An assessment of gully erosion on blue clay slopes at Ta' Leveċa, Għasri, Gozo

Abstract

This research investigates the geomorphological processes associated with natural erosion and erosion induced by anthropogenic activities experienced on the Blue Clay slopes at Ta' Leveca, Ghasri, northern Gozo. Gullies forming on the Blue Clay slopes provide an indication of severe erosion and thus are investigated in detail. Different types of gullies have been identified and an attempt is made to explain their formation. The Mediterranean precipitation pattern is one of the main factors causing erosion and this is also taken into consideration. Geomorphological mapping and slope profiling were performed during September 2002 and January 2003. The aim was to assess the rate of erosion on Blue Clay slopes, resulting in the formation of gullies during this period which coincides with the occurrence of rainfall in the Maltese Islands. Two gullies and two tracks were selected to determine soil erosion. The tracks are used for offroad activities and represent disturbed areas. The gullies are undisturbed areas and the present erosion processes occur as a result of natural elements. Sediment discharge was measured on a weekly basis with the help of sediment traps installed in the tracks and gullies. Physical and geotechnical tests were performed on material collected from both disturbed and undisturbed areas at Ta' Leveċa. The properties of Blue Clay were determined for both site conditions. The results provide an explanation for the occurrence of erosional processes and associated gully formation in specific areas at Ta' Leveċa. In the conclusion several conservation and remedial measures have been identified and suggested to reduce the rate of Blue Clay erosion at Ta' Leveċa.