If we don’t get things right, water conservation can actually make us less resilient in the face of variability and climate change, the University of Arizona’s Christopher Scott and colleagues argue in a recent paper. It’s the case for being wary of “demand hardening”, and it raises interesting questions about current Colorado River Basin conservation efforts:
[I]rrigation efficiency without caps on use – or limits to area expansion – may increase production (and productivity), but it undermines the resilience of basins under conditions of water scarcity. Eliminating slack in the system through stringent water conservation and allocation of savings to new uses can result in the “hardening” of demand that will entail crop loss or irrigated area restrictions under future conditions of water shortage. This is particularly true for the integrated management of water and land to meet ecological flow requirements under changing climate scenarios. Thus, a basin’s capacity to meet human and ecosystem water needs often follows a moving target.
The paper, which looks at the Imperial Valley and the Guadiana Basin shared by Spain and Portugal, argues that the key is to ensure that conserved water is really saved, not merely shifted to new uses (expanded agricultural or, in the case of Imperial, urban use):
Policy mechanisms to reserve surplus water in the reservoir or aquifer instead of expanding irrigation include regulated controls on irrigated area, price incentives, and provision of information to support farmer and irrigation district decision-making to better adapt to future contingencies…. Investing public resources to anticipate and offset the effects of water scarcity ex ante represents a more effective adaptive response to drought than ex post mitigation efforts.
Here are the questions this raises about the current Colorado River water conservation efforts now underway. The oldest and most well-developed effort, the shift of water from Imperial Valley to the cities of coastal California, seems vulnerable to the criticism Scott and colleagues are making. They call this “the sectoral paradox, in which savings are reallocated to alternative uses (e.g., water transferred from Imperial Valley to San Diego city).”
The two newest efforts, the basin-wide System Conservation Program and the Pilot Drought Response Actions program, seem aimed at meeting the criteria sketched out in Scott et al.’s conclusion – putting the surplus water in a reservoir, rather than devoting it to new uses.
In the Colorado River Basin, though, the line between putting water into a reservoir versus devoting it to a new use is fuzzy. The reason Lake Mead is empty is because of the previous expansion of new uses in excess of currently available supply, so in some sense water put in the reservoir now is just backfilling behind what are already too many new uses for the system to cope with. But the distinction’s still helpful, because we are where we are now, and Scott et al. offer a useful framework for looking at conservation efforts.
The paper is “Irrigation efficiency and water-policy implications for river basin resilience“, Hydrol. Earth Syst. Sci., 18, 1339-1348, 2014, doi:10.5194/hess-18-1339-2014