Numerical modelling of groundwater pumping processes

Engineers need versatile tools in order to design successful dewatering schemes to counteract the effects of changing groundwater levels in cities. In the present paper, a finite-element program is used to perform pumping analyses, involving moving phreatic surfaces and possible desaturation of materials. First, a problem of local dewatering from a line of wells is analysed, involving desaturation of the soil. The results from an analytical solution as well as those of the numerical model are compared with field data. It is shown that the numerical results, accounting for soil desaturation, are closer to field measurements. Second, the ability of the finite-element program to model falling and subsequently rising groundwater levels in cities due to variable water abstraction (as in the case of London) is assessed. The techniques show promise and are sufficiently flexible to be applied to other geologies and boundary conditions.