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3DFEMWATER/3DLEWASTE: NUMERICAL CODES FOR DELINEATING WELLHEAD PROTECTION AREAS IN AGRICULTURAL REGIONS BASED ON THE ASSIMILATIVE CAPACITY CRITERION
Citation:
Yeh, G., S. Sharp-Hansen, B. Lester, R. Strobl, AND J. Scarbrough. 3DFEMWATER/3DLEWASTE: NUMERICAL CODES FOR DELINEATING WELLHEAD PROTECTION AREAS IN AGRICULTURAL REGIONS BASED ON THE ASSIMILATIVE CAPACITY CRITERION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-92/223.
Description:
Two related numerical codes, 3DFEMWATER and 3DLEWASTE, are presented sed to delineate wellhead protection areas in agricultural regions using the assimilative capacity criterion. DFEMWATER (Three-dimensional Finite Element Model of Water Flow Through Saturated-Unsaturated Media) simulates subsurface flows, whereas 3DLEWASTE (Hybrid Three-dimensional Lagrangian-Eulerian Finite Element Model of Waste Transport Through Saturated-Unsaturated Media) models contaminant transport. oth codes treat heterogeneous and anisotropic media consisting of as many geologic formations as desired, consider both distributed and point sources/sinks that are spatially and temporally dependent, and accept four types of boundary conditions--i.e., Dirichlet (fixed-head or concentration), specified-flux, Neumann (specified-pressurehead gradient or specified-dispersive flux), and variable. he variable boundary condition in 3DFEMWATER simulates evaporation/infiltration/seepage at the soil-air interface and, in 3DLEWASTE, simulates mass infiltration into or advection out of the system. 3DLEWASTE contains options to model adsorption using a linear, Freundlich, or Langmuir isotherm, plus dispersion, and first-order decay.