Monday, August 13, 2012

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.

No comments:

Post a Comment