1165 | manual – juny 5 | Geo-environmental factors controlling gully distribution at the local scale in a Mediterranean environment | Bruno Martins; Catarina Pinheiro; Adélia Nunes; António Bento-Gonçalves e Luciano Lourenço
The study was conducted with the aim to identify the primary factors controlling gullies formation and evolution, in Central Portugal. A total of 38 permanent gullies were found in an 11 km2 area with an average length, maximum width, and width of 105m, 6.8m and 3,8m, respectively based on orthophoto-map analysis. 11 geo-environmental factors were selected. The gullies are located in an area of highly weathered granites which allowed the presence of deeply weathered crusts. The recurrence of several fires, in particular, the 2017 fire will have allowed the destruction of much of the vegetation that will have favoured not only the installation of gullies but allowed a rapid evolution of gullies already installed in the immediate period of the fire. GA identified two groups of gullies differentiated not only by morphological aspects as well as geo-environmental elements. One group of gullies is characterized by being of larger size and are located preferentially on slopes with greater slope. The second group is smaller, more conditioned by the presence of roads and paths, and located on slopes with lower slopes. Optimal scaling via PCA produced a solution slightly higher than 70% being identified as the main variables the slope, topographic ruggedness index (TRI), and vegetation gain (VG). This study contributes to identifying a better current gully erosion situation which can provide an important reference for risk assessment and control of gully erosion. Due to the size of the gullies, as well as the recurrence of forest fires affecting the study area some indispensable gully erosion control practices should be urgently implemented
Bruno Martins; Catarina Pinheiro; Adélia Nunes; António Bento-Gonçalves e Luciano Lourenço
Universidade de Coimbra (Portugal), Faculdade de Letras, Departamento de Geografia e Turismo, CEGOT, RISCOS; Universidade do Minho (Portugal), Instituto de Ciências Sociais, Departamento de Geografia
ID Abstract: manual – juny 5