Use of boundary fluxes when simulating solute transport with the MODFLOW ground-water transport process

[摘要] This report describes modifications to aU.S. Geological Survey (USGS) threedimensionalsolute-transport model (MODFLOWGWT),which is incorporated into the USGSMODFLOW ground-water model as the Ground-Water Transport (GWT) Process. Themodifications improve the capability ofMODFLOW-GWT to accurately simulate solutetransport in simulations that represent a nonzeroflux across an aquifer boundary. In suchsituations, the new Boundary Flux Package(BFLX) will allow the user flexibility to assignthe flux to specific cell faces, although thatflexibility is limited for certain types of fluxes(such as recharge and evapotranspiration, whichcan only be assigned to the top face if either is tobe represented as a boundary flux). The approachis consistent with that used in the MODPATHmodel. The application of the BFLX Package wasillustrated using a test case in which the LakePackage was active. The results using the BFLXPackage showed noticeably higher magnitudes ofvelocity in the cells adjacent to the lake thanprevious results without the BFLX Package.Consequently, solute was transported slightlyfaster through the lake-aquifer system when theBFLX Package is active. However, the overallsolute distributions did not differ greatly fromsimulations made without using the BFLXPackage.

[发布机构] U.S. Geological Survey

[学科分类] 地球科学(综合)