KSU High Plains Aquifer Study Hits a Nerve?

David Steward, Paul Bruss, Xiaoying Yang, Scott Staggenborg, Stephen Welch and Michael Apley just released a special study report on the productivity of the High Plains Aquifer in Kansas over the next 100 years, or to the year 2110.  Their Executive Summary says:

"Groundwater provides a reliable tap to sustain agricultural production, yet persistent aquifer depletion threatens future sustainability. The High Plains Aquifer supplies 30% of the nation’s irrigated groundwater, and the Kansas portion supports the congressional district with the highest market value for agriculture in the nation. We project groundwater declines to assess when the study area might run out of water, and comprehensively forecast the impacts of reduced pumping on corn and cattle production. So far, 30% of the groundwater has been pumped and another 39% will be depleted over the next 50 y given existing trends. Recharge supplies 15% of current pumping and would take an average of 500–1,300 y to completely refill a depleted aquifer. Significant declines in the region’s pumping rates will occur over the next 15–20 y given current trends, yet irrigated agricultural production might increase through 2040 because of projected increases in water use efficiencies in corn production. Water use reductions of 20% today would cut agricultural production to the levels of 15–20 y ago, the time of peak agricultural production would extend to the 2070s, and production beyond 2070 would significantly exceed that projected without reduced pumping... Findings substantiate that saving more water today would result in increased net production due to projected future increases in crop water use efficiencies."

This 4-year study can be found within the National Academy of Sciences website, and was financially supported by the National Science Foundation, USDA Agricultural Research Service and US Department of Transportation through the Kansas State University Transportation Center. It has made quite a splash.  Within just a few days we have been contacted by National Public Radio (Washington, DC), the Kansas City Star (Kansas City), Matter Magazine (California?) the Farm Futures Magazine (Chicago) and several of our GMD members - and we're not even specifically mentioned in the study, although the SD-6 LEMA is. 

Anyway, the interesting thing about this study is its conclusion that local folks can make significant economic impacts by taking positive steps now to reduce current water use which will make the same water available later when production and returns are considerably higher.  Any thoughts?

When Irrigation Efficiency Saves Water

I have been pretty critical of improving irrigation efficiencies as a means to conserve water.  There are a number of posts within this blog that deal with my concerns.  However, there are times and situations where this practice does in fact conserve, or save, water.  This is what this post is about.

In general, any situation where the irrigation water being applied is from a different source than where the inefficient water is collecting, AND, where no one is using the inefficient water losses, it is a very good idea to improve irrigation efficiencies - which simply eliminates the inefficient water sink that no one else is using.  (This is the "poor timing" water volume shown in the picture)  These efforts will save energy and other crop inputs, as well - all good things.  However, if someone else is using this source of water, all bets are off.

Another example that comes to mind is in a groundwater situation where there is a shallow, unusable aquifer perched above the irrigation water source, AND, all deep aquifer recharge is from lateral sources not connected to the perched aquifer.  In other words, the inefficient water use collects in the shallow, unused, perched aquifer and never returns to the original source.  Again, irrigation efficiency improvements under these conditions will clearly save water within the deep source aquifer.  But again, no one can be using (have rights to) the shallow water supply because the efficiency improvements, if taken far enough, are eventually going to eliminate its source.

In both of the cases just discussed, it should be noted that the consumptive crop water use does not change after the improvements - the crops continue to consume the same amount of water as before.  The savings come from the elimination of the inefficient water application that was not returning to the original source.  This is all water that, after the improvements, no longer needs to be pumped.  These situations extend the life of the original water source - which even I can define as conservation.

Other than these specific conditions, irrigation efficiency improvements do not conserve water much at all - certainly not enough to spend the amount of money folks are suggesting.  There are other benefits to increased irrigation efficiencies - like reduced energy and reduced crop inputs and a better farm operation bottom line.  Let's do it for these reasons, but be aware that consumptive water use is not being affected and it's the consumptive water use that changes aquifer storage volumes.  The fact that most argue these improvements also increase production per unit of pumped water probably tells us right off the bat that consumptive water use is increasing as a result - regardless of what pumped water is doing.

Before you buy into irrigation efficiency improvements, make sure you understand what problem it is you're trying to impact, what benefits these efforts will have, and at what cost.

Water Use Report

Recently the USGS released a report on water use in the U.S.  The press picked the headline:  "U.S. Uses Less Water Today".  The report is actually using 2005 data and comparing it to data in previous 5-year blocks of time.

From one of the press releases:  "The report concludes...even though the amount of irrigated acres has increased, irrigation application rates have steadily decreased - a change that the report's authors attribute to the increased use of more efficient irrigation systems." 

And

"We are pleased to see that irrigation efficiency played such a major role in decreasing our nation's overall water use" (John Farner, Irrigation Association).  

Inside the actual report we find recognition that irrigated acres have been increasing.  And inside the guidelines for the preparation of the 2005 report we find the statements:  "Irrigation withdrawals include conveyance losses." and "Data for the optional elements...will not be part of the national water-use analysis for 2005..." and in the mandatory elements we find "Ground-water total withdrawals.. [including conveyance losses]" and in the optional elements we find "consumptive use, by county" [not part of the report].

What seems to be really happening in this report is that the conveyance losses are being reported as use and the consumptive uses are being ignored.  Sure, irrigation efficiency will reduce conveyance losses, thus appearing to "use less water", but the real question is what's happening to the amount of actual consumptive water use?  This is the vital number that relates to long term supply and the health of any hydrologic system. 

My guess is that while pumped (diverted) water is actually less, the application of the less water on more acres is likely to result in increased consumptive water use.  Yes, you get more production from each unit of water as efficiency increases, which is a good thing, but you don't consume (use) less water.   

The judicious use of the phrases "water use" and "consumptive use" are in the report, and I think the distinctions are made - but far too subtely for most to recognize.  So the press simply concludes that water use is reduced. 

I think this is the wrong message to be sending and it leads to more money and effort put to irrigation efficiency (in the name of water conservation) in areas where reducing consumptive water use is most important.  This is one reason why water management continues to be so difficult.

Drought Tolerant Crops and Low Flow Shower Heads

Monsanto and others are working ferverishly on bringing to market a drought tolerant corn variety - one that yields respectably with 30% less water.  As good of news as this is, I'm wondering if it'll save any water or just increase yields considerably with the same water use (or more).

It's the classic question of how's it going to be used?  Remember the low flow shower heads that were supposed to save water.  Turns out most people didn't particularly like the weak water stream and ended up taking longer showers - resulting in..., well you can complete this sentence yourself.

Until the irrigation water supply is reduced enough (either by water right and use restrictions or by physical limitations of the supply) my money is on an increase of water use by producers who almost always act toward maximum profit motives.  Yes, we will achieve more yield per unit of water, a production efficiency measure that is usually considered good, but the sad truth is that more water will be used, too.  This situation can be a real problem for areas needing to reduce consumptive water use.

To be fair, this is not the fault of the seed breeders - it is the responsibility of the water managers to restrict water use if it is desired that this new technology should reduce water use while maintaining production levels (income).  Heck, what we really need from Monsanto et. al., is a corn variety bred to yield 300 bushels per acre on 10 inches of irrigation water and which immediately dies when the 11th inch of irrigation water is applied.  Now we're sure to get water savings and increased income.  Good luck with this one. 

Water Use Efficiency? Maybe Not.

Most people and governments are supportive of and even promoting irrigation water use efficiency as a way to conserve water. Take an old gravity irrigation system applying 1000 gallons of water on an irrigated patch. This 65% efficient irrigation system will consumptively use (transpire and evaporate) only 650 gallons of the 1000 pumped and applied. The rest deep percolates below the root zone to rejoin the groundwater table (a non-consumptive use). So, 650 gallons are annually used consumptively (lost to the hydro system).

The irrigator is now paid a nice government incentive ($48K - $400 an acre on 120 acres - a typical Kansas incentive rate) to upgrade to a new, 90% efficient pivot so he can conserve water. He now pumps and applies only 850 gallons to the same patch - a 15% reduction (conservation). The new system now allows the crop to transpire and evaporate 90% of the pumped water while eliminating the inefficient water use (deep percolation) totally. This government incentive has just allowed the user to increase his consumptive draw on the aquifer from 650 gallons annually to 765 gallons each year (90% of 850 gallons). While inefficient water use is eliminated, and the pumped water is reduced 15%, the consumptive water use (CU) actually increases. Believe it or not, the change in the water table of a typical aquifer system changes as a result of consumptive water use, not gross pumpage. This conversion will actually increase the groundwater decline rate - all else being equal.

As if this were not bad enough, how many pivot conversions actually irrigated more acres than the original flood system? If land is available, we usually find a 15% increase in land when 15% more water becomes available due to efficiency improvements. And every newly irrigated acre increases consumptive use above the numbers discussed here.

Without clear and restrictive polices to control irrigated acres as system conversions are being made, consumptive use will tend strongly to increase as a result. And even if CU doesn't actually increase, it usually doesn't go down much at all. And even if it does happen to drop a bit, the system pays a premium for the 1-2% reduction which is easily offset by most of the other conversions that increase CU. This is a very inefficient way to seek water conservation.