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1.
Many shoreline studies rely on historical change rates determined from aerial imagery decades to over 50 years apart to predict shoreline position and determine setback distances for coastal structures. These studies may not illustrate the coastal impacts of short-duration but potentially high-impact storm events. In this study, shoreline change rates (SCRs) are quantified at five different sites ranging from marsh to sediment bank shorelines around the Albemarle-Pamlico estuarine system (APES) for a series of historical (decadal to 50-year) and short-term (bimonthly) time periods as well as for individual storm events. Long-term (historical) SCRs of approximately ?0.5 ± 0.07 m year?1 are observed, consistent with previous work along estuarine shorelines in North Carolina. Short-term SCRs are highly variable, both spatially and temporally, and ranged from 15.8 ± 7.5 to ?19.3 ± 11.5 m year?1 at one of the study sites. The influence of wave climate on the spatial and temporal variability of short-term erosion rates is investigated using meteorological observations and coupled hydrodynamic (Delft3D) and wave (SWAN) models. The models are applied to simulate hourly variability in the surface waves and water levels. The results indicate that in the fetch-limited APES, wind direction strongly influences the wave climate at the study sites. The wave height also has an influence on short-term SCRs as determined from the wave simulations for individual meteorological events, but no statistical correlation is found for wave height and SCRs over the long term. Despite the significantly higher rates of shoreline erosion over short time periods and from individual events like hurricanes, the cumulative impact over long time periods is low. Therefore, while the short-term response of these shorelines to episodic forcing should be taken into account in management plans, the long-term trends commonly used in ocean shoreline management can also be used to determine erosion setbacks on estuarine shorelines.  相似文献   

2.
A long-term (1948–2010) shoreward energy history of upper tidal shorelines in lower Chesapeake Bay was developed using a simple calculation of kinetic energy from corresponding wind and tide data. These data were primarily used to determine the likelihood of shoreline energy increases coincident with local sea level rise. Total annual shoreward energy ranged from 620 kJ/m of shoreline in 1950 to 17,785 kJ/m of shoreline in 2009. No clear linear trends are apparent, but mean annual energy shows an increase from 2,732 kJ/m before 1982 to 6,414 kJ/m since then. This increase in mean energy was accompanied by more numerous spikes of comparatively higher annual energy. Shoreward energy delivered to lower Chesapeake Bay’s upper tidal shorelines was enabled by an increasing amount of time per year that tidal height exceeds mean high water, accompanied by increasing heights of tidal anomalies. An index termed the Hydrologic Burden was developed that incorporates the combination of time and tidal height that demonstrates this increasing trend. Although opportunities for greater shoreward energy increased as the Hydrologic Burden increased, and even though there is evidence that greater energy was delivered to the shorelines during the latter time series, energy per hour delivery was shown not to have increased, and may have decreased, due to a steady reduction in average wind speed in lower Chesapeake Bay since the mid-1980s. Energy delivery in lower Chesapeake Bay was primarily from the northeast, and energy delivery over the time series is shown to organize symmetrically around a point between the northeast and north–northeast directions. This is evidence of a self-organizational phenomenon that transcends changes in local wind and tide dynamics.  相似文献   

3.
Human population growth and sea-level rise are increasing the demand for protection of coastal property against shoreline erosion. Living shorelines are designed to provide shoreline protection and are constructed or reinforced using natural elements. While living shorelines are gaining popularity with homeowners, their ability to provide ecological services (e.g., habitat provision and trophic transfer) is not well understood, and information is needed to improve coastal and resource management decision-making. We examined benthic community responses to living shorelines in two case-study subestuaries of Chesapeake Bay using a before-after control-impact study design. At Windy Hill, a bulkhead was removed and replaced by three tombolos, sand fill, and native marsh vegetation. At Lynnhaven, 25 m of eroding marsh shoreline was stabilized with coir logs, sand fill, and native marsh vegetation. Communities of large (>?3 mm) infauna adjacent to living shorelines at both locations tended to increase in biomass by the end of the study period. Community compositions changed significantly following living shoreline construction at Windy Hill, reflecting a trend toward higher density and biomass of large bivalves at living shorelines compared to pre-construction. Increasing trends in density and biomass of clams and simultaneously decreasing density and decreasing trends in biomass of polychaetes suggest a transition toward stable infaunal communities at living shorelines over time, though longer-term studies are warranted.  相似文献   

4.
Sea level rise leads to coastal transgression, and the survival of ecosystems depends on their ability to migrate inland faster than they erode and submerge. We compared marsh extent between nineteenth-century maps and modern aerial photographs across the Chesapeake Bay, the largest estuary in North America, and found that Chesapeake marshes have maintained their spatial extent despite relative sea level rise rates that are among the fastest in the world. In the mapped region (i.e., 25% of modern Chesapeake Bay marshland), 94 km2 of marsh was lost primarily to shoreline erosion, whereas 101 km2 of marsh was created by upland drowning. Simple projections over the entire Chesapeake region suggest that approximately 100,000 acres (400 km2) of uplands have converted to wetlands and that about a third of all present-day marsh was created by drowning of upland ecosystems since the late nineteenth century. Marsh migration rates were weakly correlated with topographic slope and the amount of development of adjacent uplands, suggesting that additional processes may also be important. Nevertheless, our results emphasize that the location of coastal ecosystems changes rapidly on century timescales and that sea level rise does not necessarily lead to overall habitat loss.  相似文献   

5.
Seagrass beds have declined in Chesapeake Bay, USA as well as worldwide over the past century. Increased seston concentrations, which decrease light penetration, are likely one of the main causes of the decline in Chesapeake Bay. It has been hypothesized that dense populations of suspension-feeding bivalves, such as eastern oysters (Crassostrea virginica), may filter sufficient seston from the water to reduce light attenuation and enhance seagrass growth. Furthermore, eastern oyster populations can form large three-dimensional reef-like structures that may act like breakwaters by attenuating waves, thus decreasing sediment resuspension. We developed a quasi-three-dimensional Seagrass-Waves-Oysters-Light-Seston (SWOLS) model to investigate whether oyster reefs and breakwaters could improve seagrass growth by reducing seston concentrations. Seagrass growth potential (SGP), a parameter controlled by resuspension-induced turbidity, was calculated in simulations in which wave height, oyster abundance, and reef/breakwater configuration were varied. Wave height was the dominant factor influencing SGP, with higher waves increasing sediment resuspension and decreasing SGP. Submerged breakwaters parallel with the shoreline improved SGP in the presence of 0.2 and 0.4 m waves when sediment resuspension was dominated by wave action, while submerged groins perpendicular to the shoreline improved SGP under lower wave heights (0.05 and 0.1 m) when resuspension was dominated by along-shore tidal currents. Oyster-feeding activity did not affect SGP, due to the oysters’ distance from the seagrass bed and reduced oyster filtration rates under either low or high sediment concentrations. Although the current implementation of the SWOLS model has simplified geometry, the model does demonstrate that the interaction between oyster filtration and along-shore circulation, and between man-made structures and wave heights, should be considered when managing seagrass habitats, planning seagrass restoration projects, and choosing the most suitable methods to protect shorelines from erosion.  相似文献   

6.
In many coastal regions throughout the world, there is increasing pressure to harden shorelines to protect human infrastructures against sea level rise, storm surge, and erosion. This study examines waterbird community integrity in relation to shoreline hardening and land use characteristics at three geospatial scales: (1) the shoreline scale characterized by seven shoreline types: bulkhead, riprap, developed, natural marsh, Phragmites-dominated marsh, sandy beach, and forest; (2) the local subestuary landscape scale including land up to 500 m inland of the shoreline; and (3) the watershed scale >500 m from the shoreline. From 2010 to 2014, we conducted waterbird surveys along the shoreline and open water within 21 subestuaries throughout the Chesapeake Bay during two seasons to encompass post-breeding shorebirds and colonial waterbirds in late summer and migrating and wintering waterfowl in late fall. We employed an Index of Waterbird Community Integrity (IWCI) derived from mean abundance of individual waterbird species and scores of six key species attributes describing each species’ sensitivity to human disturbance, and then used this index to characterize communities in each subestuary and season. IWCI scores ranged from 14.3 to 19.7. Multivariate regression model selection showed that the local shoreline scale had the strongest influence on IWCI scores. At this scale, percent coverage of bulkhead and Phragmites along shorelines were the strongest predictors of IWCI, both with negative relationships. Recursive partitioning revealed that when subestuary shoreline coverage exceeded thresholds of approximately 5% Phragmites or 8% bulkhead, IWCI scores decreased. Our results indicate that development at the shoreline scale has an important effect on waterbird community integrity, and that shoreline hardening and invasive Phragmites each have a negative effect on waterbirds using subestuarine systems.  相似文献   

7.
C. Pereira  C. Coelho 《Natural Hazards》2013,69(1):1033-1050
Several coastal zones are facing shoreline retreat problems, losing territory due to energetic sea actions, negative sediment transport balances and climate change phenomena. To deal with this problem, efficient tools are necessary to help decision-makers choose the right procedures to follow. These tools should assess, estimate and project scenarios of coastal evolution in a medium-to-long-term perspective. To perform reliable projections, as many variables as possible should be analysed, and the impact of each of these variables on the shoreline evolution should be understood. This study aimed to analyse three climate change phenomena that are considered the most important in a Portuguese west coast stretch (at Aveiro region). The considered phenomena are the wave height increasing due to storms, the wave direction changes and the sea level rise. A shoreline evolution numerical model, long-term configuration, developed to support coastal zone planning and management in relation to erosion problems was applied. This work defined a methodology for classification of risk areas, considering the uncertainty associated with different wave climate sequences on simulations. As a result, different risk maps according to considered climate change effects were obtained, defining areas of high, medium and low risk of territory loss due to erosion. A generalized erosion tendency and shoreline retreat were observed, particularly in the downdrift side of groins. The sea water level rise showed lower impacts in the shoreline evolution than wave direction changes, or wave height increasing, which presents the highest impact.  相似文献   

8.
The nearshore land-water interface is an important ecological zone that faces anthropogenic pressure from development in coastal regions throughout the world. Coastal waters and estuaries like Chesapeake Bay receive and process land discharges loaded with anthropogenic nutrients and other pollutants that cause eutrophication, hypoxia, and other damage to shallow-water ecosystems. In addition, shorelines are increasingly armored with bulkhead (seawall), riprap, and other structures to protect human infrastructure against the threats of sea-level rise, storm surge, and erosion. Armoring can further influence estuarine and nearshore marine ecosystem functions by degrading water quality, spreading invasive species, and destroying ecologically valuable habitat. These detrimental effects on ecosystem function have ramifications for ecologically and economically important flora and fauna. This special issue of Estuaries and Coasts explores the interacting effects of coastal land use and shoreline armoring on estuarine and coastal marine ecosystems. The majority of papers focus on the Chesapeake Bay region, USA, where 50 major tributaries and an extensive watershed (~ 167,000 km2), provide an ideal model to examine the impacts of human activities at scales ranging from the local shoreline to the entire watershed. The papers consider the influence of watershed land use and natural versus armored shorelines on ecosystem properties and processes as well as on key natural resources.  相似文献   

9.
提要:海岸带是陆地向海洋延伸的过渡地带,是人口最为密集、人类活动最频繁的区域,全球超过50％的人口和60％的GDP总量集聚在离海岸线不足100 km的区域.海岸线对海平面上升、海岸侵蚀、港湾淤积、湿地生态资源、近海海域环境等具有重要的指示作用.本研究利用遥感影像获取了粤港澳大湾区(以下简称大湾区)1975—2018年间...  相似文献   

10.
Submerged aquatic vegetation (SAV) is an ecologically and economically valuable component of coastal estuaries that acts as an early indicator of both degrading and improving water quality. This study aimed to determine if shoreline hardening, which is associated with increased population pressure and climate change, acts to degrade SAV habitat quality at the local scale. In situ comparisons of SAV beds adjacent to both natural and hardened shorelines in 24 subestuaries throughout the Chesapeake and Mid-Atlantic Coastal Bays indicated that shoreline hardening does impact adjacent SAV beds. Species diversity, evenness, and percent cover were significantly reduced in the presence of riprap revetment. A post hoc analysis also confirmed that SAV is locally affected by watershed land use associated with increased population pressure, though to a lesser degree than impacts observed from shoreline armoring. When observed over time, SAV recovery at the local level took approximately 3 to 4 years following storm impacts, and SAV adjacent to natural shorelines showed more resilience to storms than SAV adjacent to armored shorelines. The negative impacts of shoreline hardening and watershed development on SAV shown here will inform coastal zone management decisions as increasing coastal populations and sea level rise drive these practices.  相似文献   

11.
Estuarine and coastal ecosystems respond strongly to proximate climate forcing. In this study, we present a regional, synoptic climatology as an approach to classify weather patterns that generate interannual variability in coastal and estuarine ecosystems. Synoptic climatology is a method that classifies sea level pressure data into distinct patterns representing common weather features for a specified region. A synoptic climatology was developed for the eastern United States and used to quantify surface conditions affecting Chesapeake Bay during wet and dry years. In a synthesis analysis, several mechanisms were identified that explained the link between weather patterns and ecosystem structure, principal among them is the delivery of freshwater to the Bay during spring. Wet and dry years were characterized by shifts in biogeography of the Chesapeake Bay. The shifts resulted from habitat changes and trophic interactions and included the timing and magnitude of the spring phytoplankton bloom, the distribution/abundance of mesozooplankton and gelatinous zooplankton, and juvenile indices of fish. Synoptic climatology resolved regional weather variability at a spatial scale not strongly controlled by larger-scale climate indices and explained ecosystem responses in Chesapeake Bay.  相似文献   

12.
The influence of atmospheric forcing on the flow and heat transports in the lower Chesapeake Bay and the adjacent coastal ocean were studied by comparing nontidal sea level and sea surface temperature variations in this region with meteorological data for 1992. Northeasterly and southwesterly winds caused the greatest changes in mean sea level (greater than 0.25 m) throughout the year. Northeastely winds caused a more rapid response than southwesterly winds, causing sea-level rises in less than 6 h. Barometric pressure changes typically contributed approximately 10% to extreme sea-level variations and were less influential than wind stress in most cases. Wind forcing was also responsible for summer events in which the horizontal water temperature gradient between two near-surface locations in the vicinity of the bay mouth vanished. These zero-gradient events corresponded to inflows and outflows at the bay's entrance caused by northeasterly and southwesterly winds, respectively. Wind-induced advection outside the lower Chesapeake Bay was additionally responsible for extreme heat flux variations. Heat gains and losses during the spring and fall occurred in pulsating events related to wind direction but were probably not connected to lower bay processes.  相似文献   

13.
Arctic coastal infrastructure and cultural and archeological sites are increasingly vulnerable to erosion and flooding due to amplified warming of the Arctic, sea level rise, lengthening of open water periods, and a predicted increase in frequency of major storms. Mitigating these hazards necessitates decision-making tools at an appropriate scale. The objectives of this paper are to provide such a tool by assessing potential erosion and flood hazards at Herschel Island, a UNESCO World Heritage candidate site. This study focused on Simpson Point and the adjacent coastal sections because of their archeological, historical, and cultural significance. Shoreline movement was analyzed using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, 2000, and 2011. For purposes of this analysis, the coast was divided in seven coastal reaches (CRs) reflecting different morphologies and/or exposures. Using linear regression rates obtained from these data, projections of shoreline position were made for 20 and 50 years into the future. Flood hazard was assessed using a least cost path analysis based on a high-resolution light detection and ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement in different periods of the study ranges from ?5.5 to 2.7 m·a?1 (mean ?0.6 m·a?1). Mean coastal retreat decreased from ?0.6 m·a?1 to ?0.5 m·a?1, for 1952–1970 and 1970–2000, respectively, and increased to ?1.3 m·a?1 in the period 2000–2011. Ice-rich coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map combines shoreline projections and flood hazard analyses to show that most of the spit area has extreme or very high flood hazard potential, and some buildings are vulnerable to coastal erosion. This study demonstrates that transgressive forcing may provide ample sediment for the expansion of depositional landforms, while growing more susceptible to overwash and flooding.  相似文献   

14.
Few strong relationships exist along the Chesapeake Bay shoreline between the historic erosion rate and the distribution of any of several coastal parameters which were defined and tested using traditional regression and discriminant analysis procedures To develop a simple predictive equation for shore erosion that could be used by coastal managers, the entire Chesapeake Bay shoreline was partitioned into naturally occurring reaches 2–5 km in length, and the historic erosion rate on each reach was modelled as a function of five variables (a) shoreline type, (b) “100-year” storm surge height, (c) mean tide range, (d) wave climate, and (e) potential littoral drift rate The statistical analysis yielded a multiple correlation coefficient (r 2) of 30 8%, discriminant analysis showed only the first two variables listed above are useful predictors (i e, statistically significant) of historic erosion rates A 95-mile portion of the same bay shoreline in Queen Anne’s and Talbot counties was then partitioned into shorter reach lengths (1/2–2km) and more variables were included The multiple correlation coefficient (r 2) improved slightly to 32 9%, but only shoreline type and potential littoral drift rate were found to be useful predictors of historic erosion rates Curiously, the ability to model statistically the historic shore erosion rate is best on those reaches already substantially protected by structures For Queen Anne’s and Talbot counties, the multiple regression coefficient improved to 61 5% when only reaches 1/2–2km in length protected by structures were considered.  相似文献   

15.
 Impacts on nearshore sedimentation arising from potential sea level change of the magnitude predicted in Intergovernmental Panel on Climatic Change scenarios associated with global warming are reviewed. For sandy duned coasts, the obvious sedimentation impacts include potential erosion of coastal dunes with implied deposition of the eroded material in the nearshore, possible deepening of embayments, and flooding of wetlands. For the sandy coasts a number of two-dimensional models are available for predicting shoreline change, but there are significant difficulties in applying Bruun-type models for dune erosion and assessment of sediment redistribution over the inner shelf, and for predicting the amount of shoreline retreat for a given rate of sea level rise. If the beach profile contains excessive sand relative to its equilibrium profile, sensu Dean (1991), then shoreline retreat may not occur upon sea level rise. From the evidence of Kiel Bay, at least in these semi-enclosed basin types, it is during major transgressions that maximum deposition in adjacent basins occurs, due to the sea eroding weakly consolidated and weathered surface regolith. But at the same time climatic patterns were re-adjusting and probably contributed to maximum deposition in adjacent shelf and basins below wave base. Received: 16 June 1995 / Accepted: 29 January 1996  相似文献   

16.
Vizianagaram–Srikakulam coastal shoreline consisting of beaches, mangrove swamps, tidal channel and mudflats is one of the vulnerable coasts in Andhra Pradesh, India. Five site-specific parameters, namely rate of geomorphology, coastal elevation, coastal slope, shoreline change and mean significant wave height, were chosen for constructing coastal vulnerability index and assessing coastal landscape vulnerability. The findings revealed a shift of 2.5 km in shoreline towards the land surface because of constant erosion and that of 1.82 km towards the sea due to accretion during 1997–2017. The rate of high erosion was found in zones IV and V, and high accretion was found in zones II and III. Coastal vulnerability index analysis revealed constant erosion along shoreline and sea level rise in the study area. Most of the coast in zone V has recorded very high vulnerability due to erosion, high slope, significant wave height and sea level rise. Erosion and accretion, significant wave height, sea level rise and slope are attributed to high vulnerability in zones III and IV. Zone II recorded moderate vulnerability. Relatively lower slope, mean sea wave height and sea level rise have made this zone moderately vulnerable. Very low vulnerability was found in zone I, and low vulnerability was recorded in zone II. Accretion, low slope and low sea level rise were found to be causative factors of lower vulnerability. Thus, zones III, IV and V should be accorded higher priorities for coastal management. The findings can be helpful in coastal land planning and management and preparing emergency plans of the coastal ecosystems.  相似文献   

17.
With increased shoreline hardening and development, it is important to understand the ecological processes occurring in these and adjacent coastal habitats. A common species found associated with these hard-substrate habitats in Chesapeake Bay is the grass shrimp, Palaemonetes pugio. Caging experiments were conducted from June to August 2010 to examine the effects of shrimp on the recruitment and development of hard-substrate communities. Experiments were conducted at two low-salinity sites within Chesapeake Bay and one high-salinity site in an adjacent coastal bay in Virginia. The addition of grass shrimp reduced recruitment of polychaetes and scyphistomae of the sea nettle, Chrysaora quinquecirrha, and increased recruitment of encrusting bryozoans and the oyster, Crassostrea virginica. After 12?weeks, sea nettles at one low-salinity site, dominated predator-exclusion treatments. At the high-salinity site, oysters dominated when shrimp were present. Although it is unclear whether the results of short-term caging studies can be applied across larger temporal and spatial scales, the significant effects of grass shrimp on two important Chesapeake Bay species suggests that increases in hard-substrate habitat could have broader impacts within this and other systems.  相似文献   

18.
The Poplar Island Dredged Material Placement Site in Talbot County, Maryland is proposed to be used for the restoration of Poplar Island and for the creation of desirable habitats lost through erosion of Poplar Island by the beneficial use of clean and uncontaminated dredged material from the Chesapeake Bay approach channels to the Port of Baltimore. The Poplar Island baseline environmental assessment studies included among others, seasonal water quality, benthic community, and benthic tissue contaminants, that were carried out by the Maryland Department of the Environment, in cooperation with the University of Maryland, from September 1995 to July 1996. The purpose of the study was to document the present-day levels of nutrients, trace metals, and organic contaminants in the area to establish a baseline against which subsequent levels and biological responses may be compared. The overall results of the study indicate that Poplar Island and vicinity areas are non-impacted in terms of water quality and benthic tissue contamination. The nutrient levels in the water column were below average for this region of Chesapeake Bay, while the trace metals and organic contamination in the benthic tissues were comparable to other sites within Chesapeake Bay that are not impacted by direct inputs. Concentrations were equivalent or lower than those found at Hart-Miller Island, a disposal facility outside Baltimore Harbor, Maryland containing dredged material.  相似文献   

19.
Islands rimming Pacific atolls typically form narrow, low‐lying lands that are commonly perceived to be particularly vulnerable to global changes such as sea‐level rise. As these, low islands form the only habitable land for many island nations, understanding the character of shorelines, and the rates and controls that operate to bring about changes, is an issue of central importance. The purpose of this study is to unravel the characteristics of coastal change on atoll islands of the Gilbert Island chain of the equatorial Pacific nation of Kiribati, especially as they relate to autogenic shoreline processes and El Niño/Southern Oscillation variability. Integration of field observations, differential global positioning system data, historical aerial photographs and ultra‐high resolution remote sensing images demonstrates the nature, spatial patterns and rates of change from 17 islands on Maiana and Aranuka atolls. The results illustrate that, between 2005 and 2009, ca 50% of the shorelines on these islands displayed a discernable shift in position; some shorelines were accretionary (at net rates up to ca 8 m year?1) and others were erosional (up to ca 18 m year?1). Long‐term net rates of change on Maiana between 1969 and 2009 were lower than short‐term net rates measured between 2005 and 2009. Both short‐term and long‐term observations illustrate some of the greatest change occur near terminations of the largest, north–south oriented islands, associated with longshore movement of coarse sand and gravel. Direct hits by tropical depressions and marked seasonality, factors interpreted as being essential in island growth and shoreline dynamics elsewhere, do not directly impact these equatorial atolls and can be eliminated as fundamental controls on shoreline dynamics. Similarly, observations over four years suggested that shoreline variability probably is not influenced directly by marked sea‐level change, although a recent increase in the rates of shoreline change could reflect instability related to the cumulative effect of a long‐term increase in the rate of sea‐level rise. Within this framework of global change, local anthropogenic effects, autogenic shoreline processes and El Niño/Southern Oscillation‐influenced wind and wave variability control many aspects of these dynamic shorelines. These results provide quantitative insights into the character and variability of rates of shoreline change, information essential for evaluating and mitigating the vulnerability of island nations such as Kiribati.  相似文献   

20.
Archaeological sites in beach and estuarine environments are continually threatened by diverse natural marine processes. Shoreline erosion, bluff retreat, and sea level rise all present potential for site destruction. Using historic maps, aerial imagery, and field survey methods in a GIS, 21 potentially significant archaeological sites on Georgia barrier islands were selected for determination of site‐specific rates of shoreline change using a powerful, new, moving‐boundary GIS analysis tool. A prioritized list of sites, based on the order of site loss from erosion, was generated to assist coastal managers in identifying and documenting sites most at risk. From the original selection of 21 sites, 11 sites were eroding, 8 shorelines were stable, and 2 shorelines were accreting. The methodology outlined here produces critical information on archaeological site loss rates and provides a straightforward means of prioritizing sites for detailed documentation. © 2010 Wiley Periodicals, Inc.  相似文献   

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