Mengqi Zhao, Ph.D. Candidate, Department of Civil and Environmental Engineering, Washington State University

Figure 1. Managed Aquifer Recharge, like this example for the Merti aquifer shared between Kenya and Somalia, can help provide additional water in periods of water scarcity. The photo is from the Intergovernmental Authority on Development. (IGAD).

The 2015 drought caused more than $700 million in economic losses across Washington State. Even with current water storage management, both in places where rivers, lakes, and reservoirs generally provide sufficient water and in places where aquifers are the most stable water resource across seasons, extreme drought still impacted our economy. While droughts may impact different places with varying intensity, the risk of long-term water scarcity is greater when aquifers provide water today at the expense of tomorrow’s supply. As the region faces population increases and increasing competition for water resources to provide environmental value and economic value, the risk may increase further. So what water management options can help us mitigate the impacts of drought in the future?

In our region, we are experienced in using surface reservoirs as buffers between the naturally variable water cycle and the relatively more consistent agricultural water demand. The less visible buffer underground has often been ignored. Yet interest is growing, as aquifers may also be a useful reservoir over the long term, if managed sustainably. Our research team is evaluating managed aquifer recharge (MAR), an approach that stores water in the aquifer during the snowmelt season, allowing users to pump it for irrigation during periods of water scarcity (Figure 1). We have been asking questions about how to recharge aquifer systems to optimally achieve both short-term usage and long-term water supply sustainability. Imagine that the amount of water recharged into the aquifer becomes your future available MAR entitlement to pump up when needed. The more water that recharges the aquifer, the more effective the MAR will be in mitigating drought impacts. We are interested in answering specific questions, such as ‘What timing of recharge and infiltration area would have been needed for managed aquifer recharge to provide an effective buffer against the 2015 drought?’ or ‘How effective is managed aquifer recharge for maintaining sustainable water supply during single-year drought or even multi-year droughts?’ Continue reading →

By Sonia A. Hall

Irrigation dam and diversion in Idaho. Photo: Mark Plummer under CC BY-NC-ND 2.0.

There is a difference between the amount of water diverted from streams and rivers to irrigate crops, and the amount of water consumptively used in those irrigated fields, which includes what the crops actually transpire, plus what evaporates from these fields. The difference is sometimes called return flow, as it percolates through the soil and becomes available for use further downstream (this earlier article has a diagram that reflects that, so take a look).

Decisions about water allocation and water use in the Pacific Northwest are mostly made based on diversions, because that’s what we can measure, using water meters for example. But when we discuss whether more efficient irrigation technology should be used, or ways to reduce conflicts between out-of-stream and instream water needs, consumptive use—the water used by crops and lost to evaporation—is also really important. Check out this article on METRIC, a method using remote sensing to measure water consumption in Idaho. And take a look at the 2016 Columbia River Forecast for a pilot application of METRIC in Washington State, work that is currently being expanded with support from the US Department of Agriculture as part of the Washington State University led Technology for Trade project. What do you think would be the benefits of having this technology available across the Columbia River Basin? Take a minute to comment below. And stay tuned for more on METRIC as this research progresses.