The influence of slope angle on sediment, water and seed losses on badland landscapes

By means of simulated rainfall the influence of the slope angle on the soil, water and seed erosion has been studied on badland surfaces. Slope angle has a clear positive effect controlling soil erodibility and erosion rates, but it does not have any influence on the volume of runoff after 40 minutes of rain at an intensity of 55 mm h−1. In contrast, slope angle has a clear influence on runoff initiation, with cracks and crusts as the main factors controlling the time to ponding and time to runoff. Both ponding and runoff initiation start earlier on pediments than on slopes, where more cracks exist. Steady-state infiltration rates and seed losses have an inverse relationships with slope angle. Pediments have 40 times lower erosion rates and 6 times higher seed losses than slopes. The different behaviour of seed losses between pediment and slope is due to the strategy of the seeds against erosion processes.