Water Flow Through Snow Overlying an Impermeable Boundary

A two‐layer model is constructed in order to describe water flow over an impermeable boundary. The model consists of vertical flow through an unsaturated layer and flow along a boundary in a saturated layer. The governing equations are solved for the nonsteady case, where the gradient of the thickness of the saturated layer is small compared with the slope of the impermeable boundary. It is shown that in most cases the discharge from shallow snowpacks will preserve the diurnal cycles of input at the surface, although for deep snowpacks (such as temperate glacier firn) the diurnal cycle is smoothed and only long‐term responses are expected. The flow of a diurnal meltwater wave through a small (2.10 m deep by 100 m long) snowpack is calculated as an example. The case of steady flow is also described.