Predicting Full Aquifer Recovery

Trying to understand the aquifer recovery process following a pumping season for irrigation has led to some interesting things.  First, the rate of recovery is not constant, but increases as time goes by - at least in the unconfined aquifer conditions we have here.  Secondly, there are 2 distinct stages of aquifer recovery - the first being the initial 1000 hours (41 days) and the second being everything afterwards.  Thirdly, our aquifer never recovers fully before the following year's pumpage begins to drop it again.

With data loggers in a dedicated index well taking water level measurements every 2 hours since the Summer of 2007, we have data on four full recovery stages and three full pumping stages.  (See data and graphical results here)  The data has been plotted both as a semi-log recovery curve and as a Horner recovery curve - for each recovery year.  All the plots show a distinct, 2-stage recovery process.  Here is a Powerpoint update with many of the graphs and data sets.

What is so amazing is that the theoretical full recovery (as predicted by the Horner plots) will take a full year or more to happen.  This finding has implications on the true accuracy of the annual well measurements Kansas has been collecting since the mid-1940s.  This was a surprising find.

The graph included (click to enlarge) shows the projected full recovery levels for each of the three captured recovery periods as red dots.  For ease of understanding they have been assigned to the same dates as the highest physical recovery even though these recovery levels would not be achieved for another 6 months to a year. The yellow dots are the annually measured (official water levels) for this well for all four years.  Using the annual measurements, we think this well's 2010 water level was at 2974.5'.  Using the 2010 theoretical recovery level (following the 2009 pumping season) the water level would be 2978.9' - a difference of 4.4 feet.

Discerning what the water level is for any data point is simply not all that easy and straightforward.

But what is straight forward is voting on my poll.  So go ahead, do it!

Kansas Well Records Available Online

In 1975 the Kansas Legislature required well drillers to complete a well completion form on every well they drilled - regardless of use.  These records were collected since that time and were available upon request, but really not all that available.  They eventually made their way to a computer data set which is now available online (here) within the Kansas Geological Survey website.

This is a searchable and interactive website on the 219,000 well records depository. You can return records by County, or PLSS legal description, which are then sortable by several fields.  The WWC-5 forms contain a lot of information including legal location, depth of well, well construction info, static water level, lithologic log and much more. They are individually scanned or PDF files, so if you're looking for a bunch of them, beware. 

If you're in the market for well info in Kansas, it's a good bet it's contained in this data base.   This material is also good if you're looking for probable well depths and/or static water levels for any particular area(s).  We use it quite a bit in helping the public with their groundwater queries.