Kansas GMD Water Level Changes, 1997 - 2013

More numbers.  Following are the water level changes in all 5 GMDs between the years 1997 and 2013.  These changes are based on approximately 1200 monitoring wells measured in January of each year in all five of the Kansas GMDs.  The first row would be the water level change between the January 1996 and the January 1997 measurements. Our (GMD 4) numbers are highlighted.

The central Kansas GMDs  (GMD 2 and GMD 5) are supposed to be managed for long term safe yield, so the totals and the average values posted along the bottom are not as comparable to the remaining three western GMDs as most would expect.

The contrast among the western Kansas GMDs is interesting.  GMD 1 is the smallest and oldest and is by far the most advanced along its decline and saturated thickness trends.  Much of this area is projected to have the least remaining aquifer lifetime.  GMD 3, on the other hand, is the largest district, has the most saturated thickness, the most wells, the most irrigated area, the highest water use, and consequently the largest declines.  GMD 4 is smack dab in the middle of these two extremes.

All this to confirm that the GMD 4 annual average decline rate is the .6 feet per year we've been reporting for a number of years now.  Anyway, just thought I should try to keep the data freaks engaged from time to time.  And I am very sorry about the wavy columns - I've not figured out yet how to set tabs in Blogger!

Year     GMD1   GMD2  GMD3  GMD4  GMD5    5 GMDs

96-97          0.90        -0.15         -0.43         -0.14         0.90           0.22

97-98          0.53         1.56           0.04         -0.33         0.91           0.54

98-99         -0.57         0.52         -1.29          -0.26         0.04          -0.31

99-00         -0.38         0.20         -0.89          0.00         -0.15          -0.24  

00-01         -0.44        -0.98         -2.20         -1.16        -0.44          -1.04

01-02         -0.74        -0.97         -1.75         -0.40        -0.70          -0.91  

02-03         -1.37        -0.93         -3.35         -1.51        -1.48          -1.73  

03-04         -0.89        -0.25         -1.81         -1.14        -0.97          -1.01

04-05          0.24         1.09         -0.42         -0.60          0.10           0.08  

05-06         -0.29         0.00         -1.11         -0.57         -0.11          -0.42              

06-07         -0.73        -2.48         -2.45         -0.29        -1.39          -1.47

07-08         -1.15         2.12         -1.99         -0.89          3.34           0.29  

08-09         -0.29         1.63         -3.03         -0.42          0.58          -0.31

09-10         -0.43        -0.26         -1.39          0.10          0.63          -0.27

10-11         -0.72        -0.70         -3.05         -0.50         -0.44          -1.08

11-12         -1.49        -3.06         -4.26         -0.59         -2.95          -2.47

12-13         -1.54        -1.63         -3.56         -1.39        -1.83          -1.99

Totals        -9.36        -4.29         -32.94      -10.09       -3.96         -12.13

GMD A/A   -0.55        -0.25         -1.94         -0.59        -0.23       

More on Water Levels

Kansas maintains an observation well network that it measures each year to track changes in the water level depths across the state in its major aquifers.  The annual measurements vary, usually between 1,200 and 1,500 wells, based on how many wells can be accessed each year, but a solid attempt is made to return to the same wells each year.  The 2012 measurements were taken from 1,327 wells, for example.

The statewide average change in water levels between January, 2011 and January, 2012 was a 2.28' decline.  The overall range was from a 13.63' rise to a 23.68' decline.  Keep in mind that 2011 was a very dry year for the southern half of Kansas.

An interesting look at the January, 2012 data (January, 2011 to January, 2012 change) is by GMD.  The GMDs in Kansas do not cover the entire state, but do cover 85% of the groundwater producing areas.

  GMD 1 (West Central):  1.58' decline (range: 4.85' rise to 15.57' decline)
  GMD 2 (South Central):  3.12' decline (range:  2.91' rise to 11.67' decline)
  GMD 3 (Southwest):  4.05' decline (range:  13.63' rise to 23.68' decline)
  GMD 4 (Northwest):  .57' decline (range:  4.6' rise to 5.48' decline)
  GMD 5 (South Central):  2.96' decline (range:  5.28' rise to 9.72' decline)

While I'd like GMD 4 management programs to take full credit for the state's lowest (by far) average decline rate in 2011, the truth is that our area had way more rainfall than the other areas.  We were still below average (a bit on the dry side) but not near as dry as the other GMDs.

Another way to look at the relative impacts might be to focus on the lone Index wells for each of the western GMDs.  From the 2011 calendar year pumpage, our GMD 4 (Thomas County) Index well dropped 6.69' - from a recovered level of 212.40' on March 17, 2011 to a low of 219.09' on September 4, 2011.

As of August 5, 2012, this same well has dropped 6.95' - from a recovered level of 213.70' on April 27, 2012 to a new low of 220.65' on August 5.  And the irrigation season might have another 3 weeks to go, so we expect additional declines to come.

All this to say that the GMD 4 average annual decline rate of somewhere around .5' per year may get blown out of the water this drought year of 2012.

Let's Take A Step Back And Look Long Term

This hydrograph is from the long term monitoring well located on the Kansas State University Experiment Station just west of Colby, Kansas.  It has been measured since the late 1940's with much of the record having a continuous water level chart available.  When you look closely, you see a pretty steady decline rate since 1959 except for a slight, but noticeable bump starting in 1990 and lasting until 2000.

You should be aware that from 1977 through about 2000 this region went through a remarkable conversion of the irrigation systems used to irrigate local crops - from the traditional flood systems to center pivot systems.  These new systems reported pumping reductions - sometimes up to 30%.

If pumping dropped so significantly, why didn't the water level decline rate slow accordingly?  It only slowed during the 1990's because every year of this decade but for one was above average rainfall.  Pumpage in the 90's was down even more and recharge was up a bit.  As soon as rainfall returned to normal, the decline rate did so as well.

The answer is that the water table decline rate is related solely to consumptive water use, not pumpage.  The high pumpage rates under the older, less-efficient flood irrigation systems also meant more deep percolation - recharge.  When the more efficient irrigation systems came in, less water was pumped, but less water was also recharged - the higher system efficiencies meant that a higher percentage of the pumped water went to crop production and healthier crop canopies.  With slightly higher ET use on slightly reduced irrigated acres, total ET stayed about level.  All this means that consumptive crop water use during this transition was staying about the same - thus the decline rates stayed the same.

The only way in our neck of the woods to slow the decline rate is to reduce consumptive water use - meaning crop ET.  The only way to do this is to grow lower ET crops on the same acres, reduce acres, start deficit irrigating the same acres or some combination of all these things.  As the declines continue and eventually well yields drop off, irrigators will start making these decisions by default and the economic engine of the region will begin to slide down - over time.  This is especially true since all wells will not drop off at the same rate or over the entire region at the same time.  It doesn't make it any better, but the notion that one morning the entire Ogallala will be dewatered and stop producing agricultural irrigation water is far fetched.

This is what the HPA process is all about - allowing local water users to decide to reduce CU earlier in this scenario to extend the economic life of the aquifer as they see fit.  I don't see strongly "right" or "wrong" answers here, just local preferences - IF the locals can publicly make these decisions. Let's hope they can discuss these issues in earnest and chart their best course.

Another Hydrograph to Consider

Most of our observation wells for NW Kansas are functional irrigation wells that are measured in the Winter each year after they shut down - usually in early to mid-September.  As such, these wells are normally recovering to some degree from their irrigation season pumping levels when the annual measurements are made.  About 25 of the 280-some measured wells within GMD 4 are listed as "unused", so this group of wells may need to be looked at a little differently.

The hydrograph shown (click to enlarge) is one of these wells.  It is located in SW Sheridan County and has a water level record spanning December 1964 - December 2010.  This well was one of the original wells that was measured quarterly until 1997 and annually thereafter.  The measuring frequency doesn't affect much as you can see from the hydrograph - with the overall trends being clear, regardless. 

This well is showning a decided decline since 2000, but we see that it has been as low and even lower in both 1980 and 1990.  It appears to be showing a more regional perspective on the local water table - since it is itself not pumped annually.  Statistically the entire decade of the 1990's was several inches above normal precipitation in NW Kansas while we have been a bit droughty since 2000.  The hydrograph certainly bears this out.  It also appears that the regional climate may have been wetter from 1980 - 1985 and drier from 1986 - 1990, but I'll have to check this out to be sure.

This well is 184' deep (BLS) with the December, 2010 water level being measured at 105' BLS.  How long the remaining 79' of saturated thickness may last is anyone's guess, but this particular observation well is interesting in that it has a clear decline trend from 1964 - 1980 (11 feet of decline in 16 years), then looks fairly stable since 1980, but with several, significant, decadal-termed fluctuations.  Oh, the joys of groundwater monitoring. 

If you'd like to see the full data for this observation well, use this link:  KGS Wizard Database .  If you'd like to see any specific observation well covered in this manner, let me know.  Of course you can see every observation well in Kansas on the KGS Wizard site.  More later.

Thomas County, KS Index Well

TH Cty Index Well

The Edwards Aquifer Authority posts daily the water levels from 2 index wells they monitor, and 2 discharge rates from important springs in the district.  I enjoy these daily posts which show very short term trends that are important to the region.  These are posted on Twitter every morning for the previous day.  You can follow them, too, at:  Edwards Aquifer Authority Twitter Acct



Based on their lead, I've added a link to our index well on our web page here:

TH Cty Index Well Link  This is an interactive page that returns a graph and the raw data for any date range you want to look at.  The readings are taken every two hours, and began in June, 2008.  This page contains all 3 Kansas index wells - you'll find the Thomas County well information and data at the very bottom.

Below is the graph of water level elevations (in feet above sea level) for this well since it began operation.  (click on it to enlarge)  This index well is NOT an active irrigation well, and is located about 1/2 mile to 1 mile from all irrigation wells in the area.  It shows the classic curve of declining water levels in the Spring and Summer as irrigation is going on, and water level recovery back to the time the declines start again for the next irrigation season.  For this well, highest recovery levels are:  2975.7' in Mar 2008; 2975.1' in May 2009; 2976.2' in Apr 2010; and 2975.1' in Mar 2011.  This data shows a -.6' change (decline) from 2008 to 2009; a +1.1' (increase) from 2009 to 2010; and a -1.1' (decline) from 2010 to 2011 (the full -1.1 decline is not shown on graph , but has been measured since).  Bottom line from this data - this well has declined -.6' over the past 3 years.

The yellow dots are the actual measured water levels taken in early January each year which become the official water level measurements.  From this official data, this well changed -1.4' from 2008 to 2009; + 1.3' from 2009 to 2010; and - .75' from 2010 to 2011.  The directions are all consistent, but the sizes of the changes are different.

The regional irrigation wells, of which there are about 6, cumulatively affect the water levels at this point about 5-6 feet every year.  Of course, the pumping levels are lower yet as you get closer to the individual pumping wells.  In some cases, Mid-August pumping levels can be 50 - 70 feet lower than the static water levels of these heavily pumping irrigation wells.  You can also see that the water level impacts are much quicker than the recovery impacts.  This has to do with aquifer parameters, which affect pumping cones of depression, which influence water levels.

It is interesting that the lowest pumping levels over the past 3 years are increasing slightly, which may or may not mean good news, while the recovery levels (highest annual points) bounce around a bit.  It's important to understand that these highs represent actual physical recovery levels and not theoretical recovery levels.  We're finding that the recovery periods would continue past the start of the next irrigation season if allowed to do so, meaning the theoretical high points are being influenced by pumping.  The question is, to what degree?  Do we need to consider full recovery levels from year to year in order to more definitively describe what the water table is doing?  We're working a bit on projecting full recovery levels, but it's a lot of assumptions and statistics at this point in time.

What I like about this arrangement is that longer term trends can easily be looked at - as opposed to just today's data, yesterdays levels, and a comparison to the monthly average.  Oh, the hourly and daily variations are due to changing barometric pressures.  A low pressure regime will cause the water table to rise a few inches, while high pressure lowers the level a like amount.  We can see a 5-6 inch rise or decline over a days time due to pressure alone.  The real serious water level data in Kansas is further adjusted for barometric influences as well - where the regional pressures have been recorded and can be correlated.  I only wish we had a bunch more of these index wells logged.