Estudio de los acantilados activos y del campo de dunas de Bahía Creek, Río Negro, Argentina, como base para la elaboración de un mapa de peligro geológico

Abstract

Study of the active cliffs and the dune field from Bahía Creek, Río Negro, Argentina as base for the elaboration of a geological hazard map. In this paper, a physical characterization was carried out together with the study of some socioeconomic aspects of the coastal region of Bahía Creek; so, the active cliff and the dune field of Bahía Creek were analyzed as well as the development of the local popula-tion. The recorded characteristics permitted to develop a risk assessment of the active cliff erosion, calculated as a unique numerical measure through the risk index. It was studied in three sectors, resulting medium in two sectors and low in the remaining. In addition, based on satellite images, aerial photographs and wind data, the annual migration rate for the closest dunes to the town of Bahía Creek was calculated. According to the rate of migration of the dunes, estimated at 5.71 m/year, its future location was projected in the next 10, 25, 50 and 100 years. Knowing the risk index values of the cliff and the probable location of the dunes in the future, it was possible to draw up a geological hazard map for the Bahía Creek area, which was subdivided into high, medium and low hazard. The high hazard zone considers the areas where the active cliff and active dunes are currently located and where their retreat or advance, respectively, may occur in short – medium term, i.e., months or until the next 25 years. The medium hazard zone presents marked irregular terrain and is located next to the high hazard zone and may be affected within the next 50 years by the retreat of the cliff and the dune migration. On the low hazard zone, it is inferred that it will not be modified in a lapse of at least 100 years, consequently it is advisable to build there in the future. The area of the current population settlement is almost entirely within the high hazard zone. Therefore, likely management measures to be implemented in relation to it are discussed