Thursday, August 15, 2019

Sustainability Case Studies--Chapter 4. Sustainable Water Resources Management: Groundwater Depletion

A night view of the Coachella Valley, California.
Click for photo credit.
This is the fourth post in this blog series, Sustainability Case Studies, that is based on the book The Palgrave Handbook of Sustainability:  Case Studies and Practical Solutions edited by Robert Brinkmann (yours truly) and Sandra Garren and published by Palgrave Macmillan in 2018. Each post in the series will comment on the content of the chapter as well as some general take-aways or practical teaching or personal/organizational initiatives that could be gleaned from the chapter. Links to previous posts on the series (including the post that introduced the series) follow after the chapter review.

Today's post focuses on Chapter 4 by Brian F. Thomas and Aimee C. Gibbons and is titled, Sustainable Water Resources Management:  Groundwater Depletion. Thomas is with the University of Pittsburgh and Gibbons is with the University of California at Irvine.

The chapter starts with an introductory review of groundwater issues as they relate to sustainable water management. The world's growing population requires access to water and this is putting a strain on water management all over the world. When this demand is coupled with predicted changes in climate and associated precipitation patterns, the need for sound water management is critical. The authors note that 2 billion people around the planet rely on groundwater reserves for their daily water supply. However, these reserves must be managed to avoid their depletion. The authors review how the management of groundwater evolved over the last two centuries.

After this introduction, the chapter moves on to a case study in the Coachella Valley of California. Managers have been monitoring groundwater levels in the valley since the 1910's which make the location a particularly interesting one for characterizing groundwater management over the last 100 years. Excessive water withdrawals in the middle of the 1900's to irrigate citrus and cotton harmed the local aquifer system. Since then, management plans, which included artificial recharge, have been put in place to mitigate the impacts of overuse.

The authors conducted a temporal study in the valley that looked at water well levels, replenishment, and water use. The authors found that prior to 1999, water was being used in an unsustainable way which accounted for a 4.3 meter drop throughout the valley. However, since that time water withdrawal is equivalent to water replenishment. It is important to note that the improvements are not spatially equal. Areas of the Coachella Valley continue to see a decline in groundwater levels in areas where replenishment is not taking place. Thus, the "no net withdrawal" approach to water management in the region is not fully effective due to significant spatial variation in recharge and withdrawal.

A resort in the Coachella Valley.
Click for photo credit.
One of the key takeaways from the case study is that sustainable groundwater management is far more complex than previously thought. A simple approach that uses "no net withdrawal" management may not be effective in all situations due to spatial and temporal variabilities of recharge and withdrawals. The authors provide a rich description of the challenges and barriers present in sustainable groundwater management including the vexing issue of balancing economic needs with environmental protection.

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Click here to for more information about the book.

Here are some discussion questions that can be used when using this chapter in a lesson on groundwater and sustainability.

1. How do you think water management differs between surface water reservoirs and ground water reservoirs?
2. What types of groundwater management schemes have been used in California over the last 100 years or so?
3. What types of problems can occur if groundwater is not managed appropriately?
4. Why is it important to have a regional approach to groundwater management?
5. Describe the physical geography of the Coachella Valley in California. What makes it particularly challenging for water resource management?
6. How have groundwater levels changed over space and time in the Coachella Valley? What can account for these changes?
7. Why is a "no net withdrawal" form of water management inappropriate for the Coachella Valley?
8. How can you balance economic activity, like golf courses, with the need for groundwater protection?

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