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SUSTAINABILITY THROUGHOUT TIME – BUT NOW WHAT?

September 6, 2012
Climate, Environment, groundwater, infrastructure, management, sustainability, water supplies
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I was cruising through Glacier Bay National Park when I wrote this.  Just an inspirational moment.  If you have never seen it, you should, especially as a water professional.  The entire park is a testament to the power of water and the result of changes in climate cycles that affect the hydrologic cycle.  I will post video of the journey separately, but suffice it to say that the inherent beauty of the place is difficult to describe.  Needless to say with a large concentration of glaciers in the area (most retreating), there is copious amounts of water (for now).  The Pacific Glacier has retreated 65 miles, yes MILES, in 300 years in part because of changes in oceanic moisture and evaporation.  The native people, Tlingets, moved and survived based on glacier flows end ebbs.  But that’s not my point.  Seeing this much water leads to an entirely different perspective, one that is helped by Brian Fagan’s book, Elixir which outlines the history of civilizations as they were affected by harnessing of water, or the lack of ability to do so.  Same thing applies to the Tlingets here.

Historically the key was to rely on surface waters where they were consistent, to manage water locally and carefully for the benefit of all, and when surface waters were not consistent enough to be reliable year after year, quanats, shallow wells and other mechanisms were used to extract water from glacial till or adjacent to rivers (riverbank filtration or infiltration galleries in today’s vernacular).  Or people moved or died out. The ancient people did not have the ability to dig too deep, but were creative in means to manage available supplies.

Contrast this to today where over the last 50 years we have been able to extract water from ever expanding, generally deeper sources, but to what end?  Certainly we have “managed “ surface waters, by building dams, diversions and offstream reservoirs.  These supply half the potable water use in the United States and Canada as well as a lot of irrigation.  But groundwater has been an increasing component.  Fagan makes the point that deep groundwater sources are rarely sustainable for any period of time, and that many in the past have recognized this limitation.  But have we?

Maybe not so much.  A couple years ago I was at a conference out west.  The session I was speaking at involved sustainable groundwater, a major issue for AWWA, ASCE, NGWA and the utilities and agricultural folks around the world.  One of the speakers was a geologist with the State of Utah.  Her paper concerned the issues with decreasing groundwater levels in the St. George and Cedar City, areas in southwestern Utah, where population growth is a major issue.  Her point was that despite the State efforts, they had significant drawdowns across the area.  Keep in mind that the USGS (Reilly, et al, 2009) had identified southwestern Utah as one of many areas across the US where long term decreasing groundwater levels.  My paper was a similar issue for Florida, so I stopped partway into my paper and asked her a question:  has any hydrogeologist or engineer trying to permit water in the area ever said the water supply was not sustainable?”  The room got really quiet.  She looked at me and said, “well, no.”  In fact the audience chimed in that they had never heard this from their consultants either.  The discussion was informative and interesting.  Not sure I really finished my presentation because of the discussion.

To be fair, consultants are paid to solve problems, and for water supplies, this means finding groundwater and surface water limited areas like Utah when their clients request it.  So you don’t expect to pay your consultant to find “no water.”  But where does that lead us?  The concept of sustainable yield from confined aquifer systems is based on step drawdown tests.  Ignoring the details, what this constitutes is a series of short term tests of the amount of drawdown that occurs at different pumping levels. AWWA’s manual on Groundwater can give you the details, but the results are short-term and modeling long-term results requires a series of assumptions based on the step drawdown test.  This is that had been submitted in support of permits in Utah (and many other places).  As discussed in the conference session, clearly there is something wrong with this method of modeling and calculation because, well, the results did not match the reality.  The drawdowns increased despite modeling and step drawdown tests showing the demands were sustainable.  Clearly wrong.  Competing interests, the need to cast a wider net, and many other issues are often not considered.  The results play out throughout the world.  Confined aquifers are often not sustainable, a potential problem for much of agriculture in the farm belt of the US.  Are we headed the same direction as ancient people?

The good news is that these same hydrogeologists and engineers have the ability to help solve the sustainability problem.  We need a new definition for “safe yield.”  We need a better means to estimate leakance in aquifers.  A project I did with injection wells indicated that leakance was overestimated by a factor of 1000 to 10,000, which would drastically alter the results of any model.  More work needs to be undertaken here.  The overdraw of confined groundwater is a potential long-term catastrophe waiting to happen.  And the consequences are significant.  The question is can we adapt?

Our Disappearing Groundwater

July 21, 2012
Climate, Environment, finance, funding, groundwater, infrastructure, management, sustainability, water sewer management, water supplies
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The need for more water for urban and agricultural uses has drive even more competition for limited supplies in stressed basins.  The effects of urbanization and agriculture on surface water supplies are obvious to most people.  We have also seemed the ecosystem impacts from surface water diversions and pollution.  As a result, many areas have pursued groundwater, the unseen resource.

I have been touting a USGS report (#1323 by Reilly, et al, 2009) to many in the water industry.  It is an important report that gives us a little insight on state of groundwater supplies in the US.  As we have developed arid regions and developed better pumps to irrigate in dry places, groundwater has been the obvious choice.  And it is not regulated in some states.  However the extensive and in many cases excessive use of groundwater creates the long-term potential for loss of water supplies in many jurisdictions.  Determining groundwater availability involves more than calculating the volume of groundwater within any given aquifer:  it requires a consideration of recharge, water quality, the economics of recovery or of poor quality, interconnectedness with the hydrologic system and ecosystem/user demands.  Rarely is a consultant paid to determine that sustainable water supplies are not available.  The result is the potential for aquifer drawdown that are accompanied by aquifer mining and land subsidence.  The result is declining water levels in aquifers.

Confounding the situation are confined aquifers that are disconnected for localized recharge and often have overestimated recharge.  The common practice to evaluate aquifer productivity is pump wells that have a significant drawdown for only a few hours each day, allowing an extended period for the aquifer to recover.  Reilly et al, 2009 estimates that the pumpage of fresh ground water in the United States is approximately 83 billion gallons per day (Hutson et al, 2004), which is about 8 percent of the estimated 1 trillion gallons per day of natural recharge to the Nation’s ground-water systems (Nace, 1960), which sounds like it is not a serious issue.  However, Reilly et al, 2009 found that the loss of groundwater supplies in many areas will be catastrophic, affecting economic viability of communities and potentially disrupting lives and ecological viability.

Drilling deeper is not a solution.  Deeper waters tend to have poorer water quality as a result of having been in contact with the rock formation longer and dissolving the minerals in the rock into the water. Additional power will be required to further treat limited, lower quality supplies.  Therefore, while some deep aquifers may be prolific, the quality of water obtained from a well may not be desirable or even usable for drinking water without substantial amounts of treatment.  In addition, most deeper aquifers are confined and therefore do not recharge significantly locally.  The withdrawal of water may appear to be a permanent loss of the resource in the long-term. For example, portions of the aquifer in eastern North and South Carolina were virtually denuded in due to pumpage because there is no local recharge.  As a result the aquifer was mined, exceeding its safe yield, and the large utilities converted to surface water. Likewise, most of the aquifer use in the western states of the U.S. are poised similarly since they have minimal potential for recharge.  In parts of the western plains state and Great Basin, the aquifers have dropped hundreds of feet, but with an average of 13-18 inches per year of rainfall, and high evaporation rates throughout the summer, little of this water has potential to recharge the aquifer (Bloetscher and Muniz, 2008).

 

Rarely will permit writers or consultants tell you there is no more water available, but if groundwater levels keep declining, clearly the groundwater is over allocated.  It also appears that we have misjudged recharge to most confined aquifers.  They simply do not recharge at the rates estimated creating a long-term decline.  In some cases, maybe many cases, recapturing the water needed to recharge the aquifer will not happen in our lifetimes without specific capital to do otherwise.  Nature just doesn’t recharge confined aquifers quickly.  One reason we like them for water supply.
So the questions are these:

Are many confined aquifers better suited to be drought protection, backup supplies to surface supplies, as opposed to primary water supplies?

  • What is the solution for agricultural operations and utilities where groundwater is quickly diminishing?
  • When can we start the dialogue to manage groundwater resources better in the US without all the legal and political constraints that currently work against protecting our nation’s groundwater supplies?

Clearly we won’t make everyone happy, and may make a lot of people very unhappy.  But better to make those decisions now, than in 20 or 30 years when the groundwater runs out?