Principal Investigator: Yong Shi (Georgia Institute of Technology)
Principal Investigator: Pratyush Verma (Georgia Institute of Technology)
Sponsor: GWRI
Start Date: 1995-05-01; Completion Date: 1995-05-01;
Keywords: Fractured Aquifers, Geostatistics, Aquifer Characteristics, Aquifer Parameters, Groundwater Hydrology, Groundwater Movement
Description:
Periodic droughts and localized industrialization in the Greater Atlanta area strain the available surface water supplies. The rising environmental concerns about over-use of surface water supplies have rendered groundwater resources in the Georgia Piedmont as a part of the solution to the water shortage problem. Aquifers in the Piedmont are traditionally viewed to have low permeability. However, this region includes wells with high yields up to 400 gpm. Tapping productive zones in the Piedmont region is considered as a difficult task driven by chance. This project attempts to use advanced statistical procedures to reliably locate, with high probability, zones for high-yielding wells in the Piedmont. In Part A (Babaie and Caudill, 1995) field fracture measurements at a number of locations in the greater Atlanta area were conducted. In Part B, attempts were made to determine the spatial distributions of collected data on fractures in the crystalline rocks of the Piedmont using geostatistical methods. The geostatistical outcomes were then compared with available regional groundwater discharge information. The results of these comparisons provided a means to relate surficial fracture features to the probability of siting high yield wells. The principal findings of Part B of this investigation are listed below:
(1)Among analyzed variables, density and number of fracture sets appear to be adequately representative of other fracture features.
(2)The resulting variograms of the above spatial features display well-defined structures with strong anisotropic tendencies.
(3)Based on the fitted variograms, contour maps of fracture density and the number of sets were produced. All kriged maps provided results consistent with available regional geologic maps.
(4)Available groundwater discharge information was then superimposed on the kriged maps. This led to the computation of conditional probability curves. These curves estimate the probability of siting a high yield well in zones with specific fracture feature values.
The conditional probability curve based on the composite indicator map, defined as the product of fracture density and set number, provide a promising measure to identify zones with high interconnectivity. This implies that geostatistical maps of composite fracture features can be viewed as reliable tools for siting high yield wells.