 Aquifer drainage hydrograph

An aquifer drainage hydrograph plots the time-dependent discharge from an aquifer. In the shallow constant-recharge model, early discharge grows linearly according to the rain-fed aquifer similarity solution. Sustained recharge $R$ on a finite length $L$ gives eventual steady discharge $RL$ when the other end is impermeable. After recharge stops, a separable aquifer drawdown has height proportional to $1/(t+t_0)$ and discharge proportional to $1/(t+t_0{)}^2$; this is generally a late-time description rather than an exact solution for arbitrary inherited height profiles.