 This study investigates the role of soil moisture on the threshold runoff response in a small headwater catchment in the Italian Alps. The study focuses on, I, the threshold soil moisture runoff relationship and the influence of catchment topography on this relation. High runoff ratios occurred during wet antecedent conditions when the soil moisture threshold was exceeded. This article was authored by D. Pena, H. J. Trombann-Mirveld, Agobi, and others.