Author Topic: Increased irrigation efficiency leads to increased water usage  (Read 702 times)

Offline Mr. Bill

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Interesting study about how water conservation methods lead to less water being available.

Summary, courtesy of Courthouse News: Study: Efficient Irrigation Methods Increase Water Usage

Quote
...Governments give incentives to install technologies that improve the “crop per drop” ratio in global food production. ...

But these methods are disrupting the natural flow of the water cycle.

According to the study, in lower-efficiency irrigation systems – such as traditional farming – any water not used directly in irrigation flows back into surface water systems or aquifers.

Under efficient methods, less water is “lost,” meaning less re-enters natural water systems, which leads to a decline in available water overall, according to researchers.

The study said farmers will also typically use more water if efficient irrigation methods, and government incentives, mislead them into believing they are saving money while using less water. ...

The article itself, published in Science magazine: The paradox of irrigation efficiency

Quote
...Given that crop irrigation constitutes 70% of global water extractions, which contributes up to 40% of globally available calories, governments often support increases in irrigation efficiency (IE), promoting advanced technologies to improve the “crop per drop.” This provides private benefits to irrigators and is justified, in part, on the premise that increases in IE “save” water for reallocation to other sectors, including cities and the environment. Yet substantial scientific evidence has long shown that increased IE rarely delivers the presumed public-good benefits of increased water availability. Decision-makers typically have not known or understood the importance of basin-scale water accounting or of the behavioral responses of irrigators to subsidies to increase IE. ...

This paradox, that an increase in IE at a farm scale fails to increase the water availability at a watershed and basin scale, is explained by the fact that previously nonconsumed water “losses” at a farm scale (for example, runoff) are frequently recovered and reused at a watershed and basin scale.

Advanced irrigation technologies that increase IE may even increase on-farm water consumption, groundwater extractions, and water consumption per hectare. At a farm scale, this can arise from a switch to more water-intensive crops and, with the same crop, may occur when there is a strong marginal yield response from additional water. Moreover, the absence of an increase in water consumption per hectare because of a higher IE does not necessarily mean that the water potentially available for reallocation and reuse (see supplementary materials) at a watershed or basin scale increases. Subsidies for drip irrigation may reduce the water applied per hectare and increase water extractions because a higher IE can induce increases in the irrigated area...

There are reasons why this evidence may be overlooked by policy-makers: Evidence resides in a specialized literature; subsidies for IE can promote rent-seeking behavior by beneficiaries who lobby to continue subsidies; and comprehensive water accounting from the scale of the field to that of the watershed or basin is necessary but frequently absent. ...

For preppers, I see two issues here:
  • If you are sharing a river or aquifer with agricultural users, be dubious of promises that improved irrigation efficiency will help preserve your water supply.
  • Expect future water-use regulations to be based on complex calculations of watershed-wide or basin-wide usage and supply.