Consolidation Settlement in Aquifers Caused by Pumping.

Equations are derived to calculate one-dimensional (vertical) consolidation settlement in aquifers caused by groundwater extraction. The settlement equations capture the effect that the decline in pore-water pressure caused by groundwater extraction has on increased vertical effective stress. The settlement equations for single-layered confined or unconfined aquifers and multiple-layered aquifers are derived by linking the increase in vertical effective stress to the reduction of the void ratio using the reconstructed field consolidation curve of aquifer sediments. This paper's approach blends groundwater hydraulics with the classical theory of one-dimensional consolidation widely used in geotechnical engineering. Closed-form consolidation settlement equations are presented for single-layer, homogeneous, isotropic confined aquifers with steady-state or transient groundwater flow and for single-layer, homogeneous, isotropic, unconfined aquifers under steady-state flow. The consolidation equations for consolidated settlement in heterogeneous, anisotropic, single-layer or multilayer aquifers are expressed as the numerical integration of the vertical strain induced by groundwater pumping. The numerical-integration settlement equations require the implementation of a groundwater simulation model to calculate the pore pressure decline within aquifer layers, followed by the calculation of the increase in vertical effective stress and the reduction in pore volume. One numerical example confirms the accuracy of this paper's approach to aquifer consolidation by comparing with the solution obtained with the three-dimensional poroelastic theory. [ABSTRACT FROM AUTHOR]