Groundwater Age

Here is a demonstration with transient groundwater age in a vertical 2D section of aquifer. The red box is a 2D vertical cross-section of an aquifer with no-flow boundaries on left and bottom, and sinusoidally varying in time, and linear in space pressure gradient on top, representing seasonal flow forcing. By adding an age dimension (“y”, shown in the movie) along which we advect water at unit velocity we add a “clock” to the governing equation and can visualize age as a distribution of water over age y at any point (x, z) in the aquifer.