Availability and characteristics of the historical and recent aerial photographs and orthophotographs in Spain for the analysis of rill and gully erosion

Several kinds of methodologies and techniques have been used indeed in order to monitor rill and gully erosion processes. In this paper authors provide a guidance regarding the available aerial photographs and orthophotographs for rill and gully erosion studies in Spain and covering the whole country. A set of 8 different series of aerial photographs and orthophotographs were located in Spain. Their characteristics were quite diverse, differing in scales, formats and resolution. Most of the photographs and orthophotographs proved, at least, to be suitable for their use in studies of permanent gullies, allowing the monitoring of medium and long-term erosion rates since 1945.