Limits on the morphogenetic role of rain splash transport in hillslope evolution

Abstract

An experimentally parameterized equation for rain splash transport was generalized in order to compute annual sediment transport rates for a range of climates. The resulting equation was then used to examine the conditions under which rain splash transport can play a significant morphogenetic role in water-eroded landscapes. Rain splash can generate convex hillslopes on short, steep hillslopes such as the margins of gullies in unconsolidated sediments. However, comparison of predicted profiles with long, convex hillslopes in postorogenic landscapes indicates that rain splash cannot transport sufficient quantities of sediment to produce the observed convex hillslope profiles. Rates of biogenic transport estimated from the literature also appear to be insufficient. Sheetwash transport appears to be the only process capable of molding these extensive convex hillslope profiles despite the common assumption that it generates exclusively concave forms.