Flow resistance induced by overland flow morphology

Abstract

An effort is made to develop a new physically-based overland flow model which accounts for raindrop mixing and for the complex overland flow geometry. Theoretical curves relating overland flow parameters are found and compared to field data. The curves are deduced analytically by means of a kinematic model of thin sheets of flow under rainfall and by means of a geometric model simulating a natural rill network by rectangular channels. The micro-channels may merge together at larger flow depths, thus reducing the relative roughness. The water dissipates less energy in flowing downhill and the energy in excess is available for the erosion process which stabilizes the rill network. -from Authors