Identification and characteristics of sediment sources in mountain areas: Erosion and sediment transfer in the upper Aragon catchment, Central Spanish Pyrenees (Spanish text).

摘要

Sediment sources are the areas in a catchment that generate all of or most of the sediment exported by it to the outlet. There is not complete identity between sediment sources and eroded areas. In fact, a great part of the sediment generated in the latter is stored with different resident times in sediment sinks within the catchment, and does not reach the outlet.; The reliable and easy identification of sediment sources is a very desirable applied research. In fact, the yield of sediment to the river system is closely related to several environmental problems, like losses in water quality, changes in river dynamics or reservoir siltation. Improving the knowledge of sediment sources in mountain environments will help in optimising management practices oriented to reduce the effective erosion in sensible catchments.; The objective of this Doctoral Thesis is to develop a diagnostic methodology for medium to big sized catchments, based in the use of remote sensing and simulation within GIS. This methodology has been conceived as a tool for land managers, with the objective of minimizing the sediment production. The development of this methodology has been split in three sections. In the first part is shown the usefulness of remote sensing in the development of erosion maps. A sediment transport simulation model has been developed, in order to discriminate between net erosion areas and sediment sinks. Finally, the analysis of the frequency and distribution of extreme rainfalls allows to include the timing of the erosion and sediment transport processes.; The study area is the catchment of the Yesa Reservoir in the Aragón River, in the Central Spanish Pyrenees. It covers an area of 2191 km 2.