Evaluating the importance of surface soil contributions to reservoir sediment in alpine environments: a combined modelling and fingerprinting approach in the Posets-Maladeta Natural Park
Abstract. Soil in alpine environments plays a key role in the development of ecosystem. Identify, maintain and preserve its resources, as well as recognize processes that would affect them are important and of practical interest. Environmental concerns about these fragile systems which are threatened by the human pressure and climatic change have stressed the need to gather information in soil erosion processes. As most mountain alpine environment the Benasque catchment is characterized by temperatures below freezing that can last from November to April, strong rainfall events and rugged topography. Indirect studies, such as combined model approaches, could be an alternative to evaluate soil erosion on these areas. In this study the complementary tools of Soil and Water Assessment Tool (SWAT) and fingerprinting procedure were used to assess an initial approach on soil erosion processes which take place in the area of the Posets-Maladeta National Park (Central Spanish Pyrenees). Soil erosion rates and sediment contribution of potential sediment sources (Kastanozem/Phaeozem; Fluvisol; Cambisol and channel bed sediments) were assessed. SWAT model identified Cambisols as the main source of sediment of the Benasque catchment with the highest specific sediment yields and Phaeozems and Fluvisols were identified as the lowest sediment contributors. Spring and winter performed the highest and lowest specific sediment yield, respectively. Fingerprinting procedure identified channel bed sediment and Fluvisols as the main sediment sources indicating the main influence of connectivity. The combined approach enabled us to better understand soil erosion processes in the Benasque alpine catchment.