ABSTRACT
On semi-arid hillslopes virtually all runoff occurs in the form of overland flow which is generated when rainfall intensity exceeds the surface infiltration rate. Overland flow may be conveniently divided into rill and interrill flow, of which only the latter is examined here. Interrill overland flow generally appears as a sheet of water with threads of deeper, faster flow diverging and converging around surface protuberances, rocks and vegetation.
