Simulation of Contributing Areas and Surface-Water Leakage to Potential Replacement Wells Near the Community of New Post, Sawyer County, Wisconsin, by Means of a Two-Dimensional Ground-Water-Flow Model (original) (raw)
2007
Figure 2. Diagram showing conceptual model of the hydrologic system in Sawyer County, Wis., in A, the vicinity of Grindstone Creek, and B, the vicinity of New Post, Wis. ... Figure 3. Maps showing simulated hydrologic features with analytic elements in A, the far field and B, the ...
High-capacity wells and baseflow decline in the Wolf River Basin, northeastern Wisconsin (USA)
Environmental Earth Sciences, 2016
The baseflow of the Wolf River (drainage area of 1,200 km 2) in northeastern Wisconsin has declined by over 30% during the last thirty years, whereas climatic, land cover, and soil characteristics of the basin have remained unchanged. Because groundwater basins do not always coincide with surface water basins, estimating groundwater discharge to streams using variables only pertinent to the surface water basin can be ineffective. The purpose of this study is to explain the decline in the baseflow of the Wolf River by developing a multiple regression model. To take into account variables pertaining to the groundwater basin, withdrawal rates from high capacity wells both inside the Wolf River basin and in two adjacent basins were included in the regression model. The other explanatory variables include annual precipitation and growing degree days. Groundwater discharge to the river was calculated using streamflow records with the computer program Groundwater Toolbox from the United States Geological Survey. Without the high capacity wells data, the model only explained 29.6% of the variability in the groundwater discharge. When the high capacity wells data within the Wolf River basin were included, r 2 improved to be 0.512. With the high capacity wells data in adjacent basins, r 2 improved to be 0.700. The study suggests that human activity taking place outside of the basin has had an effect on the baseflow, and should be taken into account when examining baseflow changes.
Flow of Ground Water to a Well Near a Stream – Effect of Ambient Ground‐Water Flow Direction
Groundwater, 1988
ABSTRACTAn analytical model has been developed to evaluate and improve our knowledge of steady‐state flow of ground water toward a well near a stream. This model differs from others in that the direction of ambient ground‐water flow (i.e., regional ground‐water flow) does not have to be perpendicular to a gaining stream, but can be oriented in any direction. Without using measured water levels, flow directions and rates can be calculated, i.e. estimated flow nets can be drawn based on the pumping rate, the ambient ground‐water flow rate and direction, and the location of the well and stream. The model can be used to help determine the minimum rate of pumping that will induce infiltration from a stream to a well, and the components of pumping that are derived from the stream and the aquifer. The areal distribution of flow includes: a zone of induced infiltration from a stream toward a pumping well denoted the stream capture zone, a zone that includes all ambient ground water captured...
Sources of water captured by municipal supply wells in a highly conductive aquifer western Montana
2005
The sole-source unconfined M issoula Aquifer provides drinking water to 60,000 residents. The Clark Fork River reportedly provides 50-90% o f the aquifer recharge. If this recharge source becomes contaminated, water from municipal wells may be at risk. The goal o f this study was to examine the river-groundwater recharge process and to quantify the sources o f water pumped for water supply. This goal was accomplished by investigating the geology, the groundwater occurrence and flow, aquifer properties and streambed properties. Results o f these investigations coupled with components from past studies generated a conceptual model and ultimately a transient three-dimensional groundwater flow model. Finally, water sources were assessed by particle tracking. Geologic investigations revealed a course grained aquifer with discontinuous packages o f fine grained material. Observations at 29 monitoring wells from May 2004-June 2005 enabled construction o f potentiometric maps revealing an east to west flow direction divided by the Clark Fork throughout most o f the study region. Aquifer investigations by pum ping tests, slug tests and peak delay analysis yielded hydraulic conductivities ranging from 2,000 to 48,000 ft/day in the eastern portion o f the aquifer. Streambed investigations by vertical gradient measurements, temperature monitoring and modeling, stream discharge measurements and tracer tests revealed the river to be perched above the aquifer and losing water. In Hellgate Canyon the river is perched approximately 5 ft above the aquifer and leaking 1.9-4 ft^/day per o f river bed. In the M adison Area the river is perched approximately 17ft above the aquifer and leaking 7-14 ft^/day per ft^ o f riverbed. A three-dimensional transient model was calibrated to March 17, 2005 water level data and water level changes over the study period. The ground water budget from the model suggested 82% o f the groundwater in the study region is from Clark Fork River leakage and 12% is from up gradient underflow. Particle tracking to delineate capture zones revealed dominant horizontal flow with wells adjacent to the river on the south side receiving 50-80% o f their water from the river, while distal wells on the south side are dominated by underflow and wells on the north side receive recharge from a losing portion o f Rattlesnake Creek. 10 CHAPTER II METHODS This chapter describes the field and data analysis methods for all investigations conducted during this study. This includes: geologic, groundwater occurrence and flow, aquifer property, streambed behavior, geochemical, groundwater budget, and modeling investigations. Geologic Investigation The geologic and hydrogeologic setting was characterized by performing a detailed review o f the literature, interpreting well driller's logs, examining drill cuttings and drilling four new monitoring wells. Two wells were completed in Hellgate Canyon (HGS and HGD) (Figure 4) and two wells were drilled on either side o f Madison St. Bridge (D H l and DH2) (see inset Figure 4). These wells were constructed with an air rotary drilling rig equipped with an eccentric (off-centered) bit. Environmental West Drilling Co. performed drilling and set these wells. Well cuttings were reviewed and logged during the drilling process. The two wells completed adjacent to Madison Street Bridge included the collection o f split spoon samples reviewed every five feet. The Hellgate Canyon wells were sand-packed with 10+20 silica sand and screened with 20 ft filter packed 0.12 slot PVC screen. Well HGD was drilled to bedrock (247 ft) and then cased to a depth o f 172 ft. Well HGS was drilled and finished to 51 ft. The M adison Area wells were natural packed and screened with 0.040 slot screen. Well D H l was drilled and finished to 50 ft with 10 ft o f 0.040 slot screen. Well DH2 was drilled and finished to 70 ft with 20 ft o f 0.040 slot screen (see well logs Appendix B). These well 1070' 70 ' I = 0.0024 K = 21,500