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Applying the USGS Mass‐Transport Model (MOC) to Remedial Actions by Recovery Wells
Author(s) -
ElKadi Aly L.
Publication year - 1988
Publication title -
groundwater
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 94
eISSN - 1745-6584
pISSN - 0017-467X
DOI - 10.1111/j.1745-6584.1988.tb00391.x
Subject(s) - streamlines, streaklines, and pathlines , plume , curvature , mechanics , sink (geography) , groundwater recharge , flow (mathematics) , geology , environmental science , hydrology (agriculture) , groundwater , geotechnical engineering , mathematics , meteorology , aquifer , geometry , physics , cartography , geography
The USGS two‐dimensional mass‐transport model (MOC) is widely used in the analysis of ground‐water contamination problems. A need exists to examine the accuracy of the code in situations dominated by radially convergent and divergent flow around wells. The model is applied here to situations that commonly exist in remedial actions involving recovery wells. The cases simulated are a recharge/recovery single well, a recharge/recovery doublet, and plume capture by one or two production wells. The results were tested against analytical and semianalytical solutions. Inaccuracies in model results occurred especially for the doublet case under continued long‐time simulation. Inaccuracies are caused not only by the mainly radial‐flow situation, or by the curvature nature of streamlines, but also by the arrival of contamination at the sink nodes. Better agreement of numerical and analytical solutions was obtained for the single‐well and plume‐capture situations. However, a large mass‐balance error exists for the single‐well case. Inaccuracies can be reduced by modifying the code and reducing the finite‐difference mesh (e.g., Erickson, 1985). However, the use of a very fine mesh (i.e., on the order of a few feet) may prevent the use of the code in large‐scale problems. Care must be taken in applying the model to situations where production or injection wells are close to each other.