Suelo-paisaje-erosión. Erosión por carcavas y barrancos en el Alt Penedès - Anoia (Cataluña). Un enfoque de estudio mediante tecnologías de la información espacialbases de datos, sistemas información geográfica teledetección

Abstract

This research represents a contribution to the development of methodologies to extend the applicability of geographical information systems (GIS), remote sensing and spatial databases to terrain analysis, particularly soil-landscape relationships, soil properties and hydric erosion processes, and more specifically gully erosion processes. The research is carried out in the l'Alt Penedès y l'Anoia (Catalonia), an area where vineyards for high quality and "cava" production are the main crop, but where the present manner of soil use and management, with few control measures, determines the future sustainability of the present agricultural uses. One of the main results of the present research is the soil information system (SIS), that contains semi-detailed scale information about the soils of the study area. It allowed the analysis of the spatial distribution of the main soil types, their properties and their behaviour in front of the actuation of erosion processes and anthropic transformations. Also, it constitutes the basic structure from which more detailed soil spatial databases can be developed. Another contribution is the set of methodologies, based on the multitemporal analysis of aerial photographs and digital elevation models (DEM), multispectral classification of satellite images and GIS spatial analysis, that is addressed to the analysis of gully erosion processes. The application of those methodologies to the Alt Penedès - Anoia area revealed the important influence of the anthropic factor in the acceleration of the present erosion processes, that is observed through: a) the soil properties, with the presence on surface of materials that are rich in calcium carbonate, calcilutites or sandstones from subsurface layers, b) the morphometric and morphographic analysis of the geoforms, which shows a shape of the landscape with complex slopes and large gullies, and a high density of gullies, c) the analysis of the rates of gully erosion, that have been particularly high since the generalised deforestation to plant vineyards in the XVI Century and, above all, since the advent of mechanisation. This research confirms the importance of combining field and laboratory techniques with remote sensing techniques for data acquisition and knowledge concerning the occuring erosion processes, and with GIS techniques for modelling.