Buenos Aires dunes reservations in relation to the sea level reversal

Abstract

Buenos Aires coastal barriers originated by the Holocene fluctuation of the sea level. The fine sand abundance and the onshore winds constructed the Eastern Barrier while at the south dunes climbed to old cliffs. The increase in Precipitation and the afforestation transformed sand dune fields into resort villages, and later to cities devoted to the “sun and beach” tourism. Notwithstanding that, hydrogeologic water reserves always limited some localities. The urban sprawl led to implement urban cities that were limited to the widths of these barriers. Dune forestation led to beach unbalances, that increased triggered by extratropical storms arriving from the southeast. Sand mining from the beaches was forbidden (law 8758/77). Urban growth caused the proposal of buffer areas (statement 8912/77) and to promote reserves to compensate the urban expansion along the coast (statement 3202/06). During the eighties and nineties some coastal counties promote foredune fixation with fences (locally called “enquinchados”) constructed by branches, but without a proper sand management. Today, foredune retreat is 1 m/year averaged, although at some counties it could be higher caused by some activities (stormwater patterns, coastal defences, bathing facilities). Considering the present forecasts of a higher sea level (0.4-0.8 m for year 2100) and the increase in the frequency and intensity of extratropical storms, it is clear that these dune problems would be worse. In this sense, new initiatives and management policies should be planned.