Edwards Rules Maps Digitization, TNRCC Edwards Project- Contract Number 582-9-12095

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On August 20, 1999, a digital version of the Edwards Rules Map Leander NE quadrangle was placed on the Bureau's anonymous ftp site for review by TNRCC. The Leander NE quadrangle was approved by TNRCC, and the remaining 33 quadrangles were digitized. The Edwards Rules map was captured from 34 mylar, paper blueline, and original 7.5' USGS maps. Lines depicting the boundary of the recharge and transition zones of the Edwards Aquifer were tablet digitized from the original maps using the ArcEdit module of ArcInfo. All tics and linear features from an individual map were captured during the initial digitizing session. The digitized coverages were transformed into either polyconic or stateplane (central or south-central zones) projections. Transformation error reports for all quadrangles were recorded as project documentation. The 34 individual coverages were reprojected into UTM zone 14, appended, and processed into a single polygon coverage. Polygons are assigned a numeric code specifying recharge (1) and transition (2) areas.


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