Discharge and gully erosion in a small rangeland catchment

Valley bottom gullies are a common feature in rangelands. Although these gullies are found in the bottom of drainage lines, information about the relationship between discharge and gullying is scarce (Crouch, 1990; Thomas et al., 2004). This may in part be due to the large temporal variation of this phenomenon making necessary monitoring of runoff and erosion for a large number of years. Since 1990 research is carried out on the development of valley bottom gullies in small wooded rangeland catchments in southwest Spain. Erosion varies strongly along the gully section with high losses related to headcut retreat (Schnabel et al., 1999). The importance of extreme events producing exceptional sediment losses has also been demonstrated (Schnabel, 1997). In the year 2000 investigation started in the Parapuños experimental basin. The present paper aims at understanding the relationship between gully erosion and catchment hydrology.