El Cross

Littoral 2002, The Changing Coast. EUROCOAST / EUCC, Porto – Portugal Ed. EUROCOAST – Portugal, ISBN 972-8558-09-0

Gross Approximation on the Erosive Vulnerability along the Mexican Coast
Isaac Azuz-Adeath
Ph.D., Strategic Development Center CETYS-University (México), 416 W. San Ysidro Blvd. S-L839, San Ysidro CA, 92173 USA, iazuz@ens.cetys.mx

Abstract A simple methodology is presentedfor evaluating the erosive vulnerability along the Mexican coast and the associated risk for the coastal states. The methodology uses a dynamic approach in order to consider the time-dependent beach-profile response to severe storms, statistical information for the cyclonic incidence, and some coastal socio-economic indicators developed during the course of the research. In this paper, we use selectsedimentary information from 274 sampled beaches and a common, ideal beach profile form with square berm and sloping beach face. A new empirical relationship was established between the sea-level rise and the breaking height. A sea level over elevation of 1m is considered for two different storm duration times; the first, simulating a short-duration hurricane and the second, a long-durationnortheast. Thus, we propose four qualitative levels of erosive vulnerability for the Mexican coastal zone that includes beach profile response to storm surges, cyclonic risk, and coastal socio-economic indicators. 1. INTRODUCTION Mexico is surrounded by the Gulf of Mexico, Caribbean Sea, Pacific Ocean and Cortés Sea; it has more than 11,000 km of littoral, shared by 17 of 32 coastal states, comprisingmore than 60% of the national territory. Approximately 14.7 million people live in coastal counties, where the standard of life is better than of the other Mexican counties. The Mexican coastal zone possesses different classes of ecosystems, characterized by extensive seagrasses, mangrove forests, coral reefs, lowland tidal wetlands, and broad deltaic environments. Most of the coastal geomorphicfeatures are present: sandy beaches and dunes, rocky coasts, cliffs, coastal wetlands, estuaries and coastal lagoons. Associated with the coastal zone, are important economic activities such as fishing, oil exploration, mining, aquaculture, building, tourism, ports, harbors and marinas, industry, agriculture, housing, natures reserves, which are increases over time. The Mexican beaches and resortslike Acapulco, Cán-Cún, Ixtapa, Los Cabos, and Huatulco are world famous for their scenic beauty and cultural attributes. Yet, México does not posses a National Coastal Management Plan or Coastal Laws that comprise the definition of risk areas for natural disasters. Two major types of storms impact the Mexican coasts. Hurricanes and nor´easters, affect the littoral, producing human losses. It isimperative that the country address the issue and remedy the problem. In this paper, we present the methodology developed as well as the results obtained, to evaluate the erosive vulnerability of the Mexican coast, taking into account the beach profile response to storm-surge sea-level rise, the probability of occurrence of cyclonic impacts, and some coastal socio-economic indicators. 2.SEDIMENTARY AND GEOMORPHOLOGIC INFORMATION. The Mexican coast extends roughly 11,000 km and is characterized by nine physiografic regions, according to Tamayo (1990) and CarranzaEdwards et al. (1996). For the nine regions, 274 beaches was sampled and 1,100 sand samples were collected. The full methodology and results were presented by Carranza-Edwards (2001). Figure 1 shows the nine study regions. Region 1includes the coastal states Tamaulipas (TAM) and Veracruz (VER), Region 2 comprises Veracruz (VER) and Tabasco (TAB), Region 3 Tabasco (TAB) and Campeche (CAM), Region 4 includes Campeche (CAM), Yucatan (YUC) and Quintana Roo (QR). Along the Pacific Coast, Region 5 comprises the west coast of Baja California (BC) and Baja California Sur (BCS), Region 6 includes the east coast of Baja California...