2005 Annual Water Level Data Collection Report for Kansas
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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 1,333 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 (and 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 2005 water-level measurement program.
The KGS and DWR share responsibility for acquiring annual water levels. A realignment of well distribution was undertaken for 2005 acquisition that allows the DWR offices in Stafford, Stockton, and Garden City to measure wells in nearby counties, allowing most of their wells to be measured during day trips. Following this realignment the KGS was responsible for 564 wells in 2005, an increase of 72 wells over 2004. The three DWR offices measured 769 wells in 2005, a reduction of 58 wells over 2004. Figure 2 shows the distribution of wells before realignment. The KGS's 564 wells are now in 16 counties while DWR's 769 wells are in 31 counties (Figure 3). Most wells in the network (74.6%) are currently used for irrigation. During 2005, 96.5% of all annual network wells were successfully measured. Approximately half of these measurements (45.2%) encountered water at depths of less than 100 ft. About 2.6% of network wells have depths to water greater than 300 ft (up from 2.15% in 2004). At the present time 1,299 of the 1,333 annual network wells (97.44%) have GPS-measured latitudes and longitudes; this is up from 46.74% for the 2000 acquisition year, when these GPS readings were first taken. After completion of the 2005 measurement season, 16 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 four years to fill holes in the network represent the first increase in the High Plains aquifer's annual well inventory since the mid-1980s. Reduction of the sampling holes by the yearly incorporation of enhancement wells is an ongoing process that will be based on number and location of wells retired from the network each year. Digital and analog 2005 annual raw water-level data were available for wide-spread distribution around March 1, 2005.
Figure 2--Number and organizational responsibility by county for the 2004 network wells.
Figure 3--Number and organizational responsibility by county for the 2005 network wells, following redistribution.
Data acquisition enhancements evaluated during the 2000-2004 campaigns included the introduction of a paperless data entry system centered around a small (3"x5"x1/2") handheld computer, the Palm Pilot, running WaterBug software. Results from 2000 showed this system to be an extremely effective and a highly efficient data acquisition/recording tool, so this system was supplied to and used by the DWR crew during the 2004 and 2005 data-collection campaign, and will now be a regular part of their data-collection process. The most significant enhancement for KGS was the inclusion of a person functioning as a trouble-shooter and enhancement/replacement well investigator beginning in 2000. The extra person operates alone, following the two-man crews, doing remeasurements of wells that are out of trend as well as locating and measuring wells selected as candidate enhancement or replacement wells. In 2005 the KGS crew was increased by two to handle the 72 wells added in the redistribution, bringing the total crew to nine--four two-man crews plus one "troubleshooter." Use of the KGS-developed, computerized data-acquisition system (WaterWitch/WaterBug) 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 have steadily reduced data acquisition time from 8 days in 1997 to the current 5 days for the now nine-person crew. Improvements in training/technique and routing increased the 13 wells/person/day measured in 1998 to 17.5 wells/person/day measured in 2005. Insight gained through statistical analyses of the 10% remeasurement wells (QA) continued in 2005 to prove invaluable in both improving our product and in determining the overall quality of the measurement data. Revisits and remeasurement of wells classified as out-of-trend during initial measurements (QC) improved confidence and minimized measurement errors in the database.
Spatial analysis of the 2004 water-level data identified 32 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 all locations. Twenty of the 32 sites resulted in water-level measurements in 2005, and a procedure is now in place for the incorporation of new wells into the annual network, allowing overall completeness of sampling to improve each year. The last five years have seen positive growth in the number of wells in the annual network in response to the retirement or replacement of inconsistent, plugged, or inaccessible wells.
The Quality Control (QC) program continues to achieve its objectives of identifying and quantifying sources of unwanted variation in observation-well data collection, and in flagging wells whose measurements require verification. In 2000 and 2001, most of the possible sources of unwanted variation were not significant, in strong contrast with results obtained in 1999 when most exogenous variables were significant. QC for data acquisition in recent years is remarkably free of inconsistencies compared to early field seasons. The results can be interpreted as reinforcing the need for training and the desirability of deleting troublesome wells from the monitoring program. As the Quality Control process continues to be applied to the KGS observation well-measurement program in the future, and particularly if it is applied to the entire Kansas observation-well network, the quality of the ground-water measurement data is expected to improve over time (Davis, 2003; Olea and Davis, 2003; Bohling and Wilson, 2004). For a full statistical analysis of the 2004 measurements, see Bohling and Wilson (2004).
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 under-sampled 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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