Spatial distribution and morphological features of gullies in an agropastoral area in Sardinia (Italy)

According to the United Nations Convention to Combat Desertification soil erosion is one of the main causes of desertification in the northern Mediterranean. Recently the role of channel erosion in sediment delivery has become better understood by experimental research. The aim of the present work is to set up a simplified experimental methodology to study the relations between gully erosion, land types, and land use. The experimental area (about 720 ha) is located in a hilly region threatened by desertification in central eastern Sardinia, Italy, and is characterised by uneven morphology with steep slopes, where agropastoral activities, particularly tillage with heavy machinery and overgrazing, are causing severe soil erosion and compromising agricultural productivity. Previous studies carried out in the same area highlighted the need to quantify and monitor soil erosion to be able to give management guidelines to decision makers and to farmers. In this study, carried out in May 2003, an inventory of gullies of the area was made through an integrated use of aerial photographs and field surveys. The degree of activity and morphological features of gullies were assessed in the field using simple criteria. The approach applied included the measurement of the position and shape of gully heads and their width and depth at specific points. Relations were studied among distribution, frequency, and morphological characteristics of gullies and geomorphological features and land use.