INTERA Develops Adjoint Capture Function for MODFLOW
Scientists and engineers at INTERA have completed the initial development of a new subroutine to MODFLOW-2005 that allows efficient calculation of capture functions, commonly used in the management of groundwater resources. Capture functions quantitatively define the net contribution of surface water relative to withdrawal from wells in the aquifer. Evaluation and mapping of capture functions can be used in the optimal location of pumping wells and in determining optimal pumping strategies. Traditional techniques used to estimate capture functions include analytic solutions or the parameter perturbation approach which typically requires execution of thousands of forward numerical simulations. The new approach developed by INTERA uses the adjoint methodology and results in computational efficiencies by a factor equal to the number of nodes in the model, typically on the order of several hundred thousand. With such computational savings, it is now feasible to address the uncertainties in groundwater models by embedding the problem in a stochastic framework.