Local Factors Controlling Gully Development in a Mediterranean Environment

Gullies contribute very efficiently to soil loss and degradation, particularly in Mediterranean environments. While natural factors are involved in gully formation and further development, anthropic action is almost always an element. Knowledge of formation and development factors are important if soil protection strategies and measures are to be effective. In this paper, we identify the most important factors in the development of gullies in a Mediterranean setting based on a study of the Alva gully (central Portugal). Its development in the last four years is examined, based on a study of the modification of its morphological characteristics. The analysis was based on principal component analysis (PCA) to estimate the correlation between the quantitative characteristics, geomorphological processes, and biophysical variables. The results show that the main factors that seem to control the spatial variation of soil erosion are the soil penetration resistance, slope, slope shape, and vegetation cover.