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2.1 Database Structure <br />The following paragraphs identify the key tables in HydroBase pertinent to aquifer <br />configuration Data. Appendix A provides a more detailed summary of those tables and fields. <br />Four data tables contain data pertinent to an aquifer's configuration. These are named WELLS, <br />GEOPHLOGS, AQUIFER_PICKS, REF_ELEV_ACCURACY and REF_LOC_ACCURACY. <br />The WELLS table contains the location, well elevation, permit number, well depth, and many <br />other types of information about wells in the SPDSS study area. The WELLS table is the core <br />table that links well information data with geophysical log, water level, and aquifer test data. <br />The GEOPHLOGS table of HydroBase contains the geophysical well log picks determined by <br />the DWR. The GEOPHLOGS table contains the picks for the aquifer top and bottom elevations, <br />and picks for the net sand thickness. For the alluvial aquifer, typically a pick for the bottom <br />elevation of the aquifer is all that is stored in the GEOPHLOGS table. This table is linked to the <br />WELLS table by the well_id field. <br />The AQUIFER_PICKS table of HydroBase contains the same type of aquifer configuration data <br />as the GEOPHLOGS table. The picks are derived from sources such as geophysical logs, <br />driller's logs, or historic reports, but the picks are not determined by the DWR. This table is <br />linked to the WELLS table by the well_id field. <br />The REF_ELEV_ ACCURACY table includes comments indicating the source and accuracy of <br />the elevation value. <br />The REF_LOC_ACCURACY table includes comments on the siting accuracy of the location <br />(X,Y) data. <br />2.2 Database Quality Control <br />A series of quality control steps were undertaken to check the accuracy of the data analysis and <br />processing. <br />Published contour data from Bjorklund and Brown (1957), Duke et al. (1966), Erker et al. (1967), <br />Hurr and Schneider (1972a -1972f, 1977), NHPQ (1967), Smith et al. (1964) and Willard Owens <br />Associates (1971) were scanned to a graphic image file and then digitized and assigned a <br />contour value. The digitized contour values were analyzed for quality and accuracy by the <br />following procedure. The digitized contours were overlain on the graphic image of the original <br />contour map. One hundred percent of the digitized contours were verified for the appropriate <br />contour interval and value by comparison with the contour graphic image. A similar procedure <br />was used for the point values obtained from Bjorklund and Brown (1957) Smith et al. (1964). <br />After the points were digitized, 100 percent of the assigned digitized values were checked <br />against the value labeled on the image and found to be in agreement. <br />Numerical data from each of the sources external to HydroBase were initially entered into a <br />Microsoft Excel® spreadsheet. Hand-entered data were then checked for accuracy by comparing <br />100 percent of the entered data to the original hard copy data. If errors in the data entry were <br />found, the errors were corrected in the spreadsheet. The spreadsheet was then uploaded into <br />SPDSS Phase 3 Task 42.3 TM -Final 11 <br />11/30/2006 <br />