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Acquisition Activity, Statistical Quality Control, and Spatial Quality Control for 1997 Annual Water Level Data Acquired by the Kansas Geological Survey

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I: Acquisition Activity

Richard D. Miller, Exploration Services Section


The current acquisition methodology is well established and has been in use for the last 40 years. To some degree the measurement technique has been unchanged for several decades, as dictated by physical limitations both at the surface and within the casing of wells that make up the network. Most measurements are taken in irrigation wells where access is limited by both surface and downhole pumping equipment (Figure 2). Abandoned wells and some livestock wells also provide a challenge to measure since, when properly maintained, they will have a semi-permanent seal on top the casing (welded plate, locked cap, etc.) (Figures 3, 4, and 5). Access to the piezometric surface in most measured wells is through access tubes, threaded plug holes, or open slits in the wellhead base with no possibility for direct vertical access through any kind of removable well head or cap (Figures 6 and 7). These small openings (generally <1") are in the side of the well head or in access tubes or slant pipes through the well curb/pad (Figures 8 and 9). In many cases the measuring device must make a 90-degree bend to get parallel to the well bore at or near the ground surface. For some well installations several access points are available, but for consistency reasons measurements are only made through a particular opening.

The water level measurements are taken with a steel tape lowered down the well bore assisted by a lead weight attached to the end of the tape by a copper wire (Figure 10). The lead weight serves two purposes: first, it minimizes the effects of tape coil down hole; and second, if the lead weight and copper get hung up and lost down hole it will not (at least not to date) interfere with the operation of an irrigation water pump (generally turbine type). A steel tape used for measurements in southwestern Kansas needs to be capable of reaching depths of over 400 ft. Steel tapes are annotated with both raised marking indicating feet, tenths of feet, and hundredths of feet between the end of the tape and the 30 ft mark, and with embedded plates displaying length in one-foot intervals from the 30 ft mark to 500 ft (end of tape).

Measurements are taken by coating the lower 15 ft or so of the tape with carpenter's chalk (generally blue) (Figure 11). The tape and end weight are coaxed through small access ports and generally around a corner and then slowly alongside any casing and pump in the well bore down to a predetermined depth (Figure 12). The stop depth (length of tape in hole) or tape hold is established based on previous years' water level values and measured drop in the current year's water level in nearby wells. Once the appropriate depth is reached and the tape has hung in the hole for a second or two, the tape is retrieved. Once the portion of the tape is reached with annotations in tenths of feet, the chalked surface is carefully examined to establish the location of the "cut." The cut is the line below which the chalk has been washed away by water standing in the well (Figure 13). The cut represents the water level or piezometric surface depth from the measurement point. The quality of the cut is then qualitatively established. The cut can be sharp with no indications of wash-off or moisture above the cut, and in such a case it would be considered an excellent to good measurement. The cut can also be very difficult to determine due to everything from cascading water within the borehole to casing moisture contacted by the tape during placement or extraction. If the measurer is confident a good reading has been made, the tape hold and cut line are recorded and used to calculate depth from ground surface to the top of water.

An important in-field appraisal of confidence in a water level measurement requires differencing of the previous year's water level with the current measured level to establish a water table drop or rise. This water level change is then compared to the local trend established in close proximity wells. If, in the judgment of the field staff, the relative difference between the current year and previous year's measurements is reasonably small, the value is logged, considered a good reading, and the well is tagged. If a low confidence value or an off-trend reading is determined, a second measurement is made. This process continues until a reliable reading is obtained.

Each well measured is tagged with a color-coded Tyvek tag attached to the well with a wire tie. The tag identifies the measurement participants (i.e., Kansas Geological Survey and the Division of Water Resources) and well statistics. It documents the well location, landowner's name, measuring agency, downhole access, obstructions, cut quality, oil on water, remarks, surface and measurement point access, depth to water, date, and initials of measurer. The tag also displays the KGS address and phone if inquiries are necessary. The tagging is the last operation to take place at the well prior to proceeding to the next well location.

All measurements and observations are recorded the daily field log books. These log books are transcribed into a digital file within a few days on weeks of the actual measurements. These digital data are then provided to the Geohydrology staff at the KGS on or around February 1 for tabulation, collation, and inclusion in the annually published water level report.

1997 Acquisition Activity

A field crew from the KGS acquired data from 562 wells in 17 western Kansas counties during January 1997 (Figure 14). The measurement technique and overall responsibilities associated with the 1997 annual water level measurement program were completely consistent with previous years when the KGS sponsored acquisition activities through the U.S. Geological Survey (USGS) field office formerly in Garden City, Kansas (Miller, 1996). Data acquisition was broken into three field periods with the first (primary) extending from January 2 to January 11, the second running from January 21 to January 25, and the third including March 5 and 6. During the primary acquisition phase each well was visited and appropriate data were taken. The second outing was designed to acquire Quality Assurance (QA) data and complete necessary Quality Control (QC) re-visits. The third and final trip of 1997 was intended to acquire a second set of QA data and to reacquire previously questionable or missing GPS data. All raw data acquired (with the exception of the third acquisition trip) by the KGS on the annual water level measurement program were compiled, digitally stored, and circulated to the appropriate agencies, groups, and individuals in their raw, unprocessed form (digital and/or analog) on or about February 1, 1997. This section represents a summary of all the raw data, acquisition activities, and technique development.

Figure 14--Counties in Water Level Measurement Program measured in 1997 by KGS.

KGS crews worked in 17 counties in western Kansas

Acquisition Logistics The primary measurement trip was completed in eight days by a crew of six people (Figure 15). Each person was equipped with a vehicle, GPS, field notes, maps, steel measuring tape, and associated necessary supplies. The far northwestern counties (Cheyenne, Sherman, and Wallace) were completed during the first two days, requiring overnight stays in St. Francis, Goodland, and Syracuse. The third day of measurements ended in Garden City and saw the completion of three counties (Hamilton, Kearny, and Grant). The fourth field day began in Garden City and ended in Liberal with one county finished (Finney). The fifth day ended in Meade, with four more counties (Seward, Stevens, Haskell, and Grant) completed. The crew next stayed overnight in Dodge City after completing one more county (Meade) on the sixth day. The seventh and eighth days required stays in Larned, finishing five counties on the seventh day (Ford, Gray, Finney, Hodgeman, and Ness) and the last two counties (Pawnee and Barton) on the eighth day.

Figure 15--Annual water level wells measured by KGS divided into route and team responsibilities.

KGS crews were split into several teams

During the primary acquisition trip the six crew members were divided into three teams (Figure 15). Each team was responsible for 18 to 32 wells per day along predesignated closed routes. Each day's trip was designed so team members would meet along the route after all the wells on a route were visited. This method attempts to balance workloads by compensating for variable degrees of measurement difficulty (variable amounts of time necessary to actually measure individual wells), insures no wells were overlooked during the primary measurement trip, and minimizes the number of miles traveled per well and route. Once a team completed its route, the other teams were contacted to determine if assistance was necessary to insure all routes were completed prior to sunset. Distribution of the crew members and routes was designed to insure crew members were never more than 15 to 20 miles apart. This minimal separation approach increased safety and minimized the time necessary to complete a county. Once a team completed its route and any provided requested assistance, they proceeded to a predesignated motel. The day's work sheets, route maps, and GPS measurements were collected and checked for completeness and problems encountered. Approximately 12,700 miles were logged during the primary measurement trip with the average crew member visiting 11.7 wells per day and spending about 55 minutes per well (the average time per well includes on-site and travel time).


The first QC trip was completed in four days by two people. The QC water level remeasures covered 14 counties, included 72 wells, and were completed during the second trip (first QC trip) (Figure 16). The QC trip was to verify out-of-trend measurements and to acquire missing well data. This QC re-visit resulted in confirmation or successful measurement of 62 wells previously unmeasurable or out-of-trend. Final measurements at these 62 wells took an average of nearly two hours per well and as a group were situated along routes that required a total of about 4,160 miles of vehicle travel. These 72 wells were selected after careful examination of primary trip measurements; a well was remeasured if it met any one of the following criteria:

  1. no measurement was recorded during the primary measurement trip;
  2. calculated water level was up by more than 1 ft from historical trend; or
  3. calculated water level was down by more than 4 ft from historical trend.
The QA trips were undertaken to provide data for statistical appraisal of quality through repeated measurement of water levels. Six primary QA routes were designed using wells randomly selected by computer from a list of all wells visited during the primary measurement trip (Figure 17). Fifty-four wells or about 10 percent of all the wells measured during the KGS portion of the 1997 campaign were selected for remeasurement. The 48 wells actually measured during the first QA trip required one person about 1.5 hours per well to acquire along routes totaling 1,800 miles.

Figure 16--Quality control guidelines flagged 72 wells for revisits to confirm or obtain missing measurements.

wells that could not be measured were revisited

Figure 17--Quality assurance revisits to wells measured during primary trip to establish repeatability.

a random set of wells were remeasured to check quality

The second QA trip was undertaken to provide a third water level measurement data set for 20 of the 48 QA wells successfully measured during the first QA trip (Figure 18). A total of 18 wells were remeasured by one person over two days, covering 1,400 miles, and taking 2.2 hours per well.

Figure 18--Quality assurance trip to acquire a third data set for purposes of measurement consistency analysis.

wells measured on third trip

A special QC trip was undertaken at the same time as the second QA trip to remeasure the latitude and longitude of 38 wells with initial GPS measurements 400 m or more variant from latitudes and longitudes recorded in the USGS GWSI database (Figure 19). The GPS remeasure of these 38 well sites was completed in six days and required 2,100 miles of vehicle travel.

Figure 19--GPS Measurements were acquired at wells missing measurements from primary trip or were more more than 400 m from current documented USGS location.

wells needing additional GPS measurements

Well and Measurement Point Information

As part of the KGS portion of the annual measurement program, a few of the more significant well characteristics have been compiled for incorporation into future efforts to improve and maximize information obtained from the network.

Wells Measured in 1997
Type of WellNo. of Wells
Unused (monitor or abandoned)102
Water AccessNo. of Wells
Slant pipe64
Measurement tube21
Access holes or pump base336
Open casing114
Flip-style covers23
Depth to WaterNo. of Wells
Less than 100 ft206
100 to 200 ft243
200 to 300 ft79
More than 300 ft14
Drill Depth of WellNo. of Wells
Less than 100 ft85
100 to 200 ft89
200 to 300 ft128
300 to 400 ft91
More than 400 ft72
Measurement CharacteristicsNo. of Wells
Oil on the water85 (15%)
Difficult downhole access73 (14%)
Difficult measurement point access60 (11%)
Difficult measurement (restrictions, snags, catches)130 (24%)

In-field confidence in a particular measurement was qualitatively determined through inspection of chalk cut while general accuracy was quantitatively appraised using historical and local trends. Remeasurement was necessary if the chalk cut did not allow a confident reading or if the depth to water was not within the anticipated range.

Measurement Confidence
Wells MeasuredNo. of Wells
Three times17
Four times6
Total MeasurementsNo. of Measurements
During primary and QC trips763
During QA trips84
Measurements JudgedNo. of Wells

Network Continuity

An uninterrupted historical record is important in trend determination and analysis. Significant effort was made to acquire measurements in wells missing data from any one of the last three years.

Measured in 1997 but not inNo. of Wells
1995 or 199611
1994, 1995, or 19961
Measured in 1996 but not in 199712

An issue of importance for maintaining the long-term health and continuity of the network is the identification of wells needing replacements and immediate identification of acceptable replacements. A well replacement process would allow current spatial distributions to be maintained and improved. Based on acquisition difficulties, a total of 23 wells have been identified as strong candidates for replacement. Of the 23 wells in need of replacement, 11 were unmeasurable in 1997 but have recorded measurements in 1996. Nine of the remaining 12 have not been measured in at least the last two years. The remaining three were measured during 1997 but due to plugging or access difficulties will not be visited as part of the 1998 annual measurement program.

Unique to the 1997 measurement program was the recording of latitude and longitude using a handheld GPS unit and the photographing of each well site. A total of 542 GPS-determined latitudes and longitudes were recorded at wells measured during the 1997 campaign. Photographs of 512 wells will be used to provide a visual record for future measurements. Incorporation of the GPS system, detailed site comments, and photographs into a digital database will greatly enhance location certainty, well familiarity, and identification regardless of experience with a particular well. On-site information available digitally will include not only photographs, but also measurement subtleties, downhole dangers, environmental cautions, and other concerns/comments of previous measurers.

Wells Requiring Replacement and Reason
03S 40W 09BAAMeasurement questionable.
03S 42W 26CCDBad obstruction at ~170 ft.
07S 41W 07BCBWell sounder stuck in well.
22S 24W 14BBCVarious restrictions. Cannot measure.
22S 24W 16ADBCollapsed well.
22S 39W 03BBBDirt filled in up to ~181 ft.
24S 32W 35DDPumping daily for Brookover Inc.
24S 33W 22BCCReported by property manager to be cemented.
26S 24W 32CBACannot find. Referenced windmill is gone.
26S 31W 36CABDry well confirmed by landowner.
27S 38W 23CBBTook alternate well, cannot find 23CBB.
28S 34W 15DABDry well. No major obstructions.
28S 35W 05BCCWell plugged. Irrigation well 40 ft away, but
with many restrictions, cannot measure.
29S 32W 19CCCRex Brown's well. Too crooked to continue measuring.
29S 32W 26CBBTape hung at 290 ft. Cannot get past obstruction.
30S 29W 23CADTape hangs at 200 ft and cannot get past.
30S 31W 24BBCReported plugged by landowner.
31S 32W 03DADVarious restrictions; cannot measure.
31S 34W 18BBBGot measurement, but bad catches at 20 ft intervals.
32S 38W 23BDDCasing broken off. Well recently covered.
32S 39W 02BBBNo blockage, no water, no measurement.
33S 36W 26DDDDry, no measurement possible.
33S 37W 23CDBCannot find.

Water Levels and GPS Measurements Taken in 1997
Well Site
Trip #2Trip #3 Total No. of Unique
Water levels512 486218  542
GPS537     38552

1997 Water Levels

A total of 542 of the 562 wells that make up the KGS portion of the 1997 annual water level measurement program have reliable depth-to-water levels reported in this document (Appendix A). Wells are grouped by county and then cataloged according to well ID (township, range, section system). The levels reported in Appendix A represent the most reliable measurement taken at that well during the annual measurement period. In some cases a single well may have as many as four recorded measurements (Miller et al., 1997). Determination of the best value was made by the field person(s) who measured the well. The best measurement on each well was based on quality of cut, difficulty reaching the hold line and retrieving the tape from below water level, pre-cut moisture, level of confidence that the tape was hanging unimpaired in the borehole, and accuracy of measurement point hold. Historical or local water level trends were not considered in making this judgment.

Direct comparison of primary measurements and the QA measurements reveals important information about the accuracy through repeatability of the database as a whole (Appendix B). In general, the time separation between the primary and first QA measurements is about 10 days to two weeks and six weeks to two months between the primary and second QA campaigns. This remeasure information along with parts of the primary data are integral to quality control discussions documented in subsequent sections of this report.

Data Acquisition Summary

In summary, this year's effort by the KGS staff to fully undertake the acquisition of water level measurements previously contracted to the Garden City field office of the USGS has met or exceeded most of our expectations. Based on preliminary analysis:

  1. the overall data quality is superior to years past, considering that
    1. wells mislocated were corrected
    2. wells not measured in previous years but documented as measured were identified
    3. multiple remeasurements were made at wells that did not meet minimum measurement criteria
    4. all wells were located with GPS and legal descriptions,
  2. more data have been acquired this year than in any one of the last eight years (out of a total of 562 wells available to measure)
    1997, 542 wells measured
    1996, 504 wells measured
    1995, 509 wells measured
    1994, 513 wells measured
    1993, 489 wells measured
    1992, 481 wells measured
    1991, 493 wells measured
    1990, 485 wells measured,
  3. availability of digital and analog measurement data to DWR, KGS Geohydrology staff, and GMDs has been dramatically improved (February 1 in 1997 as opposed to sometime after mid-March, on average, in previous years),
  4. the acquisition time has been reduced (1997 required 10 days; historical average has been around two months),
  5. long-term improvements to the network and data base are making great strides
    1. all wells measured in 1997 have GPS latitude and longitude
    2. errors, missing information, and incorrect information in both KGS and USGS historical data base are being identified and evaluated
    3. spatial distribution of all KGS wells based on aquifers has been determined
    4. acquisition techniques and procedures are being modified/improved based on statistical analysis, and
  6. the program costs for 1997 were equivalent to the $35,000 paid to the USGS in 1996 while providing significantly more data and data quality analysis. When calculated using equivalent* product, the cost to the Survey for 1997 water level data is about half that assessed by the USGS in 1996.

1997 KGS (actual)$65
1997 KGS (equivalent*)$31
1996 USGS$69

*Equivalent product cost does not include amortization of equipment costs or extra program activities such as QA data acquisition or analysis.


Miller, R.D., 1996, The acquisition of annual water levels in Kansas sponsored through a cooperative agreement between the KGS and USGS: Kansas Geological Survey, Open-file Report 96-39.

Miller, R.D., J. Davis, D. Laflen, J. Siceloff, B. Bennett, M. Brohammer, and P. Acker, 1997, Acquisition activity and raw data report on 1997 annual water level measurements: Kansas Geological Survey's portion: Kansas Geological Survey, Open-file Report 97-11.

Woods, J.J., and J.A. Schloss, 1996, January 1996 Kansas water levels and data related to water-level changes: Kansas Geological Survey, Technical Series 9, 124 pp.

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