Geodynamic processes on sandy slope gullies in central Spainudfield observations, methods and measurements in a singular system

摘要

Gullies developed on sandy lithologies are scarce and few studies have been reported on these landscapes. This paper presents an approachudto study such singular landforms. The studied gullies appear on the slopes of a group of mesas and cuestas of Upper Cretaceous sedimentsudlocated in the Northern piedmont of the Guadarrama Mountains, Spain.udLandforms of these gullied areas were catalogued, characterized and quantified with reconnaissance methods, providing informationudabout the most active geomorphic processes. These are being monitored in a 1.32 ha representative gullied catchment, the Barranca de losudPinos. In its high gradient slopes, where mass movements occur, high resolution topographical surveys are being carried out by TerrestrialudLaser Scanning (TLS). On low gradient slopes, runoff and rain splash are being monitored in micro plots; and in the main channel, sedimentudtransport and water discharge are being measured.udThis ensemble of methods, some of them novel, is providing patterns of sediment movement within the gully system, and a hypothesis ofudhigh activity rates has been confirmed. High gradient sand slopes without carbonate caprock erode fourfold compared to the capped slopes.udIn the low gradient slopes, those ungullied produce more runoff while exposed sands yield more sediment; sands covered by litter produceudthe least runoff and sediment. Notably, this catchment yields mainly bedload.