The objective of this paper is to present an analytic element formulation for groundwater flow in multiaquifer systems. Analytic element equations are presented for wells, line-sinks, and circular infiltration areas. Each analytic element is a solution to the governing system of differential equations, and thus simulates the leakage between aquifers exactly; the head, discharge, and leakage may be computed analytically at any point in the aquifer. Superposition of these analytic elements allows for the simulation of regional multiaquifer flow. A hypothetical example is presented of a system with three aquifers, a river network, and three pumping wells. It is demonstrated that the leakage between aquifers may vary significantly over short distances and that each aquifer has its own water divide.@en

Two of the complicating factors in modeling the regional groundwater flow at Yucca Mountain are the large distance to hydrogeologic boundaries and the large thickness of the aquifer; the hydrogeologic boundaries are up to 500 km away from Yucca Mountain, and the aquifer is up to 5000 m thick. The distant hydrogeologic boundaries may be taken into account explicitly by application of the analytic element method, which is applied to a model of this size for the first time in this study. The analytic element method makes it possible to include distant hydrogeologic boundaries and at the same time allows for local detail without the excessive computational effort that would be required with the finite difference method. Regional flow in the aquifer is modeled with a single layer, based on a theoretical argument and supported by the model results. The match between simulated and measured heads is similar to that of previous finite difference models of parts of the region; these previous studies consist of multiple layers and include inferred boundary conditions (head or flux specified) along most of the boundary of the domain. (C) 1999 Elsevier Science B.V.@en

Procedures are presented for delineating capture zones of pumping wells. First, an algorithm is presented for determining the envelopes of the capture zones by the use of the locations of stagnation points. Second, it is discussed how the streamlines are determined that separate ground originating from different sources (the dividing streamlines). Third, a procedure is presented for constructing the boundary of the capture zone for any given time. The procedures are implemented in an analytic element code and are applied to ground flow systems that can be modeled with wells, line sinks, uniform flow, and areal infiltration.@en

Comparisons are made between Dupuit‐Forchheimer solutions and solutions to the differential equation governing flow with variable density. The solutions apply to flow in the vertical plane in aquifers confined by two horizontal impervious boundaries. The comparisons serve as a validation of the Dupuit‐Forchheimer formulation presented by Strack [this issue].

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