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The current study hypothesizes that reproducing sediment units that might belong to areas difficult to reach, sample, and attest is experimentally possible. The research aims to employ available sediment samples named source soils that can easily approach and sample to mix, simulate, and produce the (non-available) sedimentary units named Target Sediment Units (TSU). The particle size distribution (PSD) percentages are essentially used in the mixture procedure to construct the non-available (target) units (TSU). Several sedimentary units were targeted, designed, and simulated; They include marsh, bay mud, and natural levee sediment units selected from the eastern Basrah side at the lower Mesopotamian plain, southern Iraq. The matching between particle size distribution (PSD) curves of simulated sediment units (SSU) and target sediment unit (TSU) was verified by applying a developed slope proximity ratio. For the three tested sediment units (marsh, buy mud, and natural levee), the ratios of slope proximity were 1.0, 0.93, and 0.99, respectively, which are well matched. For the mineralogy, the consistency limits were used as a proxy. The Casagrande plasticity chart was modified to reveal two empirical functions linking the plasticity indices to the clay mineral groups. The two predictions are reliable means to proxy the mineralogy of the fine-grained sediments. Reconstructing procedure allows the non-available sediment samples to be practically presented and it better characterizes the sediment for forensic geoscience applications; for instance, engineering geology and sedimentology applications concerning with studies of the physical and mechanical behaviors of sediments and the depositional conditions interpretations, respectively.

Chilika Lake is the largest coastal lagoon in India. The geomorphology, water quality and biological productivity of the lake had undergone significant changes over the years under the influence of natural events and anthropogenic interventions with loss of biodiversity due to silting up of the outer channel. The Chilika sand is poorly graded sandy soil with 80.1% of fine sand and 19.7% of medium sand with a specific gravity of 2.64, the optimum moisture content of 10.3% and pH 7.72. Two biopolymers, guar gum, and xanthan gum are used to stabilize the sand imparting shear strength of sand which can be used to make small (dumps) islands for the migratory birds. Better surface penetration force with guar gum solution obtained with 0.5%, 1%, 1.5%, 2% are found as 70.19 N, 72.28 N, 66.99 N, 18.76 N, respectively. The UCS values are found for guar gum with 246 kPa, 334 kPa, 419 kPa, 547 kPa for 0.5%, 1%, 1.5% and 2% guar gum, respectively, after 60 days. Hence, use of biopolymer for stabilization of sand can be used as the barrier in the lake for sustainable development of the fragile ecosystem.

Polychlorinated biphenyl (PCB) concentrations were determined in surface sediments from three recreational marinas in San Diego Bay, California. Total PCB concentrations ranged from 23 to 153, 31–294, and 151–1387 ng g− 1 for Shelter Island Yacht Basin (SIYB), Harbor Island West (HW) and Harbor Island East (HE), respectively. PCB concentrations were significantly higher in HE and PCB group composition differed relative to HW and SIYB, which were not significantly different from each other in concentration or group composition. In marina sediments there was a predominance (82–85%) of heavier molecular weight PCBs with homologous groups (6CL-7CL) comprising 59% of the total. In HE 75% of the sites exceeded the effect range median (ERM), and toxicity equivalence (TEQ dioxin-like PCBs) values were higher relative to those of HW and SIYB, suggesting a potential ecotoxicological risk.

In marine sediments, microorganisms are known to play important roles in nitrogen cycling; however, the composition and quantity of microbes taking part in each process of nitrogen cycling are currently unclear. In this study, two different types of marine sediment samples (shallow bay and deep-sea sediments) in the South China Sea (SCS) were selected to investigate the microbial community involved in nitrogen cycling. The abundance and composition of prokaryotes and seven key functional genes involved in five processes of the nitrogen cycle [nitrogen fixation, nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and anaerobic ammonia oxidation (anammox)] were presented. The results showed that a higher abundance of denitrifiers was detected in shallow bay sediments, while a higher abundance of microbes involved in ammonia oxidation, anammox, and DNRA was found in the deep-sea sediments. Moreover, phylogenetic differentiation of bacterial amoA, nirS, nosZ, and nrfA sequences between the two types of sediments was also presented, suggesting environmental selection of microbes with the same geochemical functions but varying physiological properties.

To investigate the influence of a river discharging outside a bay on circulation in the bay, we carried out current and salinity measurements from mooring systems and hydrographic observations in Matsushima Bay, Japan, and off the Naruse River, which discharges outside the bay. Previously, enhancement of horizontal circulation in the bay induced by increased freshwater input from the Naruse River was reported to have degraded the seedling yield of wild Pacific oysters in the bay, but the freshwater inflow from the river was not directly measured. Our hydrographic observations in Katsugigaura Strait, approximately 3 km southwest of the Naruse River mouth, detected freshwater derived from the river. The mooring data revealed that freshwater discharged by the river flowed into Matsushima Bay via the strait and that the freshwater transport increased when the river was in flood. The inflow through straits other than Katsugigaura was estimated by a box model analysis to be 26–145 m3 s−1 under normal river discharge conditions, and it decreased to 6 m3 s−1 during flood conditions. During flood events, the salt and water budgets in the bay were maintained by the horizontal circulation: inflow occurred mainly via Katsugigaura Strait, and outflow was mainly via other straits.

Benoa Bay is a micro tidal semi-enclosed water with a size of 10 km x 15 km of the inner bay with a narrow gap formed by Serangan Island and Benoa Peninsula. Benoa Bay is a strategic area in south of Bali Province linked to the Indian Ocean through a narrow entrance. Recently, a large amount of siltation occurred in this area, which is caused by sedimentation from five rivers discharged into the bay. The sedimentation in the lagoon is of ecological and physical concern due to the mangrove ecosystem disturbing and operation of Benoa port for the necessity of increased dredging. This paper deals with tide-induced flows in a semi-enclosed water body in a micro-tidal environment that is subjected to tide and river discharge conditions. In this study, The Coastal Modeling System (CMS) developed by Coastal Inlets Research Program was used for simulating flow, waves, sediment transport, and morphology changes in coastal areas. This CMS has effectively calibrate the data set supplemented by field observations.

Chesapeake Bay is the largest estuary in the United States and is famous for its once extensive and now severely degraded eastern oyster (Crassostrea virginica) populations, along with a number of other important fisheries including crabs, rockfish, and menhaden. Here we explore the historical ecology of Native American subsistence and land use strategies in the Fishing Bay area of Maryland's Eastern Shore, building on our broader bay-wide analyses of oyster fisheries and human-environmental interactions. Archaeological analysis of faunal remains from shell middens dated between AD 500 to 1500, along with analysis of locally collected modern oysters, help reconstruct Fishing Bay's evolution during the late Holocene, and document shellfish harvest strategies and predation pressure. These data suggest a stable and sustainable prehistoric oyster fishery in Fishing Bay, likely due to: 1) seasonal harvest and local consumption; 2) intertidal harvest that allowed replenishment from subtidal populations; and 3) ...

In this paper, we develop an elasto-viscoplastic (EVP) model for clay using the non-associated flow rule. This is accomplished by using a modified form of the Perzyna&rsquo, s overstressed EVP theory, the critical state soil mechanics, and the multi-surface theory. The new model includes six parameters, five of which are identical to those in the critical state soil mechanics model. The other parameter is the generalized nonlinear secondary compression index. The EVP model was implemented in a nonlinear coupled consolidated code using a finite-element numerical algorithm (AFENA). We then tested the model for different clays, such as the Osaka clay, the San Francisco Bay Mud clay, the Kaolin clay, and the Hong Kong Marine Deposit clay. The numerical results show good agreement with the experimental data.

Woo, H.J.; Kang, J.; Lee, J.-H., and Jang, S., 2016. Seasonal changes in sediment characteristics on the tidal flat in Geunso Bay, west coast of Korea. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 1412 - 1416. Coconut Creek (Florida), ISSN 0749-0208. Geunso Bay, located in Taean, western Korean Peninsula, is a semi-enclosed-type bay with a mean tidal range of about 6 m. Tidal flats are largely developed along the sides of the bay. A digital elevation model showed that 95% of the total area of the bay is tidal flat. Observations in both winter and summer of 2009 revealed that the surface sediments in the bay were mainly muddy sand, and the sediments were classified into five sedimentary facies: sandy silt, slightly gravelly sandy mud/sandy mud, slightly gravelly muddy sand/muddy sand, silty sand, and sand. In the eastern tidal flat, the...

An ultra-high resolution acoustic reflection survey within Corpus Christi Bay, Texas, reveals numerous oyster reefs that have died off and been buried by subsequent sedimentation. The die-offs occurred in four temporal clusters, as evidenced by nearly coterminous capping horizons across multiple reef heads. These horizons can be correlated to published, calibrated radiocarbon dates (2-σ uncertainty: ± ~900 years) derived from cored sediments, and placed into the stratigraphic context. The reefs began growing with the initial flooding of the bay at ~9600 ybp. The first die-offs are coincident with the transition from upper bay to open bay environment at ~8140 ybp, with the greatest concentration of die-offs seaward. Subsequent die-offs occurred ~7600, 6870, and 5800 ybp, with a seaward-to-landward progression. These ages appear to either post-date or be concurrent with published periods of accelerated sea level rise of ~1–4 m. However, because bay oysters ( Crassostrea virginica) are robust with respect to salinity and depth changes, we cannot directly link die-offs with punctuated sea level rise. We hypothesize instead that reef die-offs are associated with extreme salinity changes caused by droughts, based on observations during the 1950s Texas drought. During that event, bay reefs were colonized by open-ocean species ( Crassostrea equestris), which gradually replaced bay oysters progressing seaward to landward in concentration. Subsequent flooding and rapid freshening of the bay caused massive mortality of the colonizing species. These floods also brought abundant fine-grained sedimentation that could bury reefs before they could be recolonized. Such a sequence of events could explain widespread early Holocene, seaward-to-landward oyster reef die-offs during times of more frequent and severe drought conditions. A plausible climatological link exists between periods of low rainfall in Texas and periods of accelerated melting of the polar ice cap, which could explain the evident correlation between reef die-off and sea level rise.

Summary River flow and sediment transport in estuaries influence morphological development over decadal and century time scales, but hydrological and sedimentological records are typically too short to adequately characterize long-term trends. In this study, we recover archival records and apply a rating curve approach to develop the first instrumental estimates of daily delta inflow and sediment loads to San Francisco Bay (1849–1929). The total sediment load is constrained using sedimentation/erosion estimated from bathymetric survey data to produce continuous daily sediment transport estimates from 1849 to 1955, the time period prior to sediment load measurements. We estimate that ∼55% (45–75%) of the ∼1500 ± 400 million tons (Mt) of sediment delivered to the estuary between 1849 and 2011 was the result of anthropogenic alteration in the watershed that increased sediment supply. Also, the seasonal timing of sediment flux events has shifted because significant spring-melt floods have decreased, causing estimated springtime transport (April 1st to June 30th) to decrease from ∼25% to ∼15% of the annual total. By contrast, wintertime sediment loads (December 1st to March 31st) have increased from ∼70% to ∼80%. A ∼35% reduction of annual flow since the 19th century along with decreased sediment supply has resulted in a ∼50% reduction in annual sediment delivery. The methods developed in this study can be applied to other systems for which unanalyzed historic data exist.

Follets Island, a transgressive island located on the upper Texas coast, is an ideal location to study barrier island transition from a rollover subaerial barrier to subaqueous shoals. This system also allows for an examination of coastal response to accelerated sea-level rise, storms, and sediment supply. The landward shoreline retreat rate during historical time is similar to the landward retreat rate of the bay shoreline, hence its current classification as a rollover barrier. However, the island has a limited and diminishing sand supply, which makes it even more vulnerable to erosion during storms and relative sea-level rise. Four core transects that extend from the upper shoreface to the back barrier bay are used to constrain the thickness of washover, barrier and upper shoreface deposits and to estimate sediment fluxes in the context of the overall sand budget for the island over centennial timescales. Stratigraphic architecture reveals two prominent transgressive surfaces. A lower flooding surface separates red fluvial-deltaic clay from overlying bay mud and an upper erosional surface separates back-barrier deposits from overlying shoreface and foreshore deposits.

The information on the catches of rare fish species in Peter the Great Bay is presented based on trawl surveys. Several species that have not been observed previously are registered. The species composition of Peter the Great Bay has changed in recent years because of two multidirectional hydrological processes. The rise of surface water temperature leads to the increasing number of southern migrants, and the decrease of heat content of near-bottom waters in the shelf is favorable for the invasion of fishes of boreal origin into the bay.

Decreased fluvial water and sediment discharge, increasing land reclamation, changing climate, and rising sea level have had an ever-increasing impact on river deltas, particularly those deltas bordering Southeast Asia. Utilizing 100 years of navigational and bathymetric data, together with more than 50 years of fluvial discharge data, we here document the impact of human activities on the Pearl River Delta and its estuary at LingDing Bay, China, the site of recent rapid economic expansion and urbanization. Between 1906 and 1988, approximately 80 km 2 , ~ 1 km 2 /yr, of land was reclaimed from the Bay, almost entirely for agriculture. During the ensuing 20 years, 1988–2008, nearly 200 km 2 of land was reclaimed (10 km 2 /yr), mostly to be used for manufacturing and shipping facilities; even some of the previously reclaimed agricultural land was converted to industrial use. Most of the reclaimed land came from a corresponding loss of intertidal and shallow depths: between 1988 and 2008, the area occupied by supratidal and subtidal flats (− 2 to 5 m water depths) declined by ~ 180 km 2 . Channel dredging to accommodate ever larger ships, in contrast, increased areas with depths greater than 10 m by about 36 km 2 . Although water volume in the northern bay has decreased by 20% since 1906, decreasing bay area has resulted an overall 15% deepening of the bay. With continued economic expansion in the Pearl River Delta, LingDing Bay should continue to shrink in both area and water volume, although the bay should continue to deepen.

This study was carried out to estimate the benthic environments and polychaetous community in Garolim Bay, through five field surveys from April 2006 to April 2007. Garilim Bay is a semi-enclosed bay and composed of a biramous tidal channel and nearby wide tidal flats. Surface sediment in the inner bay was composed of fine grained particles whereas that in the mouth area of bay was of coarse grained ones. Benthic polychaete worms were the most dominant taxa occupying 65.1% of total benthic macrofauna. Species number was higher in the inner bay than mouth and outer area of bay, and in the bay higher on the tidal flat than channel area. Density was higher on the tidal flat than channel area. Dominant polychaetous species were Prionospio sp., Heteromastus filiformis, Lumbrineris longifolia and so on, which is known as opportunistic species. Prionospio sp. and H. filiformis inhabited mainly on the tidal flats in inner bay, while L. longifolia in the channel area and mouth of the bay. Cluster analysis and nMDS showed the typical inner-to-outward distribution of station groups, which indicated the sequential difference of the species composition of each station group. To assess the benthic healthiness of Garolim Bay by AMBI and BPI analysis, the benthic condition was analyzed from slightly polluted in the outer and mouth of the bay to moderately polluted in the inner bay. Assumed from dominant species composition and benthic healthiness condition, benthic environments of Garolim Bay was slightly unstable and disturbed and organic enrichment was currently underway by massed fisheries farms.

American Shad Alosa sapidissima in the Hudson River, New York, and coastwide have shown major long-term declines. A possible contributing factor is commercial fisheries that harvest this population outside of the Hudson River estuary. Using previously published and new reference microsatellite data from 33 baseline populations, our goals were (1) to estimate the proportion of Hudson River American Shad contributing to the two remaining major mixed-stock fisheries along the Atlantic coast in Delaware Bay and the Bay of Fundy and (2) to estimate the proportions of other American Shad stocks contributing to these two fisheries at the highest level of stock specificity. Stock composition estimates for 2009 and 2010 Delaware Bay collections were made using three models that ranged from the most simple question (Hudson River and Delaware Bay populations) to one with all 33 baseline populations included. In all cases, a Hudson River contribution nearly equal to that of the Delaware Bay contribution w...

GNSS reflectometry involves making measurements from the reflections from the Earth of navigation signals from Global Navigation Satellite Systems such as GPS and QZSS. Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides. Tidal flats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily. Tidal flats are important ecosystems. In modern Japan, we have landfilled tidal flat to create a flat ground and used it as a factory area and housing. To protect the ocean ecosystem, it is necessary to investigate the topography change of the tidal flats. We studied to explore the topography of tideland as utilization of GNSS-R. The QZSS satellite stays at a high elevation angle for a relatively long time compared to the GPS satellite. Radio waves of satellites with a low elevation angle strongly reflect, but the delay time of reflected waves is short. A satellite with a high elevation angle has a small reflected wave, but its delay is large, so it is easy to separate the reflected wave. In this research, we report the result of examining GNSS-R using QZSS.

Martinez, R.; Silva, R., and Mendoza, E., 2014. Identification of coastal erosion causes in Matanchen Bay, San Blas, Nayarit, Mexico. This work presents an analysis of the erosion processes in Matanchen Bay based on the available historical records; the possible causes were identified and discussed. The bay is located on the Pacific coast of Nayarit state, Mexico; its northern tip is a highly dynamic system that has undergone intense morphological modifications over the last 80 years. At the beginning of the 1940s an unexplained growth in the beach at the northern tip of the bay was observed, while 40 years later, and up to date, erosion processes began adversely affecting small businesses in the area. The primary causes of the erosion are the anthropogenic modifications in the bay and its surroundings, which include the construction of a hydroelectric dam system, new transport infrastructure, tourist facilities, a harbor and several dredging works in the existing port. In this paper the evolutio...

The fault segmentation of blank area in the east of Pubei Oilfield is strong, and the distribution of oil and water is complex. In view of this kind of situation, we did sedimentary microfacies research in study area. First, we established isochronous stratigraphic framework of the east of Putaohua oil layer by core and logging data ,we also established six well logging facies models, including main underwater distributary channel,underwater distributary channel,edge of underwater distributary channel,main sand sheet,sand sheet and bay mud between distributary channels;Secondly, we described the sedimentary microfacies of development area, summarized the evolution of sand and sedimentary microfacies characteristics of Putaohua oil layer; Finally, on the basis of the above work, we drew the sedimentary microfacies of study area. The study provides geological basis for the next step of exploration and development in oil field.

Kang, J., Woo, H.J., Lee, Y.-K., Son, Y.B., 2014. Seasonal sedimentary processes of the macrotidal flat in Gomso Bay, Korea. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 157–163, ISSN 0749-0208. To understand seasonal sedimentary processes, we analyzed sediment grain size, short-term sedimentation rates, and chemical tracers to determine sediment provenance in the Gomso tidal flat, which is located on the western coast of Korea. It is a funnel-shaped embayment with a mean tidal range of 4.3 m. Calculating the elevation from a digital elevation model (DEM), the landward inner bay was relatively higher than that of the outer bay. Sandy sediments generally dominated the outer bay, whereas sandy mud sediments were distributed in the inner bay. The middle bay consisted of muddy sand sediments. From February 2011 to February 2012, the net deposition rate in the inner tidal flat ...

The Naples–Dollar Bay Estuarine System (NDBES), situated in southwestern Florida, has undergone extensive modifications caused directly and indirectly by anthropogenic influences. These alterations include: (1) the substitution of mangrove-forested shorelines with concrete bulkheads and installation of residential canals; (2) installation of a regionally extensive navigational channel; and (3) canalization of the watershed, resulting in annexation of a heavily altered drainage basin ten times the size of the pre-alteration basin and with a significantly different soil and bedrock. The NDBES consists of northern Naples Bay, southern Naples Bay, and Dollar Bay, whose shorelines range from highly developed to undeveloped, respectively. This project explored the geological response of the system to these alterations using data from side-scan sonar, sediment grab samples, and vibracores. In highly urbanized northern Naples Bay, benthic substrates consist primarily of muddy sand with few oyster reefs. Southern Naples Bay and Dollar Bay, however, consist of coarser sediment, and are characterized by extensive mangrove shorelines and numerous fringing oyster reefs. The impact of anthropogenic alterations has significantly shifted sediment distributions in northern Naples Bay from a relatively coarser to a relatively fine grained substrate; to a lesser degree in southern Naples Bay, and Dollar Bay, this transition has not taken place due to the general lack of anthropogenic modifications made to this part of the system.

Twofold Bay lies at the confluence of two oceanic boundaries, the near end of the East Australian Current and waters from the Southern Ocean. The Bay is NSW's largest commercial fishing port and has been home to much anthropogenic activity, ranging from whaling, mussel farming, timber export, large boat traffic, Australian Navy activities and recreational fishing. We investigated the sediments and associated foraminifer fauna in the bay and identified four different sedimentological associations linked to local currents and water depths and three foraminiferal associations, with live to dead specimen ratios established for each sample site. Three principal biotopes have been identified using cluster analysis of foraminiferal assemblages, with each biotope characterised by a specific faunal population and substrate type: (1) Inner Bay Biotope, characterised by Elphidium aff. advenum and predominantly very fine–fine sand substrates (63–250 μm); (2) Outer Bay Biotope characterised by Discorbis dimidiatus and...

A new method developed by Schweikhardt et al. (2011) for the geochemical analysis of bay mussels is applicable (when combined with radiocarbon assessments) for examining the seasonal construction patterns and growth cycles of coastal mound sites over time. Ideally suited for the analysis of mollusk fragments in museum collections, this method allows archaeologists to evaluate divergent models about the functions of mound sites, as well as the mobility practices and social organizations of the mound builders. In this case study, the method is employed to examine two adjacent mounds (Ellis Landing, Brooks Island) in the San Francisco Bay Area, California to assess whether their occupants may have participated in a broader multi-site community dating to the Late Period (1100–250 BP).

This paper presents a two-surface plasticity constitutive model for clays based on critical-state soil mechanics. The model reproduces the mechanical response of clays under multi-axial loading conditions and predicts both drained and undrained behavior at small and large strains. The constitutive model also captures both the strain-rate-dependent behavior of clays and the drop in strength towards a residual value at very large shear strains using novel approaches. The paper also describes a hierarchical process for the determination of the model parameters relying more on simple curve fitting of model equations to experimental data points corresponding to specific soil states instead of trial-and-error simulations of entire experiments. Model parameter values are determined for London Clay, San Francisco Bay Mud, Boston Blue Clay and Lower Cromer Till, and the performance of the model in simulating mechanical response of clays is demonstrated for a variety of initial states and loading conditions.

Currently, the largest tidal wetlands restoration project on the US Pacific Coast is being planned and implemented in southern San Francisco Bay; however, knowledge of baseline conditions of salt marsh extent in the region prior to European settlement is limited. Here, analysis of 24 sediment cores collected from ten intact southern San Francisco Bay tidal marshes were used to reconstruct spatio-temporal patterns of marsh expansion to provide historic context for current restoration efforts. A process-based marsh elevation simulation model was used to identify interactions between sediment supply, sea-level rise, and marsh formation rates. A distinct age gradient was found: expansion of marshes in the central portion of southern San Francisco Bay dated to 500 to 1500 calendar years before present, while expansion of marshes in southernmost San Francisco Bay dated to 200 to 700 calendar years before present. Thus, much of the tidal marsh area mapped by US Coast Survey during the 1853–1857 period were in fact not primeval tidal marshes that had persisted for millennia but were recently formed landscapes. Marsh expansion increased during the Little Ice Age, when freshwater inflow and sediment influx were higher than during the previous millennium, and also during settlement, when land use changes, such as introduction of livestock, increased watershed erosion, and sediment delivery.

Maximum seismic shear stresses (tmax) have been recognized as one of the important parameters in design practice. This study develops ground-motion parameters for tmax and implements these in probabilistic seismic hazard analysis to provide the tmax distribution of deep soil layers for design purposes. The application of improved ground-motion parameters for tmax is demonstrated at the Oakland International Airport, where a thick Young Bay Mud deposit exists under the artificial fill. Model biases in the predictive equations of seismic shear-stressreductioncoefficients(rd)areevaluatedbycomparisonwiththesiteresponseanalysesperformedwithawiderangeofinputground motions. Based on these results, we introduce improved ground-motion parameters for tmax (Itau) as a linear combination of spectral accelerations,implementedinprobabilisticseismichazardanalysistocalculateseismichazardcurves.Conditionalmeanspectraarecalculated, givenItau at10%in50yearstoillustratethevariationsinfrequencycontentswithdepthcomparedwiththeuniformhazardspectra.Finally,tmax is calculated with depth by using hazard values of Itau and compared with the peak-ground-acceleration-based and uniform-hazard-spectra- basedcalculations.Analysisresultsshowthattmax willbeunderestimatedfordeepsoillayersbypeak-ground-acceleration-basedcalculationif themedianvalueofrd isusedindesignpractice.DOI:10.1061/(ASCE)GT.1943-5606.0000740.©2013AmericanSocietyofCivilEngineers. CE Database subject headings: Seismic design; Shear stress; Ground motion; Probability; Hazards; Soil strength. Author Keywords: Seismic design; Shear stresses; Ground motion; Probability; Hazards.

Long-term non-linear ecosystem-scale changes in water quality and biotic communities in coastal lagoons have been associated with intensification of anthropogenic pressures. In light of incipient changes in Johnson Bay (an embayment of Chincoteague Bay, Maryland-Virginia, USA), examination of nitrogen sources was conducted through synoptic water quality monitoring, stable nitrogen isotope signatures (δ15N) of in situ bioindicators, and denitrification estimates. These data were placed in the context of long-term and broader spatial analyses. Despite various watershed protection efforts, multiyear summer time studies (2004–2007) suggested that high levels of terrestrially derived nutrients still enter Johnson Bay. Total nitrogen concentrations in Johnson Bay were 132% the concentrations in the broader Chincoteague Bay during the late 1970s (mean 2004–2007 was 40.0 – 73.2 μM). Comparing total nitrogen concentrations in Johnson Bay to St. Martin River (consistently the most eutrophic region of these coastal bays), Johnson Bay has increased from 62.5% to 82.5% of the concentrations in St. Martin River during the late 1970s. Though specific sources of nitrogen inputs have not yet been definitively identified, the long-term increase in total nitrogen concentrations occurred despite increased and continued conservation and protection measures. We suggest that investigating nutrient sources can reveal potentially ineffective nutrient policies and that this knowledge can be applied towards other coastal lagoons.

Invasive species are cited as being a threat to communities and ecosystems worldwide, yet few studies have demonstrated invader impacts at these scales. Lack of historic data makes capturing large-scale community shifts problematic. We assessed long-term changes in invertebrate composition to the fouling community of a small estuary with relatively little boat traffic and no ballast water input (Morro Bay, CA). We also compared relative invasiveness of Morro Bay to international harbors (San Francisco Bay and Los Angeles/San Diego harbors). While the proportion of introduced species has not significantly changed from historic records, introduced species now occupy 86.00 % of the primary substrate. Other community shifts include; (1) a state shift to an invasive bryozoan (Watersipora subtorquata) dominated community, (2) a decrease in Mollusc richness and, (3) substantial shifts in abundance of certain species. Compared to larger more actively used harbors, Morro Bay has proportionally fewer introduced species (12.00 %) than San Francisco Bay (50.79 %) or Los Angeles/San Diego Harbors (26.23 %). Our study documents changes to a small relatively isolated estuary with little boat traffic and no ballast water input. We discuss the potential role of invasive species and other natural and anthropogenic factors as drivers of these community wide shifts. Specifically, we discuss how reintroduction of the Southern Sea Otter (Enhydra lutris nereis), an increase in sea stars (Pisaster spp.), climate change and interaction amongst potential drivers support the patterns of shifts in the Morro Bay community.

Bintuni Bay is a semi-closed bay which a lot of big rivers flow into the bay and bring a huge amount of freshwater. This bay is not directly connected to the open sea but separated by the Berau Bay. The bay of Berau has wider bay mouth as well as deeper than Bintuni Bay, the deepest part more than 70 m located at the center part of bay. Tidal force generated offshore is able to push higher salinity water (HSW) mass further into the inner bay, otherwise the low salinity water (LSW) mass pushed out toward the head of the bay. In the area where LSW and HSW masses meet each other is found steep salinity gradient (salinity front). Two times field observations were conducted with lowered CTD (Conductivity Temperature Depth) sensor from the surface layer until one meter above seabed at 30 stations, either at the end of north-east monsoon (March 2013) or at south-east monsoon (July-August 2013). The HSW mass was dominant found at deeper layer and southern side of the bay, while the LSW mass occupied surface layer at the northern side of the bay.

This research consists of scale model shake table tests to investigate the development of seismic earth pressures in soft clay. The soft clay was modeled after prototype San Francisco Bay Mud consisting of a mixture of kaolinite, bentonite, class C fly ash and water. A flexible walled testing container founded on a 1g shake table was used to house the model soil and mimic 1D site response. An array of accelerometers embedded in the model soil measure during an input earthquake motion. A scale model wall is equipped with pressure sensors to measure the seismic earth pressures over the duration of an input earthquake motion. A total of 14 time histories were run through this test set up. A single degree of freedom oscillator was added to the scale model wall and used to mimic the period of a structure. Test results show that for retaining walls with clay soils seismic earth pressures develop triangularly over the face of the wall with an amplitude of about 3.8 times the static pressures. For small building structures, the development of seismic earth pressures depends on height above the base of the wall. Although the pressure distribution is not well defined, localized peaks in pressure are observed at depths of 1/3H and 2/3H below the ground surface. Arias intensity and cumulative absolute velocity correlate linearly with the measured dynamic pressures. Differences between arias intensity and cumulative absolute velocity for each scale model configuration are not pronounced. The simplified Monnobe-Okabe method was also evaluated in this study. Although the Mononobe-Okabe method may be inappropriate for cohesive soils, a seismic coefficient of about 1/10 the PGA was back-calculated from empirically measured earth pressures. The results of this investigation provides an empirical basis to the behavior of walls in clay.

Coastal ecosystems around the world are constantly changing in response to interacting shifts in climate and land and water use by expanding human populations. The development of agricultural and urban areas in South Florida significantly modified its hydrologic regime and influenced rates of environmental change in wetlands and adjacent estuaries. This study describes changes in diatom species composition through time from four sediment cores collected across Florida Bay, for the purposes of detecting periods of major shifts in assemblage structure and identifying major drivers of those changes. We examined the magnitude of diatom assemblage change in consecutive 2-cm samples of the 210Pb-dated cores, producing a record of the past ~130 years. Average assemblage dissimilarity among successive core samples was ~30%, while larger inter-sample and persistent differences suggest perturbations or directional shifts. The earliest significant compositional changes occurred in the late 1800s at Russell Bank, Bob Allen Bank and Ninemile Bank in the central and southwestern Bay, and in the early 1900s at Trout Cove in the northeast. These changes coincided with the initial westward redirection of water from Lake Okeechobee between 1881 and 1894, construction of several canals between 1910 and 1915, and building the Florida Overseas Railroad between 1906 and 1916. Later significant assemblage restructurings occurred in the northeastern and central Bay in the late 1950s, early 1960s and early 1970s, and in the southwestern Bay in the 1980s. These changes coincide with climate cycles driving increased hurricane frequency in the 1960s, followed by a prolonged dry period in the 1970s to late 1980s that exacerbated the effects of drainage operations in the Everglades interior. Changes in the diatom assemblage structure at Trout Cove and Ninemile Bank in the 1980s correspond to documented eutrophication and a large seagrass die-off. A gradual decrease in the abundance of freshwater to brackish water taxa in the cores over ~130 years implies that freshwater deliveries to Florida Bay were much greater prior to major developments on the mainland. Salinity, which was quantitatively reconstructed at these sites, had the greatest effect on diatom communities in Florida Bay, but other factors—often short-lived, natural and anthropogenic in nature—also played important roles in that process. Studying the changes in subfossil diatom communities over time revealed important environmental information that would have been undetected if reconstructing only one water quality variable.

Florida Bay is a highly dynamic estuary that exhibits wide natural fluctuations in salinity due to changes in the balance of precipitation, evaporation and freshwater runoff from the mainland. Rapid and large-scale modification of freshwater flow and construction of transportation conduits throughout the Florida Keys during the late nineteenth and twentieth centuries reshaped water circulation and salinity patterns across the ecosystem. In order to determine long-term patterns in salinity variation across the Florida Bay estuary, we used a diatom-based salinity transfer function to infer salinity within 3.27 ppt root mean square error of prediction from diatom assemblages from four ~130 year old sediment records. Sites were distributed along a gradient of exposure to anthropogenic shifts in the watershed and salinity. Precipitation was found to be the primary driver influencing salinity fluctuations over the entire record, but watershed modifications on the mainland and in the Florida Keys during the late-1800s and 1900s were the most likely cause of significant shifts in baseline salinity. The timing of these shifts in the salinity baseline varies across the Bay: that of the northeastern coring location coincides with the construction of the Florida Overseas Railway (AD 1906–1916), while that of the east-central coring location coincides with the drainage of Lake Okeechobee (AD 1881–1894). Subsequent decreases occurring after the 1960s (east-central region) and early 1980s (southwestern region) correspond to increases in freshwater delivered through water control structures in the 1950s–1970s and again in the 1980s. Concomitant increases in salinity in the northeastern and south-central regions of the Bay in the mid-1960s correspond to an extensive drought period and the occurrence of three major hurricanes, while the drop in the early 1970s could not be related to any natural event. This paper provides information about major factors influencing salinity conditions in Florida Bay in the past and quantitative estimates of the pre- and post-South Florida watershed modification salinity levels in different regions of the Bay. This information should be useful for environmental managers in setting restoration goals for the marine ecosystems in South Florida, especially for Florida Bay.

This paper describes the species composition, vertical distribution, and the seasonal changes in the biomass of subtidal macrophytes in Sobol Bay (Peter the Great Bay, Sea of Japan). The samples were collected in the depth-range from 0.5 to 4 m. A total of 65 macrophyte species were identified, among which were 10 species of Chlorophyta, 17 of Phaeophyceae, 37 of Rhodophyta and 1 of Magnoliophyta. Multivariate analyses were performed to detect spatial and temporal variations. Maximum species richness was registered in June, with a particularly dramatic biomass increase of brown algae. Both the number of species and the biomass of macrophytes decreased with increasing depth. Depth clearly affected the patterns of seasonal fluctuations of the species composition and biomass. In the study area, the species composition of the shallow-water algal assemblages was more stable throughout the year compared to that of the algal assemblages found in deeper waters. In total, four macrophyte assemblages were identified in the bay. A Phyllospadix iwatensis and Coccophora langsdorfii dominated assemblage occupied muddy-gravel bottoms in depths from 0.5 to 2 m throughout the year. An assemblage, co-dominated by annual brown algae Desmarestia viridis and Costaria costata, occurred at depths more than 3 m at late spring. Two other assemblages occurred on the rock and boulder bottom at 0.5–2 m depths, but they were temporally separated. An assemblage co-dominated by annual laminarian algae (Undaria pinnatifida and Costaria costata) developed at late spring and was succeeded in the autumn and winter by a Tichocarpus crinitus, Ulva lactuca, Sargassum pallidum and Codium fragile co-dominated assemblage. A comparison between the data obtained in the present study and the results of a previous study conducted in 1927 shows that the macrophytes assemblages in Sobol Bay underwent little change.

A series of consolidated-drained triaxial tests were performed on precut and polished clay specimens to measure their drained residual strength. Two soils were tested during this research program: Rancho Solano Clay and San Francisco Bay Mud. Specimens were tested using a specially modified triaxial compression device which was developed to minimize the effects of end-platen restraint on the measured strengths. Special attention was paid to the influence of changing specimen area and membrane effects during the test. Triaxial test results were compared with baseline measurements of drained residual shear strength that were made for each of the clay soils using Bromhead ring shear tests and polished-specimen direct shear tests. Residual strength values measured in the triaxial device were higher than the drained residual strengths measured in the Bromhead ring shear apparatus and the direct shear device, indicating that this test approach is more challenging than the use of direct shear tests conducted on polished slickensided surfaces. Comparison of single stage and multistage triaxial test data indicates that multistage triaxial testing may work well for specimens that fail along a well-defined plane, provided that careful attention is given to the effects of end platen restraint, membrane restraint, and changes in specimen area during shear.

We measured the concentration of 12 metals in coastal waters of seven sites of San Jorge Bay in Antofagasta (northern Chile), in order to relate the presence of metals with the different uses of San Jorge Bay coastal border, and to evaluate the quality of the bay's bodies of water according to the proposed current Chilean Quality Guide for trace elements in seawater (CONAMA 2003). The results suggest that the coastal water of San Jorge Bay has very good quality according to the proposed regulation mentioned above. However, the distribution of metals such as Cu and Pb along the bay's coast line evidences a notorious effect of the industrial activity, which would involve different behavior patterns for some trace elements in some bodies of water, suggesting that the levels indicated in the environmental guideline of the Chilean legislation do not represent pollution-free environments.

Analysis of four historical bathymetric surveys over a 132-year period has revealed significant changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of San Francisco Bay estuary. From 1873 to 2005 the San Francisco Bar vertically-eroded an average of 80 cm over a 125 km 2 area, which equates to a total volume loss of 100 ± 52 million m 3 of fine- to coarse-grained sand. Comparison of the surveys indicates the entire ebb-tidal delta contracted radially, with the crest moving landward an average of 1 km. Long-term erosion of the ebb-tidal delta is hypothesized to be due to a reduction in the tidal prism of San Francisco Bay and a decrease in coastal sediment supply, both as a result of anthropogenic activities. Prior research indicates that the tidal prism of the estuary was reduced by 9% from filling, diking, and sedimentation. Compilation of historical records dating back to 1900 reveals that a minimum of 200 million m 3 of sediment has been permanently removed from the San Francisco Bay coastal system through dredging, aggregate mining, and borrow pit mining. Of this total, ∼54 million m 3 of sand-sized or coarser sediment was removed from central San Francisco Bay. With grain sizes comparable to the ebb-tidal delta, and its direct connection to the bay mouth, removal of sediments from central San Francisco Bay may limit the sand supply to the delta and open coast beaches. SWAN wave modeling illustrates that changes to the morphology of the San Francisco Bar have altered the alongshore wave energy distribution at adjacent Ocean Beach, and thus may be a significant factor in a persistent beach erosion ‘hot spot’ occurring in the area. Shoreline change analyses show that the sandy shoreline in the shadow of the ebb-tidal delta experienced long-term (1850s/1890s to 2002) and short-term (1960s/1980s to 2002) accretion while the adjacent sandy shoreline exposed to open-ocean waves experienced long-term and short-term erosion. Therefore, the recently observed accelerating rates of bay sediment removal, ebb-tidal delta erosion, and open coast beach erosion are all correlated temporally.

Headland-bay beach equilibrium planform has been a crucial problem abroad to long-term sandy beach evolution and stabilization, extensively applied to forecast long-term coastal erosion evolvement and the influences of coastal engineering as well as long-term coastal management and protection. However, little concern focuses on this in China. The parabolic relationship is the most widely used empirical relationship for determining the static equilibrium shape of headland-bay beaches. This paper utilizes the relation to predict and classify 31 headland-bay beaches and concludes that these bays cannot achieve the ultimate static equilibrium planform in South China. The empirical bay equation can morphologically estimate beach stabilization state, but it is just a referential predictable means and is difficult to evaluate headland-bay shoreline movements in years and decades. By using Digital Shoreline Analysis System suggested by USGS, the rates of shoreline recession and accretion of these different headland-bay beaches are quantitatively calculated from 1990 to 2000. The conclusions of this paper include that (a) most of these 31 bays maintain relatively stable and the rates of erosion and accretion are relatively large with the impact of man-made constructions on estuarine within these bays from 1990 to 2000; (b) two bays, Haimen Bay and Hailingshan Bay, originally in the quasi-static equilibrium planform determined by the parabolic bay shape equation, have been unstable by the influence of coastal engineering; and (c) these 31 bays have different recession and accretion characters occurring in some bays and some segments. On the one hand, some bays totally exhibit accretion, but some bays show erosion on the whole. Shanwei Bay, Houmen Bay, Pinghai Bay and Yazhou Bay have the similar planforms, characterized by less accretion on the sheltering segment and bigger accretion on the transitional and tangential segments. On the other hand, different segments of some bays have two dissimilar evolvement characters. Dacheng Bay, Shenquan Bay, Hudong Bay, Wukan Bay, Fengjia Bay, Wuchang Bay, Lingshui Bay and Tufu Bay produce accretion on the tangential segment, erosion on the transitional segment and accretion on the sheltering segment. However, Guang’ao Bay, Haimen Bay, Jinghai Bay, Sanya Bay(a), Dajiao Bay, Hailingshan Bay, Hebei Bay, Fuhu Bay, Shuidong Bay, Wangcun Bay and Bomao Bay generate erosion on the tangential part, accretion on the transitional part and accretion on the sheltering part. It seems to imply some relations between headland-bay beach evolvement and controls on headland-bay beaches, which may possibly to classify headland-bay beach types and should be further studied.

The effects of Pleistocene cold-climate geomorphology are distributed across the weathered and eroded Mid-Atlantic Coastal Plain uplands from the Wisconsinan terminal moraine south to Tidewater Virginia. Cold-climate deposits and landscape modifications are superimposed on antecedent landscapes of old, weathered Neogene upland gravels and Pleistocene marine terraces that had been built during warm periods and sea-level highstands. In New Jersey, sequences of surficial deposits define a long history of repeating climate change events. To the south across the Delmarva Peninsula and southern Maryland, most antecedent topography has been obscured by Late Pleistocene surficial deposits. These are spatially variable and are collectively described as a cold-climate alloformation. The cold-climate alloformation includes time-transgressive details of climate deterioration from at least marine isotope stage (MIS) 4 through the end of MIS 2. Some deposits and landforms within the alloformation may be as young as the Younger Dryas. Southwards along the trend of the Potomac River, these deposits and their climatic affinities become diffused. In Virginia, a continuum of erosion and surficial deposits appears to be the product of ‘normal’ temperate, climate-forced processes. The cold-climate alloformation and more temperate deposits in Virginia are being partly covered by Holocene alluvium and bay mud.