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Full-Text Articles in Physical Sciences and Mathematics
Geographic Information Systems, Data, And Water Resources, Dwight A. Brown, Philip J. Gersmehl
Geographic Information Systems, Data, And Water Resources, Dwight A. Brown, Philip J. Gersmehl
Journal of the Minnesota Academy of Science
ABSTRACT-We evaluate three data handling methods for use in a GIS analysis of land-cover change impacts on runoff. A universe of 2560 point samples is analyzed to provide runoff calculations that would se1:7e _as a comparison base to evaluate different attribute logic systems. The attribute logics ~e evaluate are two va~1at1ons of tag and one of count. We chose a two by five mile area of Dakota County, Mmnesota as the test site, and prepared raster GIS maps of soil hydrologic groups and two plausible land covers. The count 1:1~thod for handling the generalization of data produced results that were …
County-Based Priority Assessment Methodology For Phasing Of Wellhead Protection Programs, H. O. Pfannkuch, M. E. Campion, D. C. Mccaa, J. M. Palenberg
County-Based Priority Assessment Methodology For Phasing Of Wellhead Protection Programs, H. O. Pfannkuch, M. E. Campion, D. C. Mccaa, J. M. Palenberg
Journal of the Minnesota Academy of Science
ABSTRACT-Setting priorities to schedule and implement wellhead protection programs for municipal and community drinking water supplies is presented in the framework of a general risk assessment approach. This includes a hazard identification procedure representing the likelihood of contaminants being released to the surface environment, a hydrogeologic vulnerability assessment representing the risk of contaminants entering the groundwater supply, and an impact assessment, strongly linked to the population at risk. A methodology was developed to aggregate information on a county basis for Minnesota. The resulting composite risk index map shows a number of counties in the central part of the state roughly …
Factors Affecting Water-Supply Potential Of The Twin Cities Metropolitan Area Aquifer System, Michael E. Schoenberg
Factors Affecting Water-Supply Potential Of The Twin Cities Metropolitan Area Aquifer System, Michael E. Schoenberg
Journal of the Minnesota Academy of Science
ABSTRACT-The Twin Cities aquifer system in Minnesota contains five aquife~s and fou: confining units that together consist of fourteen geologic units. Unconsolidated sand and gravel aqmfers overlie bedrock sandstone and carbonate aquifers. Between 1880 and 1980, groundwater wi_thdrawals have c_aused long-term wate~ level declines of as much as 90 feet in the Prairie du Chien-Jordan aquifer and 240 feet m the deeper Mount S~monHinckley aquifer-the two major sources of groundwater supplies in the ar~a .. The estimated max1mu1:1 continuous withdrawal rate from the aquifer system is about 650 Mgal/d (million gallons per day). This compares with an average daily groundwater …