Relationships among rainfall, runoff, and suspended sediment in a small catchment with badlands

The Araguás Catchment of the Central Spanish Pyrenees has been monitored since 2004 to study weathering, erosion, and the hydrological and sediment response to rainfall events in order to understand the hydromorphological dynamics of a badland area in a relatively humid environment. This small catchment (0.45 km2) shows highly active processes of physical and chemical weathering related to seasonal variations in temperature and moisture. Erosion and sediment transport are widely studied in badlands within Mediterranean environments because they represent the dominant sediment source. To obtain information about suspended sediment and discharge, a gauging station was installed within the Araguás Catchment during the summer of 2005. The aim of this work is to determine the relationships among rainfall, runoff, and suspended sediment in this badland area. Towards this goal, we analyze the relationships between suspended sediment concentration and discharge during rainfall events.From a hydrological viewpoint, the Araguás Catchment reacts to all rainfall events with torrential flow being the most characteristic hydrological response. The results obtained between October 2005 and April 2007 reveal extremely high concentrations of suspended sediment, with values frequently exceeding 100 g l−