Abstract

(Introduction):  El Ferrol bay has faced critical erosion since the 1970s; in order to contain the destructive effect of the urban area, the erosion line has been covered by rock.

(Objective):  Describe and analyze the erosive process and propose scenarios to implement numerical models.

(Methodology):  Bibliographic information, photographs, photogrammetric charts, nautical charts, cartographic maps, and Google Earth images were reviewed and analyzed, and on-site visits were conducted.

(Results):  The sources of sand come from the Lacramarca River and the dune system. The bay has lost 6200 m (45 %) of the beach: 50 % rocky, 27 % with stones, 13 % with clearing, and 10 % without protection. The front with the greatest erosion is Plaza 28 de Julio, where breakwaters mitigate the destructive effects on the urban area. Erosion factors include buildings (dry dock, warehouses, terraces, dock access structures) on the supralittoral and intertidal zone that interfere with the coastal transport; retention of sand in the dock area by organic sludge; the rock itself; and the forced transfer of the Lacramarca River mouth in 2009 about 1000 m to the south, debouching onto a calm zone. The dune system contributes with less sand by increasing the water table.

(Conclusions):  The factors with the greatest impact are buildings, retention of sand in the south due to river relocation, and the rockfall. To allow the littoral transport of sand, the river mouth must be returned to the 2009 location and the abandoned infrastructure must be removed. Scenarios for numerical modeling are proposed to establish a recovery plan.

Keywords: coastal transport; docks; dune system; Lacramarca river; sand