Estimation of Aquifer Hydraulic Properties by Inverse Numerical Modeling of Aquifer Pumping Tests
|Publication Date:||19 March 2020|
This standard is for estimating the hydraulic properties of a groundwater system by inverse numerical modeling of aquifer pumping tests. Guidance is provided on using a numerical groundwater flow model to simulate an aquifer pumping test (APT) and estimate aquifer hydraulic properties by matching the simulated aquifer response in space and time to observations of hydraulic head (henceforth referred to as head) or water level. The methodology is based on minimizing the residual error between observed and simulated heads by adjusting (calibrating) values of the pertinent aquifer hydraulic properties (e.g., transmissivity, storativity, and leakance) such that there is a good match between the observed and simulated values. This match may be accomplished manually by trial and error; alternatively, automated optimization or nonlinear least squares regression techniques can be used to solve the inverse problem. The resulting set of aquifer hydraulic property values are then considered to be representative of the aquifer volume influenced by the APT. The aquifer hydraulic properties derived from this procedure may serve as the basis of predictive simulations of groundwater flow and solute transport under a different set of hydrologic stresses, or they may be used to assist in characterizing the statistical (ASCE 2008a, b) and geostatistical (ASCE 2010) properties of aquifer hydraulic conductivity.