Clean – Soil, Air, Water 2012, 40 (9), 911–919 911 Rodolfo Silva Casarin1 Research Article Gabriel Ruiz Martinez2 Ismael Marin˜o-Tapia2 Gregorio Posada Vanegas3 Manmade Vulnerability of the Cancun Beach Edgar Mendoza Baldwin1 System: The Case of Hurricane Wilma Edgar Escalante Mancera4 Climate change and resultant coastal erosion and flooding have been the focus of many 1Instituto de Ingenierı´a, Universidad Nacional Auto´noma de Me´xico, recent analyses. Often these studies overlook the effects of manmade modifications to Me´xico, Me´xico the coastline which have reduced its resilience to storm events. In this investigation, we 2Laboratorio de Procesos Costeros, integrate previous reports, historical photo analysis, field work, and the application of Centro de Investigacio´n y Estudios numerical models to better understand the effects of Wilma, the most destructive Avanzados del Instituto Polite´cnico Nacional, Me´rida, Me´xico hurricane to affect Cancun, Mexico. Huge waves (of significant height, >12 m), long 3Instituto EPOMEX, Universidad mean wave periods (>12 s), devastating winds (>250 km/h), and powerful currents Auto´noma de Campeche, Me´xico (>2 m/s) removed >7 million cubic meters of sand from the Cancun beach system, 4Instituto de Ciencias del Mar y leaving 68% of the sub-aerial beach as bedrock, and the rest considerably eroded. Limnologı´a, Universidad Auto´noma de Numerical simulations show that the modifications to the barrier island imposed Me´xico, Unidad Acade´mica Puerto Morelos, Me´xico by tourist infrastructure have considerably increased the rigidity of the system, increas- ing the potential erosion of the beach under extreme conditions. If there were no structural barriers, a series of breaches could occur along the beach, allowing exchange of water and alleviating storm surge on other sections of the beach. If the effects caused by anthropogenic changes to Cancun are ignored, the analysis is inaccurate and misleading. Keywords: Anthropogenic changes; Beach vulnerability; Cancun beach; Hurricane Wilma; Resilience modifications Received: December 5, 2011; revised: January 25, 2012; accepted: February 22, 2012 DOI: 10.1002/clen.201100677 1 Introduction 2–3 billion USD per year, http://sedetur.qroo.gob.mx/estadisticas/ estadisticas.php). Since the 1960s, scientists around the world have been warning Any extraordinary storm unquestionably modifies the natural about possible climate changes and their potential effect on the state of any beach, but where there have been badly planned, man- planet. The recent increase in the number and magnitude of hurri- made alterations on the coastline which cause erosion under normal canes has been related to global warming [1–3]. Consequently, eco- conditions, a hurricane will considerably accelerate this process. The systems and coastal zones around hurricane trajectories are seen to present article describes the morphodynamics of the littoral and be more vulnerable. When hurricane Wilma crossed the Yucatan lagoon systems of Cancun. The wave climate in the region and the peninsula close to the Cancun beach system, in 2005, approximately characteristics and effects of hurricane Wilma are also presented, seven million cubic meters of sand were removed from the shoreline. and evidence is given of some changes to the littoral and lagoon This caused an approximate loss of one billion USD in tourist rev- systems, caused by the hurricane, and which cannot be re-estab- enue, prompting the Mexican Federal Government to invest more lished naturally. than 50 million USD in a beach nourishment program. On the other Wilma was a record breaking hurricane in many ways, e.g.: (i) The hand, the damage caused to the sand barrier also initiated an excep- hurricane occurred in 2005, the warmest year on record and unpre- tional natural cleaning process in the Cancun lagoon system cedented in the Atlantic in terms of tropical cyclone activity [4]; (Nichupte–Bojorquez, see Fig. 1, especially at the northern end where (ii) During the strengthening episode the eye of the hurricane con- over-wash was widespread. tracted to a diameter of 2 n mi, reportedly the smallest eye known to The resort of Cancun offers the tourist long beaches of medium- the National Hurricane Center [5]; (iii) The barometric pressure fine white sand, and the clear, turquoise sea is a perfect place for registered by the hurricane was 882 mbar, the lowest recorded for bathing. Indeed, Cancun is one of the most important tourist resorts a storm in the Atlantic basin [6]; (iv) Wilma was the fastest growing in Mexico, with an incomparable infrastructure (148 hotels of 4 and tropical cyclone, intensifying its wind fields from 60 to 150 kt within 5 stars, 27 000 hotel rooms) and enviable tourist expenditure (around just 24 h, an unprecedented event for an Atlantic tropical cyclone (www.ncdc.noaa.gov/special-reports/wilma.html#overview); (v) The hurricane moved very slowly across the Mexican Caribbean, staying for over 48 h in the region. Some of the consequences of her passage Correspondence: Dr. R. Silva Casarin, Instituto de Ingenierı´a, Universidad are still being felt in the region, 6 years on; (vi) For Mexico, Wilma Nacional Auto´noma de Me´xico, Cd. Universitaria, Coyoacan, 04510, Me´xico, D. F. Me´xico was the most powerful meteorological extreme event, producing a E-mail: [email protected] rainfall of 1637 mm in 24 h. It also registered the most intense wind ß 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.clean-journal.com 912 R. Silva C. et al. Clean – Soil, Air, Water 2012, 40 (9), 911–919 Figure 1. Location of the Cancun beach system and named parts of the lagoon system. for any hurricane observed in Mexico, with a maximum speed of behind which remnants of hurricane-produced escarpments are 201.1 km/h on October 21, 2005 at 7 pm [7]; (vii) Finally, the economic preserved at the juncture of the beach with the eolian dunes. losses resulting from the passage of the hurricane were estimated at US$1–3 billon, the highest cost related to any hurricane in Mexico [8]. 2.2 Morphodynamics of the Cancun beach system All coastal landforms tend to oscillate around a particular equi- 2 Materials and methods librium. The Cancun beach system is classified as one of dynamic 2.1 Geophysical information of the Cancun beach metastable equilibrium [10]; the forms and processes of the beach and lagoon systems over time are stable. When an extreme event changes the processes and characteristics of the beach, the equilibrium is modified and The configuration of the lagoon system results from a series of beach Nature tries to recover the conditions and patterns present before ridges accreted along the mainland coast during the last Pleistocene the storm. However, if the beach is unable to restore the last equi- high stand in sea level. The sea level later fell several meters, during librium, the beach will develop a new stage of equilibrium which the early stages of the last glacial period, and these carbonate dune will be different after another storm or hurricane. In this article, ridges were left exposed. Carbonate mud deposits were laid during several extreme meteorological events are discussed, being defined the Holocene [9]. The lagoon system contains seven water bodies: as a storm event with offshore significant wave heights (Hs) >4m; Bojorquez Lagoon, Nichupte Lagoon (which is formed by North, three times the annual average significant wave height. South and Central basins, San Buenaventura is part of the North Fundamental to understanding the morphodynamic behavior of Basin), Ingles Lagoon, Caleta Lagoon, and Ciega Lagoon. the Cancun littoral system is the wave climate. A hybrid wave model Using coastal geo-morphological terminology, the area known as was used to build a wave climate database and shows that over 60 Cancun is classified as a barrier island with a headland beach system. years (1948–2007), under normal conditions, 68% of the time, the It is in the north east of the Yucatan peninsula, in the state of waves arrived from the East and the East South East. Wave directions Quintana Roo, (lat. 21.158 N, lon. 86.798 W to lat. 21.028 N, lon. did not change significantly during the year, with the exception 86.77 8W) on the Mexican Caribbean Sea. The island is around of summer, when some waves arrived from the East-Northeast. 17 km long and <700 m wide (Fig. 1). The range of modeled significant wave heights was 0.5–3 m and that The Yucatan Peninsula is part of a large limestone shelf, of of wave periods was 4–10 s, which exceeds the 1-m threshold for approximately 350 000 km2, on top of which lie carbonate rocks 3066 h/year (35% of the time). Using this framework of wave climate, and sediments. The Cancun beach system was formed by an accumu- it is easy to infer that alongshore currents will carry most sediment lation of carbonate grainstone which built a strand plain along the toward the north. However, there is little evidence of significant Yucatan coast during the late Pleistocene high stand of sea level sand accumulation at the northern end of the system (Punta (125 000 years ago). The carbonate and oolitic grainstone was mainly Cancun). On the contrary, sand loss is predominant here. This deposited by waves and by longshore currents along the prograding implies that the sand transported toward the north escapes from mainland shoreline. Punta Cancun and Punta Nizuc are remnants of this littoral cell, offshore, and to the north, driven by the prevailing a Pleistocene eolian ridge, from which tombolos, composed of bio- background shelf currents. Recent analysis of morphological data clastic-oolitic sands, extend toward the mainland, intermittently and the results of propagation models [11] clearly show that refrac- broken by channels linking the lagoon system to the open sea.