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Unformatted text preview: tions to the modified Reilly problem in which the desired discharge equals -7,800 cubic feet per day for a 300-day transient stress period.......................................................................................31 33. Plot showing results of applying the pump-capacity relations to the modified Reilly problem for two 365-day transient stress periods with three nearby wells pumping during the first transient stress period.........................................................32 34. Schematic three-dimensional perspective drawing of a representative finitedifference cell connected to a nonvertical multi-node well passing through the block-centered node ..................................................................................................................33 35. Schematic cross-sectional view of a finite-difference cell containing a horizontal well aligned with the y-direction of the grid........................................................33 36. Schematic cross-sectional view to the west of part of a MODFLOW grid containing a multi-node well that changes orientation from a vertical well at the surface to a horizontal well at depth ................................................................................35 37. Depiction of orientation and alignment of a nonvertical well on the basis of two characteristic angles .................................................................................................................35 38. Schematic cross-sectional view of part of a MODFLOW grid containing a multinode well that changes direction ............................................................................................37 39. Schematic cross-sectional view through a MODFLOW grid showing a mostly horizontal multi-node well .........................................................................................................37 40. Schematic cross section of an unconfined aquifer, showing the relation of the open and closed intervals to the position of the water table ..............................................37 41. Diagrammatic cross section showing wells with complex well screens or open intervals within a model layer...................................................................................................38 42. Schematic cross section of an unconfined aquifer showing a multi-node well and the relation of multiple screens ........................................................................................38 43. Schematic cross section illustrating components of flow into and out of well segments comprising a representative node of a multi-node well. ...................................39 vii Tables 1. 2. 3. 4. A1–1. A3–1. Properties of the confined aquifer system analyzed in the Lohman test problem ............8 Selected physical parameters used in MODFLOW simulation of ground-water flow in a three-dimensional, steady-state flow system containing a multi-node well ..............9 Modified parameters in Reilly problem for evaluating seepage face calculation in multi-node pumping well ...........................................................................................................20 Computational effort for range of variations of Reilly test problem ...................................41 Summary of parameter definition requirements for available well-loss options.............48 Inferred equivalence in MNW1to2 of LOSSTYPE options in MNW1 to those in MNW2...........................................................................................................................................66 Conversion Factors Multiply By Length 0.3048 foot (ft) 2 square inch (in ) cubic foot (ft3) foot per day (ft/d) cubic foot per second (ft3/s) cubic foot per day (ft3/d) foot per day (ft/d) Area 6.452 Volume 0.02832 Flow rate 0.3048 0.02832 0.02832 Hydraulic conductivity 0.3048 To obtain meter (m) square centimeter (cm2) cubic meter (m3) meter per day (m/d) cubic meter per second (m3/s) cubic meter per day (m3/d) meter per day (m/d) Revised Multi-Node Well (MNW2) Package for MODFLOW Ground-Water Flow Model By Leonard F. Konikow, George Z. Hornberger, Keith J. Halford, and Randall T. Hanson Abstract Wells that are open to multiple aquifers can provide preferential pathways to flow and solute transport that shortcircuit normal fluid flowlines. Representing these features in a regional flow model can produce a more realistic and reliable simulation model. This report describes modifications to the Multi-Node Well (MNW) Package of the U.S. Geological Survey (USGS) three-dimensional ground-water flow model (MODFLOW). The modifications build on a previous version and add several new features, processes, and input and output options. The input structure of the revised MNW (MNW2) is more well-centered than the original verion of MNW (MNW1) and allows the user to easily define hydraulic characteristics of each multi-node well. MNW2 also allows calculations of additional head changes due to partial penetration effects, flow into a borehole through a seepage face, changes in well discharge re...
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