The takeaways:

China's food production is forecast to decline by 37% by the last half of

the 21st century, placing a strain on the entire carrying capacity of the

world, as China's population could expand to about 1.5 billion people by the

year 2050.

Economy, E., China vs. Earth, The Nation, May 7, 2007 issue

This reduction in China's agricultural capability, and the planet’s, is

largely due to the world water crisis including mining groundwater beyond

sustainable yield, ongoing in China since the mid-20th century.

Nielsen, R., The Little Green Handbook,

en.wikipedia.org/wiki/Picador Picador, (2006)

en.wikipedia.org/wiki/Special:BookSources/0312425813 ISBN

0-312-42581-3 Ongoing in the USA roughly since the 1930s.

Also

see

According to the California Department of Water Resources, if more water

supplies aren’t found by 2020, the region will face a shortfall nearly as

great as the amount consumed today.

The United Nations' FAO states that by 2025, 1.9 billion people will be

living in countries or regions with absolute water scarcity, and two-thirds

of the world population could be under stress conditions. See FAO Hot

issues: Water scarcity.

The World Bank adds that climate change could profoundly alter future

patterns of both water availability and use, thereby increasing levels of

water stress and insecurity, both at the global scale and in sectors that

depend on water. Source:

The World Bank, 2009 "Water and Climate Change: Understanding the Risks and

Making Climate-Smart Investment Decisions". pp. 21–24. Retrieved

2011-10-24.

The average world citizen has an eco-footprint of about 2.7 global average

hectares while there are only 2.1 global average hectares of bioproductive

land and water per capita on earth. This means that humanity has already

overshot global biocapacity by 30% and now lives unsustainabily by depleting

stocks of "natural capital".

Source: Rees, William, "The Human Nature of Unsustainability", in Heinberg,

Richard and Leich,Daniel, The Post Carbon Reader: Managing the 21st Century

Sustainability Crisis, Watershed Media, 2010, ISBN 978-0-9709500-6-2

Lester Brown of the Earth Policy Institute, has said: "It would take 1.5

Earths to sustain our present level of consumption. Environmentally, the

world is in an overshoot mode."

Brown, L. R. (2011). World on the Edge. Earth Policy Institute. Norton. pp.

7. en.wikipedia.org/wiki/International_Standard_Book_Number ISBN

en.wikipedia.org/wiki/Special:BookSources/987-0-393-08029-2

987-0-393-08029-2.

Wackernagel’s Ecological Footprint - A ">study by Mathis Wackernagel has shown

that the global ecological footprint was in overshoot by .4 global hectares

per person, or roughly 23%. Wackernagel, Mathis; Russ, Thomas (ed.) (2008).

In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington,

D.C.: Environmental Information Coalition, National Council for Science and

the Environment). [First published in the Encyclopedia of Earth January 23,

2007; Last revised November 18, 2008;

Sustainability instead

"Daly Rules" approach

University of Maryland School of Public Policy professor and former Chief

Economist for the World Bank Herman E. Daly (working from theory initially

developed by Romanian economist Nicholas Georgescu-Roegen and laid out in

his 1971 opus "The Entropy Law and the Economic Process") suggests the

following three operational rules defining the condition of ecological

(thermodynamic) sustainability:

Renewable resources such as fish, soil, and groundwater must be used no

faster than the rate at which they regenerate.

Nonrenewable resources such as minerals and fossil fuels must be used no

faster than renewable substitutes for them can be put into place.

Pollution and wastes must be emitted no faster than natural systems can

absorb them, recycle them, or render them harmless.

This is a terrible fast parse of a huge amount of information. I wish I

could absorb it all and make is sensible.

I don't believe that we can technology our way to more water, but I'd love

to be wrong.