Summary of Puerto Rico's Vulnerability to Coastal Hazards

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Summary of Puerto Rico’s Vulnerability to Coastal Hazards: Risk, Mitigation, and Management with Examples

Article in Special Paper of the Geological Society of America · January 2009

DOI: 10.1130/2009.2460(11)

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The Geological Society of America Special Paper 460 2009

Summary of Puerto Rico’s vulnerability to coastal hazards: Risk, mitigation, and management with examples

David M. Bush† Department of Geosciences, University of West Georgia, 1601 Maple Street, Carrollton, Georgia 30118, USA

William J. Neal† Department of Geology, Grand Valley State University, 1 Campus Drive, Allendale, Michigan 49401, USA

Chester W. Jackson† Department of Geology, University of Georgia, 210 Field Street, Athens, Georgia 30602, USA

ABSTRACT

Puerto Rico’s high population density (430/km2) and concentrated development in the coastal zone result in communities that are highly to extremely vulnerable to coastal hazards. Tsunamis pose the greatest extreme risk (e.g., 1867 southeast coast; 1918 northwest coast), and westward-moving hurricanes have a history of severe impact (e.g., Hurricane Hugo, 1989; San Ciriaco Hurricane, 1899). The north and west coasts experience far-traveled swell from North Atlantic winter storms (e.g., the Perfect Storm of 1991) which severely impact the coast. Sea-level rise threatens fl ooding of low-lying coastal mangroves, wetlands, and low-elevation developments, and erosion of wave-cut bluffs will accelerate (e.g., south coast Municipios (equivalent of counties) of Arroyo and Guayama, just west of Cabo Mala Pascua). Anthropogenic effects have seriously modifi ed coastal processes to create high- to extreme-risk zones. Examples include removal of protective dunes and beach sediment by sand mining (e.g., Piñones, Caribe Playa Seabeach Resort, and Camuy), and erosional impacts due to marinas (e.g., erosion rates of 3 m/yr in Rincón area due to Punta Ensenada marina). Communities have taken poor courses in erosion control by emplacing shore-hardening structures along over 50 separate coastal stretches (e.g., seawalls at San Juan Harbor and Arecibo; groins in Ensenada de Boca Vieja), and utilizing poor construction designs (e.g., gabions). Beach profi ling reveals that beaches narrow and disappear in front of such structures (no dry beach in front of 55% of seawalls sur- veyed). Mitigation must come through prohibiting construction in high-risk zones, encouraging wider adoption of setback principles (e.g., Villa Palmira), relocating after storms, enforcing anti–sand-mining regulations, and better public education.

†E-mails: [email protected]; [email protected]; [email protected].

Bush, D.M., Neal, W.J., and Jackson, C.W., 2009, Summary of Puerto Rico’s vulnerability to coastal hazards: Risk, mitigation, and management with examples, in Kelley, J.T., Pilkey, O.H., and Cooper, J.A.G., eds., America’s Most Vulnerable Coastal Communities: Geological Society of America Special Paper 460, p. 149–165, doi: 10.1130/2009.2460(11). For permission to copy, contact [email protected]. ©2009 The Geological Society of America. All rights reserved.

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INTRODUCTION vulnerability as 6.2% extreme, 61.1% high, 20.4% moderate, and only 2.3% low. Bush et al. (1996b, 2001) presented coastal zone With a surface area of 8896 km2 (3435 square miles) and a hazard maps for eastern Puerto Rico (the area most impacted by population of over 3.8 million, Puerto Rico’s population density Hurricane Hugo) that depicted coastal geology and geomorphol- is ~430 people/km2. However, the island’s mountainous terrain ogy, beach characteristics, offshore (inner-shelf) characteristics, constrains private and commercial development to sites concen- and hazard potential from such events as fl ooding, marine over- trated in the coastal zone (e.g., level coastal areas, fl oodplains, wash, erosion, earthquakes, and landslides. In addition, special areas of artifi cial fi ll), or unstable hilly terrain. The high popu- consideration was given to areas where shoreline engineering or lation density and the extensive industrial, commercial, public, dense development signifi cantly increased the overall vulnera- and private development since the 1950s in the coastal zone have bility (potential for property damage) of a coastal stretch. placed both increased population and property at risk. Much development took place without knowledge or regard for the geo- STUDY AREA logic hazards that affect the coastal zone. The predictable results are recurring disasters characterized by increasing total property Puerto Rico, the easternmost and smallest of the Greater damage losses and greater potential for loss of life. Such disas- Antilles Islands (Fig. 1), is ~160 km long (east-west) and 50– ters occurred with the arrival of Hurricane Hugo in September 60 km wide (north-south). The surrounding insular shelf ranges 1989, and the passage of Hurricane Georges in October 1998 in width from less than 0.5 km on the northern shelf to over 25 km (Thieler and Bush, 1991), as well as several less intense hur- on the western shelf. The island has close to 1200 km (700 mi) ricanes in the interim. of coastline that is naturally compartmentalized by numerous Major hurricanes are reminders of both the long history of rocky headlands (Fig. 2). Adjacent compartments often have in- coastal hazard impact and the increasing cost of each new haz- dependent origins and controls (e.g., different geologic materi- ard event. Since the 1980s, greater attention has been paid to the als and structure; different orientations to marine conditions), so array of hazards threatening Puerto Rico’s coast, including earth- this compartmentalization provides a physical basis for consider- quakes and tsunamis (McCann, 1984, 1985; Hays, 1985; Lander ing segments as separate entities. This affords the potential for a and Lockridge, 1989; Díaz-Hernandez, 1990; Mercado et al., compartmentalized approach to coastal management rather than 2002; Grindlay et al., 2005), hurricanes (Thieler et al., 1989; regarding long reaches of the coast in a uniform fashion (Jackson Bush, 1991; Sola, 1995), mass wasting (Molinelli, 1984, 1985; et al., 2009). Both environmental and economic management de- Larsen and Torres-Sánchez, 1992, 1998), and shoreline erosion cisions can then be focused by compartment, and can be based on (Morelock, 1978, 1984; Morelock and Taggart 1988; Morelock environmental sensitivity, geologic setting, including natural haz- and Barreto, 2003). Shoreline erosion, a persistent hazard, is both ards, and the level and type of existing development. However, a short-term effect due to storms, as well as a long-term effect an initial understanding of the vulnerability to natural hazards due to high wave energy and sea-level rise. River fl ooding is a rests on an overview of the island’s climatic, oceanographic, and common hazard in the coastal zone due to hurricanes and other geologic settings. high-rainfall events. Perhaps the best current source for information on Puerto Puerto Rico’s Tropical Setting Rico’s coastal hazards is “The Coastal Hazards of Puerto Rico” Web site at http://coastalhazards.uprm.edu/. It was organized by Puerto Rico is situated at ~18°N latitude. The average high and is supervised by Aurelio Mercado and Harry Justiniano of temperatures in San Juan are ~35 °C (95 °F) in the summer and the Physical Oceanography Laboratory, Department of Marine 29 °C (85 °F) in the winter, and average daily lows are a few de- Sciences, University of Puerto Rico, Mayagüez, and is sponsored grees either side of 24 °C (75 °F) year-round. In the mountainous by the University of Puerto Rico Sea Grant Program. See also interior, temperatures are ~4–5 °C (10 °F) degrees cooler on aver- the Sea Grant Technical Report, Rodríguez et al. (2006), and the age than San Juan. According to the “Current Charts of Central University of Puerto Rico Sea Grant College Program Web site at American Waters” published by the U.S. Hydrographic Offi ce, http://www.seagrantpr.org/. open-sea water temperatures range from a minimum of ~25 °C After Hurricane Hugo, the U.S. Geological Survey (USGS) (77 °F) in March to a maximum of ~28 °C (82 °F) in September. began a program to assess the impact on coastal resources and Nearshore temperatures are somewhat higher and more variable. environments caused by this storm, and to provide baseline The Central Cordillera mountain belt is a primary control on data against which to measure the impact of future storm events climate. Rainfall is orographically controlled, and the east-west– (Schwab and Rodríguez, 1992; Thieler and Danforth, 1993; trending Cordillera divides the island into a humid northern Delorey et al., 1993; Thieler and Danforth, 1994a, 1994b; Rodrí- two-thirds and a much more arid southern one-third (Ehlmann, guez et al., 1994; Schwab et al., 1996a, 1996b). Storms are only 1968). Because most of the land area drains to the north, the one of many hazards affecting coastal areas. The multiplicity of northern shelf receives the bulk of terrigenous sediment eroded coastal geologic hazards and their identifi cation are discussed in from the island (Ehlmann, 1968; Calversbert, 1970). Rivers of Bush et al. (1995), which classifi ed the island’s shoreline hazard Puerto Rico discharge up to 70% of their annual sediment load spe460-11 page 151

Summary of Puerto Rico’s vulnerability to coastal hazards 151

67°0′0″W 66°0′0″W

18°0′0″N

30°0′0″N 75°0′0″W60°0′0″W

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75°0′0″W60°0′0″W 67°0′0″W 66°0′0″W

Figure 1. Location of Puerto Rico’s sandy shorelines engineered with seawalls, revetments, and gabions. The gabion locations represent some of the more recent engineering projects. Inset shows Puerto Rico’s location in the Caribbean. Underlined beach names correspond to the numbered circles and refer to the top 10 worst beaches described in the text. They are, from most vulnerable (1) to least vulnerable (10): 1—Balneario Carolina (formerly Balneario Isla Verde), 2—Rincón, 3—Cabo Mala Pascua, 4—Ensenada de Boca Vieja, 5—Piñones, 6—Puerto Nuevo, 7— Aguada, 8—Isla Verde, 9—Arecibo, and 10—Condado.

during a few days of torrential rains occurring through the year Roads and bridges were damaged or destroyed. Thousands lost (Lugo et al., 1980). Muddy sediments are introduced directly their houses or the contents of their homes. onto the shelf, and river mouths have been a source of sand Landslides, often triggered by hurricanes or other major for beaches. The rain shadow effect is so pronounced that the precipitation events, are also a problem in the steep tropical ter- southwest has an average annual rainfall of less than 100 cm/yr, rain. Hurricane Hugo’s rains caused over 400 slides (Larsen and compared to 150–180 cm/yr for San Juan, over 200 cm/yr for Torres-Sánchez, 1992), and tropical storm Isabel (1985) dumped much of the high interior, and over 400 cm/yr in the Caribbean 38 cm of rain on the steep slopes of the southern side of the island, National Rainforest of the Luquillo Mountains on the northeast generating a mudﬂ ow that killed as many as 96 people. Monroe portion of the island. Complicating factors for the rainfall distri- (1979) described zones of landslide susceptibility (highest, high, bution picture include hurricanes, tropical storms, and the pas- moderate, and low), and Larsen and Torres-Sánchez (1998) dis- sage of cool continental air masses. cussed landsliding in three areas of the island. Puerto Rico is a wet island, but rainfall is not evenly distrib- Puerto Rico lies within the northeast trade-wind belt, and uted in space and time. The rainy seasons of Puerto Rico, when these dominant winds from the north and east result in corre- many inches of rain can be dumped seemingly instantaneously, sponding wave and current patterns. Each of the four coasts of create an annual threat of intense river ﬂ ooding and landslides. Puerto Rico has its own unique climatic and environmental phe- The Three Kings Day, 1992, storm brought almost 50 cm of rain nomena. The northern coast of the island faces warm humid trade to Cayey, and over 25 cm elsewhere. Damage amounted to $200 winds and the rough open waters of the North Atlantic Ocean. As million in losses islandwide, and at least 20 people died. Tens of a result, this coast commonly is impacted by storm waves exceed- thousands of people lost electrical, water, and sanitary services. ing heights of 3 m. The southern coast faces the Caribbean Sea, spe460-11 page 152

152 Bush et al.

Figure 2. This radar image is a good way to visualize the physiography of Puerto Rico. The dominant feature is the mountainous spine of the central cordillera. Note the compartmentalized character of the coast. This is a mosaic combined from several aerial radar images. Clearly visible features includes the east-west–trending Cordillera Central mountain range, the Luquillo Mountains in the northeast, and the northwest- southeast–trending fault lineaments. Just off the east coast, part of the island of Vieques can be seen. Figure is from Bush et al. (1995). Images are courtesy of Simulation Systems, Inc. For scale, Puerto Rico is approximately 160 km long and 50–60 km wide. where gentle swells wash over reefs and into mangrove-fringing hurricane about every 12 yr, according to the statistics on the Hur- forests. A broad, fl at platform, extending past the Virgin Islands, ricane City Web site (http://www.hurricanecity.com); Fajardo, on partially shelters the east coast from Atlantic storms and reduces the east coast, experiences a direct hit about every 10 yr; Cabo wave energy. During the summer, the west coast has a lower- Rojo, the southwestern tip of Puerto Rico, experiences a direct energy wave climate because it lies in the shadow of the island hit about once every 13 yr; and San Juan experiences a direct hit relative to most storm waves, which approach from the north- about once every 17 yr. east or southeast. During the winter and spring, however, swell Tropical cyclones are typically still maturing while in the from North Atlantic winter storms (nor’easters) often approach Caribbean region and have not reached their maximum intensity from the west. During these events, large waves break along the (Ho, 1975). Low-latitude hurricanes tend to have small radii of western coast. In fact, the largest waves approach from the west/ maximum winds and are usually slow moving, tending to re- northwest, larger even than hurricane-forced waves. duce storm-surge elevations and impact. Storm surges from even Puerto Rico lies on the path of Atlantic hurricanes as they arc strong hurricanes range only from 2 to 3 m (Mercado, 1994). from east-west to southeast-northwest, and the majority of storm Tidal range in Puerto Rico is only ~0.34 m (Martínez, 1984), tracks trend along or parallel to the long axis of the island. Al- so tidal currents can be disregarded as being important in terms though a tsunami or great earthquake may prove to be the great- of sediment transport. The North Equatorial Current, which fl ows est overall hazard, hurricanes strike with the greater frequency. consistently to the west, was proposed to have some infl uence on The greatest loss of life occurred as a result of the San Ciriaco northern Puerto Rico shelf processes by Kaye (1959). In general, Hurricane of 1899, which killed 3369 people (Sola, 1995). Dam- however, impinging oceanic currents are not considered to be age from the San Ciriaco Hurricane was estimated at almost $36 important sediment movers on the insular shelf of Puerto Rico. million. Hurricane Hugo (1989) caused over $1 billion in dam- Net longshore transport was qualitatively studied by More- age; there were two deaths attributed to the storm. The 1899 San lock (1984) and Morelock et al. (1985) using geomorphic fea- Ciriaco Hurricane property damage would be almost $900 mil- tures (spits, down-drift offsets at promontories, river-mouth bars) lion in equivalent 2006 dollars. If there had been as much devel- as indicators. The dominant direction of longshore drift is to the opment in 1899 as in 1989, the damage from San Ciriaco easily west along the northern and southern coasts, to the south along would have exceeded that of Hurricane Hugo. the western coast, and to the north, though more variable, along Hurricanes also can strike from the Caribbean side of the is- the eastern coast. Headlands and embayments disrupt these re- land. Ponce, on the southern coast, experiences a direct hit from a gional patterns. Recognition of the longshore current and sedi- spe460-11 page 153

Summary of Puerto Rico’s vulnerability to coastal hazards 153 ment drift patterns is fundamental to understanding shoreline Mann et al. (2004), and Grindlay et al. (2005). Liquefaction of responses to storm events, as well as to daily weather patterns. artifi cial fi ll and some types of natural unconsolidated sediments Information on the basic physical characteristics of the coastal (e.g., some coastal-plain deposits) will cause destruction or ex- waters of Puerto Rico collected as part of a large study to prepare treme damage to buildings, highways, interchanges, and other a Comprehensive Water Quality Management Plan is given by services (e.g., utility lines). Much of the development in the San Oceanographic Program (1974). Juan metropolitan area is located on artifi cial fi ll and unconsolidated sediment. Development in steep mountainous areas, espe- Puerto Rico’s Geologic Setting cially where constructed on unconsolidated material, is highly susceptible to damage and destruction. The geologic setting of Puerto Rico accounts for many of The Puerto Rico Tsunami Warning and Mitigation Pro- its coastal hazards (Hays, 1985; Grindlay et al., 2005). The is- gram provides tsunami hazard assessments based on nearshore land owes its existence to the subduction of the North American bathym etry and light detection and ranging (LIDAR) surveys. plate beneath the Caribbean plate, resulting in the seismically ac- Risk assessment images are available on the Poseidon Tsunami tive Puerto Rico Trench that bounds the north side of the island. Web site at http://poseidon.uprm.edu/. Active seismic zones bound the island to the west (Mona Pas- sage and Mona Canyon fault zone) and to the ESE (the Anedaga COASTAL GEOLOGY OF PUERTO RICO Trench), and there is a zone of normal faults to the south (Muer- tos Trough). In addition, the Great Northern and Great Southern Kaye (1959) presents the classic discussion of the ways fault zones trend northwest-southeast across the island. Linea- in which geologic materials, structures, and oceanographic ments indicating these faults are clearly visible on Figure 2. processes shape Puerto Rico’s coast. The north coast consists of Owing to the tectonic setting, earthquakes pose a serious low-lying alluvial deposits (including beachrock and eolianites) threat to the entire island, but particularly in the coastal zone, and limestones. The other coastlines are limestones and alluvial where associated tsunamis have struck in the past. Great earth- deposits, and also volcanic and plutonic igneous rocks. The rock quakes and associated tsunamis have severely impacted the types forming the coastline (or part of the coastal zone) are a island (Díaz-Hernandez, 1990; Mercado and McCann, 1998; major factor in the development of shoreline morphology in Mann et al., 2004; Ten Brink et al., 2004), most notably in 1787 response to wave regime and shelf bathymetry. In terms of resis- and 1918. Earthquakes in 1615, 1751, 1776, and 1946 were cen- tance to erosion by wave action, the coastlines can be cate gorized tered in the Dominican Republic, but they caused severe damage as: hard (resistant), composed of limestone or igneous rock; in western Puerto Rico. The 1787 earthquake caused destruction semidurable, composed of eolianite or beachrock, which is less everywhere in Puerto Rico except the southern coast. The 1918 cemented and more erodible; erodible unconsolidated deposits, magnitude 7.3 quake almost leveled the city of Mayagüez on such as beach, alluvial fan, alluvial plain, or dune; and mangrove the western coast, and the associated tsunami killed 40 people shorelines, which are restricted to low-energy conditions. (Mercado and McCann, 1998). This same coastal area remains The coastal types in Puerto Rico are cliffs and rocky shores one of the most vulnerable to a variety of hazards. The 1867 (limestone, siliciclastics, volcanics, plutonics, alluvial), beaches earthquake created a destructive tsunami that impacted the south- and beachrock, dunes and eolianites, tombolos, estuaries and eastern coast. Tsunamis affecting Puerto Rico are summarized by lagoons, and mangrove and marsh. The geology and resulting Lander and Lockridge (1989). geomorphology of the coastline are extremely variable, with no To date, all known tsunamis affecting the island have been feature extending more than 5 to 10 km. The coastal features are the result of earthquakes; however, the Puerto Rico Trench is a discussed separately for the west, south, east, and north coastlines. potential progenitor of tsunamis for a second reason. Seafl oor The geomorphology is not just strongly related to the rocks form- mapping along the northern shelf and slope has revealed a giant ing the coastline and the structural patterns, but also to differences insular slope scar, suggesting the possibility that giant submarine in rainfall and wave energy. See “The World’s Coasts: Online— landslides may be triggering mechanisms in generating tsunamis Puerto Rico” compiled by Jack Morelock, Wilson Ramirez, and (Schwab et al., 1991; Mercado et al., 2002). Ten Brink et al. Maritza Barreto, at http://geology.uprm.edu/Morelock/wcpr.htm. (2004), however, indicated that these features may be produced by ongoing slumping rather than a single catastrophic event, but PUERTO RICO’S VULNERABLE earthquakes and potential tsunamis are implied. COASTAL COMMUNITIES The entire island is susceptible to major damage from earthquakes, and the relative risk is essentially equal across the entire In Puerto Rico, one only has to look out the window, take island. Differences in amounts of damage around the island will a walk along the beaches of the Condado or Isla Verde, or drive thus be a factor of development density, age and type of build- along the beaches of the many coastal roads to see that an un- ings, the local slope, and the strength of the soil. Discussions of counted number of buildings and infrastructure have already earthquake hazards for Puerto Rico are given by Molinelli (1985, been destroyed or are in grave danger from the encroaching sea. 1984), McCann (1985, 1984), Mercado and McCann (1998), Additionally, it is quite obvious that many unsound shoreline spe460-11 page 154

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management decisions have been made on this island; the beaches of the evaluation of the erosional impact are needed. Future stud- of which are the very lifeblood of its booming tourist industry. ies should assess the islandwide and community-by-community Most of Puerto Rico’s shoreline is eroding (Morelock, erosion situation relative to existing development; start a continu- 1978, 1984; Thieler and Danforth, 1993, 1994b; Bush et al., ous beach-profi ling program to monitor changes in shoreline posi- 1995; Thieler et al., 1995; Morelock and Barreto, 2003). Ero- tion, beach characteristics, and sand supply; make islandwide and sion is obviously far more important on sandy shorelines than community-wide recommendations as to shoreline-management on rocky stretches. This is well demonstrated by comparing the alternatives (for example, controlled development, relocation, need stable, rocky shorelines of Old San Juan and Cabo Rojo with for beach nourishment); and begin planning for sea-level rise. the eroding, unconsolidated shorelines at various other places around the island. Constructing Seawalls and Revetments at the Back Not all sections of all beaches are erosive. Some are stable of Beaches or are actually accreting; for example, Luquillo Beach, the beach between Punta Vacia Talega (the headland west of the city of Shoreline engineering structures contribute to erosion along Loíza) and the Loíza River mouth (just west of the city of Loíza). the Puerto Rico shoreline, as elsewhere (Pilkey and Wright, 1988). Unfortunately, some of the seemingly stable sections of the sandy For example, no dry beach remains in front of damaged buildings shoreline are merely central parts of the small, lunate bays com- and collapsed portions of small seawalls in front of houses along monly found on the northern coast. The fl anks of the bays grade Route 2 near Balneario El Tuque on the south coast (Fig. 4). to an erosive nature out to the rocky headlands separating the Beach narrowing and steepening in front of shore-hardening bays. Balneario de Carolina is a prime example. A “balneario” is structures have been documented by ongoing beach-profi le moni- a public swimming beach with facilities. toring (Jackson et al., 2001), demonstrating that hard stabilization Erosion is a problem for a number of reasons. Although rates contributes to shoreline erosion and degradation. Profi les in front of erosion are generally low, and land loss has not been signifi cant of structures and on adjacent unwalled beaches were taken on more in terms of area (Thieler and Danforth, 1993, 1994b), serious ero- than 50 stretches of shoreline and compared to measurements taken sion threats to shorefront buildings and infrastructure exist. The at the same sites during a previous study (Wright, 1989). Beaches complex, compartmentalized coast often does limit negative im- in front of walls and revetments had narrowed (Fig. 5), causing pacts to short shoreline reaches, and patchy development patterns increased danger to shorefront buildings from storm waves. have created limited pockets of distressed shoreline. Generally, Shoreline stabilization, emplaced to halt shoreline erosion in the following seven areas of anthropogenic actions contribute to Puerto Rico, has resulted in dramatic loss of beach recreational overall shoreline hazard vulnerability. quality and ease of beach access, as well as being an economic drain to all levels of government. A comparison of beach widths Failure to Take Shoreline Erosion into Account for different shoreline types in the San Juan metropolitan area, from Punta Boca Juana to Loíza, clearly shows that natural sandy Erosion is generally most serious on unconsolidated shore- beaches are much wider than engineered beaches (Fig. 6). lines. For example, Balneario Carolina, near the International Airport, has been monitored for decades (Figs. 1 and 3). A con- Insuffi cient Construction Setback from the Shore tinually high erosion rate prompted a series of engineering attempts to deal with the problem of threatened property; all ig- Perhaps the major “cause” of erosion is emplacement of nored the known erosion (Jackson et al., 2006). buildings too close to the shoreline (Fig. 4). Only a few beach- Serious impacts of erosion include: front communities have avoided this by requiring development to be set well back from the beach. Examples are Villa Palmira (1) land loss and the threat to shorefront buildings and infrastruc- near Playa de Humacao on the east coast and Suarez on the ture such as highways, power, water, and sewer lines; north coast. (2) the narrowing of beaches in front of walls and revetments, Puerto Rico must improve and enforce existing setback re- increasing the danger to shorefront buildings from storm quirements and improve building codes to minimize the impact waves; from the natural forces on buildings due to wind and potential (3) the perceived need for more hard stabilization structures fl ooding. Puerto Rico law prohibits building in the maritime (e.g., seawalls), which result in additional loss of beach rec- zone, defi ned as the area of land impacted by marine waters. It reational quality and ease of beach access; and is a vaguely defi ned zone on purpose, in order to allow maxi- (4) the economic impact to all levels of government of preparing mum access to the citizenry. Any nearshore land ever fl ooded for and responding to natural hazards. by any storm or high tide belongs to the public and must not be encroached upon. Unfortunately, the law is often disregarded or Although islandwide erosion rates were determined in the variances are granted. late 1980s (Thieler and Danforth, 1994a, 1994b; Thieler and Inspection and enforcement are keys to successful mitiga- Danforth, 1993), a renewal of the monitoring, and a continuation tion of development hazards. For developments already in harm’s spe460-11 page 155

Summary of Puerto Rico’s vulnerability to coastal hazards 155

Figure 3. Balneario de Carolina (previously known as Balneario de Isla Verde). Balnearios are public swimming beaches with amenities, and they are maintained by a local government. Major erosion caused by swell from a January 1988 winter storm, and the passage of Hurricane Hugo in September 1989, resulted in the emplacement of gabions. Continued erosion and deterioration of the gabions have lead to several generations of modiﬁ cations and repairs to the gabions. Ulti- mately, the gabions have failed, spilling rock and wire debris onto the recreational beach, to be replaced by a revetment, and subsequent engineering. Evolution of the beach: 1988—after the January 1988 winter storm swell erosion. View to the east. The boat ramp marks the shoreline previous to the mid-1970s. 1994—after a gabion wall has been built and begun to deteriorate. Note ﬁ lter cloth behind gabion wall. View to the east. 2001—the gabion has deteriorated to a point where it is a hazard to beach goers. 2006—an engineering system called a “Removable Porous Groin System” developed by NuShore, LLC, of Tallahassee, Florida (http://www.nushore.com). It was emplaced in an attempt to restore the beach and prevent further erosion in the area of Balneario de Carolina, Puerto Rico, just west of the bridge to Piñones.

Figure 4. No beach remains in front of these damaged buildings, and portions of small seawalls in front of houses along Route 2 near Balneario El Tuque have collapsed. spe460-11 page 156

156 Bush et al.

Figure 5. Results of a study of dry beach widths by Wright (1989). The goal of that study was to determine if there is a difference in dry beach width and beach proﬁ le steepness in front of seawalls compared to immediately adjacent unwalled beaches. Only beaches with walled plus unwalled segments were measured. On the graph, bars represent the difference in the mean widths of the natural beach and stabilized beach. Bars extending above the zero line indicate that the unwalled portion of the beach in question was wider. Bars extending down from the zero line indicate that the dry beach was wider in front of the walled portion of the beach. Clearly, beaches in front of seawalls were nar- rower. It is thus argued that hard stabilization contributes to shoreline erosion and degradation.

way, alternatives to hard engineering structures need to be incorporated in long-term planning (e.g., relocation programs, nourishment of recreational and protective beaches).

Other Shoreline Engineering Structures

Coastal communities in Puerto Rico have historically opted for various types of shore-hardening structures in order to deal with their erosion problems, even though such structures may en- hance lateral shoreline erosion and disrupt natural beach cycles (Jackson et al., 2001). The seawall/revetment option is usually expensive to design and emplace, leading coastal engineering and construction companies to tout low-cost solutions. One cost- cutting measure is to substitute the use of gabions for riprap or other heavy-duty construction materials such as solid concrete walls (Jackson et al., 2006). In the past 20 years, coastal communities in Puerto Rico, with limited resources, have opted for Figure 6. Dry beach widths versus shoreline type in the San Juan gabions in shore-hardening construction, even though the U.S. metro politan shoreline. The ~40 km stretch of shoreline goes from Army Corps of Engineers states that gabions should not be used Punta Boca Juan in the west to Loíza in the east. Beaches in front in high-energy shoreline environments (USACE, 1986). In short, of seawalls and natural rocky stretches have similar widths. Natural gabions are very poor choices for oceanfront construction be- sandy beaches are the widest. cause they deteriorate rapidly in the salt air and water. The end result is a beach narrowed in front of the seawall, and one ultimately littered with gabion debris, which is both unsightly and of sand for construction aggregate continues. In all cases, sand dangerous to beach users (Fig. 7). removal eliminates natural shore protection in the mined area, and depletes the sand budget for down-drift beaches, accelerating Sand Mining erosion. Even a small removal operation can initiate a sequence of major shoreline changes. Sand mining of beaches and dunes accounts for many A major dune ridge near Camuy on the north coast was of Puerto Rico’s problem erosion areas. Although such sand nearly completely removed for construction sand (Fig. 8). The removal is now illegal, permits are given by the Public Works De- original dune was over 20 m high, over 500 m long, and up to partment (Obras Publicas) to remove sand for highway construc- 100 m wide. tion and emergency repair purposes. The extraction limits of such A predictable chain reaction of events occurred in front of permits are often exceeded or used carte blanche. Illegal removal and around the Caribe Playa Seabeach Resort west of Cabo Mala spe460-11 page 157

Summary of Puerto Rico’s vulnerability to coastal hazards 157

Figure 7. Gabions are common in the Aguada area on the west coast. (A) A deteriorating gabion. Steel-wire mesh rup- tures, and stone ﬁ ll is dispersed by waves. Rusting wire and stones are hazardous to beach users. Cement covering is an unsightly attempt to hold the wall together. (B) A large sloping gabion limits beach access and results in little recreational beach. (C–D) A gabion wall for no reason subsequently replaced by a solid wall at a public swimming beach (Balneario Rincón) in 1992 (left) and 2002 (right). Why the gabion wall was built in the ﬁ rst place is a mystery. There is nothing to protect at this beautiful west coast location. It is a pure waste of money, and the beach access is compromised.

Pascua on the southeast coast. The resort has lost nearly 18 m a 3-m-high, 7-m-wide artifi cial dune was built in 1986. Where of beach according to the owner. The problem dates back to the sand was once mined, 54,000 cubic yards (well over 40,000 days before permitting and regulation, when an up-drift prop- cubic meters) of new sand were trucked in. The combined effects erty owner, east of the resort, sold beach sand for 50 cents per of swell from a January 1988 winter storm and Hurricane Hugo dump truck load; a bargain by anyone’s standards but a swindle in September 1989 completely destroyed the artifi cial dune and to down-drift property owners. The beach eroded where the sand washed sand more than 120 m into the forest (Fig. 10). The pat- was removed, resulting in shoreline retreat and tree loss. In an ef- tern repeated itself after subsequent storms. The 1990s brought fort to restabilize the shore, and ultimately protect the highway, a a massive rock revetment that blocks the view of the ocean from riprap groin and seawall were constructed. Today, only a narrow the road: the end product of a chain of events begun in the 1950s. gravel beach remains (Fig. 9). Undoubtedly, much of the aggregate in the concrete mak- Perhaps the most egregious example of problems set in mo- ing up the buildings lining the shore, which are now endangered tion by sand mining began in the 1950s along the idyllic stretch by beach erosion, was beach sand. What an extreme irony: sand of shoreline east of Balneario de Carolina known as Piñones. mined from the beach to build structures that are then endangered To construct the Luís Muñoz Marín International Airport in Isla by the loss of the protective beach. There should be no mining of Verde, thousands of tons of sand were mined for fi ll. Routes for beach, dune, or river sands at any time or place, no matter what trucking the sand from the beach became foot paths for people the volume. to go to the beach, and the recreational use of the area increased. With the protective dune and sand reservoir removed, shoreline Inconsistent or Uncontrolled Shoreline Stabilization retreat accelerated. Washovers were common, even during small storms. The coastal road from San Juan to Loíza (Route 187), Neighborhood inconsistencies in the type and degree of hard completed in the late 1970s, became a high-hazard zone instead stabilization lead to differential accelerated erosion (e.g., Mar of being behind a continuous protective dune ridge. In response, Azúl urbanization in Hatillo, and Las Carreras urbanization in spe460-11 page 158

158 Bush et al.

Figure 9. Only a narrow gravel beach remains in an area of previous beach sand mining. Note the row of palm tree stumps at the waterline. Figure 8. All that remains of a dune near Camuy on the north coast is a Vegetation covers a riprap wall that protects Route 3. The beach in small eolianite knob covered with a veneer of sand. The dune was origi- front of the Caribe Playa Seabeach Resort, which lies down drift of the nally over 20 m high, more than 500 m long, and nearly 100 m wide. beach in this photo, was severely affected by the sand mining.

Figure 10. Erosion at Piñones. After the natural dunes were removed by sand mining for construction of the international airport, this zone became an area of frequent fl ooding and overwash. An artifi cial dune was destroyed by winter storms and Hurricane Hugo. (A) Hugo overwash can be seen here to completely cover Route 187. Note the beachrock marking the original shoreline position and the line of dark boulders marking the positions of the artifi cial dunes. Photo courtesy of the U.S. Geological Survey. (B) A 2003 ground-level view showing the massive revetment seawall in 2003. Waves can be seen breaking at around the same position as on the top left photo. (C) A 2003 aerial view, showing the road (Route 187) curving inland, where it had to be relocated because of erosion. spe460-11 page 159

Summary of Puerto Rico’s vulnerability to coastal hazards 159

Loíza; Fig. 11). Hard stabilization must be controlled, perhaps basis, allowing no time for deliberation concerning other alter- through stricter enforcement of the permitting process, and a natives. Many miles of Puerto Rico’s recreational beaches have program of beach monitoring is needed to assess beach changes. been seriously degraded and even destroyed through attempts to Alternatives to hard stabilization, as noted already, must be eval- halt shoreline erosion to protect buildings. uated and considered. At least two communities, Luquillo and San Juan (Isla Verde to the Condado), could beneﬁ t immediately TEN EXAMPLES OF PUERTO RICO’S from beach replenishment. VULNERABLE BEACHES

Unrealistic Cost-Benefi t Considerations Several sections of developed shorelines around Puerto Rico demonstrate where danger from erosion can be foreseen Shore-hardening structures often fail, requiring additional in the near future. The time is now to approach the problem expenditures for maintenance or replacement. This results in in a unifi ed, scientifi c manner. The report Puerto Rico and the costs exceeding the value of the protected buildings. Historically, Sea—1999 (Beller et al., 1999) lays out strategies for all aspects the construction of seawalls and revetments is done on a crisis of coastal and marine planning and development. See also Bush et al. (1995) for discussion of Puerto Rico’s coastal hazards, and Bush et al. (1996a) for a general discussion of coastal hazards and management. Locations of the following beaches are shown as numbered circles in Figure 1. The beaches are listed from most (1) to least vulnerable (10), based on a qualitative assessment.

1. Balneario Carolina (Formerly Balneario Isla Verde)

This vulnerable shore provides an example of money wasted on unnecessary and ineffective engineering structures back- ing a recreational beach. The back-beach scarp is eroding at a very rapid rate due to the severance of the sand supply by the jetty at Boca de Cangrejos, and earlier removal of sand from the beach system when the channel for the entrance to the Boca de Cangrejos marina was dredged. At the eastern end of this reach, rock revetments have been in place for many years to protect the road. Historical erosion rates are from 1 to 2 m/yr. Parking lots of Balneario Carolina have fallen to erosion, along with trees and street lights (Fig. 3). An old yacht club had to be relocated, and the remains of its boat ramp are now in the surf zone. The response was to build a gabion wall, which failed and was replaced by a revetment. When erosion continued, the local government paid over $4 million for a “Removable Porous Groin System” in 2006 (lower right photo in Fig. 3). It was promised that this groin system would restore the beach and prevent further erosion; however, it too failed, leaving the beach littered with structural debris (Fig. 12). Ironically, the shoreline is now starting to recover somewhat after decades of erosion, not because of seawalls, but because sand dredged from the channel entrance is being redeposited back on the beach down drift of the jetty.

2. Rincón

Figure 11. The Las Carreras subdivision at Punta Uvero, east of the The gabion wall on the Rincón public beach (Fig. 7) protects City of Loíza. Differential erosion caused by neighborhood inconsis- nothing, but it caused beach narrowing as soon as it was emplaced. tencies in managing the shoreline. (A) As of 1988, some homeowners If local ofﬁ cials and the contractor had visited the corroding, “leak- chose to emplace boulder revetments and some did not. Arrow is di- ing” gabion wall at Aguada (Fig. 7), they would have known that rection of view of bottom photo. After being hit by Hurricane Hugo in 1989, many revetments were enlarged. (B) By 2000, additional revet- gabions are a poor choice for seawalls. Furthermore, the wall began ment had been added, and there is a complete lack of dry beach even experiencing back-wall scouring almost immediately. For an un- in calm weather. known reason, the gabion was replaced with a solid concrete wall spe460-11 page 160

160 Bush et al.

Figure 12. A January 2008 photo of the “Removable Porous Groin Figure 13. Ensenada de Boca Vieja near Levittown just west of San System” shown in 2006 in Figure 3 at the eastern end of Balneario Juan harbor was once a popular swimming beach for the residents. de Carolina. The groin has not caused accretion of the beach as was The riprapped and walled portion of the shoreline protects the electric predicted by the designers. Moreover, its “removable” capability, one generating plant of Palo Seco. Note the absence of a dry beach. of the groin’s major selling points, has not been put into action, even though the netting is deteriorating. 5. Piñones

by 2002. The Rincón wall will continue to cause beach degradation Piñones, east of the airport, is an erosive beach, primarily and loss of aesthetics through erosion of the beach. For discussions due to mining of beach sand to build the international airport. See on historical erosion along the Rincón shoreline, see Thieler et al. the discussion of Piñones in the sand-mining section. (1995) and Thieler and Rodríguez (2007). 6. Puerto Nuevo 3. Cabo Mala Pascua Puerto Nuevo and its nearby rocky headland, Punta Puerto The beach west of Cabo Mala Pascua on the southeast part Nuevo, is an example of a small community nestled in the lee of the island hosts, among other things, the Caribe Playa Sea- of a rocky headland. The headland affords some protection from beach Resort. Fallen palm trees and tree stumps at the edge of waves approaching from the north and northeast. Puerto Nuevo is the beach are clear evidence of rapid erosion (Fig. 9). An owner an old ﬁ shing village that has been located here long enough for along this stretch sold his beach sand, setting off a continuing shoreline erosion to threaten the development. The entire com- chain reaction of events. See the description of this beach in the munity is fronted by a massive seawall. Some houses have fallen sand-mining section earlier in this paper. in and others will follow soon. Little or no beach exists along the developed portion of this shoreline, and where small beaches are 4. Ensenada de Boca Vieja present, rubble from destroyed buildings is common (Fig. 14). A Department of Natural and Environmental Resources project The shoreline of Ensenada de Boca Vieja is partly riprapped built a boat house for local ﬁ shermen right on the beach. While a and walled and experiences erosion due to structures west of San good project to help the local economy, a wiser location for the Juan harbor (Fig. 13). No recreational beach remains along the structure could have been chosen, perhaps farther to the east in stretch near the Palo Seco thermoelectric generating plant. Much the lee of Punta Puerto Nuevo. of the shoreline is highly engineered with numerous riprap seawalls and groins in front of Levittown, small jetties in front of 7. Aguada the canal, a breakwater in front of the Palo Seco Thermoelectric plant, and the causeway going to Isla de Cabras. These structures In Aguada there is a steep, high scarp (3 m) in some places have affected the beach sand supply and current patterns. In the with houses at or near the edge. Near the mouth of the Río last few years, more and more revetments have been added, fur- Guayabo, the beach has been replenished, and beyond the pub- ther detracting from the swimming and recreational qualities and lic beach, the road around the headland is protected by a mas- area of this beach: an important issue, especially for the citizens sive wall of riprap, gabions, and poured cement (Fig. 7). The of Levittown. entire shoreline road is threatened by erosion, and much of this spe460-11 page 161

Summary of Puerto Rico’s vulnerability to coastal hazards 161

Figure 15. Headstones are incorporated into a seawall in front of the Puerto Rico Memorial Cemetery in Isla Verde, along a once popular Figure 14. A large gabion wall and damaged buildings on west-facing swimming beach. Note the degraded beach down drift, in front of the shoreline of Puerto Nuevo in 2000. In the lee of Punta Puerto Nuevo, high-rise condominiums in the distance. this small community is protected from storm waves from the northeast, but it is still exposed to waves from the north and west.

nearshore patch reef growth and thus reducing the protective na- reach is either riprapped or fronted by sloped gabion seawalls. ture of the islets. This effect, combined with natural erosion of the Northeast of the park, a sloping gabion wall has been replaced by eolianite, has led to the disappearance of “Isla Verde” and the ac- concrete bulkheads, riprap, or is eroding where unstabilized. Be- celeration of erosion of the main island shoreline. See also the dis- yond Punta del Boquerón, the beach is commonly scarped, and cussion of Balneario Carolina, formerly Balneario de Isla Verde. cobbles of coral and basalt have been carried onshore by strong storm waves. An old gun emplacement, now at the water’s edge, 9. Arecibo attests to shoreline retreat. The entire shorefront of the city of Arecibo, the fourth larg- 8. Isla Verde est city in Puerto Rico, is walled and has revetments, and as a consequence, there is no dry beach (Fig. 16). This armored shore The heavily developed stretch of coast east from Punta Las is especially vulnerable to the impact of large storm waves. Much Marías to Punta Cangrejos is one of the most popular destina- of the city sits upon a rocky foundation (much like San Juan) tions in Puerto Rico, hosting many high-rise condominiums and where erosion or shoreline retreat will not be a critical problem hotels. The beaches are a popular tourist attraction because of for some years. their proximity to the international airport, and single-family housing developments are common, especially in the Punta Las Marías area. It is also a heavily engineered shoreline in places. Severe signs of erosion include narrow beaches with groins and walls, contributing to beach degradation in front of the hotels and condominiums west of the Puerto Rico Memorial Cemetery, which in turn is protected by a wall and riprap that includes old headstones (Fig. 15). East of the cemetery, the beach is some- times scarped, and Hurricane Hugo washed away the dock and bar in front of the Empress Hotel on Punta El Medio, halfway between Punta Las Marías and Punta Cangrejos. Interestingly, Isla Verde (Green Isle) derives its name from an eolianite island offshore of Punta El Medio, on which enough soil had developed at one time to support lush, green vegetation. Some modest reefs had also developed on the submerged portion of this and other islets. The islands helped to protect the shoreline by breaking storm-wave energy. Increased development of Puerto Figure 16. A massive revetment protects road and buildings in Arecibo. Rico has caused pollution of nearshore waters, killing much of the Note absence of beach. Photo is courtesy of U.S. Geological Survey. spe460-11 page 162

162 Bush et al.

Construction of the breakwater at Punta Morrillos (the headland just east of Arecibo) for Arecibo Harbor resulted in a shifting of the energy in the bay, and accelerated erosion in the western part of the bay. Briggs (1961) reported 35 m of shoreline retreat between 1940 and 1959, an average of 1.7 m/yr, following breakwater construction. There is little permanent development in Puerto de Arecibo, but the area is a high-risk zone because of its low elevation and exposure to high storm-wave energy.

10. Condado

The beaches along the Condado are narrowing and consist of pocket beaches between rock outcrops. Individual properties have been defended by various types of armoring structures, which have resulted in beach loss to adjacent properties. More Figure 17. A groin trapping sand in the Condado section of San Juan, structures were then added, and today, many hotels in the Con- a popular beach for residents and tourists, especially for passengers of cruise ships docking in nearby San Juan harbor just to the west. Note dado have no beach (Fig. 17). At this point, few alternatives re- beach narrowing down drift (to the right) of the groin. main. Most likely, the future holds more engineering structures

Figure 18. A miscellaneous collection of vulnerable beaches from the west coast of Puerto Rico. There is an uncounted number of similar examples. (A) West of Rincón in 2000. (B) Near Punta de Boquerón in 2002. (C) Near Punta Guani- quilla in 2000. (D) El Combate in 2000. spe460-11 page 163

Summary of Puerto Rico’s vulnerability to coastal hazards 163 with fewer and smaller beaches. Probably the only way to in- Administration (NOAA) Ocean and Coastal Management in crease recreational quality of these beaches is through replenish- Puerto Rico Web site: http://coastalmanagement.noaa.gov/ ment, which is costly and temporary. mystate/p_rico.html. The Puerto Rico Coastal Program Web site (in Spanish) can be accessed at http://www.drna.gobierno.pr/ Other Beach Problems oficinas/arn/recursosvivientes/costasreservasrefugios/pmzc/ descripcion. Unfortunately, the “worst beaches” list exceeds ten, and there are many more examples of poor site selection, poor man- RECOMMENDATIONS agement strategy, needless or excessive engineering, and continued construction too close to the shore. Figure 18 shows some 1. A long-term study of shoreline erosion in Puerto Rico is examples of mismanaged beaches from the west coast of Puerto needed. The study should assess the islandwide and com- Rico; Figure 19 shows examples from the east and south coasts. munity-by-community erosion situation, start a continuous However, there also are many examples of beautiful beaches in beach-proﬁ ling program, make islandwide and community- ﬁ ne shape, mostly because they are largely free of major develop- wide recommendations as to shoreline-management alterna- ment pressure to date. tives and begin planning for sea-level rise. Puerto Rico needs to improve enforcement and compliance 2. Sand mining on Puerto Rico’s beaches and nearby source of existing coastal regulations. The Coastal Zone Management rivers should be halted immediately. Program is administered by the Puerto Rico Department of Natural 3. Hard stabilization must be controlled, perhaps through a and Environmental Resources. A description in English of the stricter permitting process, and a program of beach “surveil- program is available on the National Oceanic and Atmospheric lance” is needed.

Figure 19. A miscellaneous collection of vulnerable beaches from the south and east coasts of Puerto Rico. (A) The narrowing beach of Playa Cortada in 2000. (B) A marina under construction in Fajardo in 2000. Many new marinas have been built along the east coast in an effort to lure tourists away from Isla Verde and Condado. (C) The almost completely stabilized shoreline of Manzanillo in 2000. (D) An example of a growing number of individual seawalls from west of Cabo Mala Pascua in 2000. spe460-11 page 164

164 Bush et al.

4. Alternatives besides hard stabilization must be evaluated and Bush, D.M., Richmond, B.R., and Neal, W.J., 2001, Coastal zone hazard maps: Eastern Puerto Rico: Environmental Geosciences, v. 8, p. 38–60, doi: considered. This could include development setbacks, reloca- 10.1046/j.1526-0984.2001.008001038.x. tion or demolition of low-cost shorefront buildings, and beach Calversbert, R.J., 1970, Climate of Puerto Rico and the U.S. Virgin Islands: replenishment. The problem is that construction of walls and Climatology of the United States, No. 60-52: Washington, D.C., U.S. De- partment of Commerce, 29 p. revetments is usually done on a crisis basis, allowing no time Delorey, C.M., Poppe, L.J., and Rodríguez, R.W., 1993, Maps Showing the for deliberation concerning other alternatives. Effects of Hurricane Hugo on the Escollo de Arenas Sand and Gravel De- 5. At least two communities, Luquillo and San Juan (Isla Verde posit, Vieques Island, Puerto Rico: U.S. Geological Survey Miscellaneous Field Studies Map MF 93-2235, 2 sheets. to the Condado), could benefi t immediately from beach re- Díaz-Hernandez, L.E., 1990, Temblores y Terremotos de Puerto Rico: Ponce, plenishment and could probably build a case for local and/or Puerto Rico, Luis E. Díaz, 49 p. federal funding. The compartmentalized nature of the coast Ehlmann, A.J., 1968, Clay mineralogy of weathered products and river sediment, Puerto Rico: Journal of Sedimentary Petrology, v. 38, p. 885–894. means more sand will stay within a single compartment Grindlay, N.R., Hearne, M., and Mann, P., 2005, High risk of tsunami in the longer . Other compartments are candidates as well, but northern Caribbean: Eos (Transactions, American Geophysical Union), both of these are especially popular, and the San Juan area v. 86, p. 121–132. Hays, W., 1985, Fundamentals of Geology and Regional Geology for Solving is both popular and populous. Earthquake Engineering Problems in the Puerto Rico Area: U.S. Geologi- 6. Many miles of Puerto Rico’s recreational beaches have been cal Survey Open-File Report 85-731, p. 22–52. seriously degraded and even destroyed through attempts to Ho, F.P., 1975, Storm Tide Frequency Analysis for the Coast of Puerto Rico: National Weather Service, National Oceanic and Atmospheric Adminis- halt shoreline erosion to protect buildings. A concerted effort tration (NOAA) Technical Memorandum NWS HYDRO-23, 43 p. is needed to halt beach degradation in Puerto Rico. Preser- Jackson, C.W., Adams, A., Bush, D.M., Wright, E.E., and Neal, W.J., 2001, vation of recreational beaches should be given high priority, Beach width and profi le comparison between natural beaches and beaches fronting seawalls: Geological Society of America Abstracts with Pro- in many cases, higher priority than preservation of shorefront grams, v. 33, no. 2, p. 71. buildings. Jackson, C.W., Bush, D.M., and Neal, W.J., 2006, Gabions, a poor design choice for shore hardening: The Puerto Rico experience, in Klein, A.H.F., et al., eds., Proceedings of the 8th International Coastal Symposium: Jour- ACKNOWLEDGMENTS nal of Coastal Research, Special Issue, v. 39, p. 852–857. Jackson, C.W., Jr., Bush, D.M., and Neal, W.J., 2009, The Coastal Compart- This study was supported by a University of Puerto Rico Sea ment Management Plan: Using Puerto Rico as a Model: Southeastern Geol ogy, v. 46, no. 2, p. 69–84. Grant College Program Seed Money Grant. Some of the origi- Kaye, C.A., 1959, Shoreline Features and Quaternary Shoreline Changes, nal work was funded by the Federal Emergency Management Puerto Rico: U.S. Geological Survey Professional Paper 317-B, 140 p. Agency and the United States Geological Survey. Additional Lander, J.F., and Lockridge, P.A., 1989, United States Tsunamis 1690–1988: National Oceanic and Atmospheric Administration (NOAA) Publication support was provided by University of West Georgia grants to 41-2, p. 1–16, 209–224. David Bush through the Faculty Research Enhancement Award Larsen, M.C., and Torres-Sánchez, A.J., 1992, Landslides triggered by Hur- Program, the Learning Resources Committee Grant Program, ricane Hugo in eastern Puerto Rico, September, 1989: Caribbean Journal of Science, v. 28, p. 113–125. and The Student Research Assistant Program. The authors Larsen, M.C., and Torres-Sánchez, A.J., 1998, The frequency and distribution thank Lisbeth Hyman and Orrin Pilkey for their assistance in of recent landslides in three montane tropical regions of Puerto Rico: Geo- the fi eld. Thanks also go to Art Trembanis and Mike Katuna morphology, v. 24, p. 309–331, doi: 10.1016/S0169-555X(98)00023-3. Lugo, A.E.F., Quiñones, M., and Weaver, P.L., 1980, La erosión y sedimen- for their insightful comments which improved the manuscript. tacion en Puerto Rico: Caribbean Journal of Science, v. 16, p. 143–165. Mann, P., Calais, E., and Huérfano, V., 2004, Earthquake shakes “Big Bend” re- REFERENCES CITED gion of North America–Caribbean boundary zone: American Geophysical Union, Eos (Transactions, American Geophysical Union), v. 86, p. 77–88. Martínez, R.F., 1984, Las playas y dunas de Puerto Rico, in Vivaldi, J.L., ed., Beller, W., Casellas, M.A., Cerame-Vivas, M.J., El Koury, J., Gelabert, P.A., Compendio Enciclopedico de los Recursos Naturales, Volume IV: San Gonzalez Liboy, J.A., Hernandez Avial, M., Maldonado, N., Matos, Juan, Puerto Rico Department of Natural and Environmental Resources, C.A., Mignucci-Gianonni, A., Pantojza-Garcia, E., Rigau, J., Shelly, D., 114 p. Tacher-Roffe, M., and Zerbi, N., 1999, Puerto Rico and the Sea—1999: McCann, W., 1984, On the earthquakes hazard of Puerto Rico and the Virgin An Action Program for Marine Affairs. A Report to the Governor: San Islands, in Gori, P.L., and Hays, W.W., eds., A Workshop of “Geologic Juan, Puerto Rico, Puerto Rico Department of Natural and Environmental Hazards in Puerto Rico”: U.S. Geological Survey Open-File Report 84- Resources, 122 p. 761, p. 41–60. Briggs, R.P., 1961, Recent shoreline changes and sedimentation at Puerto McCann, W., 1985, The earthquake hazards of Puerto Rico and the Virgin Arecibo and vicinity, Puerto Rico: Shore and Beach, v. 29, no. 1, p. 27–36. Islands , in Hays, W.W., and Gori, P.L., eds., Proceedings of Conference Bush, D.M., 1991, Impact of Hurricane Hugo on the rocky coast of Puerto XXX; A Workshop on “Reducing Potential Losses from Earthquake Rico, in Finkl, C.W., and Pilkey, O.H., eds., Impacts of Hurricane Hugo: Hazards in Puerto Rico”: U.S. Geological Survey Open-File Report September 10–22, 1989: Journal of Coastal Research, Special Issue 8, 85-731, p. 53–72. p. 49–67. Mercado, A., 1994, On the use of NOAA’s storm surge model, SLOSH, in man- Bush, D.M., Webb, R.M.T., Hyman, L., González Liboy, J., and Neal, W.J., aging coastal hazards: The experience in Puerto Rico: Natural Hazards, 1995, Living with the Puerto Rico Shore: Durham, North Carolina, Duke v. 10, p. 235–246, doi: 10.1007/BF00596144. University Press, 193 p. Mercado, A., and McCann, W., 1998, Numerical simulation of the Bush, D.M., Pilkey, O.H., and Neal, W.J., 1996a, Living by the Rules of the 1918 Puerto Rico tsunami: Natural Hazards, v. 18, p. 57–76, doi: Sea: Durham, North Carolina, Duke University Press, 179 p. 10.1023/A:1008091910209. Bush, D.M., Richmond, B.R., and Neal, W.J., 1996b, Coastal Zone Hazards Mercado, A., Grinlay, N.R., Lynett, P., and Liu, P.L.-F., 2002, Investigation of Maps of Puerto Rico: Hurricane Hugo Impacted Portion of the Shoreline, the potential tsunami hazard on the north coast of Puerto Rico due to sub- Cibuco (Punta Garaza) to Punta Viento: U.S. Geological Survey Open- marine landslides along the Puerto Rico Trench: Mayagüez, Puerto Rico File Report 96-506, 12 p., 12 sheets. spe460-11 page 165

Summary of Puerto Rico’s vulnerability to coastal hazards 165

State Emergency Management Agency and Sea Grant College Program, Schwab, W.C., Danforth, W.W., Scanlon, K.M., and Masson, D.G., 1991, A 432 p. giant submarine slope failure on the northern insular slope of Puerto Rico: Molinelli, J., 1984, Rapid mass movement as a geologic hazard in Puerto Rico, Marine Geology, v. 96, p. 237–246, doi: 10.1016/0025-3227(91)90149-X. in Gori, P.L., and Hays, W.W., eds., A Workshop of “Geologic Hazards Schwab, W.C., Rodríguez, R.W., Danforth, W.W., and Gowen, M.H., 1996a, in Puerto Rico”: U.S. Geological Survey Open-File Report 84-761, Sediment distribution on a storm-dominated insular shelf, Luquillo, p. 80–85. Puerto Rico: Journal of Coastal Research, v. 12, p. 147–159. Molinelli, J., 1985, Earthquake vulnerability study for the metropolitan area of Schwab, W.C., Rodríguez, R.W., Danforth, W.W., Gowen, M.H., Thieler, E.R., San Juan, Puerto Rico, in Hays, W.W., and Gori, P.L., eds., Proceedings and O’Brien, T.F., 1996b, High-Resolution Marine Geologic Maps Show- of Conference XXX; A Workshop on “Reducing Potential Losses from ing Sediment Distribution on the Insular Shelf off Luquillo, Puerto Rico: Earthquake Hazards in Puerto Rico”: U.S. Geological Survey Open-File U.S. Geological Survey Miscellaneous Field Studies Map 2276. Report 85-731, p. 211–278. Sola, E.M., 1995, Historia de los Huracanes en Puerto Rico: First Book Pub- Monroe, W., 1979, Map Showing Landslides and Areas of Susceptibility to lishing, 76 p. Landsliding in Puerto Rico: U.S. Geological Survey Miscellaneous Inves- Ten Brink, U., Danforth, W., Polloni, C., Andrews, B., Llanes, P., Smith, S., tigation Series Map I-1148, scale 1:240,000. Parker, E., and Uozmi, T., 2004, New sea fl oor map of the Puerto Rico Morelock, J., 1978, The Shoreline of Puerto Rico: San Juan, Puerto Rico, De- Trench helps access earthquake and tsunami hazards: Eos (Transactions, partment of Natural and Environmental Resources, 45 p. American Geophysical Union), v. 85, p. 349, 354. Morelock, J., 1984, Coastal erosion in Puerto Rico: Shore and Beach, v. 52, Thieler, E.R., and Bush, D.M., 1991, Gilbert and Hugo: Hurricanes with power- p. 18–27. ful messages for coastal development: Journal of Geological Education, Morelock, J., and Barreto, M., 2003, An update on coastal erosion in Puerto v. 39, p. 291–299. Rico: Shore and Beach, v. 71, p. 7–11. Thieler, E.R., and Danforth, W.W., 1993, Historical Shoreline Changes in Morelock, J., and Taggart, B., 1988, USA—Puerto Rico, in Walker, H.J., ed., Puerto Rico, 1901–1987: U.S. Geological Survey Open-File Report Artifi cial Structures and Shorelines: New York, Kluwer Academic Pub- 93-574, 267 p. lishers, p. 649–658. Thieler, E.R., and Danforth, W.W., 1994a, Historical shoreline mapping (I): Morelock, J., Schwartz, M.L., Hernandez-Avila, M., and Hatfi eld, D.M., 1985, Improving techniques and reducing positioning errors: Journal of Coastal Net shore-drift on the north coast of Puerto Rico: Shore and Beach, v. 53, Research, v. 10, p. 549–563. p. 16–21. Thieler, E.R., and Danforth, W.W., 1994b, Historical shoreline mapping Oceanographic Program, 1974, Oceanographic baseline data (1971–72) for the (II): Application of the digital shoreline mapping and analysis systems formulation of marine waste disposal alternatives for Puerto Rico: San (DSMS/DSAS) to shoreline change mapping in Puerto Rico: Journal of Juan, Puerto Rico, Area of Natural Resources (now Department of Natural Coastal Research, v. 10, p. 600–620. and Environmental Resources, Department of Public Works, Common- Thieler, E.R. and Rodríguez, R.W., 2007, Trouble in paradise: Coastal erosion wealth of Puerto Rico), Report prepared for the Environmental Quality in Rincon, Puerto Rico, Geological Society of America Abstracts with Board: Final report, November 1974, Volume I: Main Report, Volume II, Programs, v. 39, no. 6, p. 96. Appendices. Reprinted by the United States Environmental Protection Thieler, E.R., Bush, D.M., and Pilkey, O.H., 1989, Shoreline response to Hur- Agency (EPA) with cooperation of the Puerto Rico Environmental Qual- ricane Gilbert: Lessons for coastal management, in Magoon, O.T., ed., ity Board and Department of Natural Resources, 237 p. Coastal Zone ‘89, Proceedings of the Sixth Symposium on Coastal and Pilkey, O.H., and Wright, H.L., III, 1988, Seawalls versus beaches, in Kraus, Ocean Management: New York, American Society of Civil Engineers, N.C., and Pilkey, O.H., eds., The effects of seawalls on beaches: Journal p. 765–775. of Coastal Research, Special Issue, v. 4, p. 41–64. Thieler, E.R., Rodríguez, R.W., and Carlo, M., 1995, Beach erosion and coastal Rodríguez, R.W., Webb, R.M.T., and Bush, D.M., 1994, Another look at the development at Rincón, Puerto Rico: Shore and Beach, v. 63, p. 18–28. impact of Hurricane Hugo on the shelf and coastal resources of Puerto USACE (U.S. Army Corps of Engineers), 1986, Use of Gabions in the Coastal Rico, USA: Journal of Coastal Research, v. 10, p. 278–296. Environment: U.S. Army Corps of Engineers Coastal Engineering Tech- Rodríguez, H., Díaz, W., and Mercado, A., 2006, Population composition, geo- nical Note CETN-III-31, 12/86, 5 p. graphic distribution, and natural hazards: Vulnerability in the coastal re- Wright, E.E., 1989, The Effect Of Hard Stabilization on The Sediment Trans- gions of Puerto Rico: Mayagüez, Puerto Rico, University of Puerto Rico port System along the Shoreline of Puerto Rico [M.S. thesis]: Durham, Sea Grant College Program Technical Report UPR/SG R-121-1-02, 27 p. North Carolina, Duke University, 200 p. Schwab, W.C., and Rodríguez, R.W., 1992, Progress of Studies on the Impact of Hurricane Hugo on the Coastal Resources of Puerto Rico: U.S. Geologi- cal Survey Open-File Report 92-717, 169 p. MANUSCRIPT ACCEPTED BY THE SOCIETY 02 JUNE 2009

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