p r e p r i n t ; C o a s t a l Zone 187 American S o c i e t y of C i v i l E n g i n e e r s S e a t t l e , WA May 1987

Beach Replenishment: The National Solution?

Orrin H. Pilkey* Tonya D. Clayton*

The records of more than 90 replenished beaches and more than 200 sand-pumping operations on East Coast barrier island shorelines, while fragmentary, reveal a wide range of experiences, with a definite trend towards over-optimism in predicting the cost and performance of replenished beaches. Models and assumptions used to predict the fate of replenished barrier island beaches need careful reevaluation. Until sounder theoretical models are developed, a purely empirical approach is the best for predicting beach behavior.

Introduction

Increasingly intensive development along our eroding coasts is forcing many communities and state and federal agencies to make difficult decisions regarding what is to be done about structures threatened by coastal hazards. The available options fall into three broad categories: (1) allow the shoreline to retreat naturally and relocate buildings accordingly; (2) attempt to stabilize the shoreline with hard structures, such as seawalls, groins, or breakwaters; or (3) attempt to stabilize the shoreline through "softer" means, .such as beach replenishment,

In light of the political difficulties of instituting the first option, and the unacceptable environmental effects of the second (e.g. destruction of the beach), beach replenishment is becoming increasingly popular as the preferred weapon in the war against coastal erosion. Not only is a wide beachldune system an effective means of protecting buildings from the effects of high tides and storm waves; the sandy beach also provides important recreational opportunities to the public at large.

Before we embrace beach replenishment as the saviour of beachfront development, however, many questions remain to be answered. How good is our present state of knowledge regarding the engineering of replenished beaches? How have nourished beaches performed in the past? Better than expected? Worse? How long do replenished beaches last? How much do replenished beaches cost? Are they affordable on a national scale? What factors most strongly affect the longevity of a replenished beach? How can we quanitify and incorporate these factors into the design and construction of future replenishment projects? Answering these questions is essential if the American public is to

"Program for the Study of Developed Shorelines, Department of Geology, Duke University, P.O. Box 6729, College Station, Durham, NC 27708

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take rational, informed decisions about the future of our sandy eaches .

What Is Success?

Like so many things, the success of a replenished beach is in the eye of the beholder. An engineer may view as a success a beach that is too costly and shortlived from the viewpoint of a politican or inland taxpayer. The Miami Beach, FL project, for example has done far better than originally anticipated in terms of both cost and durability. Within the space of a single year, however, this project received both a preservation award from the American Shore and Beach Preservation Association for staying in place for so long, and the Golden Fleece Award from Senator William Proxmire for "sandbagging the taxpayers" through the wasteful or ridiculous use of tax money.

Since the definition of success depends upon the viewer's perspective, evaluating the overall success of beach nourishment projects is not a goal of our study. Instead, we are evaluating the success of project designers in predicting the durability and cost of various projects. Evaluation of predictive success is also a means of evaluating the utility and accuracy of various engineering concepts and assumptions basic to the design of artificial beaches.

In evaluating the design of a replenished beach, two requirements must be met in order for the design to be considered successful:

1. Actual costs and volumes placed must not vastly exceed original estimates of total costs and required volumes.

2. The design beach must be maintained during the project life.

Collection and Analysis of Data

As a first step towards answering some of those questions asked above, this study which evaluates existing records of some ninety replenished Atlantic beaches from Long Island, NY to Key Biscayne, FL No new field data were collected. Instead, we draw on information already collected and published in various U.S. Army Corps of Engineers reports, Congressional documents, symposia proceedings, journal articles, consultants' reports, city and state agency records, and media reports. All told some data were collected on more than 90 replenished beaches (Fig. 1)'and over 200 replenishment operations. The data coverage, however, is by no means uniform or complete. In fact, fragmentary information about a project is the unfortunate rule rather than the exception.

Simply collecting data on the costs, volumes placed, and monitoring results of replenishment projects proved to be difficult and time-consuming, for a variety of reasons. Often, monitoring of the beach before and after placement of the fill is viewed as a luxury, and is simply forgone in favor of buying a few more cubic yards of sand for the beach. Fortunately, some states, such as Florida, are moving to require monitoring of all projects granted a state permit; these regulations will provide a valuable data base for use in the future review and development of engineering principles.

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West 11nmp1:on I\coch , N Y Long Beach I s l a n d , NJ B r i g a n t i n e , NJ

,lone.q I \cr ic l~, N Y A t l a n t i c C i t y , NJ Oak Reoch, (;J. lgo, C e d a r Iwlond Beach , , NY Ocean C i t y , NJ Rocknwny Beach , N Y Ludlam I s l a n d , NJ

S t o n e Marbor ,NJ N o r t h Wil.dwood, N,I

Belmnr R Avo Wildwood, NJ C a p e May P o i n t , NJ I n d i a n R i v e r Beach , DE Ocean C i t y , MD Virg1.ni.n Bcclch, VA New I r ~ l . c * t , N(:

Vero Beach, FL Cape H a t t e r a s , NC F t . P i e r c e , F1, A t l a n t i c R e a c h , NC L i o n s C l u b Bea F i g u r e E i g h t I s l a n d , NC S t . L u c i e I n 1 W r i g h t s v i l l e Beach , NC J u l ) i . t e r Z ~ l n n d , Masonboro I s l a n d , NC . J r n s e n Bench , FI, C a r o l i n a Reach , NC J u p i t e r I n l e t New R i v e r I n l e t , NC Palm Dench Xs Long Beach, NC S n ~ ~ t . t i I.r~kc W o M y r t l e B e a c h , SC Oceflll H: i [IRE? , 1:11 E d i s t o Beach , SC Roynton T n l c t , t l u n t i n ~ Tsl .end, SC 1)c Lrny Dcnch, I l i l t o n flead I s l a n d , SC Roca R a t o n , F T y b e e I s l a n d , CA l i i l . S s b o r o , Fl, S e a I s l a n d , CA IJompono Beach Amelia P l a n t a t i o n , FL P o r t E v e r g l e d t l a y p o r t Naval. S t a t i o n -

'd P. J o h n [I. I.,l oy tl K a t h r y n Abbey Hanna Park , FL I--L Hollywood - Ha J a c k s o n v i l l e Beach, FL (D '4 I!nu.lovclr Pnrk, S t . A u ~ u s t . i n e Reach , F1, RO Bal H a r b o u r , FI, Cape C a n a v e r a l Reach, Fl, c3

Minmi R e ~ c h , Patrick Air F o r c e B a s e , FI, t-l V.l.rgl.n 111 Kt?y , P,

1 I I ~ In 1 r w t l c-Mt.1 hor~rnc: Rc.rlr:h, Ff, * rt'

Key B i s c a y n e , FL - . S e b o s t i a n .... I n l e t , . FL 0 3

t)r:icll r c ~ ~ t r ~ n i . s l i m e n ~ pro.jccts t i t 1 . l i z e d i n t:h-i.s . s t u d y ,

Although information on a given project may exist, obtaining the data is not always possible. Details of privately funded projects are often not placed in the public domain. Even public information, however, such as that of the U.S. Army Corps of Engineers, is sometimes incomplete, incorrect, uncatalogued, or simply not preserved.

Even when monitoring data are collected, analyzed, published, and preserved, the lack of standardization among the various projects makes meaningful, quanititative comparisons extremely difficult, if not impossible.

As mentioned above, much of the available information is that of the U.S. Army Corps of Engineers (USACE), and the nature of our federal bureaucracy further complicates data extraction. Sand may be pumped up with federal money under a variety of Congressional authorizations (e.g. beach erosion control, hurricane protection, flood control, emergency restoration or repair, navigation, or mitigation of damages caused by a navigation project).

Records of pumping operations are sometimes buried within this maze of authorizations, funding sources, and report headings. The Shore Protection Manual (U.S. Army Corps of Engineers, 1982), for example, states that Wrightsville Beach has received 4.6 million cubic yards (cy) of sand in two separate operations between 1966 and 1984. However, we found that including sand from all the various funding sources yields a total volume of 6.9 million cy of sand pumped up in six separate operations during that same time.

Results

A result of our review of existing records is a compilation of case histories, and qualitative observations and generalizations drawn from that review. Compiling regional and case histories of replenishment experiences can give coastal communities a better idea, at least in a qualitative sense, of what they might realistically expect should they opt for nourishment over other management strategies. The following is a brief list of selected East Coast replenishment projects, chosen to illustrate the great variability among beach replenishment parameters such as costs (absolute costs, overruns, underruns), volumes, frequency of replenishment operations, degree and type of development in the replenishing communities, justifications (authorizations), loss rates, failures and successes, and so on.

Due to space limitations, the raw data upon which the following case histories and conclusions are based cannot be presented in this paper; they are available upon request to the authors.

Jones Beach, NY: At Jones Beach, NY the primary justification for replenishment hasnot been the preservation of private property, as is often the case, but rather the provision of a recreational beach for the very large nearby urban population. Between 1927 and 1961, the State of New York pumped more than 40 million cy of sand from the backbarrier bay onto the beach. Even in the absence of post-1961

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replenishment records, this is the largest cumulative volume we have observed pumped onto a single beach.

Rockaway Beach, NY: Rockaway Beach is an example of a heavily used urban recreational beach with intensive shorefront development as well. Between 1925 and 1962, 12 million cy were pumped onto the beach with state and local funding. In 1974, the federal government began a restoration and nourishment program here, one of the first to use offshore sands as a sediment source for beach replenishment.

The current estimated cost of completion of this project is $51 million, 30% under the initial estimate (inflation-corrected). At first glance this circumstance seems to indicate realistic original expectations for the ten-year project. However, the nourished beach has so far met with mixed success, and the design beach has not been maintained.

Long Beach Island, NJ: This community of mostly single-family homes experienced very rapid shoreline recession during 1977 and 1978. As a result, the USACE, Philadelphia District replenished the beach in 1979 with $4.6 million emergency funds. 1.5 million cy of sand were pumped onto a 3-mile stretch of beach next to Barnegat Inlet. The sand was obtained from the inlet and was considered to be coarse enough to be good quality beach sand. A large percentage of the new sand disappeared in 1.5 years, followed by a year of slight accretion, followed by rapid and complete disappearance of the remainder. The narrowed beach is no longer perceived as an emergency by the community; it is a truth of the shoreline that community apprehension over a narrow beach softens with time and the absence of storms. The rapid loss of the beach sand and recession of the shoreline back to its original position, followed by an immediate slowdown in sand loss rate, as observed here, is a common phenomenon on other East Coast replenished beaches.

Atlantic City, NJ: Prior to 1986, Atlantic City's beach was replenished at leasrfour times by the USACE. All were small replenishments of less than 1 million cy. For those projects which were monitored, response of the beach fill varied greatly along the length of the project. Along some portions of the shoreline beach loss was total and rapid; along other portions, the losses were more gradual. The 1963 beach of 580,000 cy was lost at twelve times the natural average annual erosion rate, and the 1970 beach of 780,000 cy was lost at nine times the natural average annual erosion rate. These two replenishments used relatively coarse sand from the inlet and the third (1979) was fine dune sand bulldozed back to the beach. Both coarse and fine sand disappeared rapidly; apparently other factors overshadowed the effects of grain size.

Ocean City, NJ: The 1982 beach nourishment project for this community is pergps the least successful major replenishment project on the East Coast of the U.S. Between 1952 and 1982 more than thirty replenishments were carried out, most using a city-owned dredge (1970-1980) to pump sand from the backbarrier lagoons. In 1982, 1.2 million cy of city- and state-funded sand was pumped from the nearby flood tidal delta at a cost of $5.2 million. The sand was described as

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poorly sorted containing small amounts of mud and abundant shell fragments. The entire beach disappeared in 2.5 months due to "unusual storm activity," (i.e. 18 northeasters in the first 2.5 months).

Virginia Beach, E: Since 1952 this community has had a more or less continuous program of beach replenishment, much of it handled locally. Despite this constant maintenance, however, the amount of sand placed annually has not kept up with the amount of sand lost annually to erosion, and the design beach of the federal project has not been maintained. The more than 6 million cy of sand placed so far has been obtained from Lynnhaven Inlet, dredging of Rudee Harbor, dredging of Rudee Inlet, bypassing at Rudee Inlet, and trucking from nearby sand pits and spoil piles.

Cape Hatteras, g: The National Park Service's replenishment at Cape Hatteras National Seashore is an example of nourishment on a lightly developed shoreline. Three replenishment projects carried out here all disappeared very quickly in spite of grain size differences. In 1966, 312,000 cy of "too fine" sand from the lagoon was gone within one year. In 1971-72, 520,000 cy of coarse sand from Cape Point also was gone within one year. Too small a volume placed also reportedly contributed to these rapid losses, The 1973 replenishment of 1.3 million cy was 60% gone within 16 months. No subsequent monitoring was conducted, but the 16-month report noted that the 1974 mild storm season was one reason for the relatively high retention of sand and that such high retention rates could not be expected to continue into the future.

Wrightsville Beach, K: Wrightsville Beach has been replenished under a wider variety of federal authorizations than any other East Coast beach. The numbers and justifications are as follows:

3 flood control 1 emergency 1 flood control and navigation 1 flood control, navigation, and mitigation of the effects of

that navigation project 1 mitigation of effects of navigation project

To date Wrightsville Beach may be the only beach replenishment project on the East Coast barrier island shoreline that has been funded on the basis of mitigation of damages caused by a Federal navigation project (although others are currently awaiting funding, e.g. Ft. Pierce, FL; or are under study, e.g. Folly Beach SC; Palm Beach Harbor, FL). In 1977, the USACE, Wilmington District stated that 93% of the annual erosion losses at Wrightsville Beach were due to the jetty project at Masonboro Inlet at the south ("downstream") end of the island. In 1982 this figure was revised to 46%.

The true long-term cost of replenishing a beach is sometimes lost to the intricacies of Federal record-keeping. For example, considering only funds expended from the shore protection account for Wrightsville Beach, the actual cost of completion of the ten-year project was 43% (inflation-corrected) above the original estimate. However, if we

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i n c l u d e a l l funds expended t o pump sand o n t o W r i g h t s v i l l e Beach, r e g a r d l e s s of s o u r c e , t h e c o s t over run is 672% ( c o r r e c t e d f o r i n f l a t i o n ) .

The o r i g i n a l e s t i m a t e of volume of sand r e q u i r e d was 1 . 5 m i l l i o n cy p l u s 31,800 cy/yr annua l nourishment. However, s i n c e t h e f i r s t f e d e r a l l y funded sand pumping on W r i g h t s v i l l e Beach i n 1965, 7.8 m i l l i o n cy have been placed on t h e beach. According t o USACE r e p o r t s , e r o s i o n rates were f i v e t imes g r e a t e r t h a n a n t i c i p a t e d i n beach des ign . According t o Pau l Hosier ( p e r s o n a l communication), t h e e r o s i o n rate of r e p l e n i s h e d W r i g h t s v i l l e Beach h a s t y p i c a l l y been t e n times f a s t e r t h a n t h e n a t u r a l e r o s i o n rate f o r t h i s beach.

C a r o l i n a Beach, E: This community is s e p a r a t e d from W r i g h t s v i l l e Beach bv Masonboro I s l a n d . On a per-mile b a s i s , t h i s is t h e most c o s t l y i e d e r a l l y suppor ted beach ;eplenishment p r o j e c t t o d a t e : $5.2 m i l l i o n p e r m i l e over a 20-year time span (compared t o $5.1 m i l l i o n f o r M i a m i Beach over a n 11-year time span) . C a r o l i n a Beach a l s o r e p r e s e n t s t h e g r e a t e s t c o s t over run on t h e E a s t Coast t o d a t e . The o r i g i n a l c o s t estimate w a s $1.4 m i l l i o n ( f o r C a r o l i n a Beach and Kure Beach) and t h e c o s t t o d a t e h a s been $13.5 m i l l i o n ( f o r C a r o l i n a Beach o n l y ) . The c u r r e n t e s t i m a t e d c o s t o f completion ( f o r C a r o l i n a Beach and Kure Beach) is 1312% over t h e o r i g i n a l c o s t estimate, c o r r e c t e d f o r i n f l a t i o n . A t o t a l of seven pumping p r o j e c t s have been c a r r i e d o u t : f o u r under t h e j u s t i f i c a t i o n of f l o o d c o n t r o l and t h r e e under t h e emergency umbrel la .

Hunting I s l a n d , SC: Hunting I s l a n d is a n example of a f e d e r a l beach rep len i shment p r o j e c t c a r r i e d o u t i n a s ta te park where no b u i l d i n g s of consequence are t h r e a t e n e d -- an unusua l e x p e n d i t u r e f o r a non-urban beach. Here, t o t a l volume of sand p laced roughly e q u a l s t h e o r i g i n a l estimates made by t h e USACE, C h a r l e s t o n D i s t r i c t . However, t h e s e f i g u r e s match up on ly because t h e des ign beach was n o t mainta ined. For example, even though t h e f i r s t beach f i l l l a r g e l y d i sappeared e s s e n t i a l l y w i t h i n s i x months, more sand was no t p laced u n t i l t h r e e y e a r s later. The fo l lowing i s t h e schedu le of rep len i shments f o r t h i s 2-mile replenishment p r o j e c t :

1. 1968: 750,000 cy -- 72% gone i n 6 months, due t o s torms 2. 1971: 761,324 cy -- 97% gone i n 6 months 3. 1975: 613,000 cy -- f a t e unrepor ted 4. 1980: 1 ,400,000 cy -- mostly gone by 1983

Apparent ly t h e sand f o r a l l of t h e s e p r o j e c t s w a s of " s u i t a b l e " s i z e . It was e x t r a c t e d e i t h e r from t h e ebb t i d a l d e l t a o r from e x c a v a t i o n on t h e i s l a n d .

Tybee I s l a n d , g: Sand w a s f i r s t pumped on t h i s beach i n 1976. By t h e end of one y e a r , 50% of t h e sand had d i s a p p e a r e d , and no beaches remained a t t h e n o r t h and s o u t h ends of t h e p r o j e c t . Sand remained i n t h e c e n t r a l p o r t i o n of t h e p r o j e c t a r e a , bu t t h e r e had been no e r o s i o n problem t h e r e t o beg in wi th .

T h i s p r o j e c t is a l s o encounte r ing s u b s t a n t i a l c o s t overruns . The 1985 e s t i m a t e d c o s t of completion is 656% h i g h e r t h a n t h e i n f l a t i o n - c o r r e c t e d o r i g i n a l e s t imate .

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Jacksonville Beach, FL: The USACE, Jacksonville District noted that the rate of erosion;£ this 3.6 million cy, 10-mile-long beach was initially twice that expected. Subsequent summers, however, brought significant recovery, and the beach in the long-term fairly closely met original design expectations.

Canaveral Beach, FL: Here, 2.1 miles of beach were replenished in 1974-75 with 2.7 million cy of sand obtained from dredging of the Canaveral Turning Basin. This beach apparently lasted longer than predicted and is an example of a beach where durability predictions were on the mark. Indialantic-Melbourne Beach is considered to be part of the same federal replenishment project.

Indialantic-Melbourne Beach, &: Although nearby Canaveral Beach was a successful replenishment, Indialantic-Melbourne was less so. In 1980-81, 540,000 cy were trucked in from the spoil pile of dredged sediments from the Canaveral Turning Basin (same source as Canaveral Beach). The beach at the northern end of the project disappeared quickly, while sand on the southern end was retained.

Jupiter Island, FL: This beach probably represents the largest totally private (pairfor by beachfront property owners) beach replenishment effort on the East Coast. Altogether, sand has been pumped on this beach at least 10 times; the largest replenishment consisted of 3.5 million cy placed along five miles of beach in ' 1973-74. Experience shows that a 5-year nourishment interval is to be expected here.

Delray Beach, - FL: Since 1973 a total of 4 million cy has been pumped up along 2.8 miles of Delray Beach shoreline at a cost of $8.5 million. Along the South Florida coast water turbidity is considered to be a major factor in beach replenishment. This is because of coral reefs and various other kinds of hardgrounds which harbor a rich fauna and flora. The sand for past Delray Beach replenishment has been obtained from the continental shelf, but during the last replenishment turbidity violations prompted the Department of Environmental Protection to state that sand for future nourishment could not come from offshore. In addition, at least one deep (90 ft) hole has been formed and is filling with mud. There is a strong possibility that in future storms this mud will be resuspended causing unacceptably high turbidity levels.

Miami Beach, &: This is the largest beach replenishment project on the East Coast and also among the most successful in terms of durability. 14.4 million cy were pumped up along 10.5 miles of shoreline between 1976 and 1981 at a cost-to-date of $54 million. This sand has stayed on the beach much longer than originally anticipated; reasons given for this success include:

1. The beach was pumped up along a "natural geographic reach." 2. The wave energy is generally low. 3. The beach has not yet been tested by a major storm. 4 . This was a non-eroding beach to begin with.

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Discussion

It is important at this point to reemphasize the critical importance of beach replenishment to our society. In the view of many, artificial beaches hold out hope that it will be possible to both protect existing oceanfront development and still have recreational beaches. The importance of replenishment is increased in the context of predictions of accelerating sea level rise which will certainly increase natural rates of erosion as well as cause increased rates of sand loss from replenished beaches. Thus it is critical that we establish a sound understanding of the principles governing emplacement and survival of artificial beaches.

In spite of the imperfections and limitations of the data base of this study, a number of conclusions are apparent. Most important is the observation that predictions as to the cost and durability of replenished beaches are poor. As noted in an earlier section, a successfully predicted project is one for which estimated and actual costs are reasonably close and for which the design beach is maintained. Unfortunately, there exists for only twelve beaches (all USACE projects) sufficient data to make quantitative comparisons of expectations and actual results. Our analysis of these projects reveals that north of Cape Canaveral, FL the fate of replenished beaches was never correctly predicted, with the possible exception of Jacksonville Beach, FL. In addition to the examples for which quantitative comparisons can be made, it is apparent from other examples which are less well-documented that unexpectedly rapid disappearance of restored beaches is common (e.g. Long Beach Island, Atlantic City, Ocean City, Strathmere, NJ; Cape Hatteras, Figure Eight Island, NC; portions of Rockaway Beach, NY and Indialantic-Melbourne, FL) .).

South of Cape Canaveral, project engineers successfully predicted the fate of at least three replenished beaches (Cape Canaveral Beach, Pompano Beach, and Miami Beach, FL). By the standards of virtually all of the beaches on East Coast barrier islands, the success of Miami Beach is striking. Both costs and durability were initially substantially overestimated, which from the standpoint of the public's interest is much preferable to the usual underestimation.

The Miami Beach project illustrates an interesting generalization that we believe may have wide applicability., That generalization is that sand attracts sand. Once a beach has been replenished, the community involved is well-positioned to obtain additional funding. At the time of this writing, Florida is planning to spend 50% of the state's 1987 replenishment budget nourishing the north end of Miami Beach where erosion problems are beginning to appear.

Why the poor predictability of artificial beaches? By far the most commonly given reason for beach failure is storms. The nature of the data base is such that we can neither confirm nor deny that most replenishment project failures are due to storms. But storms are part of the natural oceanographic system we work with and should not be

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viewed as unexpected, events or bad luck, as they often seem to be in media quotations.

The data indicate clearly that assumptions (such as those concerning the effects of grain size, beach length, and profile of equilibrium) and equations on which we base predictions of replenished beach behaviour need close re-examination. (These principles are reviewed in U.S. Army Corps of Engineers, 1982; Dean, 1983; and Staubie, 1986).

It is clear that in our present state of knowledge the best approach is empirical. A project involving an initial beach restoration should be considered experimental. After experience with the first sand emplacement operation a better basis will exist for predicting future behavior. It is also a reasonable first assumption that the artificial beach will erode much more rapidly than the natural beach which preceded it. The rates of erosion of the natural and unnatural beaches will often differ by an order of magnitude.

One source of error with the standard approach to beach replenishment is the assumption that a beach needs a single major restoration operation followed by only minor maintenance nourishment. This assumption is illustrated in figure 2(A), which is taken from a State of Florida publication (State of Florida, 1986). Figure 2(B) is a more realistic view of the situation, at least on the U.S. East Coast. To be successful a beach replenishment project must be planned as a series of major replenishments interspersed with smaller ones.

Planning and budgeting for beach restorations should include assumptions that storm damage will occur. To continue to view storms as accidents is avoiding an important responsibility to the American people.

On the basis of our study results, it is possible to review or critique projects in the planning stage from a fresh viewpoint. One such example is Westhampton, NY. Here, the USACE, Manhattan District has planned a major beach restoration costing on the order of $54 million to be followed by 50 years of maintenance replenishment. Total cost of the project is predicted to be on the order of $124 million, following the assumption of figure 2(A). Coastal scientists in one New York state agency, however, have suggested that the actual costs over a 50-year time span are likely to be $500 million, a figure based on regional experience with artificial beaches. Our study indicates that the $500 million figure is much closer to the likely final figure.

Ironically, the project has been proposed for the protection of 220 houses.

Conclusions

1. Recordkeeping on federal, state, local, and private beach replenishment projects is poor, As a result, quantitative (or even qualitative) analysis of past beach response is extremely difficult.

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I I i

' Pla jor restoration - - event

0 20 4 0 60 80 TEARS AFTER PRESEST

TEARS AFTER PRESEKT

Figure 2. (A) A hypothetical beach replenishment project. This figure shows a model of replenishment used by both the USACE and the State of Florida, wherein a single major restoration is followed by numerous smaller renourishment events (State of Florida, 1986). (B) This figure shows a more realistic scenario for an East Coast beach. Frequent major replenishments are required to maintain the design beach.

Field testing engineering models by using data collected from past replenishment projects is practically impossible.

2. The cost and f'lifespan" of replenished beaches are usually initially underestimated. Several replenished beaches south of Cape Canaveral, FL are exceptions to this general rule.

3. The various models and assumptions used to design replenished beaches need re-evaluation.

4 . Until better means of predicting beach fate are available, future beach replenishment projects on previously unreplenished beaches should be viewed as experiments.

5. In future planning and evaluation of beach replenishment projects on the East Coast, storms must be viewed as certainties rather than accidents.

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Acknowledgements

This s tudy would.not have been poss ib l e without t h e suppor t and cooperat ion of many people. Espec ia l ly he lp fu l were those a t t h e .

Univers i ty of F lo r ida Coas ta l Engineering Archives, t h e U.S. Army Corps of Engineers D i s t r i c t Of f i ce s , and s t a t e c o a s t a l zone management o f f i c e s .

This s tudy was funded by t h e William H. Donner Foundation and is a con t r ibu t ion of t h e Duke Univers i ty Program f o r t h e Study of Developed Shorel ines .

Data on which our conclusions a r e based a r e a v a i l a b l e upon r eques t t o t h e au thors .

References

Dean, R. G., 1983, P r i n c i p l e s of beach nourishment, CRC Handbook of Coastal Processes and Erosion, P. D. Komar, ed. , CRC P r e s s , Boca Raton.

S t a t e of F lo r ida , 1986, A Proposed Comprehensive Beach Management Program f o r t h e S t a t e of F lo r ida , Department of Natural Resources. Divis ion of Beaches and Shores , Tal lahassee.

S t aub le , D. K . and Hoel, J., 1986, Guidel ines f o r Beach Res to ra t i on P r o j e c t s , P a r t I1 - Engineering, F lo r ida Sea Grant Col lege Report, Number 77, Gainesv i l le .

U.S. Army Corps of Engineers , Coas ta l Engineering Research Center , 1984, Shore P ro t ec t i on Manual, U. S. Government P r i n t i n g O f f i c e , Publ ica t ion 008-022-00218-9, Washington.

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