Directional Analysis of the Storm Surge from Hurricane Sandy 2012, with Applications to Charleston,New Orleans,and the Philippines

Hurricane Sandy in late October 2012 drove before it a storm surge that rose to 4.28 meters above mean lower low water at The Battery in lower Manhattan, and flooded the Hugh L. Carey automobile tunnel between Brooklyn and The Battery. This study examines the surge event in New York Harbor using the Weather Research and Forecasting (WRF) atmospheric model and the Coupled-Ocean-Atmosphere-Wave- Sediment Transport / Regional Ocean Modeling System (COAWST/ROMS). We present a new technique using directional analysis to calculate and display maps of a coastline''s potential for storm surge; these maps are constructed from wind fields blowing from eight fixed compass directions. This analysis approximates the surge observed during Hurricane Sandy. The directional analysis is then applied to surge events at Charleston, South Carolina, New Orleans, Louisiana, and Tacloban City, the Philippines. Emergency managers could use these directional maps to prepare their cities for an approaching storm, on planning horizons from days to years.     

The Value of Wetlands in Protecting Southeast Louisiana from Hurricane Storm Surges

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.     

Hydraulic conditions in isothermal lakes

SUMMARY. The paper considers the forms of water movement that occur in unstratified lakes. Although not dealing directly with ecological implications, it is hoped that it will encourage the inclusion of observations of underwater weather as part of normal limnological routine. It is particularly concerned to show what observations are most effective in revealing hydraulic conditions.
Relations between wind, lake geometry and wave characteristics are examined. Factors determining the steady, wind-driven circulation are reviewed and examined in sequence: the action of wind on a water surface and the current directly generated by the wind drag; the effect of the earth's rotation; the need to balance the flow in and out of any part of the lake; the influence of lake morphometry. A simple model of lake circulation is developed that may help in the interpretation of on-lake observations. Some other features of isothermal motion are discussed including the horizontal currents associated with unsteady wind conditions (seiches).
The possible interaction between waves and currents are discussed. A tentative classification of hydraulic conditions in terms of wind speed, lake depth and fetch is suggested as a basis for forming hypotheses about the motion prior to on-lake observations and as a possible starting point for a comparative approach.     

Redistribution of sediments in three Swedish lakes

Sedimentation and redistribution of fine sediments in three Swedish lakes of different character have been investigated using settling sediment traps. The bottom shear stress from wind generated waves are calculated and the extension of erodable bottom area is related to wind conditions. Wave induced erosion and deposition during and after cessation of storms in different parts of a lake are discussed theoretically. It is shown that a single one year storm may redistribute more bottom material than the accumulated resuspension caused by frequent but smaller wind events. The settling sediment trap deposition and the concentration of suspended solids are related to the extension of erodable bottom area of particular storms. It is found that in lakes where there are relatively large areas of erosion bottoms, resuspended material from the part of the lake most susceptible to strong winds of large fetch constitutes a major part of the settled material on deep bottoms.     

Two mechanisms of aquatic and terrestrial habitat change along an Alaskan Arctic coastline

Arctic habitats at the interface between land and sea are particularly vulnerable to climate change. The northern Teshekpuk Lake Special Area (N-TLSA), a coastal plain ecosystem along the Beaufort Sea in northern Alaska, provides habitat for migratory waterbirds, caribou, and potentially, denning polar bears. The 60-km coastline of N-TLSA is experiencing increasing rates of coastline erosion and storm surge flooding far inland resulting in lake drainage and conversion of freshwater lakes to estuaries. These physical mechanisms are affecting upland tundra as well. To better understand how these processes are affecting habitat, we analyzed long-term observational records coupled with recent short-term monitoring. Nearly the entire coastline has accelerating rates of erosion ranging from 6 m/year from 1955 to 1979 and most recently peaking at 17 m/year from 2007 to 2009, yet an intensive monitoring site along a higher bluff (3–6 masl) suggested high interannual variability. The frequency and magnitude of storm events appears to be increasing along this coastline and these patterns correspond to a greater number of lake tapping and flooding events since 2000. For the entire N-TLSA, we estimate that 6% of the landscape consists of salt-burned tundra, while 41% is prone to storm surge flooding. This offset may indicate the relative frequency of low-magnitude flood events along the coastal fringe. Monitoring of coastline lakes confirms that moderate westerly storms create extensive flooding, while easterly storms have negligible effects on lakes and low-lying tundra. This study of two interacting physical mechanisms, coastal erosion and storm surge flooding, provides an important example of the complexities and data needs for predicting habitat change and biological responses along Arctic land–ocean interfaces.     

Climate and coastal dune vegetation: disturbance, recovery, and succession

The sand dune habitats found on barrier islands and other coastal areas support a dynamic plant community while protecting areas further inland from waves and wind. Foredune, interdune, and backdune habitats common to most coastal dunes have very different vegetation, likely because of the interplay among plant succession, exposure, disturbance, and resource availability. However, surprisingly few long-term data are available describing dune vegetation patterns. A nine-year census of 294 plots on St. George Island, Florida suggests that the major climatic drivers of vegetation patterns vary with habitat. Community structure is correlated with the elevation, soil moisture, and percent soil ash of each 1 m² plot. Major storms reduce species richness in all three habitats. Principle coordinate analysis suggests that changes in the plant communities through time are caused by climatic events: changes in foredune vegetation are correlated with temperature and summer precipitation, interdune vegetation with storm surge, and backdune vegetation with precipitation and storm surge. We suggest that the plant communities in foredune, interdune, and backdune habitats tend to undergo succession toward particular compositions of species, with climatic disturbances pushing the communities away from these more deterministic trajectories.     

Polymorphic buttonwood: effects of disturbance on resistance to herbivores in green and silver morphs of a Bahamian shrub

We studied consequences of storm damage on buttonwood (Conocarpus erectus) shrubs and their herbivores in the Bahamian islands. Buttonwood is polymorphic, with green shrubs producing few leaf trichomes and silver shrubs covered in dense trichomes. We first characterize traits of green vs. silver shrubs relevant for herbivores, and then assay damage by two prominent insects. Next, on replicated islands, we experimentally address how different types of storm damage (simulated hurricane surge damage vs. simulated intense wind) affected phenotypic traits of both buttonwood morphs and subsequent herbivory over a one-year sampling period. Our results show that although leaves produced by green shrubs are 21% tougher than leaves produced by silver shrubs, green leaves have 16% higher nitrogen concentrations and greater levels of herbivory. Consistent with previous observational studies of a natural hurricane at our study site, we found stronger effects of simulated surge damage than simulated wind damage. Experimental pruning of shrubs resulted in reduced toughness, higher nitrogen concentration, fewer trichomes, and greater herbivory compared to controls and compared to shrubs with their leaves stripped. The results were stronger for the silver compared to the green morph. Morph differences in buttonwood have strong consequences for herbivores, and these effects are modified by disturbance.     

The effects of wind and posture on the aerodynamic performance during the flight stage of skiing

Numerical simulation is conducted to evaluate the wind and posture effects on the aerodynamic performance of a skier during the flight stage. Both steady and unsteady models are applied on a 2D geometry. Using the Fluent code, the fundamental equations of fluid flow are solved simultaneously. In particular we focus on the influence of wind speed and direction on aerodynamic forces with several different postures of the skier in steady modeling. For a chosen case, the unsteady models are used to predict the transient characteristics of streamline distributions and aerodynamic forces. It is found that the skier's postures, wind speed, and direction play a significant role. The wind condition affects the pressure force (the form drag) on the skier and makes it a resistance or thrust regarding wind directions. The optimized posture with a minimization of resistance under a facing wind is determined as a moving-forward body of the skier. The unsteady modeling reveals that the wake around the skier and aerodynamic forces are strongly dependent on time. This initial study not only provides a qualitative and theoretical basis for the athletes to understand the effects of wind and postures, and then to optimize their postures according to the wind condition during the flight stage of skiing, but also builds the foundation for the systematic study of skiing process with more advanced CFD models in the future.     

Storm Resistant Boat Designing Based on the Geometry and Movement of Water Strider

A novel conceptual model of boat is developed based on the bionic properties of water strider. This four-legged model is called storm resistance boat. Concentrated balancing forces, asymmetry of arms and smooth motion against waves and the effect of arms length on the reduction of drag and effects of wave are the major characteristics of water strider which are considered for designing this model. The results indicate the characteristic improvement of the small boat and its resistance against strong waves as well as marine ill-conditions. This boat can be considered as a high speed rescue boat in marine traffic.     

Aerodynamics of cyclist posture, bicycle and helmet characteristics in time trial stage

The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist's upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results indicate that variations in the TT cyclist posture, the saddle position and the helmet visor can produce a significant gain in time (up to 2.2%) during stages.     

Hurricane storm surge and amphibian communities in coastal wetlands of northwestern Florida

Isolated wetlands in the Southeastern United States are dynamic habitats subject to fluctuating environmental conditions. Wetlands located near marine environments are subject to alterations in water chemistry due to storm surge during hurricanes. The objective of our study was to evaluate the effect of storm surge overwash on wetland amphibian communities. Thirty-two wetlands in northwestern Florida were sampled over a 45-month period to assess amphibian species richness and water chemistry. During this study, seven wetlands were overwashed by storm surge from Hurricane Dennis which made landfall 10 July 2005 in the Florida panhandle. This event allowed us to evaluate the effect of storm surge overwash on water chemistry and amphibian communities of the wetlands. Specific conductance across all wetlands was low pre-storm (<100 μS/cm), but increased post-storm at the overwashed wetlands ([`(x)] \bar{x}  = 7,613 μS/cm). Increased specific conductance was strongly correlated with increases in chloride concentrations. Amphibian species richness showed no correlation with specific conductance. One month post-storm we observed slightly fewer species in overwashed compared with non-overwashed wetlands, but this trend did not continue in 2006. More species were detected across all wetlands pre-storm, but there was no difference between overwashed and non-overwashed wetlands when considering all amphibian species or adult anurans and larval anurans separately. Amphibian species richness did not appear to be correlated with pH or presence of fish although the amphibian community composition differed between wetlands with and without fish. Our results suggest that amphibian communities in wetlands in the southeastern United States adjacent to marine habitats are resistant to the effects of storm surge overwash.     

Impact of internal waves on the spatial distribution of Planktothrix rubescens (cyanobacteria) in an alpine lake

The vertical and horizontal distribution of the cyanobacterium, Planktothrix rubescens, was studied in a deep alpine lake (Lac du Bourget) in a 2-year monitoring program with 11 sampling points, and a 24-h survey at one sampling station. This species is known to proliferate in the metalimnic layer of numerous deep mesotrophic lakes in temperate areas, and also to produce hepatotoxins. When looking at the distribution of P. rubescens at the scale of the entire lake, we found large variations (up to 10 m) in the depth of the biomass peak in the water column. These variations were closely correlated to isotherm displacements. We also found significant variations in the distribution of the cyanobacterial biomass in the northern and southern parts of the lake. We used a physical modeling approach to demonstrate that two internal wave modes can explain these variations. Internal waves are generated by wind events, but can still be detected several days after the end of these events. Finally, our 24-h survey at one sampling point demonstrated that the V1H1 sinusoidal motion could evolve into nonlinear fronts. All these findings show that internal waves have a major impact on the distribution of P. rubescens proliferating in the metalimnic layer of a deep lake, and that this process could influence the growth of this species by a direct impact on light availability.     

Computational fluid dynamics analysis of drag and convective heat transfer of individual body segments for different cyclist positions

This study aims at investigating drag and convective heat transfer for cyclists at a high spatial resolution. Such an increased spatial resolution, when combined with flow-field data, can increase insight in drag reduction mechanisms and in the thermo-physiological response of cyclists related to heat stress and hygrothermal performance of clothing. Computational fluid dynamics (steady Reynolds-averaged Navier-Stokes) is used to evaluate the drag and convective heat transfer of 19 body segments of a cyclist for three different cyclist positions. The influence of wind speed on the drag is analysed, indicating a pronounced Reynolds number dependency on the drag, where more streamlined positions show a dependency up to higher Reynolds numbers. The drag and convective heat transfer coefficient (CHTC) of the body segments and the entire cyclist are compared for all positions at racing speeds, showing high drag values for the head, legs and arms and high CHTCs for the legs, arms, hands and feet. The drag areas of individual body segments differ markedly for different cyclist positions whereas the convective heat losses of the body segments are found to be less sensitive to the position. CHTC-wind speed correlations are derived, in which the power-law exponent does not differ significantly for the individual body segments for all positions, where an average value of 0.84 is found. Similar CFD studies can be performed to assess drag and CHTCs at a higher spatial resolution for applications in other sport disciplines, bicycle equipment design or to assess convective moisture transfer.     

Experiment about Drag Reduction of Bionic Non-smooth Surface in Low Speed Wind Tunnel

The body surface of some organisms has non-smooth structure, which is related to drag reduction in moving fluid. To imitate these structures, models with a non-smooth surface were made. In order to find a relationship between drag reduction and the non-smooth surface, an orthogonal design test was employed in a low speed wind tunnel. Six factors likely to influence drag reduction were considered, and each factor tested at three levels. The six factors were the configuration, diameter/bottom width, height/depth, distribution, the arrangement of the rough structures on the experimental model and the wind speed. It was shown that the non-smooth surface causes drag reduction and the distribution of non-smooth structures on the model, and wind speed, are the predominant factors affecting drag reduction. Using analysis of variance, the optimal combination and levels were obtained, which were a wind speed of 44 m/s, distribution of the non-smooth structure on the tail of the experimental model, the configuratio     

Ocean Wave Simulation Based on Wind Field

Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.     

Good Days,Bad Days: Wind as a Driver of Foraging Success in a Flightless Seabird,the Southern Rockhopper Penguin

Due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. Wind can be a driver of upwelling and food abundance in marine ecosystems such as the Southern Ocean, where wind regime changes due to global warming may have important ecological consequences. Southern rockhopper penguins (Eudyptes chrysocome) have undergone a dramatic population decline in the past decades, potentially due to changing environmental conditions. We used a weighbridge system to record daily foraging mass gain (the difference in mean mass of adults leaving the colony in the morning and returning to the colony in the evening) of adult penguins during the chick rearing in two breeding seasons. We related the day-to-day variability in foraging mass gain to ocean wind conditions (wind direction and wind speed) and tested for a relationship between wind speed and sea surface temperature anomaly (SSTA). Foraging mass gain was highly variable among days, but did not differ between breeding seasons, chick rearing stages (guard and crèche) and sexes. It was strongly correlated between males and females, indicating synchronous changes among days. There was a significant interaction of wind direction and wind speed on daily foraging mass gain. Foraging mass gain was highest under moderate to strong winds from westerly directions and under weak winds from easterly directions, while decreasing under stronger easterly winds and storm conditions. Ocean wind speed showed a negative correlation with daily SSTA, suggesting that winds particularly from westerly directions might enhance upwelling and consequently the prey availability in the penguins'' foraging areas. Our data emphasize the importance of small-scale, wind-induced patterns in prey availability on foraging success, a widely neglected aspect in seabird foraging studies, which might become more important with increasing changes in climatic variability.     

A novel lake-zoning framework for large lakes based on numerical modelling

Because of the high spatial heterogeneity of the ecosystem properties of large lakes, the characterisation of lake zones is particularly helpful for designing zone-specific strategies for water management practices. In this study, we developed a lake-zoning framework by investigating the lateral dispersion of inflow pollutants through dye-tracking experiments in a case study of a large shallow lake (Lake Chaohu) in China. A two-dimensional hydrodynamic and mass transport model was used to quantify the impacts of inflow rivers on this lake. Results from 2012 to 2014 showed that the lake zoning results were more stable at the annual scale than at the seasonal scale, implying that the seasonal scale is not suitable for the establishment of lake zones. A driving factor analysis showed that inflow discharge was a more critical factor determining lake zones than wind conditions. In contrast to previous lake zoning methods, the proposed framework implements lake zoning quantitatively through hydrodynamic modelling.     

Field measurements of wind speed and reconfiguration in Arundo donax (Poaceae) with estimates of drag forces

The giant reed (Arundo donax) is well known as a species that can withstand high wind loads without mechanical damage. To examine wind impact, profiles of vertical wind speeds in the plant's natural habitat (southern France) were measured at the edge and within a stand in the main wind direction. Wind speed was recorded simultaneously at five heights. For 75 measurements of within-canopy wind speed profiles, the attenuation coefficient was 4.4 ± 0.5, a value typical for plant stands with very dense canopies. Video recordings proved that A. donax becomes streamlined with increasing wind speed, reducing the projected surface area of leaves and stem. The total projected surface area is a function of wind speed and can be characterized by a second-order polynomial regression curve. For small wind velocities up to 1 m/s, the calculated drag force is proportional to the square of the wind speed. However, when A. donax plants are subjected to higher wind speeds (1.5-10 m/s), the drag force becomes directly proportional to the wind speed. Streamlining is a potentially important adaptation for withstanding high wind loads, especially for individual plants and plants at the edge of stands, whereas in dense stands streamlining probably plays a minor role.     

PCR and Culture Identification of Pathogenic Leptospira spp. from Coastal Soil in Leyte,Philippines, after a Storm Surge during Super Typhoon Haiyan (Yolanda)

Leptospirosis is a zoonosis caused by pathogenic Leptospira spp. Most of the outbreaks of leptospirosis occur after floods caused by heavy rain in countries where Leptospira spp. are endemic. It has been believed that the overflow of seawater rarely causes outbreaks of leptospirosis because the leptospires are killed by salt water. On 8 November 2013, a storm surge caused by Super Typhoon Haiyan (Yolanda) inundated the entire coastal areas of Tacloban and Palo in Leyte, Philippines. The present study was carried out in order to determine whether the environmental leptospires in soil were able to survive after the storm surge in the affected areas. We collected 23 wet soil samples along the coastal areas of Tacloban and Palo 2 months after the storm surge. The samples were suspended in HEPES buffer, and the supernatants were cultured in liquid or semisolid Korthof''s medium supplemented with five antimicrobial agents to inhibit the growth of contaminants. Leptospires were isolated from primary cultures of 22 out of 23 samples. The DNA of pathogenic Leptospira species was detected in 11 samples (47.8%) by analysis of flaB by nested PCR. Eventually, two pathogenic Leptospira strains were isolated and showed the highest 16S rRNA gene sequence similarity to Leptospira kmetyi. When these isolates were experimentally mixed with soil, they were found to survive in seawater for 4 days. These results show the possibility that leptospires living in soil survived after the storm surge. Our findings may serve as a warning that when seawater inundates the land during a storm surge or a tsunami, an outbreak of leptospirosis could occur in the disaster-stricken area.