THE MAJOR ROLE OF GROUNDWATER IN STREAM DRAINAGE DEVELOPMENT AND STREAM DRAINAGE DENSITY

Because surface runoff is visible there has been a increasing perception over the last century that stream drainage development and stream drainage density is the result of surface runoff. There was early support for the involvement of groundwater but it was difficult to show with the available technologies. Now there is recent work showing that groundwater flow patterns have a major role. While the calculation of surface runoff has always incorporated soil permeability, little to no thought has been given to what happens to the water that infiltrates and recharges the aquifer system and it’s possible effect on stream drainage development. Recently, it has been shown that stream drainage densities determined using GIS and DEM data match calculated stream drainage densities using derivatives of basic groundwater equations, aquifer properties, and recharge rates. These studies were in the High and Western Cascades of Oregon, a stream drainage system on Mars, and the High Plains Aquifer. Further, the need to have adequate drainage systems for groundwater range from the planning of new golf courses to draining of soils for crop development in high groundwater areas is widely accepted. The role of groundwater in developing Earth landscapes needs to be similarly recognized. There are multiple processes by which emerging groundwater can affect the Earth’s surface so it should not be surprising that stream drainage development and stream drainage density reflects the groundwater flow patterns. Multiple evidence supporting groundwater’s role will be presented.