Groundwater Ridging
Groundwater ridging is yet another mechanism that contributes to runoff.
Groundwater ridging is a process that occurs in sloped drainage basins where the water table is much closer to the surface near the stream channel than it is further away from the stream.
Rainwater or snowmelt reaches the groundwater level near the stream channel more quickly than it does further up the hill away from the stream. The water table begins to rise near the stream channel more quickly than it does further away, creating a groundwater ridge close to the stream. The gradient between the groundwater ridge and the stream channel results in more rapid interflow to the stream.
In some cases the groundwater ridge can reach the soil surface and contribute to surface runoff through saturation excess overland flow.