Andrew J Long
Andy Long has more than 30 years of experience assessing groundwater flow and transport through numerical and conceptual modeling, analyzing ambient and injected tracers, and geophysical methods.
Professional Experience
Groundwater Specialist, USGS Washington Water Science Center (July 2015 – present) –
Advise and train scientists and technicians on interpretive studies and data collection and management. Advise managers in building and guiding the groundwater program. I conduct scientific investigations involving conceptual and numerical modeling.Chair and Vice Chair, Washington Hydrogeology Symposium (2017 – 2022)
Research Hydrologist, USGS Dakota Water Science Center (DWSC; 2009 – 2015) –
Developed innovative methods to better understand, quantify, and test hypotheses related to groundwater flow and transport in karst aquifers. Topics include groundwater age dating, lumped-parameter models, aquifer classification, hydrochemical evaluation, heat transport, and groundwater recharge.Adjunct Assistant Professor, South Dakota School of Mines and Technology (SDSMT; Oct 2005 – 2018) –
Served on eight graduate advisory committees for M.S. and Ph.D. students and gave numerous guest lectures.Hydrologist, USGS DWSC (Jan 1999 – Oct 2009) –
This involved numerical modeling of groundwater flow and solute transport, dye tracing experiments in karst aquifers, aquifer pumping tests, and development of new research models.Consultant (1994–1998) –
Conducted GIS analysis and groundwater modeling with MODFLOW related to a proposed low-level nuclear-waste site for the Boyd County Monitoring Committee in Nebraska. Consulted for Terra Nitrogen in Sergeant Bluff, Iowa and simulated groundwater flow and transport with MODFLOW, MOC, and GIS analysis to assess the movement of ammonia contamination.
Research assistant, SDSMT (1995–1998) –
Developed and wrote the FORTRAN computer code for a three-dimensional groundwater model to simulate dual-porosity flow in karst aquifers. Collaborated with a team of researchers on the design of a numerical model to simulate surface-water and groundwater flow, dynamically linked to atmospheric processes.
Hydrologist, Rapid City Water Department (1994-1995) –
Collaborated with the USGS to simulated groundwater flow in karst aquifers.
Science and Products
Analysis of ground-water flow in the Madison aquifer using fluorescent dyes injected in Spring Creek and Rapid Creek near Rapid City, South Dakota, 2003-04
Characterization of ground-water flow and water quality for the Madison and Minnelusa aquifers in northern Lawrence County, South Dakota
Statistical analyses of hydrologic system components and simulation of Edwards aquifer water-level response to rainfall using transfer-function models, San Antonio region, Texas
Simulated ground-water flow in the Ogallala and Arikaree aquifers, Rosebud Indian Reservation area, South Dakota
Flow-system analysis of the Madison and Minnelusa aquifers in the Rapid City area, South Dakota — Conceptual model
Science and Products
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Analysis of ground-water flow in the Madison aquifer using fluorescent dyes injected in Spring Creek and Rapid Creek near Rapid City, South Dakota, 2003-04
The Madison aquifer, which contains fractures and solution openings in the Madison Limestone, is used extensively for water supplies for the city of Rapid City and other suburban communities in the Rapid City, S. Dak., area. The 48 square-mile study area includes the west-central and southwest parts of Rapid City and the outcrops of the Madison Limestone extending from south of Spring Creek to norAuthorsLarry D. Putnam, Andrew J. LongCharacterization of ground-water flow and water quality for the Madison and Minnelusa aquifers in northern Lawrence County, South Dakota
The Madison and Minnelusa aquifers are used extensively for water supplies for the city of Spearfish and other users in northern Lawrence County, South Dakota. Ground water in the Madison and Minnelusa aquifers in the study area generally flows north from outcrop areas where recharge from sinking streams and infiltration of precipitation occurs. Ground water that moves northward and eastward arounAuthorsLarry D. Putnam, Andrew J. LongStatistical analyses of hydrologic system components and simulation of Edwards aquifer water-level response to rainfall using transfer-function models, San Antonio region, Texas
In 2003 the U.S. Geological Survey, in cooperation with the San Antonio Water System, did a study using historical data to statistically analyze hydrologic system components in the San Antonio region of Texas and to develop transfer-function models to simulate water levels at selected sites (wells) in the Edwards aquifer on the basis of rainfall. Water levels for two wells in the confined zone inAuthorsLisa D. Miller, Andrew J. LongSimulated ground-water flow in the Ogallala and Arikaree aquifers, Rosebud Indian Reservation area, South Dakota
The Ogallala and Arikaree aquifers are important water resources in the Rosebud Indian Reservation area and are used extensively for irrigation, municipal, and domestic water supplies. Continued or increased withdrawals from the Ogallala and Arikaree aquifers in the Rosebud Indian Reservation area have the potential to affect water levels in these aquifers. This report describes a conceptual modelAuthorsAndrew J. Long, Larry D. Putnam, Janet M. CarterFlow-system analysis of the Madison and Minnelusa aquifers in the Rapid City area, South Dakota — Conceptual model
The conceptual model of the Madison and Minnelusa aquifers in the Rapid City area synthesizes the physical geography, hydraulic properties, and ground-water flow components of these important aquifers. The Madison hydrogeologic unit includes the karstic Madison aquifer, which is defined as the upper, more permeable 100 to 200 ft of the Madison Limestone, and the Madison confining unit, which consiAuthorsAndrew J. Long, Larry D. Putnam