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6 Monitoring Time-series data can help establish the need for, and evaluate the perfor- mance of, beach nourishment programs and projects. This chapter discusses the need for physical, environmental, and economic time-series data and issues sur- rounding the evaluation of beach nourishment project performance. OVERVIEW Monitoring is the systematic collection of physical, environmental, or eco- nomic time-series data or a combination of these data on a beach nourishment project in order to make decisions regarding the need for or operation of the project or to evaluate the project's performance. Beach nourishment projects are continually responding to storms and seasonal changes in the physical and bio- logical environments. Thus, their dimensions and the level of protection they provide usually decrease with time. The level of protection at any given time may also vary along the beach in a given project. These data are needed to address the management questions listed in Box 6-1. Data acquisition programs must be designed with a clear definition of what data are needed and how the data will eventually be used. The objectives must be clearly defined at the outset, and the monitoring program must be designed to meet those objectives. Too often, data are collected without consideration for their analysis or how they will be used to make decisions. As a result, data collected at considerable expense may never be fully analyzed or, if analyzed, will not provide the answers needed (NRC, 19901. Obviously, appropriate mea 127

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28 BEACH NOURISHMENT AND PROTECTION surements must be made at a suitable frequency to permit decision makers to use the information in renourishment activities. Types of Monitoring The physical processes monitored are usually those that move sand within and away from the project area the fate of the sand and those that cause elevated water levels. Often, many physical monitoring programs address only the beach's response to sand-moving forces and do not include important forces such as waves and currents. Environmental monitoring is undertaken to document a project's effects on the biota of the nourishment project. It involves collecting data on the impacts that projects have on the flora and fauna in a project area and in adjacent areas. Biological data are obtained to determine whether any short- or long-term changes have occurred to the biota. Data need to be obtained on the beach where sand is placed and in any offshore borrow areas. Preconstruction data on species diver- sity, species composition, and numbers are compared with data taken during the life of the nourishment project. For example, the monitoring of turtle nesting

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MONITORING 129 areas during the nesting season may be conducted to ensure protection of nesting sites. These efforts must be carefully designed to eliminate seasonal effects that may bias conclusions. Economic monitoring is undertaken to evaluate the economic impacts of a project and to determine whether predicted economic benefits were actually real- ized, whether other unanticipated benefits resulted, whether projected construc- tion costs were correct, and whether hidden costs were incurred. It involves determining whether a project's economic justification was valid. Purposes of Monitoring Monitoring is undertaken for various purposes. Operational monitoring may simply involve periodic inspections to determine the need for remedial action. Such remedial actions might include renourishment, structure repairs, and other maintenance. Operational monitoring includes both pre- and poststorm monitor ing and the assessment of project performance. Performance monitoring is un- dertaken to develop information and procedures for design verification and to document lessons learned that may be applied in the design of future projects. Phases of Monitoring Monitoring phases coincide with project phases: preconstruction monitor- ing, construction monitoring, and postconstruction monitoring. Preconstruction monitoring involves collection of data on the physical and biological environments that describe regional and site-specific processes. It in- cludes collecting data helpful for design as well as baseline biological data. Physical data are needed on waves, currents, water levels, beach composition and profiles, and meteorological conditions. Baseline biological data include infor- mation on habitat type and physical conditions, species composition and abun- dance, and distribution patterns. Preconstruction economic data are also important and may be collected as part of the cost-benefit analysis for the project. Specifically, surveys of beach users (including information that would support both travel cost and contingent valuation analyses) are important. In addition, preconstruction assessments of the market value of commercial and residential real estate in the area would contrib- ute to a hedonic analysis of the effects of beach nourishment on property values. Construction monitoring involves collecting data on how much sand was actually placed and where, on short-term effects construction may have caused, and on the materials that were actually used (e.g., the size of the sand placed on the beach). Monitoring may include the effects of construction-induced turbidity on the biota as well as recreational values lost during construction if construction takes place during the recreational season. Postconstruction monitoring involves systematic collection of data after con

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130 BEACH NOURISHMENT AND PROTECTION struction is complete to study the project's performance. Is it functioning as intended? What, if any, are its adverse effects? What are its short- and long-term biological impacts? What economic benefits did it actually provide? What mon- etary costs were actually incurred, and what additional costs were imposed on the area when it was time to reflourish? Scale and Duration of Monitoring Programs The scale of monitoring is generally related to the scale of the project itself. Smaller projects may require only simple inexpensive measurements that provide the information needed to make operational decisions. However, for small projects with a potential for significant impacts, more extensive monitoring, commensu- rate with the project's potential for physical and biological enhancements, dam- age and economic loss, may be needed. For larger-scale projects, a more compre . . hensive monitoring program is warranted. Monitoring needs to be undertaken in order to apply the findings to the design of subsequent nourishment efforts. For example, if a borrow site experi- ences long-term adverse impacts, a different borrow site or configuration must be selected. If beach fauna show only limited impacts during nourishment, monitor- ing of these impacts may not be necessary in subsequent renourishments or for similar nourishment projects. The analysis of data from an effective monitoring program would provide feedback to the design process. Monitoring the post- construction economic impact of beach nourishment projects has not been wide- spread. There have been few follow-up analyses of projects to determine whether projected benefits were actually realized, whether secondary benefits occurred, or if unanticipated costs could be attributed to the project (Stronge, 1992a, 1994J. Monitoring programs need to be evaluated periodically and adjusted to meet the needs of a project. As experience is gained with a project, some measure- ments may be phased out or the frequency with which they are taken reduced. For example, the infilling of a borrow area may show significant changes only fol- lowing major storms; consequently, surveys need to be conducted only after such storms. Similarly, after a period of years, seasonal variations in a beach's profiles may be known, so frequent beach surveys become unnecessary. PHYSICAL MONITORING Monitoring the physical processes associated with a beach nourishment project needs to be done within the framework of a sediment budget for the project area and, when relevant, adjacent areas. A sediment budget requires that all sand sources and sinks be identified and quantified for a defined sediment budget area. The gains and losses are balanced against the changes in sand vol- ume in the area. Sand sources include rivers, local bluff erosion, and alongshore transport from adjacent areas. Sinks include ebb- and flood-tide shoals, wind

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MONITORING 131 transport of sand to back bay areas, losses to submarine canyons, and sand carried out of the area by alongshore transport. Monitoring data collected to quantify the physical processes that comprise sources, sinks, and sand volume changes in a project area can include: the previous history of the coastal site, beach profiles, waves, currents, water levels, structures, sediment characteristics, and photographic documentation. . Previous History of Site The history of a coastal site can provide important information on how a beach nourishment project may perform. Historical data may include anecdotal information in addition to well-documented information on the physical environ- ment and on the performance of earlier coastal projects. Information may in- clude: historical erosion rates from aerial photographs or shoreline-change maps; relative changes/trends in sea level; astronomical tides; local anthropogenic impacts, such as past nourishments; documented information on historical storms and wave climate; and assessment of the geological setting (i.e., the type of underlying geology that may influence coastal processes and the sediment budget). Beach Profiles Changes in the volume of sand in a beach nourishment project along with the width of the subaerial beach can be documented by periodic beach profile sur- veys. Factors to be considered in establishing a beach profile survey program include: profile line spacing, profile length (from dune line to depth of closure), survey frequency, and surveying procedures. Knowledge of the profile line spacing and length permits the accurate defini

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32 BEACH NOURISHMENT AND PROTECTION lion of sand volumes in a project area and in adjacent areas that might receive sand from the project. To accomplish this, profile lines must extend seaward to the profile closure depth. Survey frequency varies over the life of a project. Initially, surveys need to be conducted often enough to quantify seasonal changes. For example, quarterly surveys may be needed because of profile adjustments following construction, but subsequent project performance may permit less fre- quent surveys. Because substantial changes can occur as a result of major storms, it is prudent to conduct pre- and poststorm surveys in order to quantify the effects of individual storms. Various surveying procedures can be used. Onshore surveys can be conducted with standard level-rod surveying procedures. Offshore surveys extending to wading or swimming depths can also use standard level-rod proce- dures. However, surveys in deep water (soundings) require special equipment and procedures such as echo sounders or survey sleds. When two different survey procedures are employed onshore and offshore (often on different days), the two surveys must be overlapped and spliced in the surf zone a region where eleva- tion changes are significant and rapid. A survey sled avoids this problem because it allows a single survey procedure to be used across the profile from deep water to shore (Grosskopf and Kraus, 1994~. Waves Waves produce the most important forces that move sand in the coastal zone. Alongshore sand transport is caused by the suspension of sand by breaking waves and its movement by wave-induced alongshore currents. Waves also produce an increase in water level, termed setup. Wave and water-level data provide a quan- titative measure of storms affecting a project site and can be used to assess project performance in response to differences in storm wave height, period, direction, and duration and storm surge. Historical wave information, including wave height, period, and direction, are available for U.S. shorelines in the form of wave hindcasts developed for a 20-year period by the U.S. Army Corps of Engineers (USAGE). These are valuable for the design of beach nourishment projects but are generally not useful for evaluating the performance of a specific project. For this latter purpose, wave measurements are necessary. There are numerous types of wave gauges that can provide wave height and period data. They include surface-piercing gauges, pressure gauges, accelerometer buoys, and inverted echo sounders. Measurements of wave direction, necessary to determine alongshore sediment transport rates, require directional buoys in deep water, multiple gauge arrays, or pressure-gauge slope arrays in shallow water. Visual observations of nearshore wave conditions can also provide data, but they are generally inaccu- rate and are not collected during severe storm periods when observers cannot visit the beach. Waves also provide the loading on any structures that might be associated with beach nourishment projects.

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MONITORING Currents 133 Currents are typically not measured directly as part of beach nourishment project monitoring; alongshore currents are usually calculated from measured or hindcast wave conditions. Some wave gauges rely on current measurements to determine wave duration. However, data on currents associated with tidal inlets may be important in understanding the performance of some beach nourishment projects. Speed and direction can be measured by deploying current meters or by tracking floating drogues or dye. Current meters can provide data recorded at selected points over a long period several tidal cycles or longer; drogues and dye provide data for very short time intervals and reaches. Storm-driven currents are also difficult to measure unless incorporated into the regular gauging pro- gram. Water Levels Elevated water levels during storms cause flooding and allow waves to act higher up on the beach profile, where they cause erosion and damage to upland development. Water levels are routinely measured by the National Oceanic and Atmospheric Administration's National Ocean Survey at tide gauges located along U.S. coastlines (NOAA, 19931. These gauges record water levels that include the astronomical tides, and when the predicted astronomical tide is sub- tracted from the gauge record, they yield data on the meteorologically caused water levels (storm surges). In most cases, these data will be available at nearby gauges for beach nourishment projects in the United States; however, there may be special cases where data are needed nearer the project. In these cases, a local tide gauge could be installed. Structures If coastal structures such as seawalls, bulkheads, groins, nearshore breakwa- ters, and jetties are present, monitoring of their effects on waves and currents, their permeability to sand, and, ultimately, their effect on the stability of the beach nourishment project is needed. Sediment Characteristics Sediment characteristics of interest include mineralogy, specific gravity, mean grain size, grain-size distribution, grain shape, and settling velocity (Smith, 1992~. Most important are the mean grain size, size distribution, and settling velocity. Sediment data are needed for the native beach sand, the intended borrow sand, and the sand actually placed on the beach. Spatial variations in sediment characteristics may also play a role with changes in mean grain size across the

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34 BEACHNOURISHMENT AND PROTECTION profile and along the beach. Ultimately, settling velocity determines the impor- tant hydraulic characteristics of the sediment and the nearshore beach slope and equilibrium profile shape. Photographic Documentation Photography provides a relatively inexpensive method of obtaining data on the performance of beach nourishment projects. Controlled vertical aerial photo- graphs can document upland conditions, shoreline location, and beach topogra- phy at a specific point in time. They can also be used to document storm effects. Strategically positioned ground-level photographs taken from the same location over time can provide a ready indication of the success or failure of a project. In addition, videotape can supplement still photography in documenting beach con- ditions. Videos taken from a small airplane or helicopter can provide an inexpen- sive way to document beach conditions over large reaches of shoreline before and after storms. BIOLOGICAL MONITORING There are several major objectives that need to be incorporated into any biological impact assessment of a beach nourishment project. They are to: determine the existing biological resources that may be altered by the project and provide recommendations that will avoid long-term negative consequences to those resources, characterize the preconstruction temporal and spatial variability in the biological resources present within and near the project area, and evaluate the postnourishment recovery of biological resources that may be impacted by the project. Many previous monitoring studies of beach nourishment projects have failed to adequately incorporate one or more of these objectives. Although the specific design of a monitoring program may vary considerably, depending on the size and location of the project, some general guidelines can be stated. Before any nourishment project is conducted, it is essential to obtain ad- equate baseline data on carefully selected, significant flora and fauna in an area and to document natural spatial and seasonal variabilities in their numbers, spe- cies composition, and diversity. These data can then be compared with post- nourishment monitoring to evaluate the extent and duration of changes that oc- cur, both on the beach and in the borrow area. A complete monitoring program would provide adequate data to ensure that biological impacts are only short term relative to the interval between renourishment projects. If long-term impacts are experienced, other approaches to the project must be considered.

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MONITORING 135 The scope of the preliminary biological surveys required within and adjacent to a project depends largely on the quantity and quality of historical data avail- able for the area, but, as a minimum, a comprehensive assessment would include the following: . surveys to locate and quantify ecologically sensitive habitats, such as nearshore reefs, hard-bottom habitat, and nesting habitats that should not be disturbed by construction activities, including information on the sea- sonal use of the project area by threatened or endangered species or im- portant fishery resources, and surveys of other biota, such as benthic infauna, that will be affected by disturbances from dredging and nourishment activities within and adja- cent to the project area. Methods for surveying sensitive-bottom habitats vary, depending on water clarity and the size of the project. In areas where waters are clear and shallow, aerial surveys supported by diver or underwater television observations may be suffi- cient to map reef habitats. When water clarity or depths preclude visual mapping methods, side-scan sonar, underwater television or photography, and subbottom profiling systems may be used. A combination of two or more of these systems is often preferable because each has its limitations in detecting or mapping bottom types, particularly in areas where there is no bottom relief. The size of the survey area and the spacing of transects in the area will depend on the equipment used, but all bottom habitats in the area potentially affected by the project need to be mapped fully. Data on fishery resources in the project area or on use of the area by threat- ened or endangered species are often available through monitoring programs conducted by state and federal natural resource agencies. However, some pre- liminary reconnaissance may be necessary when such data are not available. Quantitative sampling of other biological resources, such as the benthic macrofaunal communities, is also usually warranted because these assemblages are the principal macrofaunal component inhabiting beach sands and borrow areas, and they form an important component of the nearshore food web. Prelimi- nary sampling of these assemblages needs to be conducted, when feasible, to select the appropriate sample size and sampling design to be used in pre- and postnourishment monitoring studies. It is not necessary to include biota that cannot be adequately quantified or that are not good indicators of the local envi- ronmental quality in any subsequent monitoring program. Similarly, emphasis is appropriately placed on monitoring only those resources and habitats of greatest concern because there is rarely enough funding to adequately monitor all aspects of the affected ecosystem. For example, if the areal extent of the intertidal zone is limited owing to low tidal amplitude, monitoring of intertidal communities may represent a lower priority compared to monitoring the borrow area, where longer

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136 BEACH NOURISHMENT AND PROTECTION term effects have been noted, or the nearshore zone in areas where there are sensitive habitats that may be disturbed. The extent, duration, and frequency of pre- and postconstruction monitoring will largely depend on the size of the project, the habitats to be affected, and the projected frequency of renourishment. Determining the sampling precision for the biological monitoring effort merits specific consideration. Elliot (1979), Green (1979), and Nelson (1991, 1993) provide more comprehensive information on recommended sampling designs, sample size, and sampling frequency and on statistical constraints that merit consideration in developing a biological monitor- ing program. Sampling precision is especially important because many previous studies involved the collection of only a few replicate samples per site. The low number of replicates used was probably not sufficient to detect statistically even major changes in the biological parameters being monitored. In addition, many studies have focused more on characterizing community structure such as faunal abundance, biomass, and measures of species diversity than on identifying and assessing trends and changes in the faunal communities with respect to trophic structure and function. There is a large variability in the physical characteristics and biological resources of beach and nearshore habitats along the coastline of the United States. The conditions that exist at a beach nourishment site need to be considered in forming the specific sampling approaches that are incorporated into a biological monitoring program. Based on the limited data available from previous monitor- ing efforts, several key questions need to be addressed in developing the biologi- cal study design: What is the duration of disturbance to the biological resources of concern, and is it compatible with the anticipated frequency of redisturbance re- sulting from subsequent renourishment operations? Are biological resources adjacent to the project area affected by construc- tion activities or subsequent movement of sediments from the project area? Do turbidity levels associated with nourishment operations exceed levels known to be harmful to the indigenous biota of concern, or, if that is not known, do the levels exceed those naturally observed over various sea- sons at the site of concern? Monitoring programs that are designed to address these questions adequately and that are relevant to the area where a project is planned will greatly improve our understanding of the biological consequences of beach nourishment activities. ECONOMIC MONITORING A well-designed economic monitoring program would attempt to answer the following questions:

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MONITORING 137 How large are the realized recreational benefits, and do they approximate those predicted for the project? What are the effects of the project on property values, and to what extent are these effects linked with storm damage reduction, enhanced aesthet- ics, and recreational amenities? What were the construction and other related costs, and were they well approximated by the cost estimates? Are there other significant but perhaps unanticipated costs and/or benefits accruing from the project? From the locality's standpoint, did the project stimulate growth, and, if so, what desirable or undesirable effects did the growth have on the commu- nity? Did the project encourage construction that places more property at risk from storm destruction? What was the actual distribution of the costs and benefits of the project- that is, who benefited and who paid? Although the USACE is charged with conducting preconstruction cost- benefit analyses, there have been few follow-up analyses of projects to determine whether projected benefits were actually realized, whether secondary benefits occurred, or whether unanticipated costs could be attributed to the project (Haveman, 1979; Stronge, 1992b, 1994~. Without such follow-up studies, it is difficult to determine whether USACE methodologies for assessing recreational and storm damage reduction benefits are sufficiently accurate for beach nourish- ment analysis, and it is impossible to determine whether its cost-benefit analyses incorporate all significant categories of costs and benefits that usually accrue from these projects. Although full-scale follow-up analyses may not be warranted for all projects, postconstruction analysis of a sampling of projects is necessary to answer these questions. As discussed in Chapter 2, none of these categories of costs and benefits is easy to estimate. Analysis of recreational benefits is in some ways the easiest because this methodology is the most well developed. The purpose of the recre- ational monitoring component would be to quantify the actual recreational ben- efits accruing specifically to the beach nourishment activity and whether the benefits were well approximated by the preconstruction analysis. This analysis requires valuing the change in use directly associated with the change in the quality/size of the beach brought about by the nourishment. Ideally, both before and after the nourishment activity, surveys based on random samples of the area's population need to be taken in conjunction with onsite surveys of beach users. The surveys would provide both information on participation rates for beach use that are unavailable from onsite surveys and a means of extrapolating survey sample to total beach use. However, onsite surveys are still useful because they provide a means of oversampling users, thus ensuring adequate coverage of this group. Both types of surveys would need to collect

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138 BEACH NOURISHMENT AND PROTECTION information on the total number of beach trips to different beaches in the area on a seasonal basis as well as the location of household residence, travel costs, and household socioeconomic variables. Given access to respondents, contingent valuation questions might also be included in the survey. Such questions are a useful way to elicit information on how individuals value quality aspects of the beach and the surrounding area that may have changed owing to the nourishment activity. As explained in Appendix E, contingent valuation questions ask people how much they would be willing to pay (in increased entrance fees, parking fees, or some other payment vehicle) for a change in quality characteristics of the beach. A pertinent experiment would be to ask such a question before construction, describing the expected outcome of the nourishment activity, and then to ask a similar postconstruction question when individuals can witness the results of the nourishment project directly. It is, of course, difficult even after construction to assess the accuracy of estimated storm damage reduction benefits. The reason is that storm events are random, and estimates must be based on expectations. However, it is possible to attempt to assess the effects of a nourishment project on property values by collecting property value data before and after the project and completing a hedonic analysis. A hedonic analysis attempts to explain property values as spe- cific functions of characteristics of the property (see Appendix E for further discussion of hedonic analysis). Data on important property characteristics are required, including distance to, view of, and accessibility of the beach. The intent would be to see how changes in the quality of the beach affect property values, controlling for all other features of the properties. There are several difficulties with hedonic analyses of this sort, however, not the least of which is timing; the added value of a beach nourishment project will begin being capitalized into property values as soon as a potential project is announced. Nonetheless, it would be useful to design a hedonic study that at- tempts to reveal the marginal value associated with beach nourishment, although it may require incorporating a lagged response in the model. It would also be useful if the hedonic analysis could be designed to separate the storm damage reduction benefits from the aesthetic and recreational benefits of the nourish- ment; however, the high correlation between these two characteristics may pre clude doing so. Beach nourishment projects can potentially have additional effects on an area although few, if any, studies have attempted to even list them. Projects may stimulate new construction and/or commercial development, for example. Such activity may have positive or negative net benefits for the community depending on the nature and size of the development and the type of community. A post- construction survey of these effects would be useful, including an assessment of their fiscal impacts (increases in the tax base and employment versus increased costs of infrastructure and services). If a nourishment project stimulates construc- tion that increases the risk to property of storm damage, then this increase needs

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MONITORING 139 to be accounted for. Further, it would be especially useful to survey the popula- tion to determine the community effects of the beach nourishment project. Because there is increasing debate over the share of beach nourishment costs incurred by federal and local partners, an analysis of the recipients of the costs and benefits would be useful. First, of course, the construction and related costs of the project need to be tallied, compared to original cost estimates, and attnb- uted to the sponsoring parties. They would then be compared with the incidence of the benefits. If properly done, such an analysis will provide accurate informa- tion as to who benefits from the project. One caveat is necessary here. If the project was made necessary by actions elsewhere (e.g., USACE dredging), these negative externalities must be taken into account. For example, some of the nourishment operations may have been dredged-matenal disposal operations in which sand was deposited on the beach only because doing so was the cheapest disposal option. Alternatively, the need for a particular project may be due to interruption of the natural sand flow by a navigational project. Information on the distribution of costs and benefits from beach nourishment projects of different types would help inform the cost-shar~ng policy makers in the future. REFERENCES Elliot, J. M. 1979. Some Methods for the Statistical Analysis of Samples of Benthic Invertebrates. Freshwater Biological Association, Scientific Publication No. 25. Kendal, U.K.: Titus Wilson & Son, Ltd. Green, R. H. 1979. Sampling Design and Statistical Methods for Environmental Biologists. New York: John Wiley & Sons. Grosskopf, W. G., and N. C. Kraus. 1994. Guidelines for surveying beach nourishment projects. Shore and Beach 62(2):9-16. Haveman, R. H. 1979. The Economic Performance of Public Investments. Baltimore: Johns Hopkins University Press. Nelson, W. G. 1991. Methods of biological monitoring of beach restoration projects: problems and solutions in the real world. Pp. 263-276 in Preserving and Enhancing Our Beach Environment: Proceedings of the 1991 National Conference on Beach Preservation Technology. Tallahassee: Florida Shore and Beach Preservation Association. Nelson, W. G. 1993. Beach restoration in the southeastern US: environmental effects and biological monitoring. Ocean and Coastal Management 19:157-182. NOAA. 1993. Tide Tables for the East Coast of North and South America. Washington, D.C.: National Ocean Survey, National Oceanic and Atmospheric Administration. NRC. 1990. Managing Troubled Waters. Marine Board, Commission on Engineering and Technical Systems. Washington, D.C.: National Academy Press. Smith, A. W. S. 1992. Description of beach sands. Shore and Beach 60(3):23-30. Stronge, W. B. 1992a. Impact of Captiva's Beaches on Property Values and Taxes. Paper prepared for the Captiva Erosion Prevention District by Regional Research Associates, Inc., Boca Raton, Fla., December. Stronge, W. B. 1992b. The economic impact of the Marco Island beach restoration: a preliminary analysis. In: New Directions in Beach Management, Proceedings of the 5th Annual National Conference on Beach Preservation Technology. Tallahassee: Florida Shore and Beach Preser- vation Association. Stronge, W. B. 1994. Beaches, tourism and economic development. Shore and Beach 62(2):6-8.