# Dupuit assumption

The Dupuit assumption holds that groundwater moves horizontally in an unconfined aquifer, and that the groundwater discharge is proportional to the saturated aquifer thickness. It was first designed by Jules Dupuit in 1863 to simplify the groundwater flow equation for analytical solutions.

The Dupuit assumption requires that the water table is relatively flat, and that the groundwater is hydrostatic (i.e., the equipotential lines are vertical):

{\displaystyle {\begin{aligned}{\frac {\partial P}{\partial z}}&=-\gamma =-\rho \,g\\[0.5em]{\frac {\partial h}{\partial z}}&=0\end{aligned}}}

where ${\displaystyle \partial P/\partial z}$ is the vertical pressure gradient, ${\displaystyle \gamma }$ is the specific weight, ${\displaystyle \rho }$ is the density of water, ${\displaystyle g}$ is the standard gravity, and ${\displaystyle \partial h/\partial z}$ is the vertical hydraulic gradient.

## References

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