4. Selecting a site 121

Fig. 4.38. Beach replenishment project, 1983. Hobe Sound on Jupiter Fig. 4.39. A house snuggled behind the low frontal dune on J u pi ter Island, Island. Photo by Bill Neal, Photo by Bill Neal.

Petm Beach County the beach the better. As a result, this county has one of the most Just about everybody in the western world has heard about extensively developed barrier systemsin the world, and beach- Palm Beach,the crown jewel of Palm BeachCounty's 45 miles of front propertyprices here are astronomical by anybody's standard. open oceanshoreline. Only slightly lessfamous are such namesas The quality of this much sought after environment is highly Delray Beach and Boca Raton. It seems as if everybody wants a variable. For example, only a small amount of beach remains in piece of the Palm Beach shoreline, and the closer the piece is to front of the seawalls at Palm Beach, but that seems to have little 122 Living with the East Florida shore

l/2 0 t kilometer drewbr I dec Brrrrrrr Fig. 4.40. Site analysis: Waveland to St. Lucie inlet. 4. Selecting a site 123 124 Living with the East Florida shore

impacton the qualityof life of the community.In fact,many Palm The northern z miles of' barrier island south end of Jupiter Beach residents oppose replenishing the beach becausea broad Island! in the county range in width from 7oo feet to about z,3oo new beachmight bring in an influx of peoplefrom the outside feet near Jupiter Inlet. Jupiter Inlet Colony is located north of the world. At the other end of the spectrum are someof the beaches inlet. The beach width in this section varies from zo to 7o feet at off Boca Raton that are relatively broad and relatively "unspoiled," mean low water and has steepslopes in the nearshore.The frontal The aestheticquality of developmentvaries as well, rangingfrom dune elevations which have been partially built upon! range from the spectacularlybeautiful hedge-lined streets of Palm Beach,to i 5 to more than zo feet. the endlesscondo rows fronting South Palm Beachand Delray From Jupiter Inlet to artificially cut in t9 t8! Beach,to the lightly developedmaritime forest at the northend of the barrier island is i t,7 miles long. The towns of Juno Beach and Lake Worth. Safetyis variableas well. We classify5.7 milesof Palm BeachShores Singer Island! are located on this island. In Palm BeachCounty's shorelineas low risk, 25.8 miles as moderate difl'erent sections the island width varies from 6oo feet to about risk, and 7.9 miles as high risk figs. 4.4i, 4.42, and 4.43!. i mile, Frontal dunes, with elevations of t 5 to 2o feet, occur for Werank 3 areasin thecounty as low-risk sites for development. most of the reach. The natural dunes are particularly well devel- In chaptert weasked the question of ourselves!where would we oped on the northern half of this island, and at Juno Beach a want our parentsto live alongFlorida's east coast, and the Juno 53-foot dune hasbeen mapped.The southern3-mile section of' the Beach area turns out to be one of those locations. Although there island Singer island! has average elevations of only to feet above is a floodrisk, evacuationfrom this areashould be reasonably safe the low-tide mark. for anyonewith a modicumof prudenceand commonsense. Two lt is worth mentioning here one of the most startling examples other areas,near Delray Beachand Boca Raton, also were classi- of unwise development we have seen on East Florida's beach front fied as low risk, but here evacuation poses somewhat more of lig. 4.44!. This is the Jupiter Reef Condo between Juno Beach a hazard. The section of shoreline classified low risk near Boca and Jupiter Inlet, It has been built virtually on the beach. It not Ratonhas a public park fronting the beach,and the park along only endangersits own inhabitants, but the structure will act as a with the highwayact as a good naturalbuAer to the forcesthat groin and will causeerosion of beachesto the south. Somehow ravagethe shoreline.The 2 areasin Palm BeachCounty classified this folly has occurred in a community where the setback line is as high risk are Highland Beachand the area south of Lake Worth generally observed. Inlet. Among other problems,both beach-frontareas have particu- The barrier island between Lake Worth Inlet and South Lake larly severe erosion. Worth Inlet another man-made inlet cut in >9z7! stretchesfor 4. Selecting a site 125 t 5,6 miles. Palm Beach and South Palm Beach are the towns on and losses from hurricanes and shoreline erosion. this island. The width of the island varies from about 6oo feet to The forces of' wind, waves, current, sea-level rise, and tides con- about 4,5oo feet. The elevation of the first row of dunes primary tinually affect the barrier beaches. The predominant winds are dunes! is less than t3 feet within the Palm Beach city limits and from the southeast,but the strongestwinds are from the northeast. increasesto z7 feet on the southern portion of the island. The The highest recorded storm tide in Palm Beach was t t.2 feet above dunesare steep, and the offshore profiles in this section also are sea level during the t 9z8 hurricane, The predominant littoral cur- steep.Often Australian pines cover thesedunes, and as discussed rents are from north to south during winter and spring and from earlier these pines do not retain or protect the dune sand very south to north during the summer and fall, with the net annual well. movement from north to south. The barrier island between South Lake Worth Inlet and Boca Hurricanes and winter storms with winds from the northeast Raton Inlet fig. 4.45! stretchesfor ]4.5 miles. The barrier width cause rapid changes in the beaches and dunes and cause property varies from 750 feet to about z,ooo feet, and the primary dune damage and evacuation problems. Between t 9oo and I 982 a total elevations range from t 5 to 23 feet above mean low water. The of t5 major hurricanes passedwithin a 5o-mile radius of Palm beaches are narrow and steep. Beach County, a frequency of i every 5.5 years, The storm of South of Boca Raton Inlet is about a t-mile section of island in October t9 to brought severe rain and a 5-foot rise in the Loxa- Palm Beach County. This stretch is about 7oo to 8oo feet wide, hatchee River and Hobe Sound, causing extensive Rooding on the The elevations are relatively low, about t2 feet above mean low bay side.The storm of Septembert 9z6 causedconsiderable dam- water, and the beach is narrow and steep. age and loss of beach material. The most severe storm to hit Palm The bay side of the barrier islands was originally lined with Beach was the September 1928 hurricane, the eye of which passed mangrove trees. However, along much of the county's shoreline right over the county. Winds of over too mph, a barometric pres- mangroves were leveled and the area filled; the estuarine and sure of 27.43 inches, and a storm surge or tide of >t.2 feet were shorelineis now lined with bulkheads. recorded. The property damage in the Palm Beach Lake Worth Palm Beach County has one of the most urbanized barrier island area was estimated at $t t million it would be about 6 times that shorelines in Florida. However, almost 9 miles of the county'stotal amount in t984 dollars!, and various sections of Highway A>A of 45 miles of beachfront is in public ownership,and an additional and State Road 7o7 were damaged. The storm of September t t- 4 miles or so is being acquired by state and countyagencies to 19, 1947, with over too-mph winds, causedsevere erosion of the meet public recreation demandsand to minimize public hazards beaches and washed out a t-mile section of Highway At A in Del- 126 Living with the East Florida shore

NATIONAL W IL0LIFE J UPITER sr iuc E N LET $i c~~ g+ W qEawa~ Q ,~ S4

Fig.4,41. Site analysis:Jupiter Island to Jupiter Inlet Colony, 4. Selecting a site 127

DANGER: Flood ri sk DANGER; Evacuat.ion dif ficult DANGER: Flood risk DANGER Severe erOSIOn CAUTION: Evacuation difficult CAUTION; Engineered shoreline CAUTIONS Next to inlet CAUTION: Beach replenishment + Non-engineered beach 3 times in 12 years + Vegetated dunes + Safest siteS on ridges + Heavily vegetated island DANGER: I 1ood risk DANGER: L'vacuation difficult DANGER: Beach erosion CAUTION: L'ngineered shoreline CAUTION: foredune DANGER: Flood risk CAUTION; Evacuation difficult CAUTION: Narrow island + Rock outcrops on beach IS LAND 128 Living with the East Florida shore

Fig. 4.42. Site analysis. Jupiter Inlet to Palm Beach Shores. 4. Selecting a site 129 130 Living with the East Florida shore

DANGER: Flood risk DANGER: Evacuation difficult CAUTION; Evacuation difficult DANGER: Beach erosion CAUTION: Eng i neered shorel ine CAUTION: Flood risk + Wide, relatively high island CAUT ION: Engineerell ShOrel ir.e + Safest sites on ridges

8 KERS W PALM BEACH jmWM MWS AIA

IOMIWI gowdIow' IMidqo LAKE doow~f WO R TH Idl'AW. FIBQIo ibrIdio , Memoo 8 looo

Flg. 4.43. Site analysis: Palm Beach Shores to South Lake Worth Inlet, 4, Selecting a site 131

LAKE WOR TH

1 1 mlle 1I2 0 rrrlo meter 132 Living with the East Florida shore

ray Beachalong with the municipalpavilion, The stormof August ishment. There have been severalbeach nourishment projects on r 949pounded Palm Beachwith r 3a-mph winds and washedout Palm BeachIsland and at Delray Beach. Sand bypasssystems on a 3-mile section of Highway ArA from Lantana to Lake Worth. Lake Worth Inlet and South Lake Worth inlet place an annual Otherhighway sections from BoyntonBeach to DelrayBeach also averageof 63,ooocubic yards and 8o,ooocubic yardsof sand, were damaged,If a hurricanestruck Palm Beachnow, the damage respectively,on the southside of the inlet. However,the fixed- to shorefront property would be greater than ever becausethere is boomtype of sandtransfer system at South Lake Worth Inlet is no natural beach buffer. inefficient and at times pumps water insteadof sand, Delray Beach The annual northeastershave caused the most severeand lasting was nourished in r 973with r.6 million cubic yards of sand place- changesalong the shoreline.The winter storms of r 957,r 962,and rnent;the same was done in r978 79. There are currently active 198r-82 were particularly notable for the considerabledamage projects to nourish Ocean Ridge Beach south of the South Lake they did to bulkheadsand beachdune profiles, Worth Inlet and to renourish Delray Beach.In r 974Palm Beach Over much of the county shorelinefrom r 883to r 983the beaches County conducteda study that recommendeda beachnourish- have generally retreated but at varying rates. As a generalrule, ent programfor 33.9miles of beachesat a costof $ r7,5 million. stretchesof r to r.g miles in length north of the inlets and their The Corps of Engineersstudy recommendedimprovement for associatedjetties haveeither remainedstable or havebuilt seaward. rz.2 miles of beachesat a cost of $22.98 million. These projects The areasimmediately south of the inlets haveexperienced severe have not been carried out as yet. retreatdue to the blockingof the littoral drifts at thejetties and Evacuation is a seriousproblem for Palm BeachCounty, Most shoaling of the inlet bars. The beachesof Palm BeachIsland ex- areason the barrier islandsare well belowthe r oo-yearliood level. periencederosion landward of the 3o-foot depth contour, arnount- Jupiter Inlet Colony residentsmust escapevia Highway 707, ing to 8,ooo,ooocubic yards between r929 and r9g5.The beaches which has low-elevation approachesto a drawbridge, From the south of South Lake Worth Inlet have experienced both retreat vicinity of JunoBeach to the SeminoleGolf Club may be oneof and buildout, but retreat exceeds buildout for the entire section in the safest areas on the east coast of Florida in terms of evacuation. spite of a sandtransfer plant at the inlet, The Army Corpsof Palm Beach has three routes of evacuation to the mainland, all via Engineersestimates that Palm BeachCounty is subject to annual drawbridges, Australian pines line most of the streetsin Northern losses of r 9o,ooo cubic yards of sand. Palm Beach and should be expected to blow down and block The shorelineof Palm BeachCounty has beenextensively engi- evacuation routes. Much of the evacuation route in South Palm neered with seawalls, groins, revetments, jetties, and beach nour- Beach lies below a 5-foot elevation along the back side of the 4. Selecting a site t33 island and is very susceptibleto flooding. The z closestroutes to The county's beach-frontcommunities are, from north to south, the mainland are drawbridges.On the Delray Beach,Gulf Stream, Deerlield Beach, Hillsboro Beach, Pompano Beach, Lauderdale and Ocean Ridge segmentof the Palm Beach County shoreline, by-the-Sea,Fort Lauderdale,Dania, Hollywood, and Hallandale. Highway At A is on fairly high ground. However, roadwaysback Broward County is highly developed.Thousands of buildings to the mainland lie below 5 feet in elevation and are therefore hug the shoreline,and more and bigger structuresgo up every day, susceptibleto flooding. Horida Highway 8o4 has a drawbridge Unfortunately this shoreline hasa long history of erosion that has over the Intracoastal Waterway. Highway 8o6 has a fixed-span resulted in emplacementof a great deal of shoreline stabilization bridge.The BocaRaton area is bestevacuated by the 4-spansta- structures: seawalls,groins, revetments,etc. The natural erosion tionary bridges to the north over Lake Rogers. rates are high but have been pushedeven higher in somecases by jettiesand other structures.For example,prior to r 96othe Corps 8roward County of Engineersestimated that the annual shoreline recessionrate of Broward County has about z4 miles of open ocean shoreline. the stretch between the county line and was 4 feet Two inlets break the Broward barrier chain. These are Hillsboro per year. During the sixties and seventies the rate accelerated to Inlet north of Pompano Beachand Port EvergladesHarbor south more than ro feet per year. Part of the acceleration may be due of Fort Lauderdale,All of Broward'sopen oceancoast is fronted to jetties at Boca Raton Inlet in southern Palm Beach County, with barrier islands. Where natural sounds and lagoons do not Between Hillsboro and Port EvergladesInlet the recessionrates exist, the Intracoastal Waterway cuts through behind the shore- have been much smaller, although Pompano Beach is an excep- line isolating the beach-front strip of land. Width of the islandsin tion with its rates of 4 to 8 feet per year. On a shorelineas heavily Broward County ranges from a mere 3oo feet or so north of Hills- stabilized as Broward, perhaps present-day recessionrates are boro Inlet to 4,5oo feet near Fort Lauderdale. Elevations of the rather meaningless. Much of the shoreline retreat now aÃects Broward County islands are usually less than r 5 feet and reach replenished or nourished beaches fig. 4.47!. Almost every com- maximums of a little more than zo feet. There is a more or less munity in the county has, or plans to have, some sort of beach continuous ridge of sand down the length of the Broward shore, nourishment project. The experienceso far indicates that replen- but it is generally lower and lessweil-developed than the ridge of ished beacheshere disappearvery quickly to 5 years!, and re- the Palm Beach County shore. Of the 24 miles of county shore- plenishrnentand re-replenishmentare required. In somecases the ont, a little more than 8 miles is in public hands, that is, owned reasonfor the quick loss of sand may be poor choiceof siting for the government. the offshoredredging. During the summerof r983 we observed 134 Living with the East Florida shore

EOVIWLAKE WO4TII ILLE I DELRAY BEACH

InT4nl'OA AL WATE 4 WAY i IIKnd-Apen 'iixndspan I,gndge blidgn

Fig.4.44. Site analysis:Ocean Ridgeto Boca Raton inlet. 4, Selecting a site 135

DANGER: Flood risk CAUTION: Evacuation difficult DANGER: Flood ri sk CAUTION: Beach erosion DANGER: EVaCuatiOn di f f iL:u1 t CAUTION'. Narrow beach + High front.al sand ridge + Non-engineered beach CAUTION: Narrow island + Rock outcrop on beach + Safest sites on ridge DANGER: F 1ood r is k DANGERE Evacuation drf ficult DANGER; Narrow beach DANGERE Flood risk + Safest sites on ridge CAUTION: Evacuation difficult + No stabilizatiOn + Protected by heavily vegetated cit.y park

8OCARArosfr Highland BOCA AA B ach LAKE drs»- EEICA brklps RAJOIE rl~ sdsese SIS». ~ b'Wps brbrps

1r2 1 mlle 1 1 0 1 kilometer f36 Living with the East Florida shore

r.

/

Fig. 4.45, Seawalland groin in front of a too-close-to-the-beachdevelop- Flg, 4.46. Shorefront condos, Boca Raton. Photo by Bill Neal. ment. Juno Beach south of Jupiter Inlet. Photo by Bill Neal,

brown-stained sand on newly replenished beaches for exatnple, fall back into the old hole, which could account for the very rapid HollywoodBeach and PompanoBeach!. Since brown staimng of disappearanceof someof the artificial Broward beaches. shellsprobably occurs on the beachwhile materialis exposedto Prudentpotential Broward beach-front property owners should air, the fact that brown shells are being pumped up tneans that a snoop around and find out what their future tax bills may be like holeis beingdug in the lowerbeach, Replenished sand may simply becauseof the community's beach stabilization projects. 4. Selecting a site 137

i ng problems are much greater when a storm moves on to land from the sea. Expected ioo-year flood levels from such storms along the open ocean shoreline are in the range of 7 to iz feet, Maxi- mum hurricane water levels actually recorded at Fort Lauderdale include a high of iz.6 feet above sealevel in the t9z6 storm and 8 feet in the Yankee storm i935!. The i947 storm produced a 9.8-foot storm surgeat Hillsboro inlet. The Yankeestorm, by the way, was so named becauseit actually moved ashore froin the north. A third type of hurricane affecting Broward County is called an "alongshore hurricane." These storms do not come ashore near the county but pass along offshore and parallel to the coastline. The last alongshore hurricane was David t979!, Of the 24 miles of Broward County shoreline,we considerabout 65 percent to be in the high-risk category and 35 percent in the moderate-risk category figs. 4.48, 4.49, and 4.5o!. We found no shorelinesegments here that we would classify as low risk. Evacuation is a major problem in Broward County and is one of Ftg. 4.47. Replenished beach at Hollywood Beach. This beach is experi- the reasonsso much of the shore is considered to be high risk. encing high rate of erosion. Photo by Bill Neai. There are iz bridges across the Intracoastal Waterway to the mainland here, but all are drawbridges and hence are risky to Broward County has had an active storm history. Between i 870 depend on in a storm crisis, A large number of people live in low- and 1970 the eyes of 7 storms passedthrough Broward County. elevation, high flood-risk zones,the most important of which are Four of thesestorms exited that is, passedfrom land to sea and the extensivefinger canal developments.There will be many thou- 3 storms made a landfall. The exiting storms can cause severe wind sands of people trying to simultaneously escape the Broward shore damage,but asa rule they do not causemajor flooding, The flood- if a big one threatens. Perhaps you might consider choosing a 138 Living with the East Florida shore

BOCARA ION I NLE 'r Oceanvue ILLSBOBO IrrLEr LIIW brldg

drew rg bridge m!~~ 1/2 0 1 mile QP3 1/2 0 kilometer

Fig.4.48. Site analysis:Oceanvue to Hillsboro Inlet.

high-risebuilding that you know is well-built and usea friend's almost surrounded by high-rises. The beach is relatively broad condo for shelter. here, but the low elevation of the island dictatesa needfor storm Wide beach-frontareas oKer the least risk. In Broward County evacuation,Another rather striking anomaly in beach-frontdevel- these can be found at the south end of Fort Lauderdale and Dania. opmentin BrowardCounty is the Marriott Hotel in Fort Lauder- Dania, an anomalous community of single-family dwellings, is dale. For somereason the motel chain was given a varianceto the 4. Selecting a site $39 coastal setback line, and the building sits far out on the beach Government Cut. Both inlets are jettied, and Government Cut is relative to adjacent, more prudently sited buildings. It is predict- the main channel for the Port of Miami. The dominant direction able that the seawall in front of the Marriott Hotel will soon be of sand movetnent along the beachesof Dade County is from reducing the sand supply and causing erosion of downstream north to south; hence,beaches to the south of jetties havesuffered southerly! beaches. erosion. Essentially no sand escapesto the south of the Govern- ment Cut jetties. Dade County Although the shorelineelsewhere in Dade County hasgenerally Dade County has about 35 miles of open ocean shoreline, of retreated, the Miami Beach strandline has more or less remained which i 5 miles are made up of barrier islands, In this discussion stationary since t 92o.The recent $6 million per mile nourishment we will restrict ourselves to the barrier beach communities. Much project has widened the beach to 3oo feet fig 4.5z!. That Miami important informationconcerning Key Biscayne,Virginia Key, Beachhad no beachduring the sixties and seventieswas due not and Miami Beachis included in the field trip guide at the end of so much to erosion as to the fact that buildings were constructed the book and will not be repeated here. Hence this discussion of right on the beach. During most of this century the shoreface,or Dade County is somewhatabbreviated, lower beach, to a depth of about 3o feet has become gradually The main beach-front communities on the Dade County shore steeper along much of the Dade shoreline. Waves approaching are, from north to south, Golden Beach, Sunny Isles fig. 4.5t!, the shore are greatly influenced by the bottom; that is, when an Bal Harbor, Surfside, Miami Beach,and Key Biscayne,Here in approachingwave "feels the bottom" it breaks. If the shorefaceis Dade County and especially in Miami Beach is one of the world' s steep, a wave will not feel the bottom and break until it is closer to most densely developed barrier island shorelines. Also here are shore.Therefore, larger waveson the averageare hitting the beach someof the world's most famous luxury hotels. today than 5o yearsago. The barrier islands range from o.z miles to t,5 miles in width. During the last too years or so, tz hurricanes have passed Elevations are generally quite low. A more or less continuous sand through Dade County, 8 of which madelandfall in the county and ridge parallelsthe beach,with elevationsranging from 5 to t2 feet. 4 of which exited back out to sea, A number of other hurricanes Behind the narrow frontal sand ridges the islands tend to be flat brushed by the Dade coast on their way north. Hurricanes that and low, much of the area being less than 5 feet in elevation. caused significant damage to Dade County occurred in 1903, Miami Beachand Bal Harbor occupy the same island that is 1906, t926 the big one!, t929, t935 storms!, t94t, 1945, t947 bordered to the north by Bakers Haulover Cut and to the south by z storms!, t948, 1949, 195D, 1964, 1965, and t966. Since t966 140 Living with the East Florida shore

Fi9. . 4.49. ~ Site analysis'.Pompano Beach to Harbor Heights. 4. Selecting a site 141

FORT LAUDERDALE 142 Living with the East Florida shore

HOLLYWOOD BE H hn LIOrr Ste'lePark ania PI'

t/2 0 t mile 0 t kilOmeter

Ftg.4.50. Site analysis:Dania to BakersHau'lover Cut. 4 Selecting a site 143

POlk Isle OOIOVOr Beverly 144 Living with the East Florida shore

Fig.4.51, Sunny isle beach.Note remnants of grolns.Photo by Bill Neal. Fig.4.52. Construction of the new t983! Miamibeach boardwalk on the new $68 million beach. Photo by Bill Neal.

there have been some close calls but no really damaging storms. suchpeople may treat the next real stormwith unduecontempt. Interestingly,a recent Corps of Engineersevacuation study indi- Hurricanesare not the only stormsthat causeshoreline damage. cated that numerous South Florida citizens think they have sur- Winter storms,often from the northeast,cause both damage fig. vivedan importanthurricane, even though no suchstorms have 4.53! and erosion. occurredsince their arrival in the sunny south. The problem is that Evacuation is, as usual in South Florida, a major problem. 4, Selecting a site 145

Fig. 4.53. Miami Beach after the OCtOber 31, 1969, StOrrn. Photo by the Miami Herald from the University of Florida coastal engineering archives. 146 Living with the East Florida shore

Sevenbridges connect the beach-frontcommunities of Dade Countyto the mainland,but only i is a fixed-spanbridge the Julia Tuttle Causeway,which is also federalHighway t95 and stateHighway i i 2!. Besidesbeing the only fixed-span bridge, the Julia TuttleCauseway has a relativelyhigh abutment elevation of 8 to to feetand is definitelythe safestway off Miami Beach.The Venetian,MacArthur, and NorthBay causeways have minitnurn elevationsof 4 feet and can be expectedto flood early.The ap- proachesto the RickenbackerCauseway, the only escaperoute fromKey Biscayne, are 3 feetin elevationand are lined by massive Australianpines that shouldbe expectedto totally block escape from this low-elevation island early on in a major storm. Addingto the problemis thefact that onceyou haveescaped to the mainland,your troublesare not over,Much of Miamiis very low in elevation and in the next big storm can expectto be flooded. Therefore,it is verycritical for all residentsof the Dadeshoreline to planahead. Find out from your localcity hall whatthe evacua- tion planis, Whatshelters can you reach in time?We think the bestadvice is to leaveyour islandabode more than 24 hoursbe- fore the storm strikes. At that stage,of course, you cannot even be certain that the storin will strike your community,! Next, drive inland and visit Aunt Sue in Orlando or see the museumsand colonialhotnes in Tallahasseeor go to the coastalengineering libraryin Gainesvilleand read about Florida's shoreline problems. For the barrier island stretch of the Dade County shoreline we consider3g percentto be high risk for developmentand 67 per- centto be moderaterisk ftgs.4.54 and 4.gg!, Most of the stretch Fig. 4.54. Site analysis: Miami Seach. 4. Selecting a site 147

D NGER: Flood ri s k DANGER: Evacuation dif ficult CAUTION: Engineered shoreline + High, artificial berm + Wide, artific ial berm

Irrplsry CAfEK MIAMI BEACH

~Z~ 1/2 0 1 1/2 0

draw- i drew. bar br!dga a ha~ ! bridge Csuse we y runlef canerI .riaad-apan Lr!dga Maurhrlhur i br!dgs Venahan paysays a y ause'way 148LivingwiththeEastFloridashore COQUE

Ftor>de

Fig.4.55. Site analysis: Fisher Island through Key Biscayne, 4. Selecting a site 149 of barrier island fronted by the replenished Miami Beachfalls in reefs, Landward of the these reefs are small, more or less circular the moderate-risk category becauseof the shock-absorbingeffect featurescalled patch reefs.These z typesof reef make up the only of the new beach. large living reef systemsof the continental United States, The beautiful reefs can best be viewed at John Pennekarnp Reef State Monroe County/Fioride Keye Park, Besidesproviding beautyfor all to enjoy,the reefs,especially "Key" comesfrom the Spanishword cayo, meaning small, low- the barrier reefs, provide protection from waves. lying island. The Florida Keys are quite different from the beach Mixed among the patch reefs fig. 4.57! are shifting shoalsof and barrier island systemsthat we havebeen discussing. They are calcareoussand made up mostly of fragments of the reefs broken a chain of 97 low-lying, limestone islands extending in an arc up during storms, around the tip of the Florida peninsula from about Miami to a The islands themselvesare the high points of the old barrier point 235 milessouth, then southwestto the Dry Tortugas fig. reef systems.There are few natural beachesin the Keys; usually 4,56!, The islandsand somebarely submergedbanks betweenare the shoreline is bare limestone. Most beaches on the Keys are composedof 2 formations of limestone named Key Largo Lime- artificial, the beachat Key West being an example. Before 1926a stone and Miami Oolite, both formed during the ice ages. The small beachwas present at Key West,but constructionof a sea- Key Largo formation is an old coral reef built upon unconsoli- wall behind the beach causedits rapid disappearance,The arti- dated quartz and carbonatesand. It is a typical coral reef with the ficial beach, madeup of crushedlimestone and dredgedsand, was expectedvariety of fossil coral headsand the shells of many dif- emplacedin r96o for $z85,ooo,Most of it disappearedwithin a ferent snails and clams. The Miami Oolite formation is composed decade. of fragmentsof shellsand of particlescalled oolites, sand-sized Goodexamples of small naturalbeaches in the Keysstill exist spheru!esof calcium carbonatethat precipitate out of seawaterrn on Marathon Key and in Bahia Honda State Park. a shallow-water environment subject to lots of wave activity. Ofteninstead of beaches,mangroves grow along all the margins The environment,The natural environment of the Florida Keys, of the islands. The mangrovecommunity is a very important one where it still exists, is breathtakingly beautiful. This beauty is due in thatit providesa nurseryfor thelarvae of manyforms of marine to many unique and fragile interelated ecosystems.Figure 4,57 is life, Redmangrove lies at the edgeof theshore and hasroots that a typical but generalized cross section of a part of the Florida are capableof beingpermanently submerged in seawater,Black Keys. mangrovetrees grow on slightlyhigher elevations with rootssub- On the seawardedge of the limestone platform are the barrier rnergedby everyhigh tide,while the third speciesof the mangrove 150 Living with the East Florida shore

/ / / / / 5 10 15 20 MILES I/' / 'I / 0 5 10 15 20 25 KILOIMETERS ! ' GRE4T WHITE 4HERQNN

KEY WE

@e~ pc+ 0 Flg. 4.66. Florida Keys index map. 4, Selecting a site 151

LONG LOWER KEY MATECUMBE M ATECUMBE KEY KEY 152 Living with the East Florida shore

Florida upland forestt West fndtes flora in F torida Bay upper Keys, Straits 'I l'

Fig.4.57. Generalized cross section across the FloridaKeys, 4. Selecting a site '153 troika, the white mangrove, has roots that are Ilooded only by ment also is accompanied by dredging and filIing that muddies the storms or spring tides. adjacent waters. The islandsare crowned with a forest fig. 4.57! called a "tropical Drinking water, by the way, arrives via pipeline from the rnain- hammock," which is a typical West Indies assemblageof exotic land a long, tenuous lifeline. trees and bushes found nowhere else on mainland America. The There is a possibility that pollution may be killing the barrier tropical hammock assemblagesare found on the northern Keys, reefs. It is not always easy to distinguish natural from man-made while on the southern Keys the native forest is dominated by pines, eIIects, but the Florida Department of Natural Resources esti- thatch palms, palmettos,and shrubsand grassestypical of nearby mates that S5 percent of Hen and Chicken Reef off Key Largo is mainland areas. Behind the Keys is fig. 4.57!, a dead. Adding to the problem are souvenir-hunting tourists who shallow bay dotted with numerousmud banks. Some of the mud remove coral heads and allow anchors to drag. Loss of the reefs banks havemangroves on them and others do not. Florida Bay is would be a greatnatural disaster.Among other eH'ects,storm-wave an importantnursery area for commercialspecies of shrimp. intensity will be much increasedwithout the protection of the reef, Look rrhat they' ve done to our Keyet People have moved to the a phenomenon observed in the Virgin Islands where sugarcane Florida Keys for many reasons,but foremost among them is the production killed onshore reefs, natural beauty of this delicate ecosystem.Unfortunately, but cer- Some of this discussion about the Keys comes from a 1975 tainly not surprisingly, developmentis rapidly destroyingthe very book, Environmental Quality by Design: South Florida, by A. R. environment that people are moving to the Keys to enjoy, Devel- Veri and others. We highly recommend this book to the reader opmenthas been especially heavy in the northernKeys. Parcels of interested in learning more about the Keys and other marine en- land have been stripped of their unique West Indian vegetation, vironments of South Florida see full entry in appendix C!, built up, flattened, and relandscaped,often unsuccessfully.Intro- The storm threat. Hurricanes pose an enormous threat to people duced plants often do poorly in the poor to nonexistent soils; on the Rorida Keys. Perusal of the index map fig. 4.56! shows thus, fertilizers and topsoil from elsewheremust be introduced. why. There is a single highway, recently expanded to four lanes, Most new residentshave septic tank systems.Combined septic that connects the Keys all the way from Key West to the mainland. tank eNuent and fertilizer seep into the porous and permeable There is no other land connection. Complete evacuation before a limestone, causing these pollutants to be rapidly introduced into big storm will be virtually impossiblebecause Route t in the Keys the adjacent marine environment. Some pollutants also may be is low and crosses numerous bridges. Flooding will close the escape transported south from the Miami area. Unfortunately, develop- road early, and you can be sure there will be fender benders, 154 Living with the East Florida shore

Fig,4.58. Repair of the old Florida Keys highway 3 days after the passage ofHurricane Donna t1960I. The new highway alsois vulnerableto suchbreakthroughs in futurehurricanes, making the evaCuation problem particularly critical. Photo furnished by Harold R. Wanless. 4. Selecting a site 155 jackknifed trucks, and other smashupsblocking the escaperoute. heed their warning until it is too late, Compounding the dangersis the fact that many residentsof the We consider the entire Florida Keys to be high risk for devel- Keys live in mobile homesthat can be destroyedby evena modest opment. There are several reasons for this classification but the hurricane. principal one is the evacuation difficulty. Finally, the Keys themselves provide no place to hide. Average elevation is only 3 feet, and maximum elevation in the whole chain is only about i8 feet. More than 99 percent of the land area of the Keysis belowthe ioo-yearflood level, and 9o percentof the land is less than 5 feet. Many residents have been lulled into a false senseof security becausethe Keys have not suffereda direct hit since Hurricane Donna ravaged the area in i96o. The worst storm occurred on September 2, t935, when a hurricane with sustained windsestimated at 2oo mph struck the Keys, caused massivedamage, and killed 4oo people. The strip of maximum damage was only 4o miles wide. In t846 a hurricane destroyed Key West. Water was5 feetdeep in the main street, and survivors clusteredat the highest point in the area only about i 7 feet! were nearly washed away by waves. Of i7 Red Crossshelters listed for the Keys, every one would be flooded in a hurricane of strength "5," and many would be inundated in hurricanes of Saffir-Simpsonclass "3" table 2.1!. A recent,previously discussed study of hurricaneevacuation risks seetables 4. i and 4.2! showsthat a seriousmisconception exists amongSouth Florida and Florida Keys residents.Many of them think theyhave beenthrough a hurricane,when the recordsshow that they have not. No wonder that Civil Defense and officials involved with evacuation are concerned that many people will not