A laboratory experiment on radial non-Darcian flow in confined aquifer under steady-state conditions

In order to analyze the non-Darcian radial flow near the pumping well in confined aquifer, a se? ries of constant pumping tests were conducted in a converging permeameter of 60 under constant head at the inlet and outlet boundaries in laboratory. The tank was filled with river sand with diameter of 0.3~0.6 mm to simulate the confined aquifer. Pressure transducers were installed in different distances along the radial direction, and the measurement of the pressure head was used to obtain the steady state drawdown curves in different radial distances. Both the measured drawdown and the mean hydraulic gradient between two adjacent pressure transducers were used to identify the occurrence of non-Darcian flow. The results show that non-Darcian flow occurs in the test with different pumping rates. The analytical solution of non-Darcian steady state flow on the basis of the power function was used to fit the experimental drawdown data. The results show that the pumping rate has slight effect on the values of the coefficients of the Izbash equation. With the average coefficients values, i. e. the non-Darcian hydraulic conductivity k=7.17 10 -7 and the power index n=1.65, the calculated drawdown match the measured data well for different pumping rates, indicating that the analytical solution is capable of describing the radial non-Darcian flow.

A laboratory experiment on radial non-Darcian flow in confined aquifer under steady-state conditions Academic Article