Drip Irrigation May Not Save Water, Analysis Finds

NY Times ^ | November 18, 2008 | HENRY FOUNTAIN

[neverdem]

Dan Porges/Peter Arnold

Observatory

In an effort to make irrigation more efficient — to obtain more “crop per drop” — farmers have adopted alternatives to flooding and other conventional methods. Among these is drip irrigation, shown above, in which water flows only to the roots. Drip systems are costly, but they save much water.

Or do they? A hydrologic and economic analysis of the Upper Rio Grande basin in the Southwest, published in The Proceedings of the National Academy of Sciences, suggests that subsidies and other policies that encourage conservation methods like drip irrigation can actually increase water consumption.

“The take-home message is that you’d better take a pretty careful look at drip irrigation before you spend a bunch of money on subsidizing it,” said Frank A. Ward, a resource economist at New Mexico State University and author of the study with Manuel Pulido-Velázquez of the Polytechnic University of Valencia in Spain.

With flood irrigation, much of the water is not used by the plants and seeps back to the source, an aquifer or a river. Drip irrigation draws less water, but almost all of it is taken up by the plants, so very little is returned. “Those aquifers are not going to get recharged,” Dr. Ward said.

Drip irrigation also generally increases crop yields, which encourages farmers to expand acreage and request the right to take even more water, thus depleting even more of it. “The indirect effect is very possibly to undermine policy attempts to reduce water consumption,” Dr. Ward said.

Policymakers, he added, must balance the need for more food and for farmers to make a living with water needs.

[BMiles2112]

Your point is that government mandated conservation has encouraged conservation. I agree. My point in all of this has been that the government should remove itself from arbitrarily regulating markets where it need not regulate. If this had been an article about government forcing more stringent electricity limitations on refrigerators, I would have made the same fundamental arguments.

[ansel12]

You don’t know my point, my post was in response to post 16, water exists on the planet and will stay constant in that way, but that has nothing to do with water regionally, or nationally, or locally, or much of anything else, or in the design of mechanical devices that use water.

By the way I suppose everyone supports the government getting involved in the design of ballcocks, that is something related to toilets that I definitely wanted government to involve itself in and they did.

[SunkenCiv]

Scientists Show That Vegetation Conditions Drive The North Africa Drought
ScienceDaily
November 24, 1999
Adapted from materials from NASA Goddard Space Flight Center

William Lau, a Goddard Space Flight Center (Greenbelt, Md.) atmospheric scientist... along with UCLA atmospheric scientists Ning Zeng and David Neelin, found that the addition of vegetation to climate computer models proved to be the missing link in what was driving the drought... changing sea surface temperatures couldn't account for much of the drought at all... another factor -- soil moisture -- ...was only enough to account for a drought half as severe as what actually happened in the Sahel. Finally, the team added natural vegetation to the model and found that the natural vegetation interacts significantly with climate, and in the case of the Sahel drought, caused enhanced drying... Also, since plants transpire by losing water through their leaves, less vegetation decreases humidity. The loss of a direct moisture supply means less rainfall, which causes weaker circulation, dampening the monsoon season... Lau said that the new model including natural vegetation changes is a much better reflection of what the Sahel region actually experienced. And it suggests that without the addition of man-made landscape changes, the climate system is fully capable of generating this devastating type of drought.