Experimental Verification of Models of Nonlinear Stream Aquifer Transients

The phenomenon of stream-aquifer interaction was investigated using a reduced scale sand tank model coupled with mathematical modeling using the Boussinesq equation. The effect of highly fluctuating transient stream level on the subsequent propagation of hydraulic transients in the adjacent aquifer was quantified using solutions to the linearized and the nonlinear Boussinesq equation. The semigroup solution of the linearized equation and the temporal-partial decomposition solution of the nonlinear equation were investigated subject to a transient, large-amplitude, periodic boundary condition. The models were verified with a limited numerical solution to the nonlinear Boussinesq equation and compared and assessed as to their ability to reproduce measured water table hydrographs at different locations in the laboratory model. Results indicated that the linearized solution and the nonlinear model coincided well with the numerical solution and with the observed hydrograph. Using decomposition the derivation of a solution to the nonlinear equation is simpler than that of a linear one.