unthinking water use, and finding acceptable alternatives for the people and industries that currently depend upon this water.