“Out of sight and out of mind” sums up the groundwater policies in many places, and the public’s understanding of the issue, despite the fact that groundwater is one of our most critical water resources.

That’s what prompted William and Rosemarie Alley to team up to write “High and Dry: Meeting the World’s Growing Dependence on Groundwater.” The duo had previously collaborated on a book on nuclear waste, but found there weren’t any books that tackled the issue of groundwater in a way that would be accessible and exciting to readers.

Rosemarie is a writer and William is the director of science and technology for the National Ground Water Association and spent nearly 20 years as chief of the Office of Groundwater for the U.S. Geological Survey. Their book provides readers with engaging narratives spanning the U.S. and the world, including three case studies: India is the poster-child for what not to do as it pumps enough groundwater each year to fill an 18in (45cm)-diameter pipeline with water to the moon and back 2,000 times; sub-Saharan Africa is an example of an area that should be developing its groundwater more to increase economic opportunity; and Arizona is a success story of how hard-won consensus among stakeholders helped solve a very complex problem.

Water Deeply recently spoke with the Alleys about what they learned writing about global groundwater issues and the ones in their backyard in California.

Water Deeply: What are the main things you hope readers take away from your book?

William Alley: Our goal was to get more people thinking about groundwater and to broaden the perspective for those that are already engaged. It’s not really on the radar screen as much as it should be.

Rosemarie Alley: Or hardly at all. Groundwater is the neglected child in the water world. It’s amazing how surface water has gotten so much attention, there are so many laws governing surface water.

Water Deeply: Do we have a good understanding about how much groundwater we have in our basins?

William: I’m glad you asked that question because it comes up a lot. It actually doesn’t matter so much oftentimes because other factors come into play. The Central Valley in California has a huge amount of groundwater in it, but you can only tap so much because it costs too much to pump it out or it’s poor water quality or there is subsidence.

Surface water is often a major constraint on groundwater. We don’t have a good handle on how much groundwater we have. But it’s not the most important piece of information to know about groundwater. You have to look at each basin independently and what the effects of pumping are on that individual basin and what impacts are acceptable.

Water Deeply: In California we hear a lot about NASA’s GRACE satellite program. Are satellites the main way we are tracking changes in groundwater?

William: It’s the way that has gotten people’s attention. But there are many other techniques like measuring water levels in wells and there are other satellite approaches like InSAR where you can look at land subsidence over broad areas. GRACE has been great for public awareness because people can look at dots on the map and see where these red spots are where there is groundwater depletion, but you need more information because groundwater is a three-dimensional system and it’s very variable. And you can’t get information about surface water impacts or water quality from GRACE.

Water Deeply: Are there still big gaps in our understanding of groundwater?

William: It’s poorly monitored, relatively speaking. We know where the aquifers are for the most part. We aren’t in an exploration mode of trying to find groundwater, but there are still some unknowns when it comes to the characteristics of those and some of the water quality impacts.

Water Deeply: Since agriculture is the biggest user of groundwater, what does that mean for our food supply in areas with serious groundwater overdraft?

William: It’s serious. We’ve come to depend on groundwater in many semi-arid areas – the Central Valley or the Snake River Plain of Idaho or the High Plains or North Africa. In areas like the Southern High Plains, there doesn’t seem to be any hope [for groundwater sustainability]; eventually that is just going to go back to dryland farming or wind farms or something like that.

Other areas like the Central Valley – on the southern part you have very serious problem going on. There is a hard road ahead to get that system into to some kind of sustainable use through the Sustainable Groundwater Management Act (SGMA) – that’s going to be a real challenge.

Water Deeply: California has been very slow to manage groundwater – is it among the worst examples you found in your research?

Rosemarie: It is very late in the game and it will remain to be seen how effective [SGMA] is.

William: There are two sides to California – there are places in California that are world leaders in managing groundwater, like Orange County Water District and Santa Clara Valley and parts of Los Angeles. Then there is the rest of the state – it was the last western state to regulate groundwater.

Water Deeply: What are the consequences of groundwater overdraft?

Rosemarie: Groundwater is either the only, or a major water source, for many of the world’s megacities – it’s a key pillar of the urbanization movement. You look at Mexico City, they have challenging water supply problems and then with subsidence on top of it.

William: It’s important to cities, it’s not just an ag problem. But 70 percent of groundwater pumping worldwide goes to agriculture, so that connection is very important. But it also provides water for much of the rural areas of the world. Particularly shallow groundwater is tapped by those rural folks as a very important resource.

It’s also tied into surface water and ecology – and we don’t really look at that so much in California. But the impacts are huge in many areas on both the surface water flows and the ecology associated with it.

Rosemarie: I don’t have a groundwater background and as I became educated in the process of researching and writing this book, that was one of the things that surprised me the most. I didn’t realize that groundwater and surface water in many instances are a connected resource. It’s an important key in understanding the environmental and health implications of how vulnerable groundwater is to contamination.

Water Deeply: Besides California, are there other places that really concerned you in their groundwater management?

William: Saudi Arabia comes to mind. They became self-sufficient in wheat while they used up a whole bunch of nonrenewable groundwater. We talk in the book about some places with “hydrological insubordination,” for example farmers in parts of Spain where they don’t follow the rules and the organizations that are supposed to be regulating them become defenders of the farmers. India is also still struggling.

Rosemarie: There’s a very pervasive attitude and it’s not just among farmers, but the idea that “it’s my well and I’ll pump as much as I want.” It’s very hard to get people to see that that doesn’t work with groundwater, it doesn’t observe property boundaries or state lines or international borders. And it’s becoming more challenging with climate change starting to be felt in certain places, like here in California.

There is a very strong analogy between the problem of groundwater and climate change. It’s hard to get people to understand a problem that develops slowly and that you can’t see. They are very related problems in that sense. And groundwater is very vulnerable because of climate change.

William: The complexity of managing groundwater is all about people, and to do it right the top-down strategy doesn’t work because you just get rebellion. So you have to go through this process that engages stakeholders but at the same time you’ve got some external force that is making sure they are held accountable.

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