Experiments on headcut growth and migration in concentrated flows typical of upland areas

Experiments were conducted to examine soil erosion by headcut development a nd migration in concentrated flows typical of upland areas. In a laboratory channel, packed sandy loam to sandy clay loam soil beds with preformed hea dcuts were subjected to simulated rain followed by overland flow. The rainf all produced a well-developed surface seal that minimized surface soil deta chment. During overland flow, soil erosion occurred exclusively at the head cut, and after a short period of time, a steady state condition was reached where the headcut migrated at a constant rate, the scour hole morphology r emained unchanged, and sediment yield remained constant. A fourfold increas e in flow discharge resulted in larger scour holes, yet aspect ratio was co nserved. A sediment bed was deposited downstream of the migrating headcut, and its slope depended weakly on flow discharge.