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1999 Annual Water Level Raw Data Report for Kansas

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Executive Summary

The Division of Water Resources (DWR) of the Kansas Department of Agriculture and the Kansas Geological Survey (KGS) manage and operate the statewide cooperative annual water level measurement program. Water level measurements are scheduled annually for about 1,400 wells spread across 47 central and western Kansas counties (Figure 1). These annual measurements are nominally made during the month of January and include wells used for stock, irrigation, household, and monitoring (some abandoned agricultural or domestic wells). The data acquired during these yearly measurements are tabulated to establish trends and allow evaluation and judgments for effective water resource management.

Figure 1--Locations of wells in 1999 water-level measurement program.

map of Kansas showing annually measured wells

The KGS and DWR share responsibility for acquiring annual water levels. The KGS measures 571 wells in 17 counties while DWR has responsibility for 831 wells in 32 counties (2 counties are shared) (Figure 2). Most wells in the network (71%) are currently used for irrigation. During 1999, 95% of all annual network wells were successfully measured. Approximately half of these measurements encountered water at depths of less than 100 ft. About 1.4% of network wells have depths to water greater than 300 ft. At the present time 571 of the 1,402 annual network wells have GPS-measured latitudes and longitudes. After completion of the 1999 measurement season, 61 network wells have been targeted for retirement due to plugging, surface or downhole obstructions, inaccessibility to the water surface as a result of changes in measurement point, destruction, or "dry hole." Attempts over the last two years to fill holes in the network represent the first increase in the High Plains Aquifer's annual well inventory since the middle 1980s. Reduction of the sampling holes by the yearly incorporation of enhancement wells will be an ongoing process that will be based on number and location of wells retired from the network each year. Digital and analog 1999 annual raw water level data were available for widespread distribution around March 8, 1999.

Figure 2--Number and organizational responsibility by county for the 1999 network wells.

map of Kansas showing how many wells are measured in each county

Data acquisition enhancements evaluated during the 1998 campaign were incorporated into the 1999 KGS program. The most significant enhancement was the inclusion of a seventh person functioning as a troubleshooter and enhancement/replacement well investigator. Field operations were also reduced by one full day. The seventh person operated alone, following the three two-man crews doing re-measurements of wells that were out of trend as well as locating and measuring wells previously selected as candidate enhancement or replacement wells. Use of the KGS-developed, computerized data acquisition system (WaterWitch) permitted on-site entry of measurements and comments, automated checks of data quality, optimized routing, and the encryption of a location stamp on each measurement. Improved routing and the computerized acquisition system reduced data acquisition time from 8 days (1997) to 6.5 (1998) and then to 5.5 (1999) for the three, two-person crews. Improvements in training/technique and routing increased the 13 wells/ person/day measured in 1998 to the almost 16 wells/person/day measured in 1999. Insight gained through statistical analyses of the 9% re-measurement wells (QA) continued in 1999 to prove invaluable in both improving our product and in determining the overall quality of the measurement data. Re-visits and re-measurement of wells classified as out-of-trend during initial measurements (QC) improved confidence and mini-mized measurement errors in the database.

Spatial analysis of the 1998 water level data identified 37 locations where new wells should be incorporated into the annual measurement network to eliminate sampling "holes." Cooperation between the groundwater management districts (GMDs), DWR, and KGS staff identified wells acceptable for inclusion in the network at 34 of the 37 locations. Even though only 14 of the 34 sites actually resulted in water level measurements, a procedure is developing for the incorporation of new wells into the annual network while the overall completeness of sampling continues to improve. The last two years have seen positive growth in the number of wells in the annual network in response the retirement or replacement of inconsistent, plugged, or inaccessible wells.

The Quality Control program continues to achieve its objectives of identifying and quantifying sources of unwanted variation in observation well data collection, and in flagging wells where measurements required verification. Probably the most significant outcome of the Quality Control program since its implementation in 1997 was this year's observation that the variance of the response variables in 1997 and 1999 were over three times greater than the variance in 1998. Careful study of these data for possible causes for this unexpected increase in variance uncovered a set of 24 wells with extremely erratic measurements. In most cases, wells in this set of 24 were difficult to measure and required multiple entries into the well bore. Removing these 24 wells from the 1999 data set eliminated all variation except aquifer code, and use of weighted tape. The overall quality and accuracy of the data set and any computation with or analysis of these data could be greatly improved by dropping these 24 wells from the network and replacing them with consistent and reliable wells. The value of intensive training of field measurers and incorporation of automatic location recording and guidance devices has been decisively demon-strated. As the Quality Control process is routinely applied to KGS observation well measurements in the future, and particularly if it is applied to the entire Kansas observation well network, the quality of the data will be pro-gressively improved with time.

The original observation well network designed in 1984 was based on a regular hexagonal pattern, with observation wells located at or near the centers of the hexagons. Unfortunately, some current observation wells are far from the centers of their hexagons, and some hexagons no longer contain a network well at all, resulting in "holes" in the network. The integrity of the network is being restored through the selection and measurement of new wells optimally located to fill existing undersampled areas. Determining the very best places for replacement wells requires a geostatistical study, which unfortunately delays the measurement of the water surface in undersampled areas. Replacement wells selected by measurement staff during the measurement campaign are preferred over leaving a "hole" in the network for that measurement year while waiting for a computer-aided replacement well to be selected for the following year. A good rule of thumb for field workers to use for selecting a replacement for a lost observation well is to choose a new well as close as possible to the center of the hexagon. It is possible to have holes form in the network if replacement wells deviate too far from the center of the hexagon. Yearly geostatistical studies will define undersampled areas (holes) and select optimum locations for replacement wells to eliminate extraneous holes in the network occasionally left by the hexagon system.

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Kansas Geological Survey, Water Level CD-ROM
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Updated March 9, 2000
Available online at URL = http://www.kgs.ku.edu/Magellan/WaterLevels/CD/Reports/OFR995/rep01.htm