Sand Transport in a Cliff Top Dune System at Fonte-De-Telha, Portugal

This study describes the present day processes which are building and modifying a system of cliff-top dunes on the mid-western Portuguese coastline (Costa Azul). The site is made up of approximately 4 km of coast consisting of intermediate/reflective beaches with a sandstone cliff 50-6Om high, which as a result of the 1755 earthquake, has been set back 4O-5Om from the back shore. On top of this rests both old and recent cliff-top dunes, those nearest the cliff edge being presently active. Initial results from field work, ground observation, aerial photography and sand grain analysis, show a complex sediment cycle within the active part of the system. This results in the nett aeolian inland movement of sediment from the beach, up over the cliff head and into the cliff-top dune field. A certain degree of negative feedback in the system arises from the downslope gravitational movement of debris eroded from the sandstone cliff-face. Future management of the area requires a more thorough investigation into the dynamics of the system. The current picture of events leads to a note of caution, as factors such as increased vegetation density obstructing inland sediment movement and a detrimental human influence may lead to damage of an important and rare site.