Measuring geomorphological vulnerability on beaches using a set ofindicators (GVI): A tool for management

Abstract

A system of indicators has been developed to evaluate beach\r\ngeomorphological vulnerability (GVI) through: intrinsic susceptibility,\r\nthe agents that model them, and their ability to remain stable over\r\ntime. The method is applied to 34 beaches on the island of Gran Canaria\r\n(Spain) that experience different levels and conditions of human\r\noccupation, marine incidence, landforms and sediments, and spatial\r\nevolution that have been recorded since 1960. In contrast with other\r\nstudies, the analysis of these dimensions (and their relationships)\r\nallows a diagnosis of the geomorphology of the beaches with an\r\nintegrated approach. The results illustrate the numerous causes that\r\ngenerate geomorphological vulnerability, such as wave intensity, the\r\npresence of dikes or breakwaters, coastline variations, the absence of\r\nforedunes and embryonic dunes, the width of the intertidal zone, or the\r\nabsence of beachrocks or lavic stones outcropping onto the shore. These\r\nvariables combine and operate differently in five defined groups of\r\nbeaches with different management needs. The most vulnerable ones were\r\nthose with strong marine incidence, which require maintenance of their\r\nlandforms in order to guarantee their stability. The opposite situation\r\nis found in beaches with little impact from anthropic and marine\r\ncomponents. These beaches are less vulnerable since they have moderate\r\nsusceptibility and high resilience. Their management requirements\r\nconsist of soft measures since they have a strong geomorphological\r\nrobustness. In this context, the proposed indicator system is a\r\npotentially relevant contribution to the management of beaches,\r\nespecially for those that are under threat.