A conceptual–numerical model to simulate hydraulic head in aquifers that are hydraulically connected to surface water bodies (pages 1435–1448)

摘要

In this paper, we present a conceptual-numerical model that can be deduced from a calibrated finite difference groundwaterflowmodel, which provides a parsimonious approach to simulate and analyze hydraulic heads and surface water body–aquiferinteraction for linear aquifers (linear response of head to stresses). The solution of linear groundwater-flow problems usingeigenvalue techniques can be formulated with a simple explicit state equation whose structure shows that the surface waterbody–aquifer interaction phenomenon can be approached as the drainage of a number of independent linear reservoirs. Thehydraulic head field could be also approached by the summation of the head fields, estimated for those reservoirs, definedover the same domain set by the aquifer limits, where the hydraulic head field in each reservoir is proportional to a specificsurface (an eigenfunction of an eigenproblem, or an eigenvector in discrete cases). All the parameters and initial conditions ofeach linear reservoir can be mathematically defined in a univocal way from the calibrated finite difference model, preservingits characteristics (geometry, boundary conditions, hydrodynamic parameters (heterogeneity), and spatial distribution of thestresses). We also demonstrated that, in practical cases, an accurate solution can be obtained with a reduced number oflinear reservoirs. The reduced computational cost of these solutions can help to integrate the groundwater component withinconjunctive use management models. Conceptual approximation also facilitates understanding of the physical phenomenonand analysis of the factors that influence it. A simple synthetic aquifer has been employed to show how the conceptual modelcan be built for different spatial discretizations, the parameters required, and their influence on the simulation of hydraulichead fields and stream–aquifer flow exchange variables. A real-world case was also solved to test the accuracy of the proposedapproaches, by comparing its solution with that obtained using finite-difference MODFLOW code. Copyright  2011 JohnWiley & Sons, Ltd.