Sand availability for nourishment of the Miramar and Chapadmalal beaches, Argentina

Abstract

The beaches of Miramar were originated by the migration of transverse dunes from the west of the city, although the provenance of the sand is of marine origin and deposited by wave action. When this input of sand diminished significantly due to the dune fixation at the Ameghino Nature Reserve, a groyne field was emplaced and, after several years, extended to provide a minimum beach width for tourist requirements. Today, artificial beach nourishment is the only method to guarantee enough sand from the near-shore. The distribution and quality of the sand as a source for the replacement of the Miramar and Chapadamalal beaches were analyzed By the mean of a side-scan sonar surveys and drag samples. Nourishment and recurrence factors were estimated in relation to the grain-size distribution on these beaches. Present near-shore beaches are composed of fine sand and extend to a depth of 10-15 m. Farther offshore there are indurated silts extending as submerged platforms to a depth of 20 m. There is another sandy bottom at a lower depth that is dominated by sand ribbons oriented toward the NE. Unfortunately, these sands are too fine and therefore considered economically unsuitable for the replacement of the Miramar and Chapadmalal beaches.