Seasonal patterns of runoff and erosion responses to simulated rainfall in a badland area in Mediterranean mountain conditions (Vallcebre, southeastern Pyrenees)

• Published in: Earth surface processes and landforms Vol. 29; no. 6; pp. 755 - 767
• Main Authors: Regüés, D., Gallart, F.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.06.2004; Wiley
• Subjects: badland; Bgi / Prodig; erosion rate; Geomorphology; Mediterranean region; mountain; Physical geography; physical weathering; rainfall simulation; runoff generation; Slopes; soil crusting; Pyrénées; Spain; MED, Western Mediterranean; Mediterranean area; Rainfall simulation; Erosion rate; Soil erosion; Mountain; Badland; Runoff; Soil moisture; Seasonal variation; Water erosion
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.1067

Regolith surface characteristics and response were examined over a three‐year period in a badland area in a Mediterranean middle‐mountain zone near Vallcebre (Eastern Pyrenees). Preliminary work carried out in this area indicated clear seasonal patterns of regolith properties driven by frost heaving in winter and crusting and erosion in the rest of the year. Rainfall simulations were performed with a small portable nozzle simulator in order to study seasonal changes in runoff generation, erosion rates and raindrop effect on bulk density changes. The results showed large seasonal variations in runoff and erosion responses. Infiltration rates after runoff start were correlated with precipitation depth before runoff start; runoff generation was therefore related to regolith saturation only to a very limited extent. Erosion rates were more controlled by runoff rates than by the weakness of regolith against raindrop splash, and sediment grain size increased with concentration. The combined role of antecedent regolith moisture and bulk density explained most of the seasonal variability in infiltration, bulk density changes during rainfall and erosion rates, but some seasonal differences in sediment detachability were not explained by these variables and may be attributed to changes in roughness. Overall, runoff and erosion responses were relatively stable during spring and autumn, whereas wide variations in infiltration rates and sediment detachment occurred in winter and summer respectively. Experiments conducted in a single season would have produced poorly representative, if not erroneous, results. Copyright © 2004 John Wiley & Sons, Ltd.