Sample records for flood dynamic surface

  1. Using sea surface temperatures to improve performance of single dynamical downscaling model in flood simulation under climate change (United States)

    Chao, Y.; Cheng, C. T.; Hsiao, Y. H.; Hsu, C. T.; Yeh, K. C.; Liu, P. L.


    There are 5.3 typhoons hit Taiwan per year on average in last decade. Typhoon Morakot in 2009, the most severe typhoon, causes huge damage in Taiwan, including 677 casualties and roughly NT 110 billion (3.3 billion USD) in economic loss. Some researches documented that typhoon frequency will decrease but increase in intensity in western North Pacific region. It is usually preferred to use high resolution dynamical model to get better projection of extreme events; because coarse resolution models cannot simulate intense extreme events. Under that consideration, dynamical downscaling climate data was chosen to describe typhoon satisfactorily, this research used the simulation data from AGCM of Meteorological Research Institute (MRI-AGCM). Considering dynamical downscaling methods consume massive computing power, and typhoon number is very limited in a single model simulation, using dynamical downscaling data could cause uncertainty in disaster risk assessment. In order to improve the problem, this research used four sea surfaces temperatures (SSTs) to increase the climate change scenarios under RCP 8.5. In this way, MRI-AGCMs project 191 extreme typhoons in Taiwan (when typhoon center touches 300 km sea area of Taiwan) in late 21th century. SOBEK, a two dimensions flood simulation model, was used to assess the flood risk under four SSTs climate change scenarios in Tainan, Taiwan. The results show the uncertainty of future flood risk assessment is significantly decreased in Tainan, Taiwan in late 21th century. Four SSTs could efficiently improve the problems of limited typhoon numbers in single model simulation.

  2. Modelling dynamic roughness during floods

    NARCIS (Netherlands)

    Paarlberg, Andries; Dohmen-Janssen, Catarine M.; Hulscher, Suzanne J.M.H.; Termes, A.P.P.


    In this paper, we present a dynamic roughness model to predict water levels during floods. Hysteresis effects of dune development are explicitly included. It is shown that differences between the new dynamic roughness model, and models where the roughness coefficient is calibrated, are most

  3. The effect of surface flooding on the physical-biogeochemical dynamics of a warm-core eddy off southeast Australia (United States)

    Baird, Mark E.; Suthers, Iain M.; Griffin, David A.; Hollings, Ben; Pattiaratchi, Charitha; Everett, Jason D.; Roughan, Moninya; Oubelkheir, Kadija; Doblin, Martina


    Warm-core eddies (WCEs) formed from the East Australian Current (EAC) play an important role in the heat, mass and biogeochemical budgets of the western Tasman Sea. The development and separation of an EAC WCE during July-December 2008 was observed using remotely sensed temperature, ocean colour and sea-level elevation, three Argo floats, a shipboard CTD, a shelf mooring array and a 15-day deployment of a Slocum glider. The eddy formed from an EAC meander during the first half of 2008 and in late August had a ˜275m deep surface mixed layer. In the two months before separation in early December, fresher and warmer EAC water flooded the top of the eddy, submerging the winter mixed layer. The rate of vertical transport due to submergence was estimated to be between 1 and 6 Sv, at the time accounting for a significant fraction of the mean southward flow of the EAC. The core of the eddy had a surface chlorophyll a concentration of <0.4mgm-3 throughout the observations. A 20-40 m thick pycnocline formed at the interface of the flooding surface waters and the submerged layer. Chlorophyll a concentration in the pycnocline ranged from 0.5 to 2 mg m -3, with depth-integrated concentration ranging between 25 and 75 mg m -2. The development of a sub-surface maximum suggests that flooding increased light levels in the pycnocline. Elevated levels of coloured dissolved organic matter in the submerged layer correspond to oxygen depletion, suggesting respiration of organic matter. A comparison is made with observations from WCEs in 1978 and 1997 in which, unusually, surface flooding did not occur, but solar heating stratified the top 50 m. In the two eddies with surface capping, surface chlorophyll a concentrations were an order of magnitude higher than the 2008 flooded eddy, but depth-integrated chlorophyll a was similar. These findings suggest that EAC WCEs with relatively shallow surface flooding contain more phytoplankton biomass than surface images would suggest, with the


    Directory of Open Access Journals (Sweden)

    E. O. Agafonnikova


    Full Text Available The dynamics features of the surface waters for the territory of the Crimea area of Krasnodar region in flash flood conditions have been studied. The parameters of flooding depending on the precipitation intensity have been defined.

  5. Spatiotemporal Dynamics and Trends in Surface Water and Flooding Extent from Three Decades of Seasonally Continuous Landsat Time Series at Subcontinental Scale: Product Development and Applications (United States)

    Tulbure, M. G.; Broich, M.; Stehman, S. V.; Shendryk, I.; Heimhuber, V.; Kommareddy, A.; Bishop-Taylor, R.


    Surface water is a critical resource in semi-arid areas. The Murray-Darling Basin (MDB) of Australia, one of the largest semi-arid basins in the world is aiming to set a worldwide example of how to balance multiple interests (i.e. environment, agriculture and urban use), but has suffered significant water shrinkages during the Millennium Drought (1999-2009), followed by extensive flooding. Baseline information and systematic quantification of surface water (SW) extent and flooding dynamics in space and time are needed for managing SW resources across the basin but are currently lacking. To synoptically quantify changes in SW extent and flooding dynamics over MDB, we used seasonally continuous Landsat TM and ETM+ data (1986 - 2011) and generic machine learning algorithms. We further mapped flooded forest at a riparian forest site that experienced severe tree dieback due to changes in flooding regime. We used a stratified sampling design to assess the accuracy of the SW product across time. Accuracy assessment yielded an overall classification accuracy of 99.94%, with producer's and user's accuracy of SW of 85.4% and 97.3%, respectively. Overall accuracy was the same for Landsat 5 and 7 data but user's and producer's accuracy of water were higher for Landsat 7 than 5 data and stable over time. Our validated results document a rapid loss in SW bodies. The number, size, and total area of SW showed high seasonal variability with highest numbers in winter and lowest numbers in summer. SW extent per season per year showed high interannual and seasonal variability, with low seasonal variability during the Millennium Drought. Examples of current uses of the new dataset will be presented and include (1) assessing ecosystem response to flooding with implications for environmental water releases, one of the largest investment in environment in Australia; (2) quantifying drivers of SW dynamics (e.g. climate, human activity); (3) quantifying changes in SW dynamics and

  6. Flood trends and population dynamics (United States)

    Di Baldassarre, G.


    Since the earliest recorded civilizations, such as those in Mesopotamia and Egypt that developed in the fertile floodplains of the Tigris and Euphrates and Nile rivers, humans tend to settle in flood prone areas as they offer favorable conditions for economic development. However, floodplains are also exposed to flood disasters that might cause severe socio-economic and environmental damages not to mention losses of human lives. A flood event turns to be a disaster when it coincides with a vulnerable environment exceeding society's capacity to manage the adverse consequences. This presentation discusses the link between hydrological risk and population change by referring to the outcomes of scientific works recently carried out in Africa and Europe. More specifically, it is shown that the severity of flood disasters, currently affecting more than 100 million people a year, might be seriously exacerbated because of population change. In fact, flood exposure and/or vulnerability might increase because of rapid population growth (and its spatial and temporal dynamics, e.g. urbanization) in the African continent and because of population ageing in many European countries. Lastly, timely and economically sustainable actions to mitigate this increasing hydrological risk are critically evaluated.


    Directory of Open Access Journals (Sweden)

    C. Ramírez-Núñez


    Full Text Available This research provides a wave flood simulation using a high resolution LiDAR Digital Terrain Model. The simulation is based on the generation of waves of different amplitudes that modify the river level in such a way that water invades the adjacent areas. The proposed algorithm firstly reconstitutes the original river surface of the studied river section and then defines the percentage of water loss when the wave floods move downstream. This procedure was applied to a gently slope area in the lower basin of Coatzacoalcos river, Veracruz (Mexico defining the successive areas where lateral flooding occurs on its downstream movement.

  8. Lateral Flooding Associated to Wave Flood Generation on River Surface (United States)

    Ramírez-Núñez, C.; Parrot, J.-F.


    This research provides a wave flood simulation using a high resolution LiDAR Digital Terrain Model. The simulation is based on the generation of waves of different amplitudes that modify the river level in such a way that water invades the adjacent areas. The proposed algorithm firstly reconstitutes the original river surface of the studied river section and then defines the percentage of water loss when the wave floods move downstream. This procedure was applied to a gently slope area in the lower basin of Coatzacoalcos river, Veracruz (Mexico) defining the successive areas where lateral flooding occurs on its downstream movement.

  9. Surface water, groundwater and unified 3D-crack network as a triple coupling dynamic system for a river watershed functioning - manifestation in catastrophic floods (United States)

    Trifonova, Tatiana; Tulenev, Nikita; Trifonov, Dmitriy; Arakelian, Sergei


    stimulating a trigger mechanism for releasing of groundwater; (ii) the crackness/fracturing structure as a characteristic property for all rocks, being dissecting by totality of cracks/fissures and along which (in the case when a good development crack becomes a fault) a vertical and/or lateral movement (of both groundwater and surface water mass) occurs as a result of excessive strain; (iii) areas of formation and modification in time of groundwater transit system, and especially the modalities for it exit on surface by different factors including tectonic processes under adjustable conditions for both localization of earthquake epicenters/volcanos activity areas and occurring floods in respect of propagating of seismic waves and dislocation of border for lithospheric plates/magma objects in the river basin region; (iv) the way of distribution over surface for water flows/fronts in the further, which can be described by nonlinear hydrodynamic approach, e.g. by different classes of solutions for Korteweg-de Vries equation, associated with observable natural phenomena. 4. Monitoring in dynamics of state of hydrostatic/hydrodynamic pressures in underground aquifers (e.g. by artesian wells in comparison with two databases: before and after the events) is an important factor in assessing of acceptable risk for the events. Combining it with monitoring of seismic activity should allow to make a more detailed forecasting and zoning of potentially dangerous areas for such natural disasters.

  10. Dynamic Flood Vulnerability Mapping with Google Earth Engine (United States)

    Tellman, B.; Kuhn, C.; Max, S. A.; Sullivan, J.


    Satellites capture the rate and character of environmental change from local to global levels, yet integrating these changes into flood exposure models can be cost or time prohibitive. We explore an approach to global flood modeling by leveraging satellite data with computing power in Google Earth Engine to dynamically map flood hazards. Our research harnesses satellite imagery in two main ways: first to generate a globally consistent flood inundation layer and second to dynamically model flood vulnerability. Accurate and relevant hazard maps rely on high quality observation data. Advances in publicly available spatial, spectral, and radar data together with cloud computing allow us to improve existing efforts to develop a comprehensive flood extent database to support model training and calibration. This talk will demonstrate the classification results of algorithms developed in Earth Engine designed to detect flood events by combining observations from MODIS, Landsat 8, and Sentinel-1. Our method to derive flood footprints increases the number, resolution, and precision of spatial observations for flood events both in the US, recorded in the NCDC (National Climatic Data Center) storm events database, and globally, as recorded events from the Colorado Flood Observatory database. This improved dataset can then be used to train machine learning models that relate spatial temporal flood observations to satellite derived spatial temporal predictor variables such as precipitation, antecedent soil moisture, and impervious surface. This modeling approach allows us to rapidly update models with each new flood observation, providing near real time vulnerability maps. We will share the water detection algorithms used with each satellite and discuss flood detection results with examples from Bihar, India and the state of New York. We will also demonstrate how these flood observations are used to train machine learning models and estimate flood exposure. The final stage of

  11. REAL-TIME high-resolution urban surface water flood mapping to support flood emergency management (United States)

    Guan, M.; Yu, D.; Wilby, R.


    Strong evidence has shown that urban flood risks will substantially increase because of urbanisation, economic growth, and more frequent weather extremes. To effectively manage these risks require not only traditional grey engineering solutions, but also a green management solution. Surface water flood risk maps based on return period are useful for planning purposes, but are limited for application in flood emergencies, because of the spatiotemporal heterogeneity of rainfall and complex urban topography. Therefore, a REAL-TIME urban surface water mapping system is highly beneficial to increasing urban resilience to surface water flooding. This study integrated numerical weather forecast and high-resolution urban surface water modelling into a real-time multi-level surface water mapping system for Leicester City in the UK. For rainfall forecast, the 1km composite rain radar from the Met Office was used, and we used the advanced rainfall-runoff model - FloodMap to predict urban surface water at both city-level (10m-20m) and street-level (2m-5m). The system is capable of projecting 3-hour urban surface water flood, driven by rainfall derived from UK Met Office radar. Moreover, this system includes real-time accessibility mapping to assist the decision-making of emergency responders. This will allow accessibility (e.g. time to travel) from individual emergency service stations (e.g. Fire & Rescue; Ambulance) to vulnerable places to be evaluated. The mapping results will support contingency planning by emergency responders ahead of potential flood events.

  12. Modelling the effects of surface water flood pulses on groundwater

    NARCIS (Netherlands)

    Schot, P.P.; Wassen, M.J.


    Flood pulses in wetlands steer ecosystem development directly through surface water processes and indirectly through the effects of the flood pulse on groundwater. Direct effects on ecosystems are exerted by e.g. inundation and deposition of sediments containing nutrients. Indirect effects include

  13. A Probabilistic Analysis of Surface Water Flood Risk in London. (United States)

    Jenkins, Katie; Hall, Jim; Glenis, Vassilis; Kilsby, Chris


    Flooding in urban areas during heavy rainfall, often characterized by short duration and high-intensity events, is known as "surface water flooding." Analyzing surface water flood risk is complex as it requires understanding of biophysical and human factors, such as the localized scale and nature of heavy precipitation events, characteristics of the urban area affected (including detailed topography and drainage networks), and the spatial distribution of economic and social vulnerability. Climate change is recognized as having the potential to enhance the intensity and frequency of heavy rainfall events. This study develops a methodology to link high spatial resolution probabilistic projections of hourly precipitation with detailed surface water flood depth maps and characterization of urban vulnerability to estimate surface water flood risk. It incorporates probabilistic information on the range of uncertainties in future precipitation in a changing climate. The method is applied to a case study of Greater London and highlights that both the frequency and spatial extent of surface water flood events are set to increase under future climate change. The expected annual damage from surface water flooding is estimated to be to be £171 million, £343 million, and £390 million/year under the baseline, 2030 high, and 2050 high climate change scenarios, respectively. © 2017 Society for Risk Analysis.

  14. Dynamics at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sylvia Ceyer, Nancy Ryan Gray


    The 2009 Gordon Conference on Dynamics at Surfaces is the 30th anniversary of a meeting held every two years that is attended by leading researchers in the area of experimental and theoretical dynamics at liquid and solid surfaces. The conference focuses on the dynamics of the interaction of molecules with either liquid or solid surfaces, the dynamics of the outermost layer of liquid and solid surfaces and the dynamics at the liquid-solid interface. Specific topics that are featured include state-to-state dynamics, non-adiabatic interactions in molecule-metal systems, photon induced desorption from semiconductor and metal surfaces, ultrafast x-ray and electron diffraction as probes of the dynamics of ablation, ultrafast vibrational spectroscopy of water surface dynamics, dynamics of a single adsorbate, growth at nano-scale mineral surfaces, dynamics of atom recombination on interstellar dust grains and the dynamics of the interaction of water with lipid bilayers. The conference brings together investigators from a variety of scientific disciplines including chemistry, physics, materials science, geology and biophysics.

  15. Combining hydraulic model, hydrogeomorphological observations and chemical analyses of surface waters to improve knowledge on karst flash floods genesis

    Directory of Open Access Journals (Sweden)

    F. Raynaud


    Full Text Available During a flood event over a karst watershed, the connections between surface and ground waters appear to be complex ones. The karst may attenuate surface floods by absorbing water or contribute to the surface flood by direct contribution of karst waters in the rivers (perennial and overflowing springs and by diffuse resurgence along the hillslopes. If it is possible to monitor each known outlet of a karst system, the diffuse contribution is yet difficult to assess. Furthermore, all these connections vary over time according to several factors such as the water content of the soil and underground, the rainfall characteristics, the runoff pathways. Therefore, the contribution of each compartment is generally difficult to assess, and flood dynamics are not fully understood. To face these misunderstandings and difficulties, we analysed surface waters during six recent flood events in the Lirou watershed (a karst tributary of the Lez, in South of France. Because of the specific chemical signature of karst waters, chemical analyses can supply information about water pathways and flood dynamics. Then, we used the dilution law to combine chemical results, flow data and field observations to assess the dynamics of the karst component of the flood. To end, we discussed the surface or karst origin of the waters responsible for the apparent runoff coefficient rise during flash karst flood.

  16. A new methodology for dynamic modelling of health risks arising from wastewater influenced urban flooding (United States)

    Jørgensen, Claus; Mark, Ole; Djordjevic, Slobodan; Hammond, Michael; Khan, David M.; Erichsen, Anders; Dorrit Enevoldsen, Ann; Heinicke, Gerald; Helwigh, Birgitte


    Indroduction Urban flooding due to rainfall exceeding the design capacity of drainage systems is a global problem and it has significant economic and social consequences. While the cost of the direct flood damages of urban flooding is well understood, the indirect damages, like the water borne diseases is in general still poorly understood. Climate changes are expected to increase the frequency of urban flooding in many countries which is likely to increase water borne diseases. Diarrheal diseases are most prevalent in developing countries, where poor sanitation, poor drinking water and poor surface water quality causes a high disease burden and mortality, especially during floods. The level of water borne diarrhea in countries with well-developed water and waste water infrastructure has been reduced to an acceptable level, and the population in general do not consider waste water as being a health risk. Hence, exposure to wastewater influenced urban flood water still has the potential to cause transmission of diarrheal diseases. When managing urban flooding and planning urban climate change adaptations, health risks are rarely taken into consideration. This paper outlines a novel methodology for linking dynamic urban flood modelling with Quantitative Microbial Risk Assessment (QMRA). This provides a unique possibility for understanding the interaction between urban flooding and the health risks caused by direct human contact with flood water and provides an option for reducing the burden of disease in the population through the use of intelligent urban flood risk management. Methodology We have linked hydrodynamic urban flood modelling with quantitative microbial risk assessment (QMRA) to determine the risk of infection caused by exposure to wastewater influenced urban flood water. The deterministic model MIKE Flood, which integrates the sewer network model in MIKE Urban and the 2D surface model MIKE21, was used to calculate the concentration of pathogens in the

  17. Dynamic computing resource allocation in online flood monitoring and prediction (United States)

    Kuchar, S.; Podhoranyi, M.; Vavrik, R.; Portero, A.


    This paper presents tools and methodologies for dynamic allocation of high performance computing resources during operation of the Floreon+ online flood monitoring and prediction system. The resource allocation is done throughout the execution of supported simulations to meet the required service quality levels for system operation. It also ensures flexible reactions to changing weather and flood situations, as it is not economically feasible to operate online flood monitoring systems in the full performance mode during non-flood seasons. Different service quality levels are therefore described for different flooding scenarios, and the runtime manager controls them by allocating only minimal resources currently expected to meet the deadlines. Finally, an experiment covering all presented aspects of computing resource allocation in rainfall-runoff and Monte Carlo uncertainty simulation is performed for the area of the Moravian-Silesian region in the Czech Republic.

  18. A Dynamic Model for Roll Motion of Ships Due to Flooding

    DEFF Research Database (Denmark)

    Xia, Jinzhu; Jensen, Jørgen Juncher; Pedersen, Preben Terndrup


    approximation to the water flow process is derived on the basis of a numerical simulation which takes into account the influence of the air compression in the equalizing compartment and improves the formula given in the existing rules.The coupled air, water and roll motion are solved numerically and presented......A dynamic model is presented of the roll motion of damaged RoRo vessels which couples the internal cross-flooding flow and the air action in the equalizing compartment. The cross flooding flow and the air motion are modelled by a modified Bernoulli equation, where artificial damping is introduced...... a very large damage hole, implying that the water surface in the flooded compartment is always at the same level as the mean water surface.Ignoring roll motion, asymptotic and numerical solutions for the cross-flooding process and the associated air flow through the air pipe are obtained. A simple...

  19. Study on coupled dynamics of ship and flooding water based on experimental and SPH methods (United States)

    Cheng, H.; Zhang, A. M.; Ming, F. R.


    The present paper studies the fluid dynamics during the flooding of a damaged ship numerically and experimentally. Attention is focused on the fluid flow characteristics and the fluid-structure interactions. The Smoothed Particle Hydrodynamics (SPH) method with an improved boundary treatment is established, which is able to capture the flow behaviors effectively. Fairly good agreement is obtained between the computational and experimental results. Based on the SPH method, the simulations are carried out for the flooding of a damaged ship with different opening sizes, opening positions, and numbers of the flooding cabins. Besides, the effects of the wave are also taken into account. The fluid behaviors are described and analyzed in detail. It is found that, during the first phase of flooding, an inflow jet with a large velocity is formed, significantly influencing the inner flows and the ship responses. During the progressive flooding phase, sloshing, crushing of the free surface, wave breaking, and vortex shedding are observed which are coupled with the ship motions. In addition, some relevant conclusions are enclosed for the motion laws of the damaged ship. This work provides physical insight into the flooding of the damaged ship, which is helpful to understand the coupled dynamics of the ship and flooding water.

  20. The dynamics of cultivation and floods in arable lands of Central Argentina

    Directory of Open Access Journals (Sweden)

    E. F. Viglizzo


    Full Text Available Although floods in watersheds have been associated with land-use change since ancient times, the dynamics of flooding is still incompletely understood. In this paper we explored the relations between rainfall, groundwater level, and cultivation to explain the dynamics of floods in the extremely flat and valuable arable lands of the Quinto river watershed, in central Argentina. The analysis involved an area of 12.4 million hectare during a 26-year period (1978–2003, which comprised two extensive flooding episodes in 1983–1988 and 1996–2003. Supported by information from surveys as well as field and remote sensing measurements, we explored the correlation among precipitation, groundwater levels, flooded area and land use. Flood extension was associated to the dynamics of groundwater level. While no correlation with rainfall was recorded in lowlands, a significant correlation (P<0.01 between groundwater and rainfall in highlands was found when estimations comprise a time lag of one year. Correlations between groundwater level and flood extension were positive in all cases, but while highly significant relations (P<0.01 were found in highlands, non significant relations (P>0.05 predominate in lowlands. Our analysis supports the existence of a cyclic mechanism driven by the reciprocal influence between cultivation and groundwater in highlands. This cycle would involve the following stages: (a cultivation boosts the elevation of groundwater levels through decreased evapotranspiration; (b as groundwater level rises, floods spread causing a decline of land cultivation; (c flooding propitiates higher evapotranspiration favouring its own retraction; (d cultivation expands again following the retreat of floods. Thus, cultivation would trigger a destabilizing feedback self affecting future cultivation in the highlands. It is unlikely that such sequence can work in lowlands. The results suggest that rather than responding directly

  1. Remote sensing estimates of impervious surfaces for pluvial flood modelling

    DEFF Research Database (Denmark)

    Kaspersen, Per Skougaard; Drews, Martin

    This paper investigates the accuracy of medium resolution (MR) satellite imagery in estimating impervious surfaces for European cities at the detail required for pluvial flood modelling. Using remote sensing techniques enables precise and systematic quantification of the influence of the past 30...

  2. Integrating human behaviour dynamics into flood disaster risk assessment (United States)

    Aerts, J. C. J. H.; Botzen, W. J.; Clarke, K. C.; Cutter, S. L.; Hall, J. W.; Merz, B.; Michel-Kerjan, E.; Mysiak, J.; Surminski, S.; Kunreuther, H.


    The behaviour of individuals, businesses, and government entities before, during, and immediately after a disaster can dramatically affect the impact and recovery time. However, existing risk-assessment methods rarely include this critical factor. In this Perspective, we show why this is a concern, and demonstrate that although initial efforts have inevitably represented human behaviour in limited terms, innovations in flood-risk assessment that integrate societal behaviour and behavioural adaptation dynamics into such quantifications may lead to more accurate characterization of risks and improved assessment of the effectiveness of risk-management strategies and investments. Such multidisciplinary approaches can inform flood-risk management policy development.

  3. Flood damage claims reveal insights about surface runoff in Switzerland (United States)

    Bernet, D. B.; Prasuhn, V.; Weingartner, R.


    A few case studies in Switzerland exemplify that not only overtopping water bodies frequently cause damages to buildings. Reportedly, a large share of the total loss due to flooding in Switzerland goes back to surface runoff that is formed and is propagating outside of regular watercourses. Nevertheless, little is known about when, where and why such surface runoff occurs. The described process encompasses surface runoff formation, followed by unchannelised overland flow until a water body is reached. It is understood as a type of flash flood, has short response times and occurs diffusely in the landscape. Thus, the process is difficult to observe and study directly. A promising source indicating surface runoff indirectly are houseowners' damage claims recorded by Swiss Public Insurance Companies for Buildings (PICB). In most of Switzerland, PICB hold a monopoly position and insure (almost) every building. Consequently, PICB generally register all damages to buildings caused by an insured natural hazard (including surface runoff) within the respective zones. We have gathered gapless flood related claim records of most of all Swiss PICB covering more than the last two decades on average. Based on a subset, we have developed a methodology to differentiate claims related to surface runoff from other causes. This allows us to assess the number of claims as well as total loss related to surface runoff and compare these to the numbers of overtopping watercourses. Furthermore, with the good data coverage, we are able to analyze surface runoff related claims in space and time, from which we can infer spatial and temporal characteristics of surface runoff. Although the delivered data of PICB are heterogeneous and, consequently, time-consuming to harmonize, our first results show that exploiting these damage claim records is feasible and worthwhile to learn more about surface runoff in Switzerland.

  4. The management of urban surface water flood risks: SUDS performance in flood reduction from extreme events. (United States)

    Viavattene, C; Ellis, J B


    The need to improve the urban drainage network to meet recent urban growth and the redevelopment of old industrial and commercial areas provides an opportunity for managing urban surface water infrastructure in a more sustainable way. The use of sustainable urban drainage systems (SUDS) can reduce urban surface water flooding as well as the pollution impact of urban discharges on receiving waters. However, these techniques are not yet well known by many stakeholders involved in the decision-making process, or at least the evidence of their performance effectiveness may be doubted compared with more traditional engineering solutions often promoted by existing 1D/2D drainage models. The use of geographic information systems (GIS) in facilitating the inter-related risk analysis of sewer surface water overflows and urban flooding as well as in better communication with stakeholders is demonstrated in this paper. An innovative coupled 1D/2D urban sewer/overland flow model has been developed and tested in conjunction with a SUDS selection and location tool (SUDSLOC) to enable a robust management approach to surface water flood risks and to improve the resilience of the urban drainage infrastructure. The paper demonstrates the numerical and modelling basis of the integrated 1D/2D and SUDSLOC approach and the working assumptions and flexibility of the application together with some limitations and uncertainties. The role of the SUDSLOC modelling component in quantifying flow, and surcharge reduction benefits arising from the strategic selection and location of differing SUDS controls are also demonstrated for an extreme storm event scenario.

  5. SURFACE FLOODS IN COIMBRA: simple and dual-drainage studies (United States)

    Leitão, J. P.; Simões, N. E.; Pina, R.; Marques, A. Sá; Maksimović, Č.; Gonçalves, Gil


    Surface water flooding occurs due to extreme rainfall and the inability of the sewer system to drain all runoff. As a consequence, a considerable volume of water is carried out over the surface through preferential flow paths and can eventually accumulate in natural (or man-made) ponds. This can cause minor material losses but also major incidents with obvious consequences in economic activities and the normal people's life. Unfortunately, due to predicted climate changes and increase of urbanisation levels, the urban flooding phenomenon has been reported more often. The Portuguese city of Coimbra is a medium size city that has suffered several river floods in the past. However, after the construction of hydraulic control structures, the number of fluvial flood events was greatly reduced. In the 1990s two new problems started. On one hand, houses started to be built on flood plain areas; on the other hand, some areas experienced a boom in the degree of urbanisation. This created flood problems of a different type dislocating the flood areas from the traditional flood areas along the river to new areas that did not reported flood in history. The catchment studied has a total area of approximately 1.5 km2 and discharges in the Coselhas brook The catchment can be divided in three regions with different characteristics: (i) the "Lower City" which is a low-lying area with 0.4 km2 and with a combined sewer system; (ii) the "Upper City" which is a considerably hilly area, highly urbanized and with an area of approximately 0.2 km2; and (iii) the remaining area which is also highly urbanized, with an area of 0.9 km2, where the main flood problems are generated. The sewer system is 34.8 km long; 29 km are of the combined type, and only 1.2 km is exclusive for storm water. The time of concentration of the catchment is estimated to be 45 min. On the 9 June 2006, an extreme rainfall event caused severe flooding in the city. After the rainfall had stopped, water continued to

  6. Floods (United States)

    Floods are common in the United States. Weather such as heavy rain, thunderstorms, hurricanes, or tsunamis can ... is breached, or when a dam breaks. Flash floods, which can develop quickly, often have a dangerous ...

  7. Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon (United States)

    Mueller, Erich R.; Grams, Paul E.; Hazel, Joseph E.; Schmidt, John C.


    Sandbars are iconic features of the Colorado River in the Grand Canyon, Arizona, U.S.A. Following completion of Glen Canyon Dam in 1963, sediment deficit conditions caused erosion of eddy sandbars throughout much of the 360 km study reach downstream from the dam. Controlled floods in 1996, 2004, and 2008 demonstrated that sand on the channel bed could be redistributed to higher elevations, and that floods timed to follow tributary sediment inputs would increase suspended sand concentrations during floods. Since 2012, a new management protocol has resulted in four controlled floods timed to follow large inputs of sand from a major tributary. Monitoring of 44 downstream eddy sandbars, initiated in 1990, shows that each controlled flood deposited significant amounts of sand and increased the size of subaerial sandbars. However, the magnitude of sandbar deposition varied from eddy to eddy, even over relatively short distances where main-stem suspended sediment concentrations were similar. Here, we characterize spatial and temporal trends in sandbar volume and site-scale (i.e., individual eddy) sediment storage as a function of flow, channel, and vegetation characteristics that reflect the reach-scale (i.e., kilometer-scale) hydraulic environment. We grouped the long-term monitoring sites based on geomorphic setting and used a principal component analysis (PCA) to correlate differences in sandbar behavior to changes in reach-scale geomorphic metrics. Sites in narrow reaches are less-vegetated, stage changes markedly with discharge, sandbars tend to remain dynamic, and sand storage change dominantly occurs in the eddy compared to the main channel. In wider reaches, where stage-change during floods may be half that of narrow sites, sandbars are more likely to be stabilized by vegetation, and floods tend to aggrade the vegetated sandbar surfaces. In these locations, deposition during controlled floods is more akin to floodplain sedimentation, and the elevation of sandbar

  8. A Geo-Environmental Assessment of Flood Dynamics in Lower Ajoy ...

    African Journals Online (AJOL)


    A Geo-Environmental Assessment of Flood Dynamics in Lower Ajoy River Inducing Sand. Splay Problem in Eastern India. Sutapa Mukhopadhyay. Abstract: Flood as a widespread destructive natural disaster is recurring in the river basins of Eastern India. Though large number of flood controlling measures have been taken ...

  9. Active and Passive Remote Sensing Data Time Series for Flood Detection and Surface Water Mapping (United States)

    Bioresita, Filsa; Puissant, Anne; Stumpf, André; Malet, Jean-Philippe


    As a consequence of environmental changes surface waters are undergoing changes in time and space. A better knowledge of the spatial and temporal distribution of surface waters resources becomes essential to support sustainable policies and development activities. Especially because surface waters, are not only a vital sweet water resource, but can also pose hazards to human settlements and infrastructures through flooding. Floods are a highly frequent disaster in the world and can caused huge material losses. Detecting and mapping their spatial distribution is fundamental to ascertain damages and for relief efforts. Spaceborne Synthetic Aperture Radar (SAR) is an effective way to monitor surface waters bodies over large areas since it provides excellent temporal coverage and, all-weather day-and-night imaging capabilities. However, emergent vegetation, trees, wind or flow turbulence can increase radar back-scatter returns and pose problems for the delineation of inundated areas. In such areas, passive remote sensing data can be used to identify vegetated areas and support the interpretation of SAR data. The availability of new Earth Observation products, for example Sentinel-1 (active) and Sentinel-2 (passive) imageries, with both high spatial and temporal resolution, have the potential to facilitate flood detection and monitoring of surface waters changes which are very dynamic in space and time. In this context, the research consists of two parts. In the first part, the objective is to propose generic and reproducible methodologies for the analysis of Sentinel-1 time series data for floods detection and surface waters mapping. The processing chain comprises a series of pre-processing steps and the statistical modeling of the pixel value distribution to produce probabilistic maps for the presence of surface waters. Images pre-processing for all Sentinel-1 images comprise the reduction SAR effect like orbit errors, speckle noise, and geometric effects. A modified

  10. Forecasting surface water flooding hazard and impact in real-time (United States)

    Cole, Steven J.; Moore, Robert J.; Wells, Steven C.


    Across the world, there is increasing demand for more robust and timely forecast and alert information on Surface Water Flooding (SWF). Within a UK context, the government Pitt Review into the Summer 2007 floods provided recommendations and impetus to improve the understanding of SWF risk for both off-line design and real-time forecasting and warning. Ongoing development and trial of an end-to-end real-time SWF system is being progressed through the recently formed Natural Hazards Partnership (NHP) with delivery to the Flood Forecasting Centre (FFC) providing coverage over England & Wales. The NHP is a unique forum that aims to deliver coordinated assessments, research and advice on natural hazards for governments and resilience communities across the UK. Within the NHP, a real-time Hazard Impact Model (HIM) framework has been developed that includes SWF as one of three hazards chosen for initial trialling. The trial SWF HIM system uses dynamic gridded surface-runoff estimates from the Grid-to-Grid (G2G) hydrological model to estimate the SWF hazard. National datasets on population, infrastructure, property and transport are available to assess impact severity for a given rarity of SWF hazard. Whilst the SWF hazard footprint is calculated in real-time using 1, 3 and 6 hour accumulations of G2G surface runoff on a 1 km grid, it has been possible to associate these with the effective rainfall design profiles (at 250m resolution) used as input to a detailed flood inundation model (JFlow+) run offline to produce hazard information resolved to 2m resolution. This information is contained in the updated Flood Map for Surface Water (uFMfSW) held by the Environment Agency. The national impact datasets can then be used with the uFMfSW SWF hazard dataset to assess impacts at this scale and severity levels of potential impact assigned at 1km and for aggregated county areas in real-time. The impact component is being led by the Health and Safety Laboratory (HSL) within the NHP

  11. Flooding (United States)

    ... have high levels of raw sewage or other hazardous substances. Early symptoms from exposure to contaminated flood water ... for commercial building and school maintenance. Basic mold hazards . ... and the waste management options available. Burying or burning is no longer ...

  12. Flood Mapping and Flood Dynamics of the Mekong Delta: ENVISAT-ASAR-WSM Based Time Series Analyses

    Directory of Open Access Journals (Sweden)

    Stefan Dech


    Full Text Available Satellite remote sensing is a valuable tool for monitoring flooding. Microwave sensors are especially appropriate instruments, as they allow the differentiation of inundated from non-inundated areas, regardless of levels of solar illumination or frequency of cloud cover in regions experiencing substantial rainy seasons. In the current study we present the longest synthetic aperture radar-based time series of flood and inundation information derived for the Mekong Delta that has been analyzed for this region so far. We employed overall 60 Envisat ASAR Wide Swath Mode data sets at a spatial resolution of 150 meters acquired during the years 2007–2011 to facilitate a thorough understanding of the flood regime in the Mekong Delta. The Mekong Delta in southern Vietnam comprises 13 provinces and is home to 18 million inhabitants. Extreme dry seasons from late December to May and wet seasons from June to December characterize people’s rural life. In this study, we show which areas of the delta are frequently affected by floods and which regions remain dry all year round. Furthermore, we present which areas are flooded at which frequency and elucidate the patterns of flood progression over the course of the rainy season. In this context, we also examine the impact of dykes on floodwater emergence and assess the relationship between retrieved flood occurrence patterns and land use. In addition, the advantages and shortcomings of ENVISAT ASAR-WSM based flood mapping are discussed. The results contribute to a comprehensive understanding of Mekong Delta flood dynamics in an environment where the flow regime is influenced by the Mekong River, overland water-flow, anthropogenic floodwater control, as well as the tides.

  13. Dynamic Floodplain representation in hydrologic flood forecasting using WRF-Hydro modeling framework (United States)

    Gangodagamage, C.; Li, Z.; Maitaria, K.; Islam, M.; Ito, T.; Dhondia, J.


    Floods claim more lives and damage more property than any other category of natural disaster in the Continental United States. A system that can demarcate local flood boundaries dynamically could help flood prone communities prepare for and even prevent from catastrophic flood events. Lateral distance from the centerline of the river to the right and left floodplains for the water levels coming out of the models at each grid location have not been properly integrated with the national hydrography dataset (NHDPlus). The NHDPlus dataset represents the stream network with feature classes such as rivers, tributaries, canals, lakes, ponds, dams, coastlines, and stream gages. The NHDPlus dataset consists of approximately 2.7 million river reaches defining how surface water drains to the ocean. These river reaches have upstream and downstream nodes and basic parameters such as flow direction, drainage area, reach slope etc. We modified an existing algorithm (Gangodagamage et al., 2007) to provide lateral distance from the centerline of the river to the right and left floodplains for the flows simulated by models. Previous work produced floodplain boundaries for static river stages (i.e. 3D metric: distance along the main stem, flow depth, lateral distance from river center line). Our new approach introduces the floodplain boundary for variable water levels at each reach with the fourth dimension, time. We use modeled flows from WRF-Hydro and demarcate the right and left lateral boundaries of inundation dynamically by appropriately mapping discharges into hydraulically corrected stages. Backwater effects from the mainstem to tributaries are considered and proper corrections are applied for the tributary inundations. We obtained river stages by optimizing reach level channel parameters using newly developed stream flow routing algorithm. Non uniform inundations are mapped at each NHDplus reach (upstream and downstream nodes) and spatial interpolation is carried out on a

  14. How frequently will the Surface Water and Ocean Topography (SWOT) observe floods? (United States)

    Frasson, R. P. M.; Schumann, G.


    The SWOT mission will measure river width and water surface elevations of rivers wider than 100 m. As the data gathered by this mission will be freely available, it can be of great use for flood modeling, especially in areas where streamgage networks are exceedingly sparse, or when data sharing barriers prevent the timely access to information. Despite having world-wide coverage, SWOT's temporal sampling is limited, with most locations being revisited once or twice every 21 days. Our objective is to evaluate which fraction of world-wide floods SWOT will observe and how many observations per event the satellite will likely obtain. We take advantage of the extensive database of floods constructed by the Dartmouth Flood Observatory, who, since 1985, searches through news sources and governmental agencies, and more recently remote sensing imagery for flood information, including flood duration, location and affected area. We cross-referenced the flood locations in the DFO archive with the SWOT prototype prior database of river centerlines and the anticipated satellite's orbit to identify how many of the SWOT swaths were located within 10 km, 20 km, and 50 km from a flood centroid. Subsequently, we estimated the probability that SWOT would have at least one observation of a flood event per distance bin by multiplying the number of swaths in the distance bin by the flood duration divided by the SWOT orbit repeat period. Our analysis contemplated 132 world-wide floods recorded between May 2016 and May 2017. From these, 29, 52, and 86 floods had at least a 50% probability of having one overpass within 10 km, 20 km, and 50 km respectively. Moreover, after excluding flood events with no river centerlines within 10 km of its centroid, the average number of swaths within 10 km of a flood centroid was 1.79, indicating that in the 37 flood events that were likely caused by river flooding, at least one measurement was guaranteed to happen during the event.

  15. Lacustrine records of Holocene flood pulse dynamics in the Upper Paraguay River watershed (Pantanal wetlands, Brazil) (United States)

    McGlue, Michael M.; Silva, Aguinaldo; Zani, Hiran; Corradini, Fabrício A.; Parolin, Mauro; Abel, Erin J.; Cohen, Andrew S.; Assine, Mario L.; Ellis, Geoffrey S.; Trees, Mark A.; Kuerten, Sidney; Gradella, Frederico dos Santos; Rasbold, Giliane Gessica


    The Pantanal is the world's largest tropical wetland and a biodiversity hotspot, yet its response to Quaternary environmental change is unclear. To address this problem, sediment cores from shallow lakes connected to the Upper Paraguay River (PR) were analyzed and radiocarbon dated to track changes in sedimentary environments. Stratal relations, detrital particle size, multiple biogeochemical indicators, and sponge spicules suggest fluctuating lake-level lowstand conditions between ~ 11,000 and 5300 cal yr BP, punctuated by sporadic and in some cases erosive flood flows. A hiatus has been recorded from ~ 5300 to 2600 cal yr BP, spurred by confinement of the PR within its channel during an episode of profound regional drought. Sustained PR flooding caused a transgression after ~ 2600 cal yr BP, with lake-level highstand conditions appearing during the Little Ice Age. Holocene PR flood pulse dynamics are best explained by variability in effective precipitation, likely driven by insolation and tropical sea-surface temperature gradients. Our results provide novel support for hypotheses on: (1) stratigraphic discontinuity of floodplain sedimentary archives; (2) late Holocene methane flux from Southern Hemisphere wetlands; and (3) pre-colonial indigenous ceramics traditions in western Brazil.

  16. Water Quality Dynamics of Urban Water Bodies during Flooding in Can Tho City, Vietnam

    Directory of Open Access Journals (Sweden)

    Hong Quan Nguyen


    Full Text Available Water pollution associated with flooding is one of the major problems in cities in the global South. However, studies of water quality dynamics during flood events are not often reported in literature, probably due to difficult conditions for sampling during flood events. Water quality parameters in open water (canals, rivers, and lakes, flood water on roads and water in sewers have been monitored during the extreme fluvial flood event on 7 October 2013 in the city of Can Tho, Vietnam. This is the pioneering study of urban flood water pollution in real time in Vietnam. The results showed that water quality is very dynamic during flooding, especially at the beginning of the event. In addition, it was observed that the pathogen and contaminant levels in the flood water are almost as high as in sewers. The findings show that population exposed to flood water runs a health risk that is nearly equal to that of being in contact with sewer water. Therefore, the people of Can Tho not only face physical risk due to flooding, but are also exposed to health risks.

  17. CADYRI, a dynamic mapping tool of human risk associated with flooding in urban areas (United States)

    Tanguy, M.; Chokmani, K.; Bernier, M.; Poulin, J.


    When a flood affects an urban area, the managers and services responsible for public safety need precise and real time information on the localization of the flooded areas, on the submersion heights in those areas, but also on the vulnerability of people exposed to this hazard. Such information is essential for an effective crisis management. Despite a growing interest in this topic over the last 15 years, the development of flood risk assessment tools mainly focused on quantitative modeling of the monetary damages caused by floods to residential buildings or to critical infrastructures. Little attention was paid to the vulnerability of people exposed to flooding but also to the effects of the failure or destruction of critical infrastructures and residential building on people health and security during the disaster. Moreover, these models do not integrate the dynamic features of the flood (extent, submersion heights) and the evolution of human vulnerability in the same mapping tool. Thus, an accurate and precise evaluation of human risk induced by urban flooding is hardly feasible using such models. This study presents CADYRI, a dynamic mapping tool of human risk associated with flooding in urban areas, which fills the actual needs in terms of flood risk evaluation and management. This innovative tool integrates a methodology of flood hazard mapping that simulates, for a given discharge, the associated water level, and subsequently determines the extent of the flooded area and the submersion heights at each point of the flooded area, using a DEM. The dynamics of human vulnerability is then mapped at the household level, according to the characteristics of the flood hazard. Three key components of human vulnerability have been identified and are integrated to CADYRI: 1, the intrinsic vulnerability of the population, estimated by specific socio-economic indicators; 2, the vulnerability of buildings, assessed by their structural features; 3, the vulnerability of

  18. Hydrodynamic Modeling of Flood Dynamics and Restoration Potential of Lower Missouri River Floodplains (United States)

    Lindner, G. A.


    Lower Missouri River floodplains have the potential to provide multiple ecosystem services including agricultural production, floodwater storage, nutrient processing, and provision of habitats. In this research, a 2-dimensional hydrodynamic model of a representative looped floodplain bottom of approximately 20 km is utilized to explore how floodplain inundation contributes to ecosystem benefits and costs. High resolution 2-dimensional hydrodynamic modeling provides insights into the way velocities, flood stages, residence times, and transported constituents (sediment, nutrients, and fish larvae, for example) are affected by levee geometry, floodplain vegetation patterns, and flood magnitude and duration. The utility of 2-dimensional numerical hydraulic models to represent the channel and floodplain are demonstrated at a scale relevant to understanding processes that control channel/floodplain dynamics. The sensitivity of model response to alternative land use scenarios, including levee setbacks and variable overbank roughness, is quantified using hydraulic parameters such as velocity, water level, conveyance, and residence time. The 2-dimensional models are calibrated to existing 1-dimensional modeling solutions and field measurements of water surface from 1993 and 2007 for the 2-year, 5-year, and 10-year recurrence intervals. Calibration runs with current levee configurations are matched to approximately ±0.1 meters. Simulations of alternative land use scenarios demonstrate the tradeoffs between ecological restoration and flood risk reductions. Levee setbacks with low hydraulic roughness associated with traditional row crop agriculture on the floodplains have the greatest potential for flood stage reductions, while native plant communities with higher roughness can negate the effects of the setbacks by increasing water levels due to enhanced frictional resistance. Residence times, which are presumed to be related to ecosystem services, demonstrate increasingly

  19. Analysis of flash flood processes dynamics in a Mediterranean catchment using a distributed hydrological model (United States)

    Roux, H.; Maubourguet, M.-M.; Castaings, W.; Dartus, D.


    The present study aims at analyzing the hydrological processes involved in flash flood generation. It focuses on small catchments located in the Mediterranean region (Southern France) and often affected by extreme events (Gaume et al., 2009; Ruin et al., 2008). The model used in this study is a spatially distributed rainfall-runoff model dedicated to extreme event simulation and developed on the basis of physical process representation. It is structured into three modules, which represent the soil component, the overland flow component and flow through the drainage network. Infiltration is described using the Green and Ampt model and the soils are assumed vertically homogeneous. Lateral subsurface flow is based on the Darcy's law for a confined aquifer. Surface runoff calculation is divided into two parts: overland flow and flow along the drainage network. Both are simulated using the 1D kinematic wave approximation of the Saint-Venant equations with the Manning friction law. In the drainage network, the friction difference between main channel and floodplain is taken into account. Determination of model parameters requires terrain measurement data, usually issued from DEM, soil survey and vegetation or land-use. Four parameters are calibrated for the entire catchment using discharge measurements. Model sensitivity to individual parameters is assessed using Monte-Carlo simulations, the model is then calibrated using these results to estimate the parameters with a data assimilation process called the adjoint state method (Bessière et al., 2008; Castaings et al., 2009). Flood events with different hydrometeorological characteristics are studied to compare the location of saturated areas, infiltration and runoff dynamics as well as importance of the subsurface flow. A better understanding of these processes is indeed necessary especially to improve the model efficiency when the simulation parameters cannot be calibrated and must therefore be transposed from gauged

  20. Calibration and validation of a small-scale urban surface water flood event using crowdsourced images (United States)

    Green, Daniel; Yu, Dapeng; Pattison, Ian


    Surface water flooding occurs when intense precipitation events overwhelm the drainage capacity of an area and excess overland flow is unable to infiltrate into the ground or drain via natural or artificial drainage channels, such as river channels, manholes or SuDS. In the UK, over 3 million properties are at risk from surface water flooding alone, accounting for approximately one third of the UK's flood risk. The risk of surface water flooding is projected to increase due to several factors, including population increases, land-use alterations and future climatic changes in precipitation resulting in an increased magnitude and frequency of intense precipitation events. Numerical inundation modelling is a well-established method of investigating surface water flood risk, allowing the researcher to gain a detailed understanding of the depth, velocity, discharge and extent of actual or hypothetical flood scenarios over a wide range of spatial scales. However, numerical models require calibration of key hydrological and hydraulic parameters (e.g. infiltration, evapotranspiration, drainage rate, roughness) to ensure model outputs adequately represent the flood event being studied. Furthermore, validation data such as crowdsourced images or spatially-referenced flood depth collected during a flood event may provide a useful validation of inundation depth and extent for actual flood events. In this study, a simplified two-dimensional inertial based flood inundation model requiring minimal pre-processing of data (FloodMap-HydroInundation) was used to model a short-duration, intense rainfall event (27.8 mm in 15 minutes) that occurred over the Loughborough University campus on the 28th June 2012. High resolution (1m horizontal, +/- 15cm vertical) DEM data, rasterised Ordnance Survey topographic structures data and precipitation data recorded at the University weather station were used to conduct numerical modelling over the small (present during the flood event via the

  1. Modeling of type-2 fuzzy cubic B-spline surface for flood data problem in Malaysia (United States)

    Bidin, Mohd Syafiq; Wahab, Abd. Fatah


    Malaysia possesses a low and sloping land areas which may cause flood. The flood phenomenon can be analyzed if the surface data of the study area can be modeled by geometric modeling. Type-2 fuzzy data for the flood data is defined using type-2 fuzzy set theory in order to solve the uncertainty of complex data. Then, cubic B-spline surface function is used to produce a smooth surface. Three main processes are carried out to find a solution to crisp type-2 fuzzy data which is fuzzification (α-cut operation), type-reduction and defuzzification. Upon conducting these processes, Type-2 Fuzzy Cubic B-Spline Surface Model is applied to visualize the surface data of the flood areas that are complex uncertainty.

  2. The dynamic capacity calculation method and the flood control ability of the Three Gorges Reservoir (United States)

    Zhang, Shanghong; Jing, Zhu; Yi, Yujun; Wu, Yu; Zhao, Yong


    To evaluate the flood control ability of a river-type reservoir, an accurate simulation method for the flood storage, discharge process, and dynamic capacity of the reservoir is important. As the world's largest reservoir, the storage capacity and flood control capacity of the Three Gorges Reservoir (TGR) has attracted widespread interest and academic debate for nearly 20 years. In this study, a model for calculating the dynamic capacity of a river-type reservoir is established based on data from 394 river cross sections and 2.5-m resolution digital elevation model (DEM) data of the TGR area. The storage capacity and flood control capacity of the TGR were analysed based on the scheduling procedures of a normal impoundment period. The results show that the static capacity of the TGR is 43.43 billion m3, the dynamic flood control capacity is 22.45 billion m3, and the maximum floodwater flow regulated by the dynamic capacity at Zhicheng is no more than 67,700 m3/s. This study supply new simulation method and up-to-date high-precision data to discuss the 20 years debate, and the results reveal the TGR design is conservative for flood control according to the Preliminary Design Report of the Three Gorges Project. The dynamic capacity calculation method used here can provide a reference for flood regulation of large river-type reservoirs.

  3. Race, Income Inequality, and Impervious Surfaces in Relation to Flooding Associated with Hurricane Harvey (United States)

    de Sherbinin, A. M.; Mills, J.; Borkovska, O.


    Differential vulnerability is a concept that suggests that certain demographic groups - the poor, less educated, or minorities - are likely to be more impacted by climate extremes such as floods owing to their higher sensitivity and lower adaptive capacity. Differential exposure represents the concept that these same groups may be more highly exposed to flood events by virtue of their residing in less desirable, low-lying neighborhoods with higher percentages of impervious surface cover. This paper tests the hypothesis that poor communities of color were differentially exposed to flood risks in the aftermath of Hurricane Harvey, which struck Houston, Texas in August 2017. We explore the spatial relationship among census tracts with high percentages of low income communities of color, those with high percentages of impervious surface, and those most impacted by floods. We incorporat datasets disseminated by the NASA Socioeconomic Data and Application Center (SEDAC) - the Global Man-made Impervious Surface (GMIS) data set and the U.S. Census Grids 2010 - together with the American Community Survey (ACS) 2011-2015 and flood extent and depth data from FEMA. Preliminary analysis suggests that predominantly non-white neighborhoods have higher percentages of impervious surface cover, but that impervious surface cover is negatively correlated with flood risk. This paper will situate these findings in the context of a larger body of research exploring differential exposure to flood risks during Hurricanes Katrina and Sandy, as well as differential exposure to extreme heat in urban environments in Houston and beyond.

  4. Variability in eddy sandbar dynamics during two decades of controlled flooding of the Colorado River in the Grand Canyon (United States)

    Mueller, Erich R.; Grams, Paul E.; Hazel, Joseph E.; Schmidt, John C.


    Sandbars are iconic features of the Colorado River in the Grand Canyon, Arizona, U.S.A. Following completion of Glen Canyon Dam in 1963, sediment deficit conditions caused erosion of eddy sandbars throughout much of the 360 km study reach downstream from the dam. Controlled floods in 1996, 2004, and 2008 demonstrated that sand on the channel bed could be redistributed to higher elevations, and that floods timed to follow tributary sediment inputs would increase suspended sand concentrations during floods. Since 2012, a new management protocol has resulted in four controlled floods timed to follow large inputs of sand from a major tributary. Monitoring of 44 downstream eddy sandbars, initiated in 1990, shows that each controlled flood deposited significant amounts of sand and increased the size of subaerial sandbars. However, the magnitude of sandbar deposition varied from eddy to eddy, even over relatively short distances where main-stem suspended sediment concentrations were similar. Here, we characterize spatial and temporal trends in sandbar volume and site-scale (i.e., individual eddy) sediment storage as a function of flow, channel, and vegetation characteristics that reflect the reach-scale (i.e., kilometer-scale) hydraulic environment. We grouped the long-term monitoring sites based on geomorphic setting and used a principal component analysis (PCA) to correlate differences in sandbar behavior to changes in reach-scale geomorphic metrics. Sites in narrow reaches are less-vegetated, stage changes markedly with discharge, sandbars tend to remain dynamic, and sand storage change dominantly occurs in the eddy compared to the main channel. In wider reaches, where stage-change during floods may be half that of narrow sites, sandbars are more likely to be stabilized by vegetation, and floods tend to aggrade the vegetated sandbar surfaces. In these locations, deposition during controlled floods is more akin to floodplain sedimentation, and the elevation of sandbar

  5. A dynamic compartment model for assessing the transfer of radionuclide deposited onto flooded rice-fields

    International Nuclear Information System (INIS)

    Keum, Dong-Kwon; Lee, Han-Soo; Choi, Heui-Ju; Kang, Hee-Seok; Lim, Kwang-Muk; Choi, Young-Ho; Lee, Chang-Woo


    A dynamic compartment model has been studied to estimate the transfer of radionuclides deposited onto flooded rice-fields after an accidental release. In the model, a surface water compartment and a direct shoot-base absorption from the surface water to the rice-plant, which are major features discriminating the present model from the existing model, has been introduced to account for the flooded condition of rice-fields. The model has been applied to the deposition experiments of 137 Cs on rice-fields that were performed at three different times to simulate the deposition before transplanting (May 2) and during the growth of the rice (June 1 and August 12), respectively. In the case of the deposition of May 2, the root-uptake is the most predominant process for transferring 137 Cs to the rice-body and grain. When the radionuclide is applied just after transplanting (June 1), the activity of the body is controlled by the shoot-base absorption and the activity of the grain by the root-uptake. The deposition just before ear-emergence (August 12) shows that the shoot-base absorption contributes entirely to the increase of both the activities of the body and grain. The model prediction agrees within one or two factors with the experimental results obtained for a respective deposition experiment

  6. Coupled Land-Atmosphere Dynamics Govern Long Duration Floods: A Pilot Study in Missouri River Basin Using a Bayesian Hierarchical Model (United States)

    Najibi, N.; Lu, M.; Devineni, N.


    Long duration floods cause substantial damages and prolonged interruptions to water resource facilities and critical infrastructure. We present a novel generalized statistical and physical based model for flood duration with a deeper understanding of dynamically coupled nexus of the land surface wetness, effective atmospheric circulation and moisture transport/release. We applied the model on large reservoirs in the Missouri River Basin. The results indicate that the flood duration is not only a function of available moisture in the air, but also the antecedent condition of the blocking system of atmospheric pressure, resulting in enhanced moisture convergence, as well as the effectiveness of moisture condensation process leading to release. Quantifying these dynamics with a two-layer climate informed Bayesian multilevel model, we explain more than 80% variations in flood duration. The model considers the complex interaction between moisture transport, synoptic-to-large-scale atmospheric circulation pattern, and the antecedent wetness condition in the basin. Our findings suggest that synergy between a large low-pressure blocking system and a higher rate of divergent wind often triggers a long duration flood, and the prerequisite for moisture supply to trigger such event is moderate, which is more associated with magnitude than duration. In turn, this condition causes an extremely long duration flood if the surface wetness rate advancing to the flood event was already increased.

  7. A simple statistical method for analyzing flood susceptibility with incorporating rainfall and impervious surface (United States)

    Chiang, Shou-Hao; Chen, Chi-Farn


    Flood, as known as the most frequent natural hazard in Taiwan, has induced severe damages of residents and properties in urban areas. The flood risk is even more severe in Tainan since 1990s, with the significant urban development over recent decades. Previous studies have indicated that the characteristics and the vulnerability of flood are affected by the increase of impervious surface area (ISA) and the changing climate condition. Tainan City, in southern Taiwan is selected as the study area. This study uses logistic regression to functionalize the relationship between rainfall variables, ISA and historical flood events. Specifically, rainfall records from 2001 to 2014 were collected and mapped, and Landsat images of year 2001, 2004, 2007, 2010 and 2014 were used to generate the ISA with SVM (support vector machine) classifier. The result shows that rainfall variables and ISA are significantly correlated to the flood occurrence in Tainan City. With applying the logistic function, the likelihood of flood occurrence can be estimated and mapped over the study area. This study suggests the method is simple and feasible for rapid flood susceptibility mapping, when real-time rainfall observations can be available, and it has potential for future flood assessment, with incorporating climate change projections and urban growth prediction.

  8. Coupled 1-D sewer and street networks and 2-D flooding model to rapidly evaluate surface inundation (United States)

    Kao, Hong-Ming; Hsu, Hao-Ming


    Flash floods have occurred frequently in the urban areas around the world and cause the infrastructure and people living to expose continuously in the high risk level of pluvial flooding. According to historical surveys, the major reasons of severe surface inundations in the urban areas can be attributed to heavy rainfall in the short time and/or drainage system failure. In order to obtain real-time flood forecasting with high accuracy and less uncertainty, an appropriate system for predicting floods is necessary. For the reason, this study coupled 1-D sewer and street networks and 2-D flooding model as an operational modelling system for rapidly evaluating surface inundation. The proposed system is constructed by three significant components: (1) all the rainfall-runoff of a sub-catchment collected via gullies is simulated by the RUNOFF module of the Storm Water Management Model (SWMM); (2) and directly drained to the 1-D sewer and street networks via manholes as inflow discharges to conduct flow routing by using the EXTRAN module of SWMM; (3) after the 1-D simulations, the surcharges from manholes are considered as point sources in 2-D overland flow simulations that are executed by the WASH123D model. It can thus be used for urban flood modelling that reflects the rainfall-runoff processes, and the dynamic flow interactions between the storm sewer system and the ground surface in urban areas. In the present study, we adopted the Huwei Science and Technology Park, located in the south-western part of Taiwan, as the demonstration area because of its high industrial values. The region has an area about 1 km2 with approximately 1 km in both length and width. It is as isolated urban drainage area in which there is a complete sewer system that collects the runoff and drains to the detention pond. Based on the simulated results, the proposed modelling system was found that the simulated floods fit to the survey records because the physical rainfall-runoff phenomena in

  9. Nested 1D-2D approach for urban surface flood modeling (United States)

    Murla, Damian; Willems, Patrick


    Floods in urban areas as a consequence of sewer capacity exceedance receive increased attention because of trends in urbanization (increased population density and impermeability of the surface) and climate change. Despite the strong recent developments in numerical modeling of water systems, urban surface flood modeling is still a major challenge. Whereas very advanced and accurate flood modeling systems are in place and operation by many river authorities in support of flood management along rivers, this is not yet the case in urban water management. Reasons include the small scale of the urban inundation processes, the need to have very high resolution topographical information available, and the huge computational demands. Urban drainage related inundation modeling requires a 1D full hydrodynamic model of the sewer network to be coupled with a 2D surface flood model. To reduce the computational times, 0D (flood cones), 1D/quasi-2D surface flood modeling approaches have been developed and applied in some case studies. In this research, a nested 1D/2D hydraulic model has been developed for an urban catchment at the city of Gent (Belgium), linking the underground sewer (minor system) with the overland surface (major system). For the overland surface flood modelling, comparison was made of 0D, 1D/quasi-2D and full 2D approaches. The approaches are advanced by considering nested 1D-2D approaches, including infiltration in the green city areas, and allowing the effects of surface storm water storage to be simulated. An optimal nested combination of three different mesh resolutions was identified; based on a compromise between precision and simulation time for further real-time flood forecasting, warning and control applications. Main streets as mesh zones together with buildings as void regions constitute one of these mesh resolution (3.75m2 - 15m2); they have been included since they channel most of the flood water from the manholes and they improve the accuracy of

  10. Phosphorus Dynamics in Long-Term Flooded, Drained, and Reflooded Soils

    Directory of Open Access Journals (Sweden)

    Juan Tian


    Full Text Available In flooded areas, soils are often exposed to standing water and subsequent drainage, thus over fertilization can release excess phosphorus (P into surface water and groundwater. To investigate P release and transformation processes in flooded alkaline soils, wheat-growing soil and vegetable-growing soil were selected. We flooded-drained-reflooded two soils for 35 d, then drained the soils, and 10 d later reflooded the soils for 17 d. Dissolved reactive phosphorus (DRP, soil inorganic P fractions, Olsen P, pH, and Eh in floodwater and pore water were analyzed. The wheat-growing soil had significantly higher floodwater DRP concentrations than vegetable-growing soil, and floodwater DRP in both soils decreased with the number of flooding days. During the reflooding period, DRP in overlying floodwater from both soils was less than 0.87 mg/L, which was 3–25 times less than that during the flooding period. Regardless of flooding or reflooding, pore water DRP decreased with flooding days. The highest concentration of pore water DRP observed at a 5-cm depth. Under the effect of fertilizing and flooding, the risk of vertical P movement in 10–50 cm was enhanced. P diffusion occurred from the top to the bottom of the soils. After flooding, Al-P increased in both soils, and Fe-P, O-P, Ca2-P decreased, while Fe-P, Al-P, and O-P increased after reflooding, When Olsen P in the vegetable-growing soil exceeded 180.7 mg/kg and Olsen P in the wheat-growing soil exceeded 40.8 mg/kg, the concentration of DRP in pore water increased significantly. Our results showed that changes in floodwater and pore water DRP concentrations, soil inorganic P fractions, and Olsen P are significantly affected by fertilizing and flooding; therefore, careful fertilizer management should be employed on flooded soils to avoid excess P loss.

  11. Nitrogen dynamics in flooded soil systems: An overview on concepts and performance of models

    NARCIS (Netherlands)

    Khairudin, Nurul; Gaydon, Donald S.; Jing, Qi; Zakaria, Mohamad P.; Struik, Paul C.; Keesman, Karel J.


    Extensive modelling studies on nitrogen (N) dynamics in flooded soil systems have been published. Consequently, many N dynamics models are available for users to select from. With the current research trend, inclined towards multi-disciplinary research, and with substantial progress in understanding

  12. Influence of urban surface properties and rainfall characteristics on surface water flood outputs - insights from a physical modelling environment (United States)

    Green, Daniel; Pattison, Ian; Yu, Dapeng


    Surface water (pluvial) flooding occurs when excess rainfall from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flood events pose a major hazard to urban regions across the world, with nearly two thirds of flood damages in the UK being caused by surface water flood events. The perceived risk of surface water flooding appears to have increased in recent years due to several factors, including (i) precipitation increases associated with climatic change and variability; (ii) population growth meaning more people are occupying flood risk areas, and; (iii) land-use changes. Because urban areas are often associated with a high proportion of impermeable land-uses (e.g. tarmacked or paved surfaces and buildings) and a reduced coverage of vegetated, permeable surfaces, urban surface water flood risk during high intensity precipitation events is often exacerbated. To investigate the influence of urbanisation and terrestrial factors on surface water flood outputs, rainfall intensity, catchment slope, permeability, building density/layout scenarios were designed within a novel, 9m2 physical modelling environment. The two-tiered physical model used consists of (i) a low-cost, nozzle-type rainfall simulator component which is able to simulate consistent, uniformly distributed rainfall events of varying duration and intensity, and; (ii) a reconfigurable, modular plot surface. All experiments within the physical modelling environment were subjected to a spatiotemporally uniform 45-minute simulated rainfall event, while terrestrial factors on the physical model plot surface were altered systematically to investigate their hydrological response on modelled outflow and depth profiles. Results from the closed, controlled physical modelling experiments suggest that meteorological factors, such as the duration and intensity of simulated rainfall, and terrestrial factors, such as model slope

  13. Assessing surface water flood risk and management strategies under future climate change: Insights from an Agent-Based Model. (United States)

    Jenkins, K; Surminski, S; Hall, J; Crick, F


    Climate change and increasing urbanization are projected to result in an increase in surface water flooding and consequential damages in the future. In this paper, we present insights from a novel Agent Based Model (ABM), applied to a London case study of surface water flood risk, designed to assess the interplay between different adaptation options; how risk reduction could be achieved by homeowners and government; and the role of flood insurance and the new flood insurance pool, Flood Re, in the context of climate change. The analysis highlights that while combined investment in property-level flood protection and sustainable urban drainage systems reduce surface water flood risk, the benefits can be outweighed by continued development in high risk areas and the effects of climate change. In our simulations, Flood Re is beneficial in its function to provide affordable insurance, even under climate change. However, the scheme does face increasing financial pressure due to rising surface water flood damages. If the intended transition to risk-based pricing is to take place then a determined and coordinated strategy will be needed to manage flood risk, which utilises insurance incentives, limits new development, and supports resilience measures. Our modelling approach and findings are highly relevant for the ongoing regulatory and political approval process for Flood Re as well as for wider discussions on the potential of insurance schemes to incentivise flood risk management and climate adaptation in the UK and internationally. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Carbon Dynamics and Export from Flooded Wetlands: A Modeling Approach (United States)

    Described in this article is development and validation of a process based model for carbon cycling in flooded wetlands, called WetQual-C. The model considers various biogeochemical interactions affecting C cycling, greenhouse gas emissions, organic carbon export and retention. ...

  15. Dynamical modeling of surface tension

    International Nuclear Information System (INIS)

    Brackbill, J.U.; Kothe, D.B.


    In a recent review it is said that free-surface flows ''represent some of the difficult remaining challenges in computational fluid dynamics''. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin. This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin are discussed

  16. Multitemporal SAR Data and 2D Hydrodynamic Model Flood Scenario Dynamics Assessment

    Directory of Open Access Journals (Sweden)

    Santina Scarpino


    Full Text Available The increasing number of floods and the severity of their consequences, which is caused by phenomena, such as climate change and uncontrolled urbanization, create a growing need to develop operational procedures and tools for accurate and timely flood mapping and management. Synthetic Aperture Radar (SAR, with its day, night, and cloud-penetrating capacity, has proven to be a very useful source of information during calibration of hydrodynamic models considered indispensable tools for near real-time flood forecasting and monitoring. The paper begins with the analysis of radar signatures of temporal series of SAR data, by exploiting the short revisit time of the images that are provided by the Cosmo-SkyMed constellation of four satellites, in combination with a Digital Elevation Model for the extraction of flood extent and spatially distributed water depth in a flat area with complex topography during a flood event. These SAR-based hazard maps were then used to perform a bi-dimensional hydraulic model calibration on the November 2010 flood event at the mouth of the Bradano River in Basilicata, Italy. Once the best fit between flood predictions of hydrodynamic models was identified and the efficacy of SAR data in correcting hydrodynamic inconsistencies with regard to reliable assessment of flood extent and water-depth maps was shown by validation with the December 2013 Bradano River event. Based on calibration and validation results, the paper aims to show how the combination of the time series of Synthetic Aperture Radar (SAR and Digital Elevation Model (DEM derived water-depth maps with the data from the hydrodynamic model can provide valuable information for flood dynamics monitoring in a flat area with complex topography. Future research should focus on the integration and implementation of the semi-automatic proposed method in an operational system for near real-time flood management.

  17. Dust Dynamics Near Planetary Surfaces (United States)

    Colwell, Joshua; Hughes, Anna; Grund, Chris

    Observations of a lunar "horizon glow" by several Surveyor spacecraft in the 1960s opened the study of the dynamics of charged dust particles near planetary surfaces. The surfaces of the Moon and other airless planetary bodies in the solar system (asteroids, and other moons) are directly exposed to the solar wind and ionizing solar ultraviolet radiation, resulting in a time-dependent electric surface potential. Because these same objects are also exposed to bombardment by micrometeoroids, the surfaces are usually characterized by a power-law size distribution of dust that extends to sub-micron-sized particles. Individual particles can acquire a charge different from their surroundings leading to electrostatic levitation. Once levitated, particles may simply return to the surface on nearly ballistic trajectories, escape entirely from the moon or asteroid if the initial velocity is large, or in some cases be stably levitated for extended periods of time. All three outcomes have observable consequences. Furthermore, the behavior of charged dust near the surface has practical implications for planned future manned and unmanned activities on the lunar surface. Charged dust particles also act as sensitive probes of the near-surface plasma environment. Recent numerical modeling of dust levitation and transport show that charged micron-sized dust is likely to accumulate in topographic lows such as craters, providing a mechanism for the creation of dust "ponds" observed on the asteroid 433 Eros. Such deposition can occur when particles are supported by the photoelectron sheath above the dayside and drift over shadowed regions of craters where the surface potential is much smaller. Earlier studies of the lunar horizon glow are consistent with those particles being on simple ballistic trajectories following electrostatic launching from the surface. Smaller particles may be accelerated from the lunar surface to high altitudes consistent with observations of high altitude

  18. Retrospective Analysis of Recent Flood Events With Persistent High Surface Runoff From Hydrological Modelling (United States)

    Joshi, S.; Hakeem, K. Abdul; Raju, P. V.; Rao, V. V.; Yadav, A.; Diwakar, P. G.; Dadhwal, V. K.


    Floods are one of the most common and widespread disasters in India, with an estimated 40Mha of land prone to this natural disaster (National Flood Commission, India). Significant loss of property, infrastructure, livestock, public utilities resulting in large economic losses due to floods are recurrent every year in many parts of India. Flood forecasting and early warning is widely recognized and adopted as non-structural measure to lower the damages caused by the flood events. Estimating the rainfall excess that results into excessive river flow is preliminary effort in riverine flood estimation. Flood forecasting models are in general, are event based and do not fully account for successive and persistent excessive surface runoff conditions. Successive high rainfall events result in saturated soil moisture conditions, favourable for high surface runoff conditions. The present study is to explore the usefulness of hydrological model derived surface runoff, running on continuous times-step, to relate to the occurrence of flood inundation due to persistent and successive high surface runoff conditions. Variable Infiltration Capacity (VIC), a macro-scale hydrological model, was used to simulate daily runoff at systematic grid level incorporating daily meteorological data and land cover data. VIC is a physically based, semi-distributed macroscale hydrological model that represents surface and subsurface hydrologic process on spatially distributed grid cell. It explicitly represents sub-grid heterogeneity in land cover classes, taking their phenological changes into account. In this study, the model was setup for entire India using geo-spatial data available from multiple sources (NRSC, NBSS&LUP, NOAA, and IMD) and was calibrated with river discharge data from CWC at selected river basins. Using the grid-wise surface runoff estimates from the model, an algorithm was developed through a set of thresholds of successive high runoff values in order to identify grids

  19. Surface Water and Flood Extent Mapping, Monitoring, and Modeling Products and Services for the SERVIR Regions (United States)

    Anderson, Eric


    SERVIR is a joint NASA - US Agency for International Development (USAID) project to improve environmental decision-making using Earth observations and geospatial technologies. A common need identified among SERVIR regions has been improved information for disaster risk reduction and in specific surface water and flood extent mapping, monitoring and forecasting. Of the 70 SERVIR products (active, complete, and in development), 4 are related to surface water and flood extent mapping, monitoring or forecasting. Visit for more product details.

  20. Map showing flood and surface water information in the Sugar House quadrangle, Salt Lake County, Utah (United States)

    Van Horn, Richard; Fields, F.K.


    In the past man has built on land that might be covered by floodwaters, with little consideration of the consequences. The result has been disastrous to those in the path of floodwaters and has cost the loss of thousands of lives and untold billions of dollars in property damage in the United States. Salt Lake County, of which the Sugar House quadrangle is a part, has had many floods in the past and can be expected to have more in the future. Construction has taken place in filled or dried-up marshes and lakes, in spring areas, and even in stream channels. Lack of prior knowledge of these and other forms of surface water (water at the surface of the ground) can increase construction and maintenance costs significantly.The map shows the area that probably will be covered by floods at least once in every 100 years on the long-term average (unit IRF, intermediate regional flood), the area that probably will be covered by floods from the worst possible combination of very wet weather and high streamflow reasonably expected of the area (unit SPF, standard project flood), the mapped extent of streamflow by channel shifting or flooding in the past 5,000 years (unit fa), and the probable maximum extent of damaging flash floods and mudflows from small valleys in the Wasatch Range. The map also shows the location of water at the surface of the ground: lakes, streams, springs, weep holes, canals, and reservoirs. Lakes and marshes that existed within the past 100 years, but now are drained, filled, or dried up, are also shown.The following examples show that the presence of water can be desirable or undesirable, depending on how the water occurs. Floods, the most spectacular form of surface water, may result in great property damage and loss of life. Lakes normally are beneficial, in that they may support plant growth and provide habitats for fish and other wildlife, provide water for livestock, and can be used for recreation. Springs may or may not be desirable: they may

  1. Land-use, climate and floods dynamics in Northeastern Italy (Veneto) (United States)

    Sofia, Giulia; Roder, Giulia; Tarolli, Paolo


    The Veneto Region in North-eastern Italy is today one of the most extensive inhabited and economically competitive urban landscapes in Europe, where infrastructure transformations have been recently accompanied by a number of serious hydraulic dysfunctions. Major concerns arise for frequent rainfall events which can couple with land-use changes with consequences on flooding (Sofia et al. 2014). The aim of this work is to propose a preliminary long-term, region-scale analysis of land-use, rainfall regime and flood dynamics in the region. To investigate the changes in floods, we considered the events registered in Veneto starting from the ~1900 to the year 2000 (Guzzetti and Tonelli, 2004). For this time frame, we analyzed trends in the number of flooded locations, flood events, as well as trends in the number of flooding days. We then investigated the accumulated percentages of flooded sites contributed by the accumulated percentage of flooding days in each year. The idea is to investigate, for the given period, the presence of drastic changes in the curve steepness (knickpoints), implying that less days of flood contribute to a notable increase in the percentage of the flooded locations. For the land-use dynamics we considered the urban area extent for three timeframes in the last century (60s, 90s, 2000s). From these, we created area cartograms in which the sizes of each drainage catchment in Veneto was deformed in proportion to the urban areas in each municipality, as well as in proportion to changes in soil sealing, and we related these maps to the number of flooded locations. For the climatic characterization, we considered a measure of the aggressivity and irregularity of the rainfall regime, to quantify the incidence of intense rainfall events on the yearly amount of precipitation. In spite of the limitations due to the different awareness of the impact of floods on the territory during the years, the floods analysis shows some recent knickpoints, indicating

  2. Nannofossil and sequence chronostratigraphy of a marine flooding surface in the Turonian of Trinidad

    Energy Technology Data Exchange (ETDEWEB)

    Huang, T.C. [Exxon Exploration Company, Houston, TX (United States)


    A multi-well regional study in the Southern basin, Trinidad, reveals a very pronounced marine flooding surface in Turonian- age sediments. This surface is correlatable with global Turonian marine transgressions and genetically ties with the best hydrocarbon source rocks known in Trinidad. The Turonian marine flooding surface yields abundant nannoplankton. Most notable is Lithastrinus moratus Stover, a short-ranging marker of the Lithastrinus evolutionary series. Two morphotypes of Lithastrinus moratus have been found. The more delicate eight-rayed form evolves from Lithastrinus floralls in early Turonian time. Based on observations in Ste. Croix-1, Rocky Palace-1, Rochard-1, Marac-1, Moniga East-15, Iguana River-1, Lizard Spring-I and Antilles Brighton-102, it occurs more frequently in the lower Turonian, but is rare in Trinidad. It has a more robust seven-rayed descendant that appears to be restricted to a narrow interval associated with peak Turonian marine transgression and usually dominates the nannofossil assemblage in the condensed section. The highest stratigraphic occurrence of this form coincides with the lowest occurrence of Marthastentes furcatus based on core sample studies. The age of the marine flooding surface is therefore well constrained to be in zone CC12 and is considered to be correlative with the 89 million year marine flooding surface. The marine flooding surface appears intercontinentally correlatable as it has also been identified in the Arcadia Shale of the Eagle Ford Group in Texas. Because of its wide areal distribution and ease of paleontological recognition, this surface is ideal for regional hydrocarbon source rock mapping, stratal correlation and structural control.

  3. Dynamic Critical Rainfall-Based Flash Flood Early Warning and Forecasting for Medium-Small Rivers (United States)

    Liu, Z.; Yang, D.; Hu, J.


    China is extremely frequent food disasters hit countries, annual flood season flash floods triggered by rainfall, mudslides, landslides have caused heavy casualties and property losses, not only serious threaten the lives of the masses, but the majority of seriously restricting the mountain hill areas of economic and social development and the people become rich, of building a moderately prosperous society goals. In the next few years, China will focus on prevention and control area in the flash flood disasters initially built "for the surveillance, communications, forecasting, early warning and other non-engineering measure based, non-engineering measures and the combinations of engineering measures," the mitigation system. The latest progresses on global torrential flood early warning and forecasting techniques are reviewed in this paper, and then an early warning and forecasting approach is proposed on the basis of a distributed hydrological model according to dynamic critical rainfall index. This approach has been applied in Suichuanjiang River basin in Jiangxi province, which is expected to provide valuable reference for building a national flash flood early warning and forecasting system as well as control of such flooding.

  4. Dynamics of water and nutrients for potted plants induced by flooded bench fertigation : experiments and simulation

    NARCIS (Netherlands)

    Otten, W.


    Dynamics of water and nutrients as affected by physical and chemical characteristics of a substrate, fertigation method and schedule, and plant uptake were studied for a flooded bench fertigation system for potted plants, through a detailed experimental study of the root environment and a

  5. Source and composition of surface water dissolved organic matter (DOM) and the effect of flood events on the organic matter cycling (United States)

    Bondar-Kunze, Elisabeth; Welti, Nina; Tritthart, Michael; Baker, Andrew; Pinay, Gilles; Hein, Thomas


    Floodplains are often simultaneously affected by land use change, river regulation and loss of hydrological dynamics which alter the surface water connectivity between floodplain and river main channel. These alterations can have significant impacts on the sources of organic matter and their degradation and thus, the carbon cycling of riverine landscapes. Although floodplains are known to be important sources of dissolved organic matter (DOM) within watersheds, reduced hydrological connectivity impair their role. The key questions of our research were to determine i) to what extent the degree of connection between the Danube River and its floodplain controlled the DOM composition with its backwater systems, and ii) what were the effects of the DOM changes on carbon cycling in floodplains during two flood events with different magnitude? In this study we report on the variations in DOM spectrophotometric properties of surface waters in different connected floodplain areas and during two flood events of different magnitude in a section of the Alluvial Zone National Park of the Danube River downstream Vienna, Austria. Two backwater floodplain systems were studied, one backwater system mostly disconnected from the fluvial dynamics except during high flood events (Lower Lobau) and the second one, recently restored and connected even during mean flow conditions (Orth). Fluorescence excitation-emission matrix (EEM) spectrophotometry and water chemical analyses were applied to investigate the DOM dynamics. In both backwater systems 15 sites were sampled monthly for two years and every second day during a flood event.

  6. Real-time dynamic control of the Three Gorges Reservoir by coupling numerical weather rainfall prediction and flood forecasting

    DEFF Research Database (Denmark)

    Wang, Y.; Chen, H.; Rosbjerg, Dan


    In reservoir operation improvement of the accuracy of forecast flood inflow and extension of forecast lead-time can effectively be achieved by using rainfall forecasts from numerical weather predictions with a hydrological catchment model. In this study, the Regional Spectrum Model (RSM), which...... is developed by the Japan Meteorological Agency, was used to forecast rainfall with 5 days lead-time in the upper region of the Three Gorges Reservoir (TGR). A conceptual hydrological model, the Xinanjiang Model, has been set up to forecast the inflow flood of TGR by the Ministry of Water Resources Information...... Center. Here, the flood forecast model coupled with the rainfall forecast from RSM has been employed to carry out real-time dynamic control of the Flood Limiting Water Level (FLWL) of TGR in order to improve the hydropower generation without increasing the flood risk. Taking the flood events of the flood...

  7. Towards a better understanding of flood generation and surface water inundation mechanisms using NASA remote sensing data products (United States)

    Lucey, J.; Reager, J. T., II; Lopez, S. R.


    Floods annually cause several weather-related fatalities and financial losses. According to NOAA and FEMA, there were 43 deaths and 18 billion dollars paid out in flood insurance policies during 2005. The goal of this work is to improve flood prediction and flood risk assessment by creating a general model of predictability of extreme runoff generation using various NASA products. Using satellite-based flood inundation observations, we can relate surface water formation processes to changes in other hydrological variables, such as precipitation, storage and soil moisture, and understand how runoff generation response to these forcings is modulated by local topography and land cover. Since it is known that a flood event would cause an abnormal increase in surface water, we examine these underlying physical relationships in comparison with the Dartmouth Flood Observatory archive of historic flood events globally. Using ground water storage observations (GRACE), precipitation (TRMM or GPCP), land use (MODIS), elevation (SRTM) and surface inundation levels (SWAMPS), an assessment of geological and climate conditions can be performed for any location around the world. This project utilizes multiple linear regression analysis evaluating the relationship between surface water inundation, total water storage anomalies and precipitation values, grouped by average slope or land use, to determine their statistical relationships and influences on inundation data. This research demonstrates the potential benefits of using global data products for early flood prediction and will improve our understanding of runoff generation processes.

  8. Surface water and groundwater water interaction model in catastrophic floods and mudslides in the beds of mountain rivers (United States)

    Tulenev, Nikita


    Catastrophic floods and mudslides / mudflows are very dangerous disaster. Water volumes appear suddenly and continuously increasing in intensity and can spread with great speed, leading to catastrophic consequences - destruction and casualties [1]. These phenomena are typically nonlinear processes occurring in an open system with spatially distributed feedback [2]. Currently, most researchers consider as causes of such powerful water flows seasonal rapid melting of glaciers and intense rain showers. However, their localization is often in line with a separate small mountain river and dynamics of development raises a number of issues, primarily in connection with the justification of the amounts of water that are distributed on the surface and demonstrate the complex hydrodynamic behavior with obvious elements of self-organization. Highlights in this project we consider the interaction of groundwater and surface water by means of the transport system 3D - cracks. In this case there are, two types of emissions to the surface of groundwater - the flash and relatively protracted continuous replenishment of surface runoff due to smooth outpouring of underground streams. We rely on the concept, in which groundwater and surface water are not isolated systems, and is closely related to each other in the territory of a single watershed in the functioning of the overall transport system - 3D-network of cracks in the rock (visible manifestation of which is on the surface and the riverbed itself [3]). Evaluative analysis of groundwater discharge into the river channel can hold a first approximation, by analogy with the artesian well, working in a mode of self-flowing. And in a similar way as it is possible to calculate the pressure at the bottom of the well based on its flow rate, we can estimate the pressure in the aquifer based on the amount obtained by mudflow or flood. In the case of a violent release according to our calculations, such pressure can reach tens of

  9. Assessing impacts of dike construction on the flood dynamics of the Mekong Delta (United States)

    Tran, Dung Duc; van Halsema, Gerardo; Hellegers, Petra J. G. J.; Phi Hoang, Long; Quang Tran, Tho; Kummu, Matti; Ludwig, Fulco


    Recent flood dynamics of the Mekong Delta have raised concerns about an increased flood risk downstream in the Vietnamese Mekong Delta. Accelerated high dike building on the floodplains of the upper delta to allow triple cropping of rice has been linked to higher river water levels in the downstream city of Can Tho. This paper assesses the hydraulic impacts of upstream dike construction on the flood hazard downstream in the Vietnamese Mekong Delta. We combined the existing one-dimensional (1-D) Mekong Delta hydrodynamic model with a quasi-two-dimensional (2-D) approach. First we calibrated and validated the model using flood data from 2011 and 2013. We then applied the model to explore the downstream water dynamics under various scenarios of high dike construction in An Giang Province and the Long Xuyen Quadrangle. Calculations of water balances allowed us to trace the propagation and distribution of flood volumes over the delta under the different scenarios. Model results indicate that extensive construction of high dikes on the upstream floodplains has had limited effect on peak river water levels downstream in Can Tho. Instead, the model shows that the impacts of dike construction, in terms of peak river water levels, are concentrated and amplified in the upstream reaches of the delta. According to our water balance analysis, river water levels in Can Tho have remained relatively stable, as greater volumes of floodwater have been diverted away from the Long Xuyen Quadrangle than the retention volume lost due to dike construction. Our findings expand on previous work on the impacts of water control infrastructure on flood risk and floodwater regimes across the delta.

  10. The interplay between human population dynamics and flooding in Bangladesh: a spatial analysis

    Directory of Open Access Journals (Sweden)

    G. di Baldassarre


    Full Text Available In Bangladesh, socio-economic and hydrological processes are both extremely dynamic and inter-related. Human population patterns are often explained as a response, or adaptation strategy, to physical events, e.g. flooding, salt-water intrusion, and erosion. Meanwhile, these physical processes are exacerbated, or mitigated, by diverse human interventions, e.g. river diversion, levees and polders. In this context, this paper describes an attempt to explore the complex interplay between floods and societies in Bangladeshi floodplains. In particular, we performed a spatially-distributed analysis of the interactions between the dynamics of human settlements and flood inundation patterns. To this end, we used flooding simulation results from inundation modelling, LISFLOOD-FP, as well as global datasets of population distribution data, such as the Gridded Population of the World (20 years, from 1990 to 2010 and HYDE datasets (310 years, from 1700 to 2010. The outcomes of this work highlight the behaviour of Bangladeshi floodplains as complex human–water systems and indicate the need to go beyond the traditional narratives based on one-way cause–effects, e.g. climate change leading to migrations.

  11. Remote sensing of vegetation dynamics in response to flooding and fire in the Okavango Delta, Botswana (United States)

    Neuenschwander, Amy Lynn


    The Okavango Delta, an internationally recognized wetland, is undergoing natural and anthropogenic change at a variety of spatio-temporal scales. The objective of this research was to utilize remotely sensed imagery to assess the spatio-temporal distribution of flooding and fire and their subsequent influences on vegetation as represented by vegetation index trajectories in the Okavango Delta. The characterization of the spatio-temporal dynamics of vegetation spectral response via a time-series of remotely sensed data not only informs ecosystem and disturbance theory but also presents new methodological applications for multi-temporal change analysis. Disentangling these components from a signal is critical for better assessing the interrelationships among climatic oscillations, disturbance regimes, and human management on ecosystem response. This research tested six hypotheses regarding flooding and fire, and found that the largest number of fires occurred either within 5 km of the border to the Wildlife Management Areas or within the active (flooded a minimum of every two years) floodplains. These hypotheses indicate that burning is highest where people have access into the management areas and where the natural resources are plentiful. Periodicities from vegetation signal time-series did not confirm published climate-driven periodicities of 3, 8, and 18-years but did reveal seasonal (6 month) and quasi-decadal periodicities. Vegetation trajectories were more predictable with increasing flood frequency and duration, but were less predictable with increased fire frequency. The fact that increased burning resulted in less predictable behavior indicates the potential of quantifying the anthropogenic influence on the landscape using remotely sensed imagery. Flooding and fire were not statistically correlated to the residual dynamics, refuting the conceptualization of flooding and fire as disturbance and supporting the interpretation of flooding and fire as

  12. Dynamic modeling of surfactant flooding in low permeable argillaceous reservoirs (United States)

    Kuznetsova, A. N.; Gunkin, A. S.; Rogachev, M. К


    This article reveals the current state and problems of the Russian oil production sector. Physicochemical enhanced oil recovery methods are proposed as a solution. The investigation of surfactant treatment efficiency and their integrated effect on oil and reservoir rock is conducted as well as its applicability analysis for low permeable poly-mineral reservoir. The results of dynamic modeling of oil displacement by the developed surfactant composition in a low permeable reservoir are presented.

  13. Flood-pulse and riverscape dynamics in a braided glacial river. (United States)

    Malard, Florian; Uehlinger, Urs; Zah, Rainer; Tockner, Klement


    River ecosystems are increasingly viewed as dynamic riverscapes; their extent, composition, and configuration vary in response to the pulsing of discharge. Although compositional and configurational shifts in riverscapes are thought to control ecosystem processes and biodiversity, attempts to quantify riverscape dynamics of braided rivers are scarce. We measured monthly changes in the length, spatial arrangement, and age distribution of clear (groundwater-fed) and turbid-water (glacial-fed) channels during two annual cycles in a braided glacial river. Biological data from concurrent studies were used to assess the effects of seasonal changes in the size and pattern of the riverscape on local zoobenthic density, standing crop of epilithic algae, and spatiotemporal distribution of the hyporheos. The hydrological processes involved in the expansion-contraction cycle of the riverscape resulted in a complex, albeit predictable, pattern of change in the proportion and spatial arrangement of clear and turbid channels. On average, 30% of the riverscape was renewed at monthly intervals. Surface hydrological connectivity and the length of turbid channels increased logarithmically with increasing discharge. The length of clear channels increased up to a threshold discharge of 1.5 m3/s, above which surface flooding resulted in the contraction and fragmentation of clear water bodies. Turbid channels exhibited a unimodal age distribution, whereas clear channels had two cohorts that appeared during the expansion and contraction phases. The renewal pattern and configuration of the riverscape changed little between years despite differences in discharge and the occurrence of several rainfall-induced spates. The density of benthic invertebrate communities in the main channel decreased with increasing size of aquatic habitats indicating that local zoobenthic density was affected by dilution-concentration effects. The disproportionate increase in the proportion of glacial-fed habitats

  14. Trace Element and Pesticide Dynamics During a Flood Event in the Save Agricultural Watershed: Soil-River Transfer Pathways and Controlling Factors


    El Azzi, Désirée; Probst, Jean-Luc; Teisserenc, Roman; Merlina, Georges; Baqué, David; Julien, Frédéric; Payre-Suc, Virginie; Guiresse, Agnès Maritchù


    Agricultural practices are the main source of water contamination in rural areas. Rainfall events, and subsequently, soil leaching and storm runoff are mainly controlling the transfer of pollutants from diffuse sources in watersheds during floods. These periods are also very important to better understand their dynamics, particularly their different soil-river transfer pathways (surface runoff SR, subsurface runoff SSR, and groundwater flow GF). This study focuses on riverin...

  15. Condensation and Wetting Dynamics on Micro/Nano-Structured Surfaces (United States)

    Olceroglu, Emre

    -condensable gases (NCGs), a novel characterization technique has been developed based on image tracking of droplet growth rates. The full-field dynamic characterization of superhydrophobic surfaces during condensation has been achieved using high-speed microscopy coupled with image-processing algorithms. This method is able to resolve heat fluxes as low as 20 W/m 2 and heat transfer coefficients of up to 1000 kW/m2, across an array of 1000's of microscale droplets simultaneously. Nanostructured surfaces with mixed wettability have been used to demonstrate delayed flooding during superhydrophobic condensation. These surfaces have been optimized and characterized using optical and electron microscopy, leading to the observation of self-organizing microscale droplets. The self-organization of small droplets effectively delays the onset of surface flooding, allowing the superhydrophobic surfaces to operate at higher supersaturations. Additionally, hierarchical surfaces have been fabricated and characterized showing enhanced droplet growth rates as compared to existing models. This enhancement has been shown to be derived from the presence of small feeder droplets nucleating within the microscale unit cells of the hierarchical surfaces. Based on the experimental observations, a mechanistic model for growth rates has been developed for superhydrophobic hierarchical surfaces. While superhydrophobic surfaces exhibit high heat transfer rates they are inherently unstable due to the necessity to maintain a non-wetted state in a condensing environment. As an alternative condensation surface, a novel design is introduced here using ambiphilic structures to promote the formation of a thin continuous liquid film across the surface which can still provide the benefits of superhydrophobic condensation. Preliminary results show that the ambiphilic structures restrain the film thickness, thus maintaining a low thermal resistance while simultaneously maximizing the liquid-vapor interface available for

  16. Dynamics of Wetting of Ultra Hydrophobic Surfaces (United States)

    Mohammad Karim, Alireza; Kim, Jeong-Hyun; Rothstein, Jonathan; Kavehpour, Pirouz; Mechanical and Industrial Engineering, University of Massachusetts, Amherst Collaboration


    Controlling the surface wettability of hydrophobic and super hydrophobic surfaces has extensive industrial applications ranging from coating, painting and printing technology and waterproof clothing to efficiency increase in power and water plants. This requires enhancing the knowledge about the dynamics of wetting on these hydrophobic surfaces. We have done experimental investigation on the dynamics of wetting on hydrophobic surfaces by looking deeply in to the dependency of the dynamic contact angles both advancing and receding on the velocity of the three-phase boundary (Solid/Liquid/Gas interface) using the Wilhelmy plate method with different ultra-hydrophobic surfaces. Several fluids with different surface tension and viscosity are used to study the effect of physical properties of liquids on the governing laws.

  17. Dynamic flood webmapping: an operational and cost-limited tool to optimize crisis management

    Directory of Open Access Journals (Sweden)

    Strappazzon Quentin


    Full Text Available Due to strong climate variations and the multiplication of flood events, protection based strategies are no longer sufficient to handle a watershed scale crisis. Monitoring, prediction and alert procedures are required to ensure effective crisis and post-crisis management which explains the recent interest for real time predictions systems. Nevertheless, this kind of system, when fully implemented with in-situ monitoring network, meteorological forecast inputs, hydrological and hydraulic modelling and flood mapping, are often postponed or cancelled because of both their cost and time scale. That is why Prolog Ingénierie and the SyAGE have developed, as an economical and technical sustainable alternative, a tool providing shared access to a real time mapping of current and predicted flooded areas along with a dynamic listing of exposed stakes (such as public buildings, sensible infrastructures, environmental buildings, roads. The update of these maps is performed from the combination of predicted water levels in the river and a flood envelop library (based on 1D/2D hydraulic model results for a wide panel of discharges and hydraulic structures states conditions. This tool has already been implemented on the downstream part of the Yerres River, a tributary of the Seine River in France.

  18. Causal Dynamics of Discrete Surfaces

    Directory of Open Access Journals (Sweden)

    Pablo Arrighi


    Full Text Available We formalize the intuitive idea of a labelled discrete surface which evolves in time, subject to two natural constraints: the evolution does not propagate information too fast; and it acts everywhere the same.

  19. Influence of snow depth and surface flooding on light transmission through Antarctic pack ice (United States)

    Arndt, Stefanie; Meiners, Klaus M.; Ricker, Robert; Krumpen, Thomas; Katlein, Christian; Nicolaus, Marcel


    Snow on sea ice alters the properties of the underlying ice cover as well as associated physical and biological processes at the interfaces between atmosphere, sea ice, and ocean. The Antarctic snow cover persists during most of the year and contributes significantly to the sea-ice mass due to the widespread surface flooding and related snow-ice formation. Snow also enhances the sea-ice surface reflectivity of incoming shortwave radiation and determines therefore the amount of light being reflected, absorbed, and transmitted to the upper ocean. Here, we present results of a case study of spectral solar radiation measurements under Antarctic pack ice with an instrumented Remotely Operated Vehicle in the Weddell Sea in 2013. In order to identify the key variables controlling the spatial distribution of the under-ice light regime, we exploit under-ice optical measurements in combination with simultaneous characterization of surface properties, such as sea-ice thickness and snow depth. Our results reveal that the distribution of flooded and nonflooded sea-ice areas dominates the spatial scales of under-ice light variability for areas smaller than 100 m-by-100 m. However, the heterogeneous and highly metamorphous snow on Antarctic pack ice obscures a direct correlation between the under-ice light field and snow depth. Compared to the Arctic, light levels under Antarctic pack ice are extremely low during spring (<0.1%). This is mostly a result of the distinctly different dominant sea ice and snow properties with seasonal snow cover (including strong surface melt and summer melt ponds) in the Arctic and a year-round snow cover and widespread surface flooding in the Southern Ocean.

  20. Dynamic Factor Models for the Volatility Surface

    DEFF Research Database (Denmark)

    van der Wel, Michel; Ozturk, Sait R.; Dijk, Dick van

    The implied volatility surface is the collection of volatilities implied by option contracts for different strike prices and time-to-maturity. We study factor models to capture the dynamics of this three-dimensional implied volatility surface. Three model types are considered to examine desirable...

  1. Simulation of Gas-Surface Dynamical Interactions (United States)


    surface. The substrate with lattice constant a is represented in a simple ball and spring picture. on the particular problem. Time-independent...παvwell , (26) Simulation of Gas-Surface Dynamical Interactions 4 - 10 RTO-EN-AVT-142 g E ad v mvc ∆ v’well vc cM Figure 4

  2. Dynamics of pollutant indicators during flood events in a small river under strong anthropogenic pressures (United States)

    Brion, Natacha; Carbonnel, Vincent; Elskens, Marc; Claeys, Philippe; Verbanck, Michel A.


    In densely populated regions, human activities profoundly modify natural water circulation as well as water quality, with increased hydrological risks (floods, droughts,…) and chemical hazards (untreated sewage releases, industrial pollution,…) as consequence. In order to assess water and pollutants dynamics and their mass-balance in strongly modified river system, it is important to take into account high flow events as a significant fraction of water and pollutants loads may occur during these short events which are generally underrepresented in classical mass balance studies. A good example of strongly modified river systems is the Zenne river in and around the city of Brussels (Belgium).The Zenne River (Belgium) is a rather small but dynamic rain fed river (about 10 m3/s in average) that is under the influence of strong contrasting anthropogenic pressures along its stretch. While the upstream part of its basin is rather characterized by agricultural land-use, urban and industrial areas dominate the downstream part. In particular, the city of Brussels (1.1M inhabitants) discharges in the Zenne River amounts of wastewater that are large compared to the natural riverine flow. In order to assess water and pollutants dynamics and their mass-balance in the Zenne hydrographic network, we followed water flows and concentrations of several water quality tracers during several flood episodes with an hourly frequency and at different locations along the stretch of the River. These parameters were chosen as indicators of a whole range of pollutions and anthropogenic activities. Knowledge of the high-frequency pollutants dynamics during floods is required for establishing accurate mass-balances of these elements. We thus report here the dynamics of selected parameters during entire flood events, from the baseline to the decreasing phase and at hourly frequency. Dynamics at contrasting locations, in agricultural or urban environments are compared. In particular, the

  3. Droplet impact dynamics on flexible superhydrophobic surfaces (United States)

    Kim, Jeong-Hyun; Gorman, William; Shang, Jessica


    In this talk, we will present a series of droplet impact experiments performed on elastic superhydrophobic surfaces. A commercial superhydrophobic paint, WX2100, was sprayed on smooth PDMS surfaces that were prepared by a standard soft lithography technique. The droplet spreading and retraction dynamics, trajectory, and substrate response will be presented for different surface lengths and Weber numbers. The elasticity of the superhydrophobic surfaces was found to affect dynamics of the droplets and the substrate. The contact time of the droplet on an elastic superhydrophobic surface was reduced by as much as 22% compared to the rigid superhydrophobic surface. The reduction in the contact time was even observed at low Weber number, We 20, which was much lower than the critical Weber number reported in literature. A variety of surface deflection behavior was observed after the second impact of the rebounding droplet. When the droplet motion was in phase with the surface motion, the deflection of the surface was found to deviate and increase from the original decay of the surface deflection. However, when the droplet motion was out of phase with the surface, the displacement of the surface was reduced and dampened quickly by the droplet body force.

  4. Piloting a real-time surface water flood nowcasting system for enhancing operational resilience of emergency responders (United States)

    Yu, Dapeng; Guan, Mingfu; Wilby, Robert; Bruce, Wright; Szegner, Mark


    Emergency services (such as Fire & Rescue, and Ambulance) can face the challenging tasks of having to respond to or operate under extreme and fast changing weather conditions, including surface water flooding. UK-wide, return period based surface water flood risk mapping undertaken by the Environment Agency provides useful information about areas at risks. Although these maps are useful for planning purposes for emergency responders, their utility to operational response during flood emergencies can be limited. A street-level, high resolution, real-time, surface water flood nowcasting system, has been piloted in the City of Leicester, UK to assess emergency response resilience to surface water flooding. Precipitation nowcasting over 7- and 48-hour horizons are obtained from the UK Met Office and used as inputs to the system. A hydro-inundation model is used to simulate urban surface water flood depths/areas at both the city and basin scale, with a 20 m and 3 m spatial resolution respectively, and a 15-minute temporal resolution, 7-hour and 48-hour in advance. Based on this, we evaluate both the direct and indirect impacts of potential surface water flood events on emergency responses, including: (i) identifying vulnerable populations (e.g. care homes and schools) at risk; and (ii) generating novel metrics of accessibility (e.g. travel time from service stations to vulnerable sites; spatial coverage with certain legislative timeframes) in real-time. In doing so, real-time information on potential risks and impacts of emerging flood incidents arising from intense rainfall can be communicated via a dedicated web-based platform to emergency responders thereby improving response times and operational resilience.

  5. Exploiting diverse crowd-sourced data as part of a mixed-methods approach to validating modelled flood extents and dynamics (United States)

    Rollason, Edward; Bracken, Louise; Hardy, Richard; Large, Andy


    The use of flood models for evaluating flood risk from rivers and the sea is now a standard practice across Europe since the introduction of the 2007 EU Floods Directive requiring the assessment and mapping of flood risk from all major rivers and the sea. The availability of high quality topographic data from LiDAR and other remotely sensed sources has led to the increasing adoption of 2 dimensional models for simulating the dynamics of flooding on the floodplain. However, the ability to effectively validate dynamic floodplain inundation has not kept pace with the increasing complexity and spatial resolution of flood models. Validation remains dependent upon in-channel validation using flood level gauges or post-event data collection of wrack-marks, sometimes supplemented by community-derived anecdotal data. This poster presents the findings of a 'mixed-methods approach' to flood model validation using the winter 2016 floods on the River Tyne, UK. Using flood inundation results from a simple LISFLOOD-FP model of the River Tyne at Corbridge, the research develops a novel mixed-methods approach to validating both the maximum flood depths and extents, and the dynamics of the flood through the event. A crowd-sourced dataset of anecdotal information on flood dynamics, supported by photographic and video evidence, as well as community-derived, high definition UAV footage captured 24 and 48 hours after the peak of the event, allows for the comprehensive reconstruction of the flood dynamics and a more complete validation of the effectiveness of the model in reconstructing not just the maximum flood extent but also the dynamics of the rising and falling stages of an event. The findings of the research indicate the potential for making use of a much greater variety of locally-sourced data, particularly exploiting new technologies which offer opportunities for the collection of high quality data in the immediate aftermath of flooding events when traditional agencies may still

  6. Assessment of the Influence of the Hydrological Regime of the Volga River on the Dynamics of Flooding on Sarpinsky Island

    Directory of Open Access Journals (Sweden)

    A.S. Rulev


    Full Text Available The seasonal dynamics of flooding on Sarpinsky Island, which is included in the city of Volgograd, following the damming by the Volga HPP has been considered. The following research problems have been set: firstly, to establish seasonal patterns of flooding in the island territory; secondly, to find out if there is a flooding threat to social infrastructure facilities. The flooded area of the island has been assessed by Landsat multispectral images with a spatial resolution of 30 m. Only images with the survey date corresponding to the peak of high waters (with the difference of not more than 7–10 days have been analyzed. The flooding areas of the island have been calculated for the date when flooding peaked (April–May during the period from 1985 to 2016. The phases of spring flooding determined by the island landscape and the water discharge from the Volga HPP have been revealed. The curve of the area of flooding reaches maximum values after the water discharge is up to 11–12 km3, which depends on the initial filling of floodplain reservoirs (landscape depressions in depth without any increase in the area of flooding. The average shift between the peaks of water discharge and the area of flooding is 10–15 days and reflects gradual filling of floodplain reservoirs on Sarpinsky Island after the beginning of water discharge from the Volga HPP. It has been found that there is no threat to infrastructure facilities on Sarpinsky Island under the current volumes of water discharge during the flooding period. The obtained results are important for urban planning on the island, as well as for management of the regimes of water passage through the dam of the Volga HPP.

  7. Surface Mining and Reclamation Effects on Flood Response of Watersheds in the Central Appalachian Plateau Region (United States)

    Ferrari, J. R.; Lookingbill, T. R.; McCormick, B.; Townsend, P. A.; Eshleman, K. N.


    Surface mining of coal and subsequent reclamation represent the dominant land use change in the central Appalachian Plateau (CAP) region of the United States. Hydrologic impacts of surface mining have been studied at the plot scale, but effects at broader scales have not been explored adequately. Broad-scale classification of reclaimed sites is difficult because standing vegetation makes them nearly indistinguishable from alternate land uses. We used a land cover data set that accurately maps surface mines for a 187-km2 watershed within the CAP. These land cover data, as well as plot-level data from within the watershed, are used with HSPF (Hydrologic Simulation Program-Fortran) to estimate changes in flood response as a function of increased mining. Results show that the rate at which flood magnitude increases due to increased mining is linear, with greater rates observed for less frequent return intervals. These findings indicate that mine reclamation leaves the landscape in a condition more similar to urban areas rather than does simple deforestation, and call into question the effectiveness of reclamation in terms of returning mined areas to the hydrological state that existed before mining.

  8. Atomic probes of surface structure and dynamics

    International Nuclear Information System (INIS)

    Heller, E.J.; Jonsson, H.


    Progress for the period Sept. 15, 1992 to Sept. 14, 1993 is discussed. Semiclassical methods that will allow much faster and more accurate three-dimensional atom--surface scattering calculations, both elastic and inelastic, are being developed. The scattering of He atoms from buckyballs is being investigated as a test problem. Somewhat more detail is given on studies of He atom scattering from defective Pt surfaces. Molecular dynamics simulations of He + and Ar + ion sputtering of Pt surfaces are also being done. He atom scattering from Xe overlayers on metal surfaces and the thermalized dissociation of H 2 on Cu(110) are being studied. (R.W.R.) 64 refs

  9. Computational fluid dynamics simulations of the Late Pleistocene Lake Bonneville flood (United States)

    Abril-Hernández, José M.; Periáñez, Raúl; O'Connor, Jim E.; Garcia-Castellanos, Daniel


    At approximately 18.0 ka, pluvial Lake Bonneville reached its maximum level. At its northeastern extent it was impounded by alluvium of the Marsh Creek Fan, which breached at some point north of Red Rock Pass (Idaho), leading to one of the largest floods on Earth. About 5320 km3 of water was discharged into the Snake River drainage and ultimately into the Columbia River. We use a 0D model and a 2D non-linear depth-averaged hydrodynamic model to aid understanding of outflow dynamics, specifically evaluating controls on the amount of water exiting the Lake Bonneville basin exerted by the Red Rock Pass outlet lithology and geometry as well as those imposed by the internal lake geometry of the Bonneville basin. These models are based on field evidence of prominent lake levels, hypsometry and terrain elevations corrected for post-flood isostatic deformation of the lake basin, as well as reconstructions of the topography at the outlet for both the initial and final stages of the flood. Internal flow dynamics in the northern Lake Bonneville basin during the flood were affected by the narrow passages separating the Cache Valley from the main body of Lake Bonneville. This constriction imposed a water-level drop of up to 2.7 m at the time of peak-flow conditions and likely reduced the peak discharge at the lake outlet by about 6%. The modeled peak outlet flow is 0.85·106 m3 s−1. Energy balance calculations give an estimate for the erodibility coefficient for the alluvial Marsh Creek divide of ∼0.005 m y−1 Pa−1.5, at least two orders of magnitude greater than for the underlying bedrock at the outlet. Computing quasi steady-state water flows, water elevations, water currents and shear stresses as a function of the water-level drop in the lake and for the sequential stages of erosion in the outlet gives estimates of the incision rates and an estimate of the outflow hydrograph during the Bonneville Flood: About 18 days would have been required for the

  10. Surfaces and polymers: The dynamics of intimacy (United States)

    Kumar, Subhalakshmi; Yu, Changqian; Wong, Janet; Hong, Liang; Bae, Sung Chul; Granick, Steve


    The dynamics of a hydrophobic polymer melt, well above its glass transition, is probed when it is confined to thicknesses of a few nanometers. The ability of the surface forces apparatus to produce controlled thin films is coupled with measurements using fluorescence recovery after photobleaching technique. Insight into the effects of degree of confinement on diffusion of the polymer molecules and heterogeneity in their dynamic behavior is sought.

  11. Surface-Assisted Dynamic Search Processes. (United States)

    Shin, Jaeoh; Kolomeisky, Anatoly B


    Many chemical and biological systems exhibit intermittent search phenomena when participating particles alternate between dynamic regimes with different dimensionalities. Here we investigate theoretically a dynamic search process of finding a small target on a two-dimensional surface starting from a bulk solution, which is an example of such an intermittent search process. Both continuum and discrete-state stochastic descriptions are developed. It is found that depending on the scanning length λ, which describes the area visited by the reacting molecule during one search cycle, the system can exhibit three different search regimes: (i) For small λ values, the reactant finds the target mostly via three-dimensional bulk diffusion; (ii) for large λ values, the reactant molecule associates to the target mostly via surface diffusion; and (iii) for intermediate λ values, the reactant reaches the target via a combination of three-dimensional and two-dimensional search cycles. Our analysis also shows that the mean search times have different scalings as a function of the size of the surface segment depending on the nature of the dynamic search regime. Search dynamics are also sensitive to the position of the target for large scanning lengths. In addition, it is argued that the continuum description underestimates mean search times and does not always correctly describe the most optimal conditions for the surface-assisted dynamic processes. The importance of our findings for real natural systems is discussed.

  12. Chemical Dynamics at Surfaces of Metal Nanomaterials (United States)


    method to determine 3D molecular structures One of the major problems in experimentally studying heterogeneous catalysis is the lack of tools...the determinations of molecular structures and dynamics on the surfaces of metal nanomaterials – the critical component of heterogeneous catalysts...for the determinations of molecular structures on the surfaces of metal nanomaterials. Practical catalysts, e.g. oxide-supported metal clusters, are

  13. Urban Surface Water Quality, Flood Water Quality and Human Health Impacts in Chinese Cities. What Do We Know?

    Directory of Open Access Journals (Sweden)

    Yuhan Rui


    Full Text Available Climate change and urbanization have led to an increase in the frequency of extreme water related events such as flooding, which has negative impacts on the environment, economy and human health. With respect to the latter, our understanding of the interrelationship between flooding, urban surface water and human health is still very limited. More in-depth research in this area is needed to further strengthen the process of planning and implementation of responses to mitigate the negative health impacts of flooding in urban areas. The objective of this paper is to assess the state of the research on the interrelationship between surface water quality, flood water quality and human health in urban areas based on the published literature. These insights will be instrumental in identifying and prioritizing future research needs in this area. In this study, research publications in the domain of urban flooding, surface water quality and human health were collated using keyword searches. A detailed assessment of these publications substantiated the limited number of publications focusing on the link between flooding and human health. There was also an uneven geographical distribution of the study areas, as most of the studies focused on developed countries. A few studies have focused on developing countries, although the severity of water quality issues is higher in these countries. The study also revealed a disparity of research in this field across regions in China as most of the studies focused on the populous south-eastern region of China. The lack of studies in some regions has been attributed to the absence of flood water quality monitoring systems which allow the collection of real-time water quality monitoring data during flooding in urban areas. The widespread implementation of cost effective real-time water quality monitoring systems which are based on the latest remote or mobile phone based data acquisition techniques is recommended

  14. Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona (United States)

    Wright, Scott A.; Kaplinski, Matt


    In canyon rivers, debris fan constrictions create rapids and downstream pools characterized by secondary flow structures that are closely linked to channel morphology. In this paper we describe detailed measurements of the three-dimensional flow structure and sandbar dynamics of two pools along the Colorado River in the Grand Canyon during a controlled flood release from Glen Canyon Dam. Results indicate that the pools are characterized by large lateral recirculation zones (eddies) resulting from flow separation downstream from the channel constrictions, as well as helical flow structures in the main channel and eddy. The lateral recirculation zones are low-velocity areas conducive to fine sediment deposition, particularly in the vicinity of the separation and reattachment points and are thus the dominant flow structures controlling sandbar dynamics. The helical flow structures also affect morphology but appear secondary in importance to the lateral eddies. During the controlled flood, sandbars in the separation and reattachment zones at both sites tended to build gradually during the rising limb and peak flow. Deposition in shallow water on the sandbars was accompanied by erosion in deeper water along the sandbar slope at the interface with the main channel. Erosion occurred via rapid mass failures as well as by gradual boundary shear stress driven processes. The flow structures and morphologic links at our study sites are similar to those identified in other river environments, in particular sharply curved meanders and channel confluences where the coexistence of lateral recirculation and helical flows has been documented.

  15. A geo-environmental assessment of flood dynamics in lower ajoy ...

    African Journals Online (AJOL)

    Flood as a widespread destructive natural disaster is recurring in the river basins of Eastern India. Though large number of flood controlling measures have been taken in the river valleys from the early ages but it is to be noted that spatial dimension of the flood affected area and the magnitude of flood are being increased ...

  16. Dynamic air layer on textured superhydrophobic surfaces

    KAUST Repository

    Vakarelski, Ivan Uriev


    We provide an experimental demonstration that a novel macroscopic, dynamic continuous air layer or plastron can be sustained indefinitely on textured superhydrophobic surfaces in air-supersaturated water by a natural gas influx mechanism. This type of plastron is an intermediate state between Leidenfrost vapor layers on superheated surfaces and the equilibrium Cassie-Baxter wetting state on textured superhydrophobic surfaces. We show that such a plastron can be sustained on the surface of a centimeter-sized superhydrophobic sphere immersed in heated water and variations of its dynamic behavior with air saturation of the water can be regulated by rapid changes of the water temperature. The simple experimental setup allows for quantification of the air flux into the plastron and identification of the air transport model of the plastron growth. Both the observed growth dynamics of such plastrons and millimeter-sized air bubbles seeded on the hydrophilic surface under identical air-supersaturated solution conditions are consistent with the predictions of a well-mixed gas transport model. © 2013 American Chemical Society.

  17. Kettle holes formed by glacial outburst floods: identification when their surface expression has been removed? (United States)

    Marren, Philip; Fay, Helen; Duller, Robert


    Kettle holes and obstacle marks formed by the transport, deposition and burial of ice-blocks during glacial outburst floods (jökulhlaups) are a common geomorphological feature on proglacial outwash plains. Indeed, they represent one of the few features which can unequivocally identify glacially-sourced flood deposits in the geomorphological and sedimentary record. Despite an abundance of work on the surface expression of jökulhlaup-generated ice-block structures, descriptions of the subsurface expression of these features in the sedimentary record are limited. There is currently no comprehensive model of the sedimentary characteristics of these features. This is a major gap in our knowledge, as the positive identification of ice-block features constitutes an unambiguous criterion for the identification of former jökulhlaup deposits in the Quaternary sedimentary record. We address this by describing several examples of ice-block impact in the sedimentary record from southern Iceland. Our work recognizes key criteria for the identification of ice-block impact in the sedimentary record, enabling them to be identified in sedimentary sections where their geomorphological expression has since been removed or buried. These key criterion combine: (1) structures formed by the interaction of water flow with the ice-block body during transportation and immobilization; (2) distinctive sedimentological features of surrounding deposits; and, (3) the post-burial mechanical disruption on the deposits. Formulating a suite of key criteria with which to positively identify the sedimentary impact of ice-blocks limits the possibility of misidentification in the sedimentary record, and provides a means of identifying previously unrecognized Quaternary catastrophic glacial floods.

  18. Flood Damage Analysis: First Floor Elevation Uncertainty Resulting from LiDAR-Derived Digital Surface Models

    Directory of Open Access Journals (Sweden)

    José María Bodoque


    Full Text Available The use of high resolution ground-based light detection and ranging (LiDAR datasets provides spatial density and vertical precision for obtaining highly accurate Digital Surface Models (DSMs. As a result, the reliability of flood damage analysis has improved significantly, owing to the increased accuracy of hydrodynamic models. In addition, considerable error reduction has been achieved in the estimation of first floor elevation, which is a critical parameter for determining structural and content damages in buildings. However, as with any discrete measurement technique, LiDAR data contain object space ambiguities, especially in urban areas where the presence of buildings and the floodplain gives rise to a highly complex landscape that is largely corrected by using ancillary information based on the addition of breaklines to a triangulated irregular network (TIN. The present study provides a methodological approach for assessing uncertainty regarding first floor elevation. This is based on: (i generation an urban TIN from LiDAR data with a density of 0.5 points·m−2, complemented with the river bathymetry obtained from a field survey with a density of 0.3 points·m−2. The TIN was subsequently improved by adding breaklines and was finally transformed to a raster with a spatial resolution of 2 m; (ii implementation of a two-dimensional (2D hydrodynamic model based on the 500-year flood return period. The high resolution DSM obtained in the previous step, facilitated addressing the modelling, since it represented suitable urban features influencing hydraulics (e.g., streets and buildings; and (iii determination of first floor elevation uncertainty within the 500-year flood zone by performing Monte Carlo simulations based on geostatistics and 1997 control elevation points in order to assess error. Deviations in first floor elevation (average: 0.56 m and standard deviation: 0.33 m show that this parameter has to be neatly characterized in order

  19. Floods and Flash Flooding (United States)

    Floods and flash flooding Now is the time to determine your area’s flood risk. If you are not sure whether you ... If you are in a floodplain, consider buying flood insurance. Do not drive around barricades. If your ...

  20. Flood regime and leaf fall determine soil inorganic nitrogen dynamics in semiarid riparian forests. (United States)

    Shah, J J Follstad; Dahm, C N


    Flow regulation has reduced the exchange of water, energy, and materials between rivers and floodplains, caused declines in native plant populations, and advanced the spread of nonnative plants. Naturalized flow regimes are regarded as a means to restore degraded riparian areas. We examined the effects of flood regime (short [SIFI] vs. long [LIFI] inter-flood interval) on plant community and soil inorganic nitrogen (N) dynamics in riparian forests dominated by native Populus deltoides var. wislizenii Eckenwalder (Rio Grande cottonwood) and nonnative Tamarix chinensis Lour. (salt cedar) along the regulated middle Rio Grande of New Mexico. The frequency of inundation (every 2-3 years) at SIFI sites better reflected inundation patterns prior to the closure of an upstream dam relative to the frequency of inundation at LIFI sites (> or =10 years). Riparian inundation at SIFI sites varied from 7 to 45 days during the study period (April 2001-July 2004). SIFI vs. LIFI sites had higher soil moisture but greater groundwater table elevation fluctuation in response to flooding and drought. Rates of net N mineralization were consistently higher at LIFI vs. SIFI sites, and soil inorganic N concentrations were greatest at sites with elevated leaf-litter production. Sites with stable depth to ground water (approximately 1.5 m) supported the greatest leaf-litter production. Reduced leaf production at P. deltoides SIFI sites was attributed to drought-induced recession of ground water and prolonged inundation. We recommend that natural resource managers and restoration practitioners (1) utilize naturalized flows that help maintain riparian groundwater elevations between 1 and 3 m in reaches with mature P. deltoides or where P. deltoides revegetation is desired, (2) identify areas that naturally undergo long periods of inundation and consider restoring these areas to seasonal wetlands, and (3) use native xeric-adapted riparian plants to revegetate LIFI and SIFI sites where

  1. Detection of mixing dynamics during pumping of a flooded coal mine. (United States)

    Elliot, Trevor; Younger, Paul L


    In complex hydrogeological environments the effective management of groundwater quality problems by pump-and-treat operations can be most confidently achieved if the mixing dynamics induced within the aquifer by pumping are well understood. The utility of isotopic environmental tracers (C-, H-, O-, S-stable isotopic analyses and age indicators-(14) C, (3) H) for this purpose is illustrated by the analysis of a pumping test in an abstraction borehole drilled into flooded, abandoned coal mineworkings at Deerplay (Lancashire, UK). Interpretation of the isotope data was undertaken conjunctively with that of major ion hydrochemistry, and interpreted in the context of the particular hydraulic setting of flooded mineworkings to identify the sources and mixing of water qualities in the groundwater system. Initial pumping showed breakdown of initial water quality stratification in the borehole, and gave evidence for distinctive isotopic signatures (δ(34) S(SO4) ≅ -1.6‰, δ(18) O(SO4 ) ≅ +15‰) associated with primary oxidation of pyrite in the zone of water table fluctuation-the first time this phenomenon has been successfully characterized by these isotopes in a flooded mine system. The overall aim of the test pumping-to replace an uncontrolled outflow from a mine entrance in an inconvenient location with a pumped discharge on a site where treatment could be provided-was swiftly achieved. Environmental tracing data illustrated the benefits of pumping as little as possible to attain this aim, as higher rates of pumping induced in-mixing of poorer quality waters from more distant old workings, and/or renewed pyrite oxidation in the shallow subsurface. © 2013, National Ground Water Association.

  2. Spatial and temporal dynamic of surface water and vegetation dynamic using remotely sensed data in the Murray -Darling Basin, Australia (United States)

    Tulbure, M. G.; Kingsford, R.; Broich, M.


    Australia is the driest inhabited continent and river systems have highly variable flows in space and time. The Murray-Darling Basin (MDB), a catchment covering 14% of the continent contains the nation's largest rivers and important groundwater systems. The basin has highly variable rainfall patterns in space and time and the vast majority of rainfall is lost to evapotranspiration with only 4% becoming runoff. The basin is home to several wetlands of high hydrological and ecological value with a number of them being recognised as wetlands of international importance. The basin produces more than a third of Australia's food supply, making it the most important agricultural area in the country. However, variation in surface and ground water availability exacerbated by a long period of drought, combined with high water demands for irrigation and in several major cities, and the need for water to maintain ecosystem health in the floodplains have led to the need of managing water resources in an integrated fashion. Several dams have been constructed in the basin, which store water during wet periods which is released during dry periods as environmental flows. Assessment of water resources and understanding of the effectiveness of environmental flows requires knowledge of 1) long term trends in occurrence and extent of surface water, 2) what is the vegetation response to flooding and 3) whether water reached target vegetation communities. However, such information does not exist at the basin level. Satellite remote sensing is the only viable way for synoptically mapping and monitoring the extent and dynamic of flooding and vegetation response to flooding. Moreover, recent La Nina -induced, extreme flooding broke a decade long of drought and made 2010 the wettest calendar year on record in the MDB and across vast areas of Australia. This represents a unique opportunity to develop predictive models relating flow regime to vegetation response and identify trends over long

  3. Field Observation on Seed Arrival into Surface Layers of Sand Bars after Several Floods in Kinugawa River (United States)

    Miyamoto, Hitoshi; Oishi, Tetsuya; Ohtsuki, Kazuaki; Ohmura, Sohei; Iimura, Hayata


    This presentation gives the results of field observation on seed arrival into surface layers of sand bars after several floods during 2016 in Kinugawa River, Japan. The seed arrival could be an onset of secondary succession on sand bars, leading to their well-vegetated states after several decades that cause river management issues both on flood disaster prevention and riverine ecosystem alteration. Kinugawa River had the largest record flood in September 9-10, 2015. It resulted in the levee failure and the corresponding flood disaster in Joso City located in the downstream part of Kinugawa River. It also had the large impact on the riverine vegetation environment, resulting in making many sand bars and gravel beds be bare surface states. In order to investigate the very initial state of the seed arrival into the created bare surfaces by small to medium flood events, 3 channel sections with 6 observation points in total were chosen and observed during the rainy season in 2016. A steel ling with a pile was used for measuring the depth of active surface layers on the sand bars during the flood events. The sediments in the active surface layers were sampled for making the grain size accumulation curve as well as for counting the number of seeds within the sample sediments. The results showed that the sample sediments with the smaller mean diameters, ranging around 0.1 - 6.4 mm, kept much more seeds than those with the larger mean diameters over 12 mm. The number of seeds decreases with the small percentile (around 10-20th) in particle diameter rather than the mean diameter. Furthermore, relationships were discussed in detail between the number of seeds, the depth of the active layers, and bed shear stresses calculated by a numerical simulation model.

  4. Molecular Dynamics Simulations for Predicting Surface Wetting

    Directory of Open Access Journals (Sweden)

    Jing Chen


    Full Text Available The investigation of wetting of a solid surface by a liquid provides important insights; the contact angle of a liquid droplet on a surface provides a quantitative measurement of this interaction and the degree of attraction or repulsion of that liquid type by the solid surface. Molecular dynamics (MD simulations are a useful way to examine the behavior of liquids on solid surfaces on a nanometer scale. Thus, we surveyed the state of this field, beginning with the fundamentals of wetting calculations to an examination of the different MD methodologies used. We highlighted some of the advantages and disadvantages of the simulations, and look to the future of computer modeling to understand wetting and other liquid-solid interaction phenomena.

  5. Surface-water dynamics and land use influence landscape connectivity across a major dryland region. (United States)

    Bishop-Taylor, Robbi; Tulbure, Mirela G; Broich, Mark


    Landscape connectivity is important for the long-term persistence of species inhabiting dryland freshwater ecosystems, with spatiotemporal surface-water dynamics (e.g., flooding) maintaining connectivity by both creating temporary habitats and providing transient opportunities for dispersal. Improving our understanding of how landscape connectivity varies with respect to surface-water dynamics and land use is an important step to maintaining biodiversity in dynamic dryland environments. Using a newly available validated Landsat TM and ETM+ surface-water time series, we modelled landscape connectivity between dynamic surface-water habitats within Australia's 1 million km 2 semiarid Murray Darling Basin across a 25-yr period (1987-2011). We identified key habitats that serve as well-connected "hubs," or "stepping-stones" that allow long-distance movements through surface-water habitat networks. We compared distributions of these habitats for short- and long-distance dispersal species during dry, average, and wet seasons, and across land-use types. The distribution of stepping-stones and hubs varied both spatially and temporally, with temporal changes driven by drought and flooding dynamics. Conservation areas and natural environments contained higher than expected proportions of both stepping-stones and hubs throughout the time series; however, highly modified agricultural landscapes increased in importance during wet seasons. Irrigated landscapes contained particularly high proportions of well-connected hubs for long-distance dispersers, but remained relatively disconnected for less vagile organisms. The habitats identified by our study may serve as ideal high-priority targets for land-use specific management aimed at maintaining or improving dispersal between surface-water habitats, potentially providing benefits to biodiversity beyond the immediate site scale. Our results also highlight the importance of accounting for the influence of spatial and temporal

  6. The impact of extreme flooding events and anthropogenic stressors on the macrobenthic communities’ dynamics (United States)

    Cardoso, P. G.; Raffaelli, D.; Lillebø, A. I.; Verdelhos, T.; Pardal, M. A.


    Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Over period 1980-2000, the environment of the Mondego estuary, Portugal, has deteriorated through eutrophication, manifested in the replacement of seagrasses by opportunistic macroalgae, degradation of water quality and increased turbidity, and the system has also experienced extreme flood events. A restoration plan was implemented in 1998 which aimed to reverse the eutrophication effects, especially to restore the original natural seagrass ( Zostera noltii) community. This paper explores the interactions between extreme weather events (e.g. intense floods) and anthropogenic stressors (e.g. eutrophication) on the dynamics of the macrobenthic assemblages and the socio-economic implications that follow. We found that during the previous decade, the intensification of extreme flooding events had significant effects on the structure and functioning of macrobenthic communities, specifically a decline in total biomass, a decline in species richness and a decline in suspension feeders. However, the earlier eutrophication process also strongly modified the macrobenthic community, seen as a decline in species richness, increase in detritivores and a decline in herbivores together with a significant increase in small deposit-feeding polychaetes. After the implementation of the management plan, macrobenthic assemblages seemed to be recovering from eutrophication, but it is argued here that those earlier impacts reduced system stability and the resilience of the macrobenthic assemblages, so that its ability to cope with other stressors was compromised. Thus

  7. Bioinspired, dynamic, structured surfaces for biofilm prevention (United States)

    Epstein, Alexander K.

    Bacteria primarily exist in robust, surface-associated communities known as biofilms, ubiquitous in both natural and anthropogenic environments. Mature biofilms resist a wide range of biocidal treatments and pose persistent pathogenic threats. Treatment of adherent biofilm is difficult, costly, and, in medical systems such as catheters, frequently impossible. Adding to the challenge, we have discovered that biofilm can be both impenetrable to vapors and extremely nonwetting, repelling even low surface tension commercial antimicrobials. Our study shows multiple contributing factors, including biochemical components and multiscale reentrant topography. Reliant on surface chemistry, conventional strategies for preventing biofilm only transiently affect attachment and/or are environmentally toxic. In this work, we look to Nature's antifouling solutions, such as the dynamic spiny skin of the echinoderm, and we develop a versatile surface nanofabrication platform. Our benchtop approach unites soft lithography, electrodeposition, mold deformation, and material selection to enable many degrees of freedom—material, geometric, mechanical, dynamic—that can be programmed starting from a single master structure. The mechanical properties of the bio-inspired nanostructures, verified by AFM, are precisely and rationally tunable. We examine how synthetic dynamic nanostructured surfaces control the attachment of pathogenic biofilms. The parameters governing long-range patterning of bacteria on high-aspect-ratio (HAR) nanoarrays are combinatorially elucidated, and we discover that sufficiently low effective stiffness of these HAR arrays mechanoselectively inhibits ˜40% of Pseudomonas aeruginosa biofilm attachment. Inspired by the active echinoderm skin, we design and fabricate externally actuated dynamic elastomer surfaces with active surface microtopography. We extract from a large parameter space the critical topographic length scales and actuation time scales for achieving

  8. Lacustrine records of Holocene flood pulse dynamics in the Upper Paraguay River watershed (Pantanal wetlands, Brazil) (United States)

    McGlue, Michael M.; Silva, Aquinaldo; Zani, Hiran; Corradini, Fabricio A.; Parolin, Mauro; Abel, Erin J.; Cohen, Andrew S.; Assine, Mario L.; Ellis, Geoffrey S.; Trees, Mark A.; Kuerten, Sidney; Gradella, Frederico dos Santos; Rasbold, Giliane Gessica


    The Pantanal is the world's largest tropical wetland and a biodiversity hotspot, yet its response to Quaternary environmental change is unclear. To address this problem, sediment cores from shallow lakes connected to the UpperParaguayRiver (PR) were analyzed and radiocarbon dated to track changes in sedimentary environments. Stratal relations, detrital particle size, multiple biogeochemical indicators, and sponge spicules suggest fluctuating lake-level lowstand conditions between ~ 11,000 and 5300 cal yr BP, punctuated by sporadic and in some cases erosive flood flows. A hiatus has been recorded from ~ 5300 to 2600 cal yr BP, spurred by confinement of the PR within its channel during an episode of profound regional drought. Sustained PR flooding caused a transgression after ~ 2600 cal yr BP, with lake-level highstand conditions appearing during the Little Ice Age. Holocene PR floodpulsedynamics are best explained by variability in effective precipitation, likely driven by insolation and tropical sea-surface temperature gradients. Our results provide novel support for hypotheses on: (1) stratigraphic discontinuity of floodplain sedimentary archives; (2) late Holocene methane flux from Southern Hemisphere wetlands; and (3) pre-colonial indigenous ceramics traditions in western Brazil.

  9. Framework for Dynamic Modelling of Urban Floods at Different Topographical Resolutions

    NARCIS (Netherlands)

    Seyoum, S.D.


    Floods are among the most frequent and costly natural disasters in terms of human hardship and economic loss. The impacts of flooding are especially devastating in urban areas as these areas are densely populated and contain vital infrastructures. Urban flood risks and their impacts are expected to

  10. Surface water flooding, groundwater contamination, and enteric disease in developed countries: A scoping review of connections and consequences. (United States)

    Andrade, L; O'Dwyer, J; O'Neill, E; Hynds, P


    Significant volumes of research over the past four decades has sought to elucidate the social, infrastructural, economic, and human health effects of climate change induced surface flooding. To date, epidemiological and public health studies of flooding events have focused on mental health effects, vector-borne diseases, and infectious enteric disease due to floodwater contact (i.e. typically low consumption rates). The inherent nature of groundwater (i.e. out of sight, out of mind) and the widely held belief that aquifers represent a pristine source of drinking water due to natural attenuation may represent the "perfect storm" causing direct consumption of relatively large volumes of surface flood-contaminated groundwater. Accordingly, the current study sought to systematically identify and synthesize all available peer-reviewed literature pertaining to the nexus between surface flooding, groundwater contamination and human gastroenteric outcomes. Just 14 relevant studies were found to have been published during the period 1980-2017, thus highlighting the fact that this potentially significant source of climate-related exposure to environmental infection has remained understudied to date. Studies differed significantly in terms of type and data reporting procedures, making it difficult to discern clear trends and patterns. Approximately 945 confirmed cases of flood-related enteric disease were examined across studies; these concurred with almost 10,000 suspected cases, equating to approximately 20 suspected cases per confirmed case. As such, no regional, national or global estimates are available for the human gastrointestinal health burden of flood-related groundwater contamination. In light of the demonstrable public health significance of the concurrent impacts of groundwater susceptibility and climate change exacerbation, strategies to increase awareness about potential sources of contamination and motivate precautionary behaviour (e.g. drinking water testing

  11. Elemental characteristics of surface suspended particulates off the Changjiang estuary during the 1998 flood (United States)

    Hsu, Shih-Chieh; Lin, Fei-Jan


    Surface suspended particulate matter (SPM) samples were collected on two latitudinal transects over the Changjiang estuary, covering a wide salinity regime from 8 to 30‰, instantaneously after the largest Changjiang flood peak in August 1998 that caused severe disaster in China. They have been analyzed for 20 major and trace elements and 7 rare earth elements (REEs) using ICP-MS. The SPM concentrations varied a very wide range of up to two orders of magnitude, sharply decreasing southward from 18 mg/l in the Changjiang river mouth to less than 1 mg/l at around 28°N, which may be representative of a background in the East China Sea (ECS) shelf. All selected particulate elements exhibit large variability in space. SPM collected around the Changjiang river mouth was dominated by the lithogenic components approximately accounting for 80% or more of the bulk, and when going south the proportions decreased to less than half of the total. Based on the results of enrichment factor (EF) calculation, elements Fe, Ti, Mn, Ba, Sr, Co, Be, Tl, Nb, V, Ni, and Mo with mean EF values of less than 3 were categorized into the unpolluted group, and elements Zn, Cu, Pb, As, Ag, and Sb with EF values of higher than 5 into the polluted group. This investigation demonstrated that anthropogenic metals could be dispersed over a large extent along the Chinese coast and on the ECS shelf although a majority of terrigenous sediments would be deposited within the Changjiang estuary. Additionally, our study reveals that the Qiantangjiang might contribute non-negligible pollutants to Hangzhou Bay. We therefore argue that the study area has been in moderate pollution, different from most of previous suggestions. Overall, most samples have similar chondrite- and especially UCC-normalized distribution patterns (UCC: upper continental crust); the sample/UCC ratios of REEs generally vary within a factor of 3 and display a flat (or slightly convex) pattern, essentially revealing little fractionation

  12. Flooding and Flood Management (United States)

    Brooks, K.N.; Fallon, J.D.; Lorenz, D.L.; Stark, J.R.; Menard, Jason; Easter, K.W.; Perry, Jim


    Floods result in great human disasters globally and nationally, causing an average of $4 billion of damages each year in the United States. Minnesota has its share of floods and flood damages, and the state has awarded nearly $278 million to local units of government for flood mitigation projects through its Flood Hazard Mitigation Grant Program. Since 1995, flood mitigation in the Red River Valley has exceeded $146 million. Considerable local and state funding has been provided to manage and mitigate problems of excess stormwater in urban areas, flooding of farmlands, and flood damages at road crossings. The cumulative costs involved with floods and flood mitigation in Minnesota are not known precisely, but it is safe to conclude that flood mitigation is a costly business. This chapter begins with a description of floods in Minneosta to provide examples and contrasts across the state. Background material is presented to provide a basic understanding of floods and flood processes, predication, and management and mitigation. Methods of analyzing and characterizing floods are presented because they affect how we respond to flooding and can influence relevant practices. The understanding and perceptions of floods and flooding commonly differ among those who work in flood forecasting, flood protection, or water resource mamnagement and citizens and businesses affected by floods. These differences can become magnified following a major flood, pointing to the need for better understanding of flooding as well as common language to describe flood risks and the uncertainty associated with determining such risks. Expectations of accurate and timely flood forecasts and our ability to control floods do not always match reality. Striving for clarity is important in formulating policies that can help avoid recurring flood damages and costs.

  13. Surface water floods in Switzerland: what insurance claim records tell us about the damage in space and time (United States)

    Bernet, Daniel B.; Prasuhn, Volker; Weingartner, Rolf


    Surface water floods (SWFs) have received increasing attention in the recent years. Nevertheless, we still know relatively little about where, when and why such floods occur and cause damage, largely due to a lack of data but to some degree also because of terminological ambiguities. Therefore, in a preparatory step, we summarize related terms and identify the need for unequivocal terminology across disciplines and international boundaries in order to bring the science together. Thereafter, we introduce a large (n = 63 117), long (10-33 years) and representative (48 % of all Swiss buildings covered) data set of spatially explicit Swiss insurance flood claims. Based on registered flood damage to buildings, the main aims of this study are twofold: First, we introduce a method to differentiate damage caused by SWFs and fluvial floods based on the geographical location of each damaged object in relation to flood hazard maps and the hydrological network. Second, we analyze the data with respect to their spatial and temporal distributions aimed at quantitatively answering the fundamental questions of how relevant SWF damage really is, as well as where and when it occurs in space and time. This study reveals that SWFs are responsible for at least 45 % of the flood damage to buildings and 23 % of the associated direct tangible losses, whereas lower losses per claim are responsible for the lower loss share. The Swiss lowlands are affected more heavily by SWFs than the alpine regions. At the same time, the results show that the damage claims and associated losses are not evenly distributed within each region either. Damage caused by SWFs occurs by far most frequently in summer in almost all regions. The normalized SWF damage of all regions shows no significant upward trend between 1993 and 2013. We conclude that SWFs are in fact a highly relevant process in Switzerland that should receive similar attention like fluvial flood hazards. Moreover, as SWF damage almost always

  14. Assimilation of GRACE Terrestrial Water Storage Observations into a Land Surface Model for the Assessment of Regional Flood Potential (United States)

    Reager, John T.; Thomas, Alys C.; Sproles, Eric A.; Rodell, Matthew; Beaudoing, Hiroko K.; Li, Bailing; Famiglietti, James S.


    We evaluate performance of the Catchment Land Surface Model (CLSM) under flood conditions after the assimilation of observations of the terrestrial water storage anomaly (TWSA) from NASA's Gravity Recovery and Climate Experiment (GRACE). Assimilation offers three key benefits for the viability of GRACE observations to operational applications: (1) near-real time analysis; (2) a downscaling of GRACE's coarse spatial resolution; and (3) state disaggregation of the vertically-integrated TWSA. We select the 2011 flood event in the Missouri river basin as a case study, and find that assimilation generally made the model wetter in the months preceding flood. We compare model outputs with observations from 14 USGS groundwater wells to assess improvements after assimilation. Finally, we examine disaggregated water storage information to improve the mechanistic understanding of event generation. Validation establishes that assimilation improved the model skill substantially, increasing regional groundwater anomaly correlation from 0.58 to 0.86. For the 2011 flood event in the Missouri river basin, results show that groundwater and snow water equivalent were contributors to pre-event flood potential, providing spatially-distributed early warning information.

  15. Pulsed laser stereophotography of plasmas and dynamically moving surfaces

    International Nuclear Information System (INIS)

    Paisley, D.L.


    A pulsed laser is used as a light source for illuminating the surface of a dynamic event of 3 mm//μs. At a predetermined time during the dynamic action, a stereo camera is used to record a pair of images of the dynamically moving surface. The stereoimage pair can be quantified for surface contour

  16. Redox-controlled release dynamics of thallium in periodically flooded arable soil. (United States)

    Antić-Mladenović, Svetlana; Frohne, Tina; Kresović, Mirjana; Stärk, Hans-Joachim; Savić, Dubravka; Ličina, Vlado; Rinklebe, Jörg


    To our knowledge, this is the first work to mechanistically study the impact of the redox potential (E H ) and principal factors, such as pH, iron (Fe), manganese (Mn), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), chlorides (Cl - ) and sulfates (SO 4 2- ), on the release dynamics of thallium (Tl) in periodically flooded soil. We simulated flooding using an automated biogeochemical microcosm system that allows for systematical control of pre-defined redox windows. The E H value was increased mechanistically at intervals of approximately 100 mV from reducing (-211 mV) to oxidizing (475 mV) conditions. Soluble Tl levels (0.02-0.28 μg L -1 ) increased significantly with increases in E H (r = 0.80, p Thallium mobilization was found to be related to several simultaneous processes involving the gradual oxidation of Tl-bearing sulfides, reductive dissolution of Fe-Mn oxides and desorption from mineral sorbents. Manganese oxides did not appear to have a considerable effect on Tl retention under oxidizing conditions. Before conducting the microcosm experiment, Tl geochemical fractionation was assessed using the modified BCR sequential extraction procedure. The BCR revealed a majority of Tl in the residual fraction (77.7%), followed by reducible (13.3%) and oxidizable fractions (5.9%). By generating high levels of Tl toxicity at low doses, Tl released under oxidizing conditions may pose an environmental threat. In the future, similar studies should be conducted on various soils along with a determination of the Tl species and monitoring of the Tl content in plants to achieve more detailed insight into soluble Tl behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Performance Evaluation with Different Mobility Models for Dynamic Probabilistic Flooding in MANETs

    Directory of Open Access Journals (Sweden)

    Abdalla M. Hanashi


    Full Text Available Broadcasting is an essential and effective data propagation mechanism, with several of important applications such as route discovery, address resolution, as well as many other network services. As data broadcasting has many advantages, also causing a lot of contention, collision, and congestion, which induces what is known as "broadcast storm problems". Broadcasting has traditionally been based on the flooding protocol, which simply overflows the network with high number of rebroadcast messages until the messages reach to all network nodes. A good probabilistic broadcasting protocol can achieve higher saved rebroadcast, low collisions and less number of relays. In this paper, we propose a dynamic probabilistic approach that dynamically fine-tunes the rebroadcasting probability according to the number of neighbour's nodes distributed in the ad hoc network for routing request packets (RREQs. The performance of the proposed approach is investigated and compared with the simple AODVand fixed probabilistic schemes using the GloMoSim network simulator under different mobility models. The performance results reveal that the improved approach is able to achieve higher saved rebroadcast and low collision as well as low number of relays than the fixed probabilistic scheme and simple AODV.

  18. International approaches to the hydraulic control of surface water runoff in mitigating flood and environmental risks

    Directory of Open Access Journals (Sweden)

    Ballard Bridget Woods


    Full Text Available This paper compares and contrasts a number of international approaches to the hydraulic control of surface water runoff from new development and redevelopment, known as sustainable drainage systems (SuDS or low impact development (LID. The paper provides a commentary on the progress and current status of national standards for SuDS in the UK to control the frequency, flow rate and volume of runoff from both frequent and extreme rainfall events, and the best practice design criteria presented in the revised UK CIRIA SuDS Manual, published in November 2015. The paper then compares these design criteria and standards with those developed and applied in China, USA, France and Germany and also looks at the drivers behind their development. The benefits of these different approaches are assessed in the context of flood risk mitigation, climate resilience and wider environmental protection objectives, including water quality, morphology and ecology. The paper also reviews the design approaches promoted by the new SuDS Manual and internationally for delivering additional benefits for urban spaces (such as recreation, visual character, education and economic growth through multi-functional urban design.

  19. Flood-Induced Surface Blooms Alter Deep Chlorophyll Maxima Community Structure in Lake Michigan. (United States)

    Aguilar, C.; Cuhel, R. L.; Seline, L.


    Watershed-wide floods can bring increased nutrients and phytoplankton to receiving waters. This input can alter physical, chemical and phytoplankton community structure in a major way. Phytoplankton species composition and size distribution are key factors in their use as ecological indicators. Since 2003, phytoplankton communities in Lake Michigan have shifted from diatom and big cell (>10μm)- dominated to small cell picocyanobacteria-dominated phytoplankton (Quagga Mussels, dampened seasonal cycling of silicate indicated a basin-wide reduction of diatom production, and unicellular Cyanobacteria became dominant in deep chlorophyll maximum (DCM) zones. In the DCM, Synechococcus-like cells reached populations of at least 210,000 cells/ml. DCM chlorophyll (chl) remained similar (3-4μg/l) but late summer species composition changed dramatically to mostly 10μm fraction increased from previous years, and over 75% of the particulate Si was also in this size fraction. Because of the rapid sinking of diatoms during calm weather of late June-early July of 2008, particulate Si did not reach high values in surfaces waters (ca. 1.5μM) but remained at a consistently higher level than in 2007. Sinking of diatoms from the surface depleted chl in a progression from inshore to offshore during July 2008. In July surface chl was higher 40-70 km offshore than in the coastal zone. Surface phytoplankton waxed and waned in population density as if a wave or lens moved continuously further offshore, with sinking cells depleting the surface algae following behind the crest. In the wake, strong DCM populations with higher chl and particulate Si accumulated in the 30-45m zone at the bottom of the thermocline. However, in 2008 DCM zones, picocyanobacteria attained only 70,000 cells/mL, one-third of the same dates in 2007. The ratio of chlorophyll per Synechococcus cell in 2008 was about 5-fold higher than in 2007, corroborating microscopic observations of lowered picoplanktonic abundance

  20. Multi-source data fusion and modeling to assess and communicate complex flood dynamics to support decision-making for downstream areas of dams: The 2011 hurricane irene and schoharie creek floods, NY (United States)

    Renschler, Chris S.; Wang, Zhihao


    In light of climate and land use change, stakeholders around the world are interested in assessing historic and likely future flood dynamics and flood extents for decision-making in watersheds with dams as well as limited availability of stream gages and costly technical resources. This research evaluates an assessment and communication approach of combining GIS, hydraulic modeling based on latest remote sensing and topographic imagery by comparing the results to an actual flood event and available stream gages. On August 28th 2011, floods caused by Hurricane Irene swept through a large rural area in New York State, leaving thousands of people homeless, devastating towns and cities. Damage was widespread though the estimated and actual floods inundation and associated return period were still unclear since the flooding was artificially increased by flood water release due to fear of a dam break. This research uses the stream section right below the dam between two stream gages North Blenheim and Breakabeen along Schoharie Creek as a case study site to validate the approach. The data fusion approach uses a GIS, commonly available data sources, the hydraulic model HEC-RAS as well as airborne LiDAR data that were collected two days after the flood event (Aug 30, 2011). The aerial imagery of the airborne survey depicts a low flow event as well as the evidence of the record flood such as debris and other signs of damage to validate the hydrologic simulation results with the available stream gauges. Model results were also compared to the official Federal Emergency Management Agency (FEMA) flood scenarios to determine the actual flood return period of the event. The dynamic of the flood levels was then used to visualize the flood and the actual loss of the Old Blenheim Bridge using Google Sketchup. Integration of multi-source data, cross-validation and visualization provides new ways to utilize pre- and post-event remote sensing imagery and hydrologic models to better

  1. Chemical Flooding in Heavy-Oil Reservoirs: From Technical Investigation to Optimization Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Si Le Van


    rather than using a water slug in between. The results of the pre-evaluation show that two sequences of the ASP group have the highest NPV corresponding to the dissimilar applied oil prices. In the post-evaluation, the successful use of response surface methodology (RSM in the estimation and optimization procedures with coefficients of determination R2 greater than 0.97 shows that the project can possibly gain 4.47 $MM at a mean oil price of 46.5 $/bbl with the field scale of a quarter five-spot pattern. Further, with the novel assumption of normal distribution for the oil price variation, the chemical flooding sequence of concurrent alkali-surfactant-polymer injection with a buffering polymer solution is evaluated as the most feasible scheme owing to the achievement of the highest NPV at the highly possible oil price of 40–55 $/bbl compared to the other scheme.

  2. Using seismic arrays to quantify the physics of a glacial outburst flood and its legacy on upland river dynamics (United States)

    Gimbert, Florent; Cook, Kristen; Andermann, Christoff; Hovius, Niels; Turowski, Jens


    In the Himalayas fluvial erosion is thought to be controlled by the intense annual Indian Summer Monsoon precipitation. However, this region is also exposed to catastrophic floods generated by the sudden failure of landslides or moraine dams. These floods are rare and particularly devastating. Thus they have a strong impact on rivers and adjacent hillslopes, and they represent a hazard for local populations. Due to the difficulties to observe these floods and quantify their physics using traditional methods, their importance for the long-term evolution of Himalayan Rivers remains largely unknown, and no consistent early warning system exists to anticipate these events, especially in trans-boundary regions. Here we show that seismic arrays can be used to (i) reliably anticipate outburst floods and to (ii) quantify multiple and key fluvial processes associated with their propagation and their lasting impacts on upland river dynamics. We report unique seismic observations of a glacial lake outburst flood event that occurred the 5th of July 2016 in the Bhote Koshi River (Central Nepal). Precursory seismic signals are identified from the onset of the lake drainage event such that an early warning alarm may be turned on about an hour before the outburst flood wave reaches areas with an exposed population. Using our network of stations we observe for the first time that the outburst flood wave is in fact made of two distinct waves, namely a water flow wave and a bedload sediment wave. As expected these two waves travel at different speeds. We find that the ratio between the two wave speeds matches with that previously found at much smaller scales in flume laboratory experiments. Based on the physical modelling of both water-flow- and bedload- induced seismic noise we provide estimates of flow depth and bedload transport characteristics (flux, moving grains sizes) prior, during and after the flood. In particular we show that bedload sediment flux is enhanced by up to a

  3. Dynamics of subcritical CO/sub 2//brine floods for heavy oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, G.; Faroug, S.M.


    Immiscible carbon dioxide flooding is an important, field-proven heavy oil recovery method, particularly suited for thin, marginal, or otherwise poor heavy oil reservoirs, where thermal recovery processes are likely to be uneconomical. This paper describes dynamics of this recovery technique, based upon experiments conducted in a scaled model. The experiments represent a medium heavy oil (1032 mPa.s at 23/sup 0/ C) occurring in a shallow, thin sand. Carbon dioxide was injected at subcritical conditions (5.5 MPa, 21-23/sup 0/ C), together with brine. The scaled experiment results showed that oil recoveries at CO/sub 2/ and brine breakthroughs were ratedependent. While recovery at CO/sub 2/ breakthrough decreased with increasing rate, recovery at brine breakthrough increased. Reduction of interfacial tension between brine and oil, leading to the formation of brine-in-oil emulsions, was found to be an additional effective mechanism of heavy oil recovery by CO/sub 2//brine injection.

  4. Surface dynamics using pulsed electron beams (United States)

    Chan, Ally S. Y.; Jones, Robert G.


    Line of sight time of flight has been used to measure the translational energy of ethene formed by dissociative electron attachment of adsorbed dihalocarbons (XCH 2CH 2Y) on Cu(111) at 100 K. A pulsed electron beam was used to generate low energy secondary electrons at the surface, which were the active agents in initiating the decomposition, XCH 2CH 2Y(ads)+e -→XCH 2CH 2rad (ads)+Y(chem)+e -, XCH 2CH 2rad (ads)→C 2H 4(g)+X(chem). For 1,2-dichloroethane (DCE) adsorbed with a spacer layer of chemisorbed chlorine between it and the Cu(111)surface, the TOF data could be fitted using three Maxwell distributions with fast (960 K), slow (180 K) and diffusion ('20 K') components. For a single monolayer of DCE adsorbed directly on the clean Cu(111) surface the fast (1230 K) and slow (225 K) components increased in temperature, indicating that the copper surface was affecting the reaction. For 1-bromo-2-chloroethane the results were the same, consistent with both molecules dissociating via a common intermediate, ClC 2H 4rad (ads). For 1,2-dibromoethane the intermediate is different, BrC 2H 4rad , and decomposition of a monolayer of this molecule on clean Cu(111) exhibited fast (1850 K) and slow (270 K) components, both higher than the corresponding temperatures for DCE. The dynamics of these reactions and the origin of the two Maxwell distributions are discussed in terms of the energy available within the radical, and from the formation of the chemisorbed halogen when the radical dissociates.

  5. Flood dynamics and fish recruitment in a large-scale temperate floodplain

    NARCIS (Netherlands)

    Górski, K.; Nagelkerke, L.A.J.; Winter, H.V.; Leeuw, J.J. de; Middelkoop, H.; Buijse, A.D.


    Natural river floodplains provide key habitats for spawning and as a nursery for many riverine fish species. Periodic flooding plays a principal role in the ecological processes in floodplain systems resulting in high productivity and diversity, as formulated in the Flood Pulse concept (FPC).

  6. Static and dynamic friction of hierarchical surfaces. (United States)

    Costagliola, Gianluca; Bosia, Federico; Pugno, Nicola M


    Hierarchical structures are very common in nature, but only recently have they been systematically studied in materials science, in order to understand the specific effects they can have on the mechanical properties of various systems. Structural hierarchy provides a way to tune and optimize macroscopic mechanical properties starting from simple base constituents and new materials are nowadays designed exploiting this possibility. This can be true also in the field of tribology. In this paper we study the effect of hierarchical patterned surfaces on the static and dynamic friction coefficients of an elastic material. Our results are obtained by means of numerical simulations using a one-dimensional spring-block model, which has previously been used to investigate various aspects of friction. Despite the simplicity of the model, we highlight some possible mechanisms that explain how hierarchical structures can significantly modify the friction coefficients of a material, providing a means to achieve tunability.

  7. Effects of ecological flooding on the temporal and spatial dynamics of carabid beetles (Coleoptera, Carabidae and springtails (Collembola in a polder habitat

    Directory of Open Access Journals (Sweden)

    Tanja Lessel


    Full Text Available Within the scope of the Integrated Rhine Program an ecological flood gate and channel was inserted into the polder “Ingelheim” to enhance animal and plant diversity. In 2008, carabid beetles and springtails were collected, using pitfall traps, to measure the effects of ecological flooding and a strong precipitation event at a flood-disturbed and a dry location in this area. At both localities, xerophilic and mesophilic carabid beetle species were dominant throughout the study period. The total number of individuals of hygrophilic species was comparatively constant, while species number increased, partly due to the changed moisture conditions caused by ecological flooding and strong precipitation. Carabid beetle diversity and evenness decreased marginally when ecological flooding was absent. Springtails represent a less mobile arthropod order, and as such the impact of ecological flooding was stronger. An increase in both numbers of species and individuals of hygrophilic and hygrotolerant species occurred in the flood-disturbed location after ecological flooding. After the sites at both locations had dried, the number of individuals belonging to these species declined rapidly. In contrast to carabid species, the strong precipitation event showed no influence on hygrophilic springtail species. Thus, collembolan diversity and evenness decreased markedly in the absence of flooding. We showed that ecological flooding has an influence on the spatial and temporal dynamics of different arthropod groups that inhabit the polder “Ingelheim”. These findings demonstrate the importance of using different arthropod groups as bioindicators in determining the ecological value of a particular polder design.

  8. Soil N, P, and C dynamics of upland and seasonally flooded forests of the Brazilian Pantanal

    Directory of Open Access Journals (Sweden)

    George L. Vourlitis


    Full Text Available Seasonal variations in cerrado nutrient availability and mineralization are poorly understood, especially for “hyperseasonal” cerrado, which experiences both flooding and drought over an annual cycle. Here we quantified seasonal variations in soil ammonium (NH4+, phosphorus (P, and organic C (SOC concentration and net mineralization in upland and seasonally flooded cerrado forests of the Brazilian Pantanal, and hypothesized that NH4+, P, and SOC concentrations and net mineralization would decline under flooding and increase during the dry season as soil becomes unsaturated. We found that C and nutrient concentrations and mineralization were significantly affected by seasonal variations in hydrology; however, differences between flooded and upland forests varied over time and were not always related to flooding. Soil extractable P, but not net mineralization, was approximately 10-times higher in the upland forest, while the flooded forest had higher extractable NH4+ concentration than the upland forest under both flooded and drained conditions. Soil C concentration was significantly higher in the upland forest even though C mineralization was similar for both forests. Thus, despite the large seasonal and spatial variations in hydrology, the effects of flooding depended on the particular response variable studied and the season. While a limited survey of the literature indicates that forests exposed to intermittent flooding had on average higher concentrations of extractable NH4+ and P, the upland and hyperseasonal forests studied here were richer in extractable NH4+ (upland and flooded and P (upland compared to other upland and hyperseasonal forests and woodlands. Given that the forests studied here shared nearly a third of the total tree species and had similar physiognomy, these results suggest that nutrient controls on cerrado structural diversity may be similar in upland and hyperseasonal cerrado.

  9. Tree Population Dynamics on a Floodplain: A Tradeoff between Tree Mortality and Seedling Recruitment Induced by Stochastic Floods (United States)

    Miyamoto, H.; Kimura, R.


    This presentation proposes a stochastic evaluation method for examining tree population states in a river cross section using an integrated model with Monte Carlo simulation. The integrated model consists of four processes as sub-models, i.e., tree population dynamics, flow discharge stochasticity, stream hydraulics, and channel geomorphology. A floodplain of the Kako River in Japan was examined as a test site, which is currently well vegetated and features many willows that have been growing in both individual size and overall population over the last several decades. The model was used to stochastically evaluate the effects of hydrologic and geomorphologic changes on tree population dynamics through the Monte Carlo simulation. The effects including the magnitude of flood impacts and the relative change in the floodplain level are examined using very simple scenarios for flow regulation, climate change, and channel form changes. The stochastic evaluation method revealed a tradeoff point in floodplain levels, at which the tendency of a fully vegetated state switches to that of a bare floodplain under small impacts of flood. It is concluded from these results that the states of tree population in a floodplain can be determined by the mutual interactions among flood impacts, seedling recruitment, tree growth, and channel geomorphology. These interactions make it difficult to obtain a basic understanding of tree population dynamics from a field study of a specific floodplain. The stochastic approach used in this presentation could constitute an effective method for evaluating fundamental channel characteristics for a vegetated floodplain.

  10. Sensitivity Analysis of the Surface Runoff Coefficient of HiPIMS in Simulating Flood Processes in a Large Basin

    Directory of Open Access Journals (Sweden)

    Yueling Wang


    Full Text Available To simulate flood processes at the basin level, the GPU-based High-Performance Integrated Hydrodynamic Modelling System (HiPIMS is gaining interest as computational capability increases. However, the difficulty of coping with rainfall input to HiPIMS reduces the possibility of acquiring a satisfactory simulation accuracy. The objective of this study is to test the sensitivity of the surface runoff coefficient in the HiPIMS source term in the Misai basin with an area of 797 km2 in south China. To achieve this, the basin was divided into 909,824 grid cells, to each of which a Manning coefficient was assigned based on its land use type interpreted from remote sensing data. A sensitivity analysis was conducted for three typical flood processes under four types of surface runoff coefficients, assumed a priori, upon three error functions. The results demonstrate the crucial role of the surface runoff coefficient in achieving better simulation accuracy and reveal that this coefficient varies with flood scale and is unevenly distributed over the basin.

  11. Moisture Sources and Large-Scale Dynamics Associated with a Flash Flood Event in Portugal (United States)

    Liberato, Margarida L. R.; Ramos, Alexandre M.; Trigo, Ricardo M.; Trigo, Isabel F.; María Durán-Quesada, Ana; Nieto, Raquel; Gimeno, Luis


    through FCT (Fundação para a Ciência e a Tecnologia, Portugal) through project STORMEx FCOMP-01-0124-FEDER-019524 (PTDC/AAC-CLI/121339/2010). Margarida L. R. Liberato was also supported by a FCT grant (SFRH/BPD/45080/2008). Liberato M. L. R., A. M. Ramos, R. M. Trigo, I. F. Trigo, A. M. Durán-Quesada, R. Nieto, and L. Gimeno (2012) Moisture Sources and Large-scale Dynamics Associated with a Flash Flood Event. Lagrangian Modeling of the Atmosphere, Geophysical Monograph Series (in press). Stohl, A., and P. James (2004), A Lagrangian analysis of the atmospheric branch of the global water cycle. Part I: Method description, validation, and demonstration for the August 2002 flooding in central Europe, J. Hydrometeorol., 5, 656-678. Stohl, A., and P. James (2005), A Lagrangian analysis of the atmospheric branch of the global water cycle. Part II: Earth's river catchments, ocean basins, and moisture transports between them, J. Hydrometeorol., 6, 961-984. Zêzere, J. L., R. M. Trigo, and I. F. Trigo (2005), Shallow and deep landslides induced by rainfall in the Lisbon region (Portugal): Assessment of relationships with the North Atlantic Oscillation, Nat. Hazards Earth Syst. Sci., 5, 331-344.

  12. Coastal Zone Hazards Related to Groundwater-Surface Water Interactions and Groundwater Flooding (United States)

    Kontar, Y. A.; Ozorovich, Y. R.; Salokhiddinov, A. T.


    Worldwide, as many as half a million people have died in natural and man-made disasters since the turn of the 21st century (Wirtz, 2008). Further, natural and man-made hazards can lead to extreme financial losses (Elsner et al, 2009). Hazards, hydrological and geophysical risk analysis related to groundwater-surface water interactions and groundwater flooding have been to a large extent under-emphasized for coastal zone applications either due to economical limitations or underestimation of its significance. This is particularly true for tsunamis creating salt water intrusion to coastal aquifers, even though most tsunami hazard assessments have in the past relied on scenario or deterministic type models (Geist and Parsons, 2006), and to increasing mineralization of potable water because of intensive water diversions and also the abundance of highly toxic pollutants (mainly pesticides) in water, air and food, which contribute to the deterioration of the coastal population's health (Glantz, 2007). In the wake of pressing environmental and economic issues, it is of prime importance for the scientific community to shed light onto the great efforts by hydrologists and geophysicists to quantify conceptual uncertainties and to provide quality assurances of potential coastal zone hazard evaluation and prediction. This paper proposes consideration of two case studies which are important and significant for future development and essential for feasibility studies of hazards in the coastal zone. The territory of the Aral Sea Region in Central Asia is known as an ecological disaster coastal zone (Zavialov, 2005). It is now obvious that, in order to provide reasonable living conditions to the coastal zone population, it is first of all necessary to drastically improve the quality of the water dedicated to human needs. Due to their intensive pollution by industrial wastes and by drainage waters from irrigated fields, the Syr Darya and Amu Darya rivers can no longer be considered

  13. Quantum surface and intertwiner dynamics in loop quantum gravity (United States)

    Feller, Alexandre; Livine, Etera R.


    We introduce simple generic models of surface dynamics in loop quantum gravity (LQG). A quantum surface is defined as a set of elementary patches of area glued together. We provide it with an extra structure of locality (nearest neighbors), thought of as induced by the whole spin network state defining the 3d bulk geometry around the quantum surface. Here, we focus on classical surface dynamics, using a spinorial description of surface degrees of freedom. We introduce two classes of dynamics, to be thought as templates for future investigation of LQG dynamics with the dynamics of quantum black holes in mind. The first defines global dynamics of the closure defect of the surface, with two basic toy models, either a dissipative dynamics relaxing towards the closure constraint or a Hamiltonian dynamics precessing the closure defect. The second class of dynamics describes the isolated regime, when both area and closure defect are conserved throughout the evolution. The surface dynamics is implemented through U (N ) transformations and generalizes to a Bose-Hubbard Hamiltonian with a local quadratic potential interaction. We briefly discuss the implications of modeling the quantum black hole dynamics by a surface Bose-Hubbard model.

  14. Dynamic Water Storage during Flash Flood Events in the Mountainous Area of Rio de Janeiro/Brazil - Case study: Piabanha River Basin (United States)

    Araujo, L.; Silva, F. P. D.; Moreira, D. M.; Vásquez P, I. L.; Justi da Silva, M. G. A.; Fernandes, N.; Rotunno Filho, O. C.


    Flash floods are characterized by a rapid rise in water levels, high flow rates and large amounts of debris. Several factors have relevance to the occurrence of these phenomena, including high precipitation rates, terrain slope, soil saturation degree, vegetation cover, soil type, among others. In general, the greater the precipitation intensity, the more likely is the occurrence of a significant increase in flow rate. Particularly on steep and rocky plains or heavily urbanized areas, relatively small rain rates can trigger a flash flood event. In addition, high rain rates in short time intervals can temporarily saturate the surface soil layer acting as waterproofing and favoring the occurrence of greater runoff rates due to non-infiltration of rainwater into the soil. Thus, although precipitation is considered the most important factor for flooding, the interaction between rainfall and the soil can sometimes be of greater importance. In this context, this work investigates the dynamic storage of water associated with flash flood events for Quitandinha river watershed, a tributary of Piabanha river, occurred between 2013 and 2014, by means of water balance analyses applied to three watersheds of varying magnitudes (9.25 km², 260 km² and 429 km²) along the rainy season under different time steps (hourly and daily) using remotely sensed and observational precipitation data. The research work is driven by the hypothesis of a hydrologically active bedrock layer, as the watershed is located in a humid region, having intemperate (fractured) rock layer, just below a shallow soil layer, in the higher part of the basin where steep slopes prevail. The results showed a delay of the variation of the dynamic storage in relation to rainfall peaks and water levels. Such behavior indicates that the surface soil layer, which is not very thick in the region, becomes rapidly saturated along rainfall events. Subsequently, the water infiltrates into the rocky layer and the water

  15. Itzï (version 17.1): an open-source, distributed GIS model for dynamic flood simulation (United States)

    Guillaume Courty, Laurent; Pedrozo-Acuña, Adrián; Bates, Paul David


    Worldwide, floods are acknowledged as one of the most destructive hazards. In human-dominated environments, their negative impacts are ascribed not only to the increase in frequency and intensity of floods but also to a strong feedback between the hydrological cycle and anthropogenic development. In order to advance a more comprehensive understanding of this complex interaction, this paper presents the development of a new open-source tool named Itzï that enables the 2-D numerical modelling of rainfall-runoff processes and surface flows integrated with the open-source geographic information system (GIS) software known as GRASS. Therefore, it takes advantage of the ability given by GIS environments to handle datasets with variations in both temporal and spatial resolutions. Furthermore, the presented numerical tool can handle datasets from different sources with varied spatial resolutions, facilitating the preparation and management of input and forcing data. This ability reduces the preprocessing time usually required by other models. Itzï uses a simplified form of the shallow water equations, the damped partial inertia equation, for the resolution of surface flows, and the Green-Ampt model for the infiltration. The source code is now publicly available online, along with complete documentation. The numerical model is verified against three different tests cases: firstly, a comparison with an analytic solution of the shallow water equations is introduced; secondly, a hypothetical flooding event in an urban area is implemented, where results are compared to those from an established model using a similar approach; and lastly, the reproduction of a real inundation event that occurred in the city of Kingston upon Hull, UK, in June 2007, is presented. The numerical approach proved its ability at reproducing the analytic and synthetic test cases. Moreover, simulation results of the real flood event showed its suitability at identifying areas affected by flooding

  16. The role of deep Earth dynamics in driving the flooding and emergence of New Guinea since the Jurassic (United States)

    Harrington, Lauren; Zahirovic, Sabin; Flament, Nicolas; Müller, R. Dietmar


    The paleogeography of New Guinea indicates fluctuating periods of flooding and emergence since the Jurassic, which are inconsistent with estimates of global sea level change since the Eocene. The role of deep Earth dynamics in explaining these discrepancies has not been explored, despite the strongly time-dependent geodynamic setting within which New Guinea has evolved. We aim to investigate the role of subduction-driven mantle flow in controlling long-wavelength dynamic topography and its manifestation in the regional sedimentary record, within a tectonically complex region leading to orogeny. We couple regionally refined global plate reconstructions with forward geodynamic models to compare trends of dynamic topography with estimates of eustasy and regional paleogeography. Qualitative corroboration of modelled mantle structure with equivalent tomographic profiles allows us to ground-truth the models. We show that predicted dynamic topography correlates with the paleogeographic record of New Guinea from the Jurassic to the present. We find that subduction at the East Gondwana margin locally enhanced the high eustatic sea levels from the Early Cretaceous (∼145 Ma) to generate long-term regional flooding. During the Miocene, however, dynamic subsidence associated with subduction of the Maramuni Arc played a fundamental role in causing long-term inundation of New Guinea during a period of global sea level fall.

  17. Dynamics of subcritical CO/sub 2//brine floods for heavy-oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Rojas, G.A.; Ali, S.M.F.


    Immiscible CO/sub 2/ flooding is an important, field-proven heavy-oil recovery method, particularly suited for thin, marginal, or otherwise poor heavy-oil reservoirs, where thermal recovery processes are likely to be uneconomical. This paper describes the dynamics of this recovery technique on the basis of experiments conducted in a scaled model. The experiments represent a medium-heavy oil (1032 mPa . s at 23/sup 0/C (1,032 cp at 73/sup 0/F)) occurring in a shallow, thin sand. CO/sub 2/ was injected together with brine at subcritical conditions (5.5 MPa and 21 to 23/sup 0/C (800 psi and 70 to 73/sup 0/F)). The CO/sub 2/ and brine superficial velocities were varied from 0.18 to 2.9 m/d (0.6 to 9.5 ft/D). This broad range of velocities permitted the study of the effect of the viscous, diffusive, and gravitational forces on the CO/sub 2/ slug (20% HCPV) process for heavy-oil recovery. It was found that viscous forces completely dominant CO/sub 2/ injection. Also, the mass transfer between CO/sub 2/ and oil had a stabilizing effect on the brine injection. Although the molecular diffusion of CO/sub 2/ in oil was high, it was not high enough to mobilize appreciable amounts of oil from uninvaded zones. The scaled experiment results showed that oil recoveries at CO/sub 2/ and brine breakthroughs were rate-dependent. While recovery at CO/sub 2/ breakthrough decreased with increasing rate, recovery at brine breakthrough increased. Reduction of interfacial tension (IFT) between brine and oil, leading to the formation of brine-in-oil emulsions, was found to be an additional effective mechanism of heavy-oil recovery by CO/sub 2//brine injection.


    Directory of Open Access Journals (Sweden)

    M. G. Tulbure


    Full Text Available Surface water is a critical resource in semi-arid areas. The Murray-Darling Basin (MDB of Australia, one of the largest semi-arid basins in the world is aiming to set a worldwide example of how to balance multiple interests (i.e. environment, agriculture and urban use, but has suffered significant water shrinkages during the Millennium Drought (1999-2009, followed by extensive flooding. Baseline information and systematic quantification of surface water (SW extent and flooding dynamics in space and time are needed for managing SW resources across the basin but are currently lacking. To synoptically quantify changes in SW extent and flooding dynamics over MDB, we used seasonally continuous Landsat TM and ETM+ data (1986 – 2011 and generic machine learning algorithms. We further mapped flooded forest at a riparian forest site that experienced severe tree dieback due to changes in flooding regime. We used a stratified sampling design to assess the accuracy of the SW product across time. Accuracy assessment yielded an overall classification accuracy of 99.94%, with producer’s and user’s accuracy of SW of 85.4% and 97.3%, respectively. Overall accuracy was the same for Landsat 5 and 7 data but user’s and producer’s accuracy of water were higher for Landsat 7 than 5 data and stable over time. Our validated results document a rapid loss in SW bodies. The number, size, and total area of SW showed high seasonal variability with highest numbers in winter and lowest numbers in summer. SW extent per season per year showed high interannual and seasonal variability, with low seasonal variability during the Millennium Drought. Examples of current uses of the new dataset will be presented and include (1 assessing ecosystem response to flooding with implications for environmental water releases, one of the largest investment in environment in Australia; (2 quantifying drivers of SW dynamics (e.g. climate, human activity; (3 quantifying changes in SW

  19. Spatiotemporal Dynamics of Surface Water Extent from Three Decades of Seasonally Continuous Landsat Time Series at Subcontinental Scale (United States)

    Tulbure, M. G.; Broich, M.; Stehman, Stephen V.


    Surface water is a critical resource in semi-arid areas. The Murray-Darling Basin (MDB) of Australia, one of the largest semi-arid basins in the world is aiming to set a worldwide example of how to balance multiple interests (i.e. environment, agriculture and urban use), but has suffered significant water shrinkages during the Millennium Drought (1999-2009), followed by extensive flooding. Baseline information and systematic quantification of surface water (SW) extent and flooding dynamics in space and time are needed for managing SW resources across the basin but are currently lacking. To synoptically quantify changes in SW extent and flooding dynamics over MDB, we used seasonally continuous Landsat TM and ETM+ data (1986 - 2011) and generic machine learning algorithms. We further mapped flooded forest at a riparian forest site that experienced severe tree dieback due to changes in flooding regime. We used a stratified sampling design to assess the accuracy of the SW product across time. Accuracy assessment yielded an overall classification accuracy of 99.94%, with producer's and user's accuracy of SW of 85.4% and 97.3%, respectively. Overall accuracy was the same for Landsat 5 and 7 data but user's and producer's accuracy of water were higher for Landsat 7 than 5 data and stable over time. Our validated results document a rapid loss in SW bodies. The number, size, and total area of SW showed high seasonal variability with highest numbers in winter and lowest numbers in summer. SW extent per season per year showed high interannual and seasonal variability, with low seasonal variability during the Millennium Drought. Examples of current uses of the new dataset will be presented and include (1) assessing ecosystem response to flooding with implications for environmental water releases, one of the largest investment in environment in Australia; (2) quantifying drivers of SW dynamics (e.g. climate, human activity); (3) quantifying changes in SW dynamics and

  20. The dynamics and structures of adsorbed surfaces

    International Nuclear Information System (INIS)

    Nielsen, M.; Ellenson, W.D.; McTague, J.P.


    This article reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N 2 , Ar, H 2 , D 2 , O 2 , Kr, and He. Measurements on layers of larger molecules such as CD 4 and ND 3 have been reported very recently. Inelastic neutron scattering measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36 Ar and D 2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility of molecules such as NH 3 or the internal modes of adsorbed molecules such as C 4 H 10 . Neutron scattering measurements where substrates other than graphite products are used as the adsorbents will not be reviewed here. However, the power of the technique will be demonstrated in an example of H 2 physisorbed to activated alumina and in an example where hydrogen is chemisorbed to Raney nickel. (author)

  1. Effect of surface modification and hybridization on dynamic ...

    Indian Academy of Sciences (India)

    The paper evaluates effect of fibre surface modification and hybridization on dynamic mechanical properties of Roystonea regia/epoxy composites. Surface modification involved alkali and silane treatments. Alkali treatment proved to be more effective on dynamic mechanical properties as compared to silane treatment.

  2. Real-Time Global Flood Estimation Using Satellite-Based Precipitation and a Coupled Land Surface and Routing Model (United States)

    Wu, Huan; Adler, Robert F.; Tian, Yudong; Huffman, George J.; Li, Hongyi; Wang, JianJian


    A widely used land surface model, the Variable Infiltration Capacity (VIC) model, is coupled with a newly developed hierarchical dominant river tracing-based runoff-routing model to form the Dominant river tracing-Routing Integrated with VIC Environment (DRIVE) model, which serves as the new core of the real-time Global Flood Monitoring System (GFMS). The GFMS uses real-time satellite-based precipitation to derive flood monitoring parameters for the latitude band 50 deg. N - 50 deg. S at relatively high spatial (approximately 12 km) and temporal (3 hourly) resolution. Examples of model results for recent flood events are computed using the real-time GFMS ( To evaluate the accuracy of the new GFMS, the DRIVE model is run retrospectively for 15 years using both research-quality and real-time satellite precipitation products. Evaluation results are slightly better for the research-quality input and significantly better for longer duration events (3 day events versus 1 day events). Basins with fewer dams tend to provide lower false alarm ratios. For events longer than three days in areas with few dams, the probability of detection is approximately 0.9 and the false alarm ratio is approximately 0.6. In general, these statistical results are better than those of the previous system. Streamflow was evaluated at 1121 river gauges across the quasi-global domain. Validation using real-time precipitation across the tropics (30 deg. S - 30 deg. N) gives positive daily Nash-Sutcliffe Coefficients for 107 out of 375 (28%) stations with a mean of 0.19 and 51% of the same gauges at monthly scale with a mean of 0.33. There were poorer results in higher latitudes, probably due to larger errors in the satellite precipitation input.

  3. Temporal dynamics of flooding, evaporation, and desiccation cycles and observations of salt crust area change at the Bonneville Salt Flats, Utah (United States)

    Bowen, Brenda B.; Kipnis, Evan L.; Raming, Logan W.


    The Bonneville Salt Flats (BSF) in Utah is a dynamic saline playa environment responding to natural and anthropogenic forces. Over the last century, the saline groundwater from below BSF has been harvested to produce potash via evaporative mining, mostly used as agricultural fertilizers, while the surface halite crust has provided a significant recreational site for land speed racing. Perceptions of changes in the salt crust through time have spurred debates about land use and management; however, little is known about the timescales of natural change as the salt crust responds to climatic parameters that drive flooding, evaporation, and desiccation (FED) cycles that control surface salt growth and dissolution. Climate data over the last 30 years are examined to identify annual patterns in surface water balance at BSF to identify annual and seasonal climate constraints on FED cycles. Landsat satellite data from 1986 to the present are used to map the areal extent of the surface halite salt crust at BSF at the end of the desiccation season (between August 15 and October 30) annually. Overall, the observed area of the desiccation-stage BSF halite crust has varied from a maximum of 156 km2 in 1993 to a minimum of 72 km2 in 2014 with an overall trend of declining area of halite observed over the 30 years of analysis. Climatic variables that influence FED cycles and seasonal salt dissolution and precipitation have also varied through this time period; however, the relationship between surface water fluxes and salt crust area do not clearly correlate, suggesting that other processes are influencing the extent of the salt. Intra-annual analyses of salt area and weather illustrate the importance of ponded surface water, wind events, and microtopography in shaping a laterally extensive but thin and ephemeral halite crust. Examination of annual to decadal changes in salt crust extent and environmental parameters at BSF provides insights into the processes driving change and

  4. Dynamic recrystallization in friction surfaced austenitic stainless steel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Puli, Ramesh, E-mail:; Janaki Ram, G.D.


    Friction surfacing involves complex thermo-mechanical phenomena. In this study, the nature of dynamic recrystallization in friction surfaced austenitic stainless steel AISI 316L coatings was investigated using electron backscattered diffraction and transmission electron microscopy. The results show that the alloy 316L undergoes discontinuous dynamic recrystallization under conditions of moderate Zener-Hollomon parameter during friction surfacing. - Highlights: Black-Right-Pointing-Pointer Dynamic recrystallization in alloy 316L friction surfaced coatings is examined. Black-Right-Pointing-Pointer Friction surfacing leads to discontinuous dynamic recrystallization in alloy 316L. Black-Right-Pointing-Pointer Strain rates in friction surfacing exceed 400 s{sup -1}. Black-Right-Pointing-Pointer Estimated grain size matches well with experimental observations in 316L coatings.

  5. The impact of bathymetry input on flood simulations (United States)

    Khanam, M.; Cohen, S.


    Flood prediction and mitigation systems are inevitable for improving public safety and community resilience all over the worldwide. Hydraulic simulations of flood events are becoming an increasingly efficient tool for studying and predicting flood events and susceptibility. A consistent limitation of hydraulic simulations of riverine dynamics is the lack of information about river bathymetry as most terrain data record water surface elevation. The impact of this limitation on the accuracy on hydraulic simulations of flood has not been well studies over a large range of flood magnitude and modeling frameworks. Advancing our understanding of this topic is timely given emerging national and global efforts for developing automated flood predictions systems (e.g. NOAA National Water Center). Here we study the response of flood simulation to the incorporation of different bathymetry and floodplain surveillance source. Different hydraulic models are compared, Mike-Flood, a 2D hydrodynamic model, and GSSHA, a hydrology/hydraulics model. We test a hypothesis that the impact of inclusion/exclusion of bathymetry data on hydraulic model results will vary in its magnitude as a function of river size. This will allow researcher and stake holders more accurate predictions of flood events providing useful information that will help local communities in a vulnerable flood zone to mitigate flood hazards. Also, it will help to evaluate the accuracy and efficiency of different modeling frameworks and gage their dependency on detailed bathymetry input data.

  6. Channel-Dynamic Control on the Establishment of Riparian Trees After Large Floods in Northwestern California (United States)

    Thomas E. Lisle


    Large floods in northwestern California in the past two decades have mobilized extensive areas of valley floors, removed streamside trees, and widened channels. Channel cross sections were surveyed to illustrate an hypothesis on the linkage between sediment transport, colonization of channel margins by trees, and streambank recovery. Riparian trees, e.g., white alder...

  7. Braided River Evolution and Bifurcation Dynamics During Floods and Low Flow in the Jamuna River (United States)

    Marra, W. A.; Kleinhans, M. G.; Addink, E.


    River bifurcations have become recognised over the last decade as being critical but poorly understood elements in many channel systems, including braided and anastomosing rivers, fluvial lowland plains and deltas. They control the partitioning of both water and sediment with consequences for the downstream evolution and for river and coastal management. Avulsion studies and bifurcation modelling suggest that symmetrical bifurcations are inherently unstable. However, the simultaneous activity of channels in deltas, anastomosing rivers and large braided rivers such as the Jamuna suggest that symmetrical bifurcations are stable in agreement with sediment transport optimisation theories. These theories are still a matter of debate. Our objective is to understand the stability and evolution of the braid pattern through studying the dynamics of the bifurcations under natural discharge conditions: both during floods and low flow. Using a series of Landsat TM images taken at irregular intervals showing inter-annual variation, we studied the evolution of a large number of bifurcations in the Jamuna river between 1999 and 2004. The images were first classified into water, bare sediment and vegetation. The contiguous water body of the river was then selected and translated into a network description with bifurcations and confluences at the nodes and interconnecting channels. Channel width is a crucial attribute of the network channels as this allows the calculation of bifurcation asymmetry. The key step here is to describe river network evolution by identifying the same node in multiple subsequent images as well as new and abandoned nodes, in order to distinguish migration of bifurcations from avulsion processes. Nodes in two subsequent images were linked through distance and angle of the downstream connected channels. Once identified through time, the changes in node position and the changes in the connected channels can be quantified Along the entire river the well

  8. Structure and Dynamics of Floods in the upper Delaware River Basin: An Integrated Seasonal Forecasting System for New York City Reservoirs (United States)

    Najibi, N.; Devineni, N.


    The National Weather Service River Forecasting System (NWS-RFS) issues 3-month lead probabilistic forecasts of streamflow for many river basins in the contiguous United States from 12 river forecasting centers. The Ensemble Streamflow Prediction system from NWS-RFS uses conceptual hydrologic models to issue streamflow forecasts based on the current soil moisture, river, and reservoir conditions by assuming that past meteorological events will recur in the future with historical probabilities. Recent investigations focusing on the teleconnection between anomalous sea surface temperature conditions and regional/continental hydroclimatology show that interannual and interdecadal variability in exogenous climatic indices modulates the regional streamflow patterns. In this work, we present a comprehensive framework to quantify the structure and dynamics of floods for the upper Delaware River Basin based on the interaction between the exogenous climate and weather patterns and antecedent flow regimes. We focus on estimating the conditional distribution of flood volume, duration, peak and timing based on large-scale climatic teleconnections (seasonal sea level pressure and pre-season sea surface temperature) and macroscale hydrological factors (start of the season's flow, seasonal rainfall duration and intensity, pre-season snow depth and cover in watershed, and concurrent rain over snow (ROS) events). Statistical techniques such as the semi-parametric k-nearest neighbor resampling, multivariate Kalman filters, and hierarchical Bayesian methods are explored as a strategy to address both model and parameter uncertainties. Ultimately proactive decision models embedded into the operating rules based on the forecasted future conditions -instead of reactive decisions based on current observed conditions- can result in risk mitigation.

  9. A Dynamic Model for Roll Motion of Ships due to Flooding

    DEFF Research Database (Denmark)

    Xia, Jinzhu; Jensen, Jørgen Juncher; Pedersen, Preben Terndrup


    Because of the large undivided deck spaces, RoRo vessels are often sensitive to rapid capsizing due to sudden ingress of water. Following a high-energy damage, a rapidly increasing heeling moment is induced by the ingress of water, which generates a roll motion of the damaged vessel. If, addition......, additionally, the car deck is flooded and/or the cargo is shifted, the heeling moment may exceed the residual restoring moment, which results in capsizing....

  10. Flooding dynamics in a large low-gradient alluvial fan, the Okavango Delta, Botswana, from analysis and interpretation of a 30-year hydrometric record

    Directory of Open Access Journals (Sweden)

    P. Wolski


    Full Text Available The Okavango Delta is a flood-pulsed wetland, which supports a large tourism industry and the subsistence of the local population through the provision of ecosystem services. In order to obtain insight into the influence of various environmental factors on flood propagation and distribution in this system, an analysis was undertaken of a 30-year record of hydrometric data (discharges and water levels from one of the Delta distributaries. The analysis revealed that water levels and discharges at any given channel site in this distributary are influenced by a complex interplay of flood wave and local rainfall inputs, modified by channel-floodplain interactions, in-channel sedimentation and technical interventions, both at the given site and upstream. Additionally, cyclical variation of channel vegetation due to intermittent nutrient loading, possibly sustained by nutrient recycling, may play a role. It is shown that short and long-term flood dynamics are mainly due to variation in floodplain flows. As a consequence, discharge data collected within the main channels of distributaries do not adequately represent flooding dynamics in the system. The paper contributes to the understanding of seasonal and long-term flood pulsing and their variation in low gradient systems of channels and floodplains.

  11. Response of riparian vegetation across Australia's largest river basin to inter and intra-annual flooding: dynamics quantified from time series of Landsat and MODIS data (United States)

    Broich, M.; Tulbure, M. G.; Keith, D.; Kingsford, R.; Lucas, R.; Lippmann, T.


    Australia is a continent subject to high rainfall variability. The resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB; 72 Landsat path-rows) of Australia as a case study. The MDB is the country's primary agricultural area with scarce water resources impacted by climate change and extensive zones with degrading riparian vegetation. We advance our understanding of the relationship between climate-driven flooding dynamics and vegetation response at the sub-continental to local and inter to intra-annual scale based on two decades of Landsat and one decade of MODIS imagery. We Landsat TM and ETM+ data to synoptically map spatially detailed dynamics of flooding with an internally consistent machine learning algorithm. We derived riparian phenology (Fig 1) from MODIS data and attributed differences in vegetation response to flooding dynamics, vegetation types and sub-basin land use. Vegetation community response to flooding varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Phenological degradation trends were observed over riparian forests and woodlands in the middle and lower parts of the basin that are primarily farmed and were we identified flooding regimes to have changed the most to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a boom and bust cycle related to less extensive flooding dynamics. This pattern was found across different areas of the basin. As expected, flooding regimes and vegetation response patterns were fine grained confirming the choice of a spatially explicit, internally consistent analysis leading the path for ongoing monitoring. Remote sensing-based monitoring of the response of riparian vegetation to flooding can be used to quantify spatially explicit changes in vegetation community

  12. The COMET-L3 experiment on long-term melt. Concrete interaction and cooling by surface flooding

    International Nuclear Information System (INIS)

    Alsmeyer, H.; Cron, T.; Fluhrer, B.; Messemer, G.; Miassoedov, A.; Schmidt-Stiefel, S.; Wenz, T.


    The COMET-L3 experiment considers the long-term situation of corium/concrete interaction in an anticipated core melt accident of a light-water-reactor, after the metal melt is layered beneath the oxide melt. The experimental focus is on cavity formation in the basemat and the risk of long term basemat penetration. The experiment investigates the two-dimensional concrete erosion in a cylindrical crucible fabricated from siliceous concrete in the first phase of the test, and the influence of surface flooding in the second phase. Decay heating in the two-component metal and oxide melt is simulated by sustained induction heating of the metal phase that is overlaid by the oxide melt. The inner diameter of the concrete crucible was 60 cm, the initial mass of the melt was 425 kg steel and 211 kg oxide at 1665 C, resulting in a melt height of 450 mm. The net power to the metal melt was about 220 kW from 0 s to 1880 s, when the maximum erosion limit of the crucible was reached and heating was terminated. In the initial phase of the test (less than 100 s), the overheated, highly agitated metal melt causes intense interaction with the concrete, which leads to fast decrease of the initial melt overheat and reduction of the initially high concrete erosion rate. Thereafter, under quasistationary conditions until about 800 s, the erosion by the metal melt slows down to some 0.07 mm/s into the axial direction. Lateral erosion is a factor 3 smaller. Video observation of the melt surface shows an agitated melt with ongoing gas release from the decomposing concrete. Several periods of more intense gas release, gas driven splashing, and release of crusts from the concrete interface indicate the existence and iterative break-up of crusts that probably form at the steel/concrete interface. Surface flooding of the melt is initiated at 800 s by a shower from the crucible head with 0.375 litre water/s. Flooding does not lead to strong melt/water interactions, and no entrapment reactions or

  13. Riemann Surfaces: Vector Bundles, Physics, and Dynamics

    DEFF Research Database (Denmark)

    Sikander, Shehryar

    We construct quantum representation of a subgroup of the mapping class group of a genus two surface. Our construction relies on realizing this subgroup as the orbifold fundamental group of a Teichmueller curve, pulling back the Hitchin connection to this Tecihmueller curve, and computing the mono...

  14. Sperm cell surface dynamics during activation and fertilization

    NARCIS (Netherlands)

    Boerke, A.|info:eu-repo/dai/nl/304822922


    Before the sperm cell can reach the oocyte it needs to be activated and to undergo a series of preparative steps. The sperm surface dynamics was studied in relation to this activation process and the modifications and removal of sperm surface components havebeen investigated. Bicarbonate-induced

  15. CF3+ etching silicon surface: A molecular dynamics study

    NARCIS (Netherlands)

    Zhao, C.; Lu, X.; He, P.; Zhang, P.; Sun, W.; Zhang, Jingwei; Chen, F.; Gou, F.


    In this study, a molecular dynamics simulation method has been employed to investigate CF3 + ions, bombarding Si surface with the energy of 100, 200, 300 and 400 eV and an incident angle of 45 degrees with respect to the normal. The simulation results show that when CF3+ ions approach the Si surface

  16. Dynamic characteristics of numerical systems for induction surface heating (United States)

    Kozulina, T.; Blinov, K.; Galunin, S.


    This paper describes the development, investigation and optimization of induction surface heating process of a workpice taking into account its rotation by numerical simulation in a commercial package ANSYS® [1]. During the investigation it is necessary to select the optimal dynamic characteristics of the heating process in order to obtain the required temperature level and uniform temperature distribution on the surface of the workpiece.

  17. Dynamic surface properties of poly(methylalkyldiallylammonium chloride) solutions

    Czech Academy of Sciences Publication Activity Database

    Novikova, A. A.; Vlasov, P. S.; Lin, S.-Y.; Sedláková, Zdeňka; Noskov, B. A.


    Roč. 80, November (2017), s. 122-127 ISSN 1876-1070 Institutional support: RVO:61389013 Keywords : polymer solutions * dynamic surface tension * dilational surface rheology Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 4.217, year: 2016

  18. Analysis on the Dynamics of Burst Debris Flood at the Inclined Pressure-Shaft of Svandalsflona Hydropower Project, Norway (United States)

    Panthi, K. K.


    Long-term stability of the waterway system of the hydropower plants is crucial and should not be underestimated. The compromise may result in severe economic consequences related to revenue loss caused by the plant closedown for needed repair, extra resources and time required for repair work, and third party loss related to industries and societies at large. In addition, possible contractual disputes between the clients and the contractors may arise in some occasions. Serious accidents may happen during repair and construction work with loss of life, since engineering geological environment (conditions) in the rock mass changed once under water for long period. This article focuses on one of the recent shaft collapse that happened in Norway in 2008. The article discusses and analyses the dynamics of burst debris flood that took place on 9 May 2009, while removing the slide rock mass deposited in the 45° inclined shaft of the Svandalsflona hydropower plant located at the Southern Norway. Careful review on the geological conditions inside the shaft, evaluation on the course of events, investigations on the inspections and inspections reports, assessment on the temperature and precipitation conditions have been carried out to come to the conclusion on what might have triggered the sudden burst flood.

  19. HERA: A dynamic web application for visualizing community exposure to flood hazards based on storm and sea level rise scenarios (United States)

    Jones, Jeanne M.; Henry, Kevin; Wood, Nathan J.; Ng, Peter; Jamieson, Matthew


    The Hazard Exposure Reporting and Analytics (HERA) dynamic web application was created to provide a platform that makes research on community exposure to coastal-flooding hazards influenced by sea level rise accessible to planners, decision makers, and the public in a manner that is both easy to use and easily accessible. HERA allows users to (a) choose flood-hazard scenarios based on sea level rise and storm assumptions, (b) appreciate the modeling uncertainty behind a chosen hazard zone, (c) select one or several communities to examine exposure, (d) select the category of population or societal asset, and (e) choose how to look at results. The application is designed to highlight comparisons between (a) varying levels of sea level rise and coastal storms, (b) communities, (c) societal asset categories, and (d) spatial scales. Through a combination of spatial and graphical visualizations, HERA aims to help individuals and organizations to craft more informed mitigation and adaptation strategies for climate-driven coastal hazards. This paper summarizes the technologies used to maximize the user experience, in terms of interface design, visualization approaches, and data processing.

  20. Applications of multiscale waveform inversion to marine data using a flooding technique and dynamic early-arrival windows

    KAUST Repository

    Boonyasiriwat, Chaiwoot


    A recently developed time-domain multiscale waveform tomography (MWT) method is applied to synthetic and field marine data. Although the MWT method was already applied to synthetic data, the synthetic data application leads to a development of a hybrid method between waveform tomography and the salt flooding technique commonly use in subsalt imaging. This hybrid method can overcome a convergence problem encountered by inversion with a traveltime velocity tomogram and successfully provides an accurate and highly resolved velocity tomogram for the 2D SEG/EAGE salt model. In the application of MWT to the field data, the inversion process is carried out using a multiscale method with a dynamic early-arrival muting window to mitigate the local minima problem of waveform tomography and elastic effects. With the modified MWT method, reasonably accurate results as verified by comparison of migration images and common image gathers were obtained. The hybrid method with the salt flooding technique is not used in this field data example because there is no salt in the subsurface according to our interpretation. However, we believe it is applicable to field data applications. © 2010 Society of Exploration Geophysicists.

  1. HERA: A dynamic web application for visualizing community exposure to flood hazards based on storm and sea level rise scenarios (United States)

    Jones, Jeanne M.; Henry, Kevin; Wood, Nathan; Ng, Peter; Jamieson, Matthew


    The Hazard Exposure Reporting and Analytics (HERA) dynamic web application was created to provide a platform that makes research on community exposure to coastal-flooding hazards influenced by sea level rise accessible to planners, decision makers, and the public in a manner that is both easy to use and easily accessible. HERA allows users to (a) choose flood-hazard scenarios based on sea level rise and storm assumptions, (b) appreciate the modeling uncertainty behind a chosen hazard zone, (c) select one or several communities to examine exposure, (d) select the category of population or societal asset, and (e) choose how to look at results. The application is designed to highlight comparisons between (a) varying levels of sea level rise and coastal storms, (b) communities, (c) societal asset categories, and (d) spatial scales. Through a combination of spatial and graphical visualizations, HERA aims to help individuals and organizations to craft more informed mitigation and adaptation strategies for climate-driven coastal hazards. This paper summarizes the technologies used to maximize the user experience, in terms of interface design, visualization approaches, and data processing.

  2. Bulk water freezing dynamics on superhydrophobic surfaces (United States)

    Chavan, S.; Carpenter, J.; Nallapaneni, M.; Chen, J. Y.; Miljkovic, N.


    In this study, we elucidate the mechanisms governing the heat-transfer mediated, non-thermodynamic limited, freezing delay on non-wetting surfaces for a variety of characteristic length scales, Lc (volume/surface area, 3 mm commercial superhydrophobic spray coatings, showing a monotonic increase in freezing time with coating thickness. The added thermal resistance of thicker coatings was much larger than that of the nanoscale superhydrophobic features, which reduced the droplet heat transfer and increased the total freezing time. Transient finite element method heat transfer simulations of the water slab freezing process were performed to calculate the overall heat transfer coefficient at the substrate-water/ice interface during freezing, and shown to be in the range of 1-2.5 kW/m2K for these experiments. The results shown here suggest that in order to exploit the heat-transfer mediated freezing delay, thicker superhydrophobic coatings must be deposited on the surface, where the coating resistance is comparable to the bulk water/ice conduction resistance.

  3. Dynamic interactions of Leidenfrost droplets on liquid metal surface (United States)

    Ding, Yujie; Liu, Jing


    Leidenfrost dynamic interaction effects of the isopentane droplets on the surface of heated liquid metal were disclosed. Unlike conventional rigid metal, such conductive and deformable liquid metal surface enables the levitating droplets to demonstrate rather abundant and complex dynamics. The Leidenfrost droplets at different diameters present diverse morphologies and behaviors like rotation and oscillation. Depending on the distance between the evaporating droplets, they attract and repulse each other through the curved surfaces beneath them and their vapor flows. With high boiling point up to 2000 °C, liquid metal offers a unique platform for testing the evaporating properties of a wide variety of liquid even solid.

  4. Surface-Confined Dynamic Covalent System Driven by Olefin Metathesis. (United States)

    Liu, Chunhua; Park, Eunsol; Jin, Yinghua; Liu, Jie; Yu, Yanxia; Zhang, Wei; Lei, Shengbin; Hu, Wenping


    Understanding how the constitutional dynamics of a dynamic combinatorial library (DCL) adapts to surfaces (compared to bulk solution) is of fundamental importance to the design of adaptive materials. Submolecular resolved scanning tunneling microscopy (STM) can provide detailed insights into olefin metathesis at the interface. Analysis of the distribution of products has revealed the important role of environmental pressure, reaction temperature, and substituent effects in surface-confined olefin metathesis. We also report an unprecedented preferred deposition and assembly of linear polymers, and some specific oligomers, on the surface that are hard to obtain otherwise. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The Dynamics and Structures of Adsorbed Surfaces

    DEFF Research Database (Denmark)

    Nielsen, M; Ellenson, W. D.; McTague, J. P.


    Reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace....... Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... of molecules such as NH3 or the internal modes of adsorbed molecules such as C4H10. Neutron scattering measurements where substrates other than graphite products are used as the adsorbents will not be reviewed here. However, the power of the technique will be demonstrated in an example of H2 physisorbed...

  6. Early dynamics of stereoscopic surface slant perception. (United States)

    Caziot, Baptiste; Backus, Benjamin T; Lin, Esther


    Surface orientation is an important visual primitive that can be estimated from monocular or binocular (stereoscopic) signals. Changes in motor planning occur within about 200 ms after either type of signal is perturbed, but the time it takes for apparent (perceived) slant to develop from stereoscopic cues is not known. Apparent slant sometimes develops very slowly (Gillam, Chambers, & Russo, 1988; van Ee & Erkelens, 1996). However, these long durations could reflect the time it takes for the visual system to resolve conflicts between slant cues that inevitably specify different slants in laboratory displays (Allison & Howard, 2000). We used a speed-accuracy tradeoff analysis to measure the time it takes to discriminate slant, allowing us to report psychometric functions as a function of response time. Observers reported which side of a slanted surface was farther, with a temporal deadline for responding that varied block-to-block. Stereoscopic slant discrimination rose above chance starting at 200 ms after stimulus onset. Unexpectedly, observers discriminated slant from binocular disparity faster than texture, and for stereoscopic whole-field stimuli faster than stereoscopic slant contrast stimuli. However, performance after the initial deviation from chance increased more rapidly for slant-contrast stimuli than whole-field stimuli. Discrimination latencies were similar for slants about the horizontal and vertical axes, but performance increased faster for slants about the vertical axis. Finally, slant from vertical disparity was somewhat slower than slant from horizontal disparity, which may reflect cue conflict. These results demonstrate, in contradiction with the previous literature, that the perception of slant from disparity happens very quickly-in fact, more quickly than the perception of slant from texture-and in comparable time to the simple perception of brightness from luminance.

  7. Land Surface Microwave Emissivity Dynamics: Observations, Analysis and Modeling (United States)

    Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Kumar, Sujay; Ringerud, Sarah


    Land surface microwave emissivity affects remote sensing of both the atmosphere and the land surface. The dynamical behavior of microwave emissivity over a very diverse sample of land surface types is studied. With seven years of satellite measurements from AMSR-E, we identified various dynamical regimes of the land surface emission. In addition, we used two radiative transfer models (RTMs), the Community Radiative Transfer Model (CRTM) and the Community Microwave Emission Modeling Platform (CMEM), to simulate land surface emissivity dynamics. With both CRTM and CMEM coupled to NASA's Land Information System, global-scale land surface microwave emissivities were simulated for five years, and evaluated against AMSR-E observations. It is found that both models have successes and failures over various types of land surfaces. Among them, the desert shows the most consistent underestimates (by approx. 70-80%), due to limitations of the physical models used, and requires a revision in both systems. Other snow-free surface types exhibit various degrees of success and it is expected that parameter tuning can improve their performances.

  8. Groundwater discharge and phosphorus dynamics in a flood-pulse system: Tonle Sap Lake, Cambodia (United States)

    Burnett, William C.; Wattayakorn, Gullaya; Supcharoen, Ratsirin; Sioudom, Khamfeuane; Kum, Veasna; Chanyotha, Supitcha; Kritsananuwat, Rawiwan


    Tonle Sap Lake (Cambodia), a classic example of a "flood pulse" system, is the largest freshwater lake in SE Asia, and is reported to have one of the highest freshwater fish productions anywhere. During the dry season (November-April) the lake drains through a tributary to the Mekong River. The flow in the connecting tributary completely reverses during the wet monsoon (May-October), adding huge volumes of water back to the lake, increasing its area about six fold. The lake is likely phosphorus limited and we hypothesized that groundwater discharge, including recirculated lake water, may represent an important source of P and other nutrients. To address this question, we surveyed hundreds of kilometers of the lake for natural 222Rn (radon), temperature, conductivity, GPS coordinates and water depth. All major inorganic nutrients and phosphorus species were evaluated by systematic sampling throughout the lake. Results showed that there were radon hotspots, all at the boundaries between the permanent lake and the floodplain, indicating likely groundwater inputs. A radon mass balance model indicates that the groundwater flow to Tonle Sap Lake is approximately 10 km3/yr, about 25% as large as the floodwaters entering from the Mekong River during the wet monsoon. Our results suggest that the groundwater-derived dissolved inorganic phosphorus (DIP) contribution to Tonle Sap is more than 30% of the average inflows from all natural sources. Since the productivity of the lake appears to be phosphorus limited, this finding suggests that the role of groundwater is significant for Tonle Sap Lake and perhaps for other flood pulse systems worldwide.

  9. Molecular dynamics simulation of annealed ZnO surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Min, Tjun Kit; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)


    The effect of thermally annealing a slab of wurtzite ZnO, terminated by two surfaces, (0001) (which is oxygen-terminated) and (0001{sup ¯}) (which is Zn-terminated), is investigated via molecular dynamics simulation by using reactive force field (ReaxFF). We found that upon heating beyond a threshold temperature of ∼700 K, surface oxygen atoms begin to sublimate from the (0001) surface. The ratio of oxygen leaving the surface at a given temperature increases as the heating temperature increases. A range of phenomena occurring at the atomic level on the (0001) surface has also been explored, such as formation of oxygen dimers on the surface and evolution of partial charge distribution in the slab during the annealing process. It was found that the partial charge distribution as a function of the depth from the surface undergoes a qualitative change when the annealing temperature is above the threshold temperature.

  10. Structure and dynamics at the liquid surface of benzyl alcohol

    International Nuclear Information System (INIS)

    Dietter, J.; Morgner, H.


    A molecular dynamics simulation of a liquid layer of benzyl alcohol has been performed in order to compare the results with those obtained in experimental studies of our group. The main result of the experimental work was a strong orientational ordering of the benzyl alcohol molecules in the surface as well as an exceptionally large surface potential of ca. 0.6 V. According to the experiments the surface molecules orientate in such a way that the benzene ring points toward the vapor phase while the CH 2 group and the OH group are directed towards the bulk of the liquid. The simulation confirms this orientation of the surface molecules. The surface potential resulting from the simulation is 350 mV. The simulation reveals that the rather large surface potential can be understood as a consequence of the mean orientation of the molecular dipole moment in the surface region. The mean orientation of the molecules themselves in the surface is due to the tendency of the system to maintain the hydrogen bonding structure of the bulk in the surface region as well. The preferential orientation of the surface molecules causes a change of the dynamics of the individual components of the molecules when switching from bulk to surface which depends on the separation of these components from the polar group. This becomes most obvious in case of the reorientation dynamics of the molecular axes, e.g. the reorientation of the benzene ring is faster than the reorientation of the OH group. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  11. Mapping global surface water inundation dynamics using synergistic information from SMAP, AMSR2 and Landsat (United States)

    Du, J.; Kimball, J. S.; Galantowicz, J. F.; Kim, S.; Chan, S.; Reichle, R. H.; Jones, L. A.; Watts, J. D.


    A method to monitor global land surface water (fw) inundation dynamics was developed by exploiting the enhanced fw sensitivity of L-band (1.4 GHz) passive microwave observations from the Soil Moisture Active Passive (SMAP) mission. The L-band fw (fwLBand) retrievals were derived using SMAP H-polarization brightness temperature (Tb) observations and predefined L-band reference microwave emissivities for water and land endmembers. Potential soil moisture and vegetation contributions to the microwave signal were represented from overlapping higher frequency Tb observations from AMSR2. The resulting fwLBand global record has high temporal sampling (1-3 days) and 36-km spatial resolution. The fwLBand annual averages corresponded favourably (R=0.84, pretrievals showed favourable classification accuracy for water (commission error 31.84%; omission error 28.08%) and land (commission error 0.82%; omission error 0.99%) and seasonal wet and dry periods when compared to independent water maps derived from Landsat-8 imagery. The new fwLBand algorithms and continuing SMAP and AMSR2 operations provide for near real-time, multi-scale monitoring of global surface water inundation dynamics, potentially benefiting hydrological monitoring, flood assessments, and global climate and carbon modeling.

  12. Nanoparticles dynamics on a surface: fractal pattern formation and fragmentation

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.


    In this paper we review our recent results on the formation and the post-growth relaxation processes of nanofractals on surface. For this study we developed a method which describes the internal dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate...... that these kinetic processes determine the final shape of the islands on surface after post-growth relaxation. We consider different scenarios of fractal relaxation and analyze the time evolution of the island's morphology....

  13. Measurement of Dynamic Friction Coefficient on the Irregular Free Surface

    International Nuclear Information System (INIS)

    Yeom, S. H.; Seo, K. S.; Lee, J. H.; Lee, K. H.


    A spent fuel storage cask must be estimated for a structural integrity when an earthquake occurs because it freely stands on ground surface without a restriction condition. Usually the integrity estimation for a seismic load is performed by a FEM analysis, the friction coefficient for a standing surface is an important parameter in seismic analysis when a sliding happens. When a storage cask is placed on an irregular ground surface, measuring a friction coefficient of an irregular surface is very difficult because the friction coefficient is affected by the surface condition. In this research, dynamic friction coefficients on the irregular surfaces between a concrete cylinder block and a flat concrete slab are measured with two methods by one direction actuator

  14. Quantitative Analysis of Urban Pluvial Flood Alleviation by Open Surface Water Systems in New Towns: Comparing Almere and Tianjin Eco-City

    Directory of Open Access Journals (Sweden)

    Zhengnan Zhou


    Full Text Available Increased surface runoff generated in urban areas due to larger proportion of impervious surfaces has, in many cases, exceeded the capacity of urban drainage systems. In response to such challenge, this paper introduces the quantitative analysis of pluvial flood alleviation by open surface water systems in the case of Almere in the Netherlands and compares it with Tianjin Eco-City in China, with the aim of optimizing land use planning and urban design for new urban districts. The methodology is a combination of quantitative and qualitative analysis. With the analytical tool of ArcGIS, the authors have investigated the influence of spatial distribution of surface water system on the reduction of pluvial flood risks. The conclusions include some preliminary principles: (1 a densely distributed surface water network is preferable; (2 areas farther away from water body require water sensitive spatial intervention; and (3 optimizing the allocation of different types of ground surface could contribute to pluvial flood alleviation. An alternative design proposal for a typical urban block in Tianjin Eco-City has been put forward to illustrate these principles.

  15. Structure, biomimetics, and fluid dynamics of fish skin surfaces* (United States)

    Lauder, George V.; Wainwright, Dylan K.; Domel, August G.; Weaver, James C.; Wen, Li; Bertoldi, Katia


    The interface between the fluid environment and the surface of the body in swimming fishes is critical for both physiological and hydrodynamic functions. The skin surface in most species of fishes is covered with bony scales or toothlike denticles (in sharks). Despite the apparent importance of fish surfaces for understanding aquatic locomotion and near-surface boundary layer flows, relatively little attention has been paid to either the nature of surface textures in fishes or possible hydrodynamic effects of variation in roughness around the body surface within an individual and among species. Fish surfaces are remarkably diverse and in many bony fishes scales can have an intricate surface texture with projections, ridges, and comblike extensions. Shark denticles (or scales) are toothlike and project out of the skin to form a complexly textured surface that interacts with free-stream flow. Manufacturing biomimetic foils with fishlike surfaces allows hydrodynamic testing and we emphasize here the importance of dynamic test conditions where the effect of surface textures is assessed under conditions of self-propulsion. We show that simple two-dimensional foils with patterned cuts do not perform as well as a smooth control surface, but that biomimetic shark skin foils can swim at higher self-propelled speeds than smooth controls. When the arrangement of denticles on the foil surface is altered, we find that a staggered-overlapped pattern outperforms other arrangements. Flexible foils made of real shark skin outperform sanded controls when foils are moved with a biologically realistic motion program. We suggest that focus on the mechanisms of drag reduction by fish surfaces has been too limiting and an additional role of fish surface textures may be to alter leading edge vortices and flow patterns on moving surfaces in a way that enhances thrust. Analysis of water flow over an artificial shark skin foil under both static and dynamic conditions shows that a shear layer

  16. Population dynamics of the migratory fish Prochilodus lineatus in a neotropical river: the relationships with river discharge, flood pulse, El Niño and fluvial megafan behaviour

    Directory of Open Access Journals (Sweden)

    Marinke J. M. Stassen

    Full Text Available The relative importance of flood pulse dynamics and megafan behaviour for the Sábalo (Prochilodus lineatus catches in the neotropical Pilcomayo River is studied. The Sábalo catches can mainly be explained by decreased river discharges in the preceding years resulting in smaller inundated areas during rainy season floods and thereby in a decreased area of feeding grounds for the fishes. The decreased river discharges and the related decline of Sábalo catches in the 1990's can be linked to the 90-95 El Niño event. In 2007 the Sábalo catches were comparable to the catches before the "El Niño" event. The connectivity (continuity between the main river and flood plain areas, which is influenced by sedimentation processes, is also of great importance and very probably plays a more important role since the late 1990's.

  17. Electrostatic cloaking of surface structure for dynamic wetting (United States)

    Shiomi, Junichiro; Nita, Satoshi; Do-Quang, Minh; Wang, Jiayu; Chen, Yu-Chung; Suzuki, Yuji; Amberg, Gustav


    Dynamic wetting problems are fundamental to the understanding of the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, as surfaces may often be naturally charged, or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena. Here we investigate the interplay between electric forces and surface structures in dynamic wetting. While surface microstructures can significantly hinder the spreading, we find that the electrostatics can ``cloak'' the microstructures, i.e. deactivate the hindering. We identify the physics in terms of reduction in contact-line friction, which makes the dynamic wetting inertial force dominant and insensitive to the substrate properties. This work was financially supported in part by, the Japan Society for the Promotion of Science, Swedish Governmental Agency for Innovation Systems, and the Japan Science and Technology Agency.

  18. Sub-nanometer glass surface dynamics induced by illumination

    International Nuclear Information System (INIS)

    Nguyen, Duc; Nienhaus, Lea; Haasch, Richard T.; Lyding, Joseph; Gruebele, Martin


    Illumination is known to induce stress and morphology changes in opaque glasses. Amorphous silicon carbide (a-SiC) has a smaller bandgap than the crystal. Thus, we were able to excite with 532 nm light a 1 μm amorphous surface layer on a SiC crystal while recording time-lapse movies of glass surface dynamics by scanning tunneling microscopy (STM). Photoexcitation of the a-SiC surface layer through the transparent crystal avoids heating the STM tip. Up to 6 × 10 4 s, long movies of surface dynamics with 40 s time resolution and sub-nanometer spatial resolution were obtained. Clusters of ca. 3-5 glass forming units diameter are seen to cooperatively hop between two states at the surface. Photoexcitation with green laser light recruits immobile clusters to hop, rather than increasing the rate at which already mobile clusters hop. No significant laser heating was observed. Thus, we favor an athermal mechanism whereby electronic excitation of a-SiC directly controls glassy surface dynamics. This mechanism is supported by an exciton migration-relaxation-thermal diffusion model. Individual clusters take ∼1 h to populate states differently after the light intensity has changed. We believe the surrounding matrix rearranges slowly when it is stressed by a change in laser intensity, and clusters serve as a diagnostic. Such cluster hopping and matrix rearrangement could underlie the microscopic mechanism of photoinduced aging of opaque glasses

  19. Using a Bayesian Probabilistic Forecasting Model to Analyze the Uncertainty in Real-Time Dynamic Control of the Flood Limiting Water Level for Reservoir Operation

    DEFF Research Database (Denmark)

    Liu, Dedi; Li, Xiang; Guo, Shenglian


    Dynamic control of the flood limiting water level (FLWL) is a valuable and effective way to maximize the benefits from reservoir operation without exceeding the design risk. In order to analyze the impacts of input uncertainty, a Bayesian forecasting system (BFS) is adopted. Applying quantile water...... inflow values and their uncertainties obtained from the BFS, the reservoir operation results from different schemes can be analyzed in terms of benefits, dam safety, and downstream impacts during the flood season. When the reservoir FLWL dynamic control operation is implemented, there are two fundamental......, also deterministic water inflow was tested. The proposed model in the paper emphasizes the importance of analyzing the uncertainties of the water inflow forecasting system for real-time dynamic control of the FLWL for reservoir operation. For the case study, the selected quantile inflow from...

  20. Analysis of flood inundation in ungauged basins based on multi-source remote sensing data. (United States)

    Gao, Wei; Shen, Qiu; Zhou, Yuehua; Li, Xin


    Floods are among the most expensive natural hazards experienced in many places of the world and can result in heavy losses of life and economic damages. The objective of this study is to analyze flood inundation in ungauged basins by performing near-real-time detection with flood extent and depth based on multi-source remote sensing data. Via spatial distribution analysis of flood extent and depth in a time series, the inundation condition and the characteristics of flood disaster can be reflected. The results show that the multi-source remote sensing data can make up the lack of hydrological data in ungauged basins, which is helpful to reconstruct hydrological sequence; the combination of MODIS (moderate-resolution imaging spectroradiometer) surface reflectance productions and the DFO (Dartmouth Flood Observatory) flood database can achieve the macro-dynamic monitoring of the flood inundation in ungauged basins, and then the differential technique of high-resolution optical and microwave images before and after floods can be used to calculate flood extent to reflect spatial changes of inundation; the monitoring algorithm for the flood depth combining RS and GIS is simple and easy and can quickly calculate the depth with a known flood extent that is obtained from remote sensing images in ungauged basins. Relevant results can provide effective help for the disaster relief work performed by government departments.

  1. Static and Dynamic Wetting Behavior of Triglycerides on Solid Surfaces. (United States)

    Michalski; Saramago


    Triglyceride wetting properties on solid surfaces of different hydro-phobicities were investigated using three different methods, namely, the sessile drop method for static contact angle measurements, the Wilhelmy method for dynamic contact angle measurements, and the captive bubble method to investigate thin triglyceride film stability. For solid surfaces having a surface free energy higher than the surface tension of triglycerides (tributyrin, tricaprylin, and triolein), a qualitative correlation was observed between wetting and solid/triglyceride relative hydrophobicities. On surfaces presenting extreme hydrophobic or hydrophilic properties, medium-chain triglycerides had a behavior similar to that of long-chain unsaturated ones. On a high-energy surface (glass), tricaprylin showed an autophobic effect subsequent to molecular adsorption in trident conformation on the solid, observed with the three methods. Thin triglyceride films between an air bubble and a solid surface were stable for a short time, for solids with a surface free energy larger than the triglyceride surface tension. If the solid surface had a lower surface free energy, the thin film collapsed after a time interval which increased with triglyceride viscosity. Copyright 2000 Academic Press.

  2. Influence of Flood Detention Capability in Flood Prevention for Flood Disaster of Depression Area


    Chia Lin Chan; Yi Ju Yang; Chih Chin Yang


    Rainfall records of rainfall station including the rainfall potential per hour and rainfall mass of five heavy storms are explored, respectively from 2001 to 2010. The rationalization formula is to investigate the capability of flood peak duration of flood detention pond in different rainfall conditions. The stable flood detention model is also proposed by using system dynamic control theory to get the message of flood detention pond in this research. When rainfall freque...

  3. Mapping spatio-temporal flood inundation dynamics at large river basin scale using time-series flow data and MODIS imagery (United States)

    Huang, Chang; Chen, Yun; Wu, Jianping


    Flood inundation is crucial to the survival and prosperity of flora and fauna communities in floodplain and wetland ecosystems. This study tried to map flood inundation characteristics in the Murray-Darling Basin, Australia, utilizing hydrological and remotely sensed data. It integrated river flow time series and Moderate Resolution Imaging Spectroradiometer (MODIS) images to map inundation dynamics over the study area on both temporal and spatial dimensions. Flow data were analyzed to derive flow peaks and Annual Exceedance Probabilities (AEPs) using the annual flood series method. The peaks were linked with MODIS images for inundation detection. Ten annual maximum inundation maps were generated for water years 2001-2010, which were then overlaid to derive an inundation frequency map. AEPs were also combined with the annual maximum inundation maps to derive an inundation probability map. The resultant maps revealed spatial and temporal patterns of flood inundation in the basin, which will benefit ecological and environmental studies when considering response of floodplain and wetland ecosystems to flood inundation.

  4. Numerical Simulation of Flood Levels for Tropical Rivers

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Thamer Ahmed; Said, Salim; Bardaie, Mohd Zohadie; Basri, Shah Nor, E-mail: [University Putra Malaysia, Faculty of Engineering (Malaysia)


    Flood forecasting is important for flood damage reduction. As a result of advances in the numerical methods and computer technologies, many mathematical models have been developed and used for hydraulic simulation of the flood. These simulations usually include the prediction of the flood width and depth along a watercourse. Results obtained from the application of hydraulic models will help engineers to take precautionary measures to minimize flood damage. Hydraulic models were used to simulate the flood can be classified into dynamic hydraulic models and static hydraulic models. The HEC-2 static hydraulic model was used to predict water surface profiles for Linggi river and Langat river in Malaysia. The model is based on the numerical solution of the one dimensional energy equation of the steady gradually varied flow using the iteration technique. Calibration and verification of the HEC-2 model were conducted using the recorded data for both rivers. After calibration, the model was applied to predict the water surface profiles for Q10, Q30, and Q100 along the watercourse of the Linggi river. The water surface profile for Q200 for Langat river was predicted. The predicted water surface profiles were found in agreement with the recorded water surface profiles. The value of the maximum computed absolute error in the predicted water surface profile was found to be 500 mm while the minimum absolute error was 20 mm only.

  5. Numerical Simulation of Flood Levels for Tropical Rivers

    International Nuclear Information System (INIS)

    Mohammed, Thamer Ahmed; Said, Salim; Bardaie, Mohd Zohadie; Basri, Shah Nor


    Flood forecasting is important for flood damage reduction. As a result of advances in the numerical methods and computer technologies, many mathematical models have been developed and used for hydraulic simulation of the flood. These simulations usually include the prediction of the flood width and depth along a watercourse. Results obtained from the application of hydraulic models will help engineers to take precautionary measures to minimize flood damage. Hydraulic models were used to simulate the flood can be classified into dynamic hydraulic models and static hydraulic models. The HEC-2 static hydraulic model was used to predict water surface profiles for Linggi river and Langat river in Malaysia. The model is based on the numerical solution of the one dimensional energy equation of the steady gradually varied flow using the iteration technique. Calibration and verification of the HEC-2 model were conducted using the recorded data for both rivers. After calibration, the model was applied to predict the water surface profiles for Q10, Q30, and Q100 along the watercourse of the Linggi river. The water surface profile for Q200 for Langat river was predicted. The predicted water surface profiles were found in agreement with the recorded water surface profiles. The value of the maximum computed absolute error in the predicted water surface profile was found to be 500 mm while the minimum absolute error was 20 mm only.

  6. A Modified Dynamic Surface Controller for Delayed Neuromuscular Electrical Stimulation. (United States)

    Alibeji, Naji; Kirsch, Nicholas; Dicianno, Brad E; Sharma, Nitin


    A widely accepted model of muscle force generation during neuromuscular electrical stimulation (NMES) is a second-order nonlinear musculoskeletal dynamics cascaded to a delayed first-order muscle activation dynamics. However, most nonlinear NMES control methods have either neglected the muscle activation dynamics or used an ad hoc strategies to tackle the muscle activation dynamics, which may not guarantee control stability. We hypothesized that a nonlinear control design that includes muscle activation dynamics can improve the control performance. In this paper, a dynamic surface control (DSC) approach was used to design a PID-based NMES controller that compensates for EMD in the activation dynamics. Because the muscle activation is unmeasurable, a model based estimator was used to estimate the muscle activation in realtime. The Lyapunov stability analysis confirmed that the newly developed controller achieves semi-global uniformly ultimately bounded (SGUUB) tracking for the musculoskeletal system. Experiments were performed on two able-bodied subjects and one spinal cord injury subject using a modified leg extension machine. These experiments illustrate the performance of the new controller and compare it to a previous PID-DC controller that did not consider muscle activation dynamics in the control design. These experiments support our hypothesis that a control design that includes muscle activation improves the NMES control performance.

  7. Dynamics of H2 on Ti/Al(100) surfaces

    NARCIS (Netherlands)

    Chen, Jian-Cheng


    What is the catalytic role played by titanium in the hydrogen storage material NaAlH4? This thesis aims at unraveling the dynamics of an elementary reaction: H2 dissociation on Ti/Al(100) surfaces. Although this reaction is not the rate limiting step in the hydrogen storage of NaAlH4, it is an

  8. Ti and Zr surfaces studied by molecular dynamics

    International Nuclear Information System (INIS)

    Pascuet, Maria I.; Passianot, Roberto C.; Monti, Ana M.


    The interaction between point defects technique and the (0001), (1-210), (10-10) surfaces in Ti and Zr is studied by the molecular dynamics technique. Both of metals are in the hexagonal structure and within a temperature range of 100 to 900 K. The atomic interactions are modeled by EAM-type many-body potentials, that were used previously in static simulations. New migration mechanisms are unraveled and others are verified with respect to those already proposed in the static studies. Also included is an analysis of the vacancy stability in the sub-surface layers of the prismatic surfaces. (author)

  9. Decay of surface nanostructures via long-time-scale dynamics

    International Nuclear Information System (INIS)

    Voter, A.F.; Stanciu, N.


    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have developed a new approach for extending the time scale of molecular dynamics simulations. For infrequent-event systems, the category that includes most diffusive events in the solid phase, this hyperdynamics method can extend the simulation time by a few orders of magnitude compared to direct molecular dynamics. The trajectory is run on a potential surface that has been biased to raise the energy in the potential basins without affecting the transition state region. The method is described and applied to surface and bulk diffusion processes, achieving microsecond and millisecond simulation times. The authors have also developed a new parallel computing method that is efficient for small system sizes. The combination of the hyperdynamics with this parallel replica dynamics looks promising as a general materials simulation tool

  10. Dynamic stability of communities of amphibians in short-term-flooded forest ecosystems

    Directory of Open Access Journals (Sweden)

    O. V. Zhukov


    Full Text Available The estimation of stability of amphibian populations on the basis of data of population dynamics is given. The paper shows an attempt to estimate the direction of dynamic changes of amphibian populations, and defines the rate of the system deviation from the stationary state due to possible influence of the environmental factors by using concepts such as reactivity, degree of reactivity and flexibility of the system when using their indexes. It is found that populations of amphibians are quite stable with regard to quantifying these species. Characteristic feature is the elasticity of the system. It is confirmed by the elasticity of the system species Bufo bufo (Linnaeus, 1758. TypePelobates fuscus (Laurenti, 1768 is defined as a factor of stability of the system in quantitative terms. Dependenceof dynamics of the population on its size is established using the regression equation. Dynamics of groups depends on the action of possible predictors in response to which the population of B. bufo is not changed. The ecosystem is characterized as a place of interaction between biotic factors and factors of abiotic origin, which are due to the external action. Internal factor of the ecosystem stability is the influence of some amphibian populations on the other ones. The system features sustainable and relatively stable number of B. bufo, which does not affect the level of its stability. Stationary state of the grouping is unstable due to dynamic matrix, which describes the behavior of the group in the vicinity of the first stationary state. The second steady state is stableone, and the system returns to the stationary state with the help of wave-like dynamics. On the basis of our study it is established that the number of groups of amphibians remains stable, the systems behave differently, and dynamics of their return to the stationary state is elastic or reactive one. Еcosystems within lime-ash oak forests in the Central floodplain of the Samarariver

  11. A New Method for Urban Storm Flood Inundation Simulation with Fine CD-TIN Surface

    Directory of Open Access Journals (Sweden)

    Zhifeng Li


    Full Text Available Urban storm inundation, which frequently has dramatic impacts on city safety and social life, is an emergent and difficult issue. Due to the complexity of urban surfaces and the variety of spatial modeling elements, the lack of detailed hydrological data and accurate urban surface models compromise the study and implementation of urban storm inundation simulations. This paper introduces a Constrained Delaunay Triangular Irregular Network (CD-TIN to model fine urban surfaces (based on detailed ground sampling data and subsequently employs a depression division method that refers to Fine Constrained Features (FCFs to construct computational urban water depressions. Storm-runoff yield is placed through mass conservation to calculate the volume of rainfall, runoff and drainage. The water confluences between neighboring depressions are provided when the water level exceeds the outlet of a certain depression. Numerical solutions achieved through a dichotomy are introduced to obtain the water level. Therefore, the continuous inundation process can be divided into different time intervals to obtain a series of inundation scenarios. The main campus of Beijing Normal University (BNU was used as a case study to simulate the “7.21” storm inundation event to validate the usability and suitability of the proposed methods. In comparing the simulation results with in-situ observations, the proposed method is accurate and effective, with significantly lower drainage data requirements being obtained. The proposed methods will also be useful for urban drainage design and city inundation emergency preparations.

  12. Reaction dynamics of molecular hydrogen on silicon surfaces

    DEFF Research Database (Denmark)

    Bratu, P.; Brenig, W.; Gross, A.


    Experimental and theoretical results on the dynamics of dissociative adsorption and recombinative desorption of hydrogen on silicon are presented. Using optical second-harmonic generation, extremely small sticking probabilities in the range 10(-9)-10(-5) could be measured for H-2 and D-2 on Si(111......)7X7 and Si(100)2X1. Strong phonon-assisted sticking was observed for gases at 300 K and surface temperatures between 550 K and 1050 K. The absolute values as well as the temperature variation of the adsorption and desorption rates show surprisingly little isotope effect, and they differ only little...... between the two surfaces. These results indicate that tunneling, molecular vibrations, and the structural details of the surface play only a minor role for the adsorption dynamics. Instead, they appear to be governed by the localized H-Si bonding and Si-Si lattice vibrations. Theoretically, an effective...

  13. Critical bifurcation surfaces of 3D discrete dynamics

    Directory of Open Access Journals (Sweden)

    Michael Sonis


    Full Text Available This paper deals with the analytical representation of bifurcations of each 3D discrete dynamics depending on the set of bifurcation parameters. The procedure of bifurcation analysis proposed in this paper represents the 3D elaboration and specification of the general algorithm of the n-dimensional linear bifurcation analysis proposed by the author earlier. It is proven that 3D domain of asymptotic stability (attraction of the fixed point for a given 3D discrete dynamics is bounded by three critical bifurcation surfaces: the divergence, flip and flutter surfaces. The analytical construction of these surfaces is achieved with the help of classical Routh–Hurvitz conditions of asymptotic stability. As an application the adjustment process proposed by T. Puu for the Cournot oligopoly model is considered in detail.

  14. Flood Simulations and Uncertainty Analysis for the Pearl River Basin Using the Coupled Land Surface and Hydrological Model System

    Directory of Open Access Journals (Sweden)

    Yongnan Zhu


    Full Text Available The performances of hydrological simulations for the Pearl River Basin in China were analysed using the Coupled Land Surface and Hydrological Model System (CLHMS. Three datasets, including East Asia (EA, high-resolution gauge satellite-merged China Merged Precipitation Analysis (CMPA-Daily, and the Asian Precipitation Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE daily precipitation were used to drive the CLHMS model to simulate daily hydrological processes from 1998 to 2006. The results indicate that the precipitation data was the most important source of uncertainty in the hydrological simulation. The simulated streamflow driven by the CMPA-Daily agreed well with observations, with a Pearson correlation coefficient (PMC greater than 0.70 and an index of agreement (IOA similarity coefficient greater than 0.82 at Liuzhou, Shijiao, and Wuzhou Stations. Comparison of the Nash-Sutcliffe efficiency coefficient (NSE shows that the peak flow simulation ability of CLHMS driven with the CMPA-Daily rainfall is relatively superior to that with the EA and APHRODITE datasets. The simulation results for the high-flow periods in 1998 and 2005 indicate that the CLHMS is promising for its future application in the flood simulation and prediction.

  15. Drop impact and rebound dynamics on an inclined superhydrophobic surface. (United States)

    Yeong, Yong Han; Burton, James; Loth, Eric; Bayer, Ilker S


    Due to its potential in water-repelling applications, the impact and rebound dynamics of a water drop impinging perpendicular to a horizontal superhydrophobic surface have undergone extensive study. However, drops tend to strike a surface at an angle in applications. In such cases, the physics governing the effects of oblique impact are not well studied or understood. Therefore, the objective of this study was to conduct an experiment to investigate the impact and rebound dynamics of a drop at various liquid viscosities, in an isothermal environment, and on a nanocomposite superhydrophobic surface at normal and oblique impact conditions (tilted at 15°, 30°, 45°, and 60°). This study considered drops falling from various heights to create normal impact Weber numbers ranging from 6 to 110. In addition, drop viscosity was varied by decreasing the temperature for water drops and by utilizing water-glycerol mixtures, which have similar surface tension to water but higher viscosities. Results revealed that oblique and normal drop impact behaved similarly (in terms of maximum drop spread as well as rebound dynamics) at low normal Weber numbers. However, at higher Weber numbers, normal and oblique impact results diverged in terms of maximum spread, which could be related to asymmetry and more complex outcomes. These asymmetry effects became more pronounced as the inclination angle increased, to the point where they dominated the drop impact and rebound characteristics when the surface was inclined at 60°. The drop rebound characteristics on inclined surfaces could be classified into eight different outcomes driven primarily by normal Weber number and drop Ohnesorge numbers. However, it was found that these outcomes were also a function of the receding contact angle, whereby reduced receding angles yielded tail-like structures. Nevertheless, the contact times of the drops with the coating were found to be generally independent of surface inclination.

  16. Memory effects in nonadiabatic molecular dynamics at metal surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob


    We study the effect of temporal correlation in a Langevin equation describing nonadiabatic dynamics at metal surfaces. For a harmonic oscillator, the Langevin equation preserves the quantum dynamics exactly and it is demonstrated that memory effects are needed in order to conserve the ground state......, this approach is readily extended to anharmonic potentials. Using density functional theory, we calculate representative Langevin trajectories for associative desorption of N-2 from Ru(0001) and find that memory effects lower the dissipation of energy. Finally, we propose an ab initio scheme to calculate...

  17. Dynamic inundation mapping of Hurricane Harvey flooding in the Houston metro area using hyper-resolution modeling and quantitative image reanalysis (United States)

    Noh, S. J.; Lee, J. H.; Lee, S.; Zhang, Y.; Seo, D. J.


    Hurricane Harvey was one of the most extreme weather events in Texas history and left significant damages in the Houston and adjoining coastal areas. To understand better the relative impact to urban flooding of extreme amount and spatial extent of rainfall, unique geography, land use and storm surge, high-resolution water modeling is necessary such that natural and man-made components are fully resolved. In this presentation, we reconstruct spatiotemporal evolution of inundation during Hurricane Harvey using hyper-resolution modeling and quantitative image reanalysis. The two-dimensional urban flood model used is based on dynamic wave approximation and 10 m-resolution terrain data, and is forced by the radar-based multisensor quantitative precipitation estimates. The model domain includes Buffalo, Brays, Greens and White Oak Bayous in Houston. The model is simulated using hybrid parallel computing. To evaluate dynamic inundation mapping, we combine various qualitative crowdsourced images and video footages with LiDAR-based terrain data.

  18. Global and regional aspects for genesis of catastrophic floods - the problems of forecasting and estimates for mass and water balance (surface and groundwater contribution) (United States)

    Trifonova, Tatiana; Arakelian, Sergei; Trifonov, Dmitriy; Abrakhin, Sergei


    1. The principal goal of present talk is, to discuss the existing uncertainty and discrepancy between water balance estimation for the area under heavy rain flood, on the one hand from the theoretical approach and reasonable data base due to rainfall going from atmosphere and, on the other hand the real practicle surface water flow parameters measured by some methods and/or fixed by some eye-witness (cf. [1]). The vital item for our discussion is that the last characteristics sometimes may be noticeably grater than the first ones. Our estimations show the grater water mass discharge observation during the events than it could be expected from the rainfall process estimation only [2]. The fact gives us the founding to take into account the groundwater possible contribution to the event. 2. We carried out such analysis, at least, for two catastrophic water events in 2015, i.e. (1) torrential rain and catastrophic floods in Lousiana (USA), June 16-20; (2) Assam flood (India), Aug. 22 - Sept. 8. 3. Groundwater flood of a river terrace discussed e.g. in [3] but in respect when rise of the water table above the land surface occurs coincided with intense rainfall and being as a relatively rare phenomenon. In our hypothesis the principal part of possible groundwater exit to surface is connected with a crack-net system state in earth-crust (including deep layers) as a water transportation system, first, being in variated pressure field for groundwater basin and, second, modified by different reasons ( both suddenly (the Krimsk-city flash flood event, July 2012, Russia) and/or smoothly (the Amur river flood event, Aug.-Sept. 2013, Russia) ). Such reconstruction of 3D crack-net under external reasons (resulting even in local variation of pressures in any crack-section) is a principal item for presented approach. 4. We believe that in some cases the interconnection of floods and preceding earthquakes may occur. The problem discuss by us for certain events ( e.g. in addition to

  19. Modeling Apple Surface Temperature Dynamics Based on Weather Data

    Directory of Open Access Journals (Sweden)

    Lei Li


    Full Text Available The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management.

  20. GIS Support for Flood Rescue

    DEFF Research Database (Denmark)

    Liang, Gengsheng; Mioc, Darka; Anton, François


    Under flood events, the ground traffic is blocked in and around the flooded area due to damages to roads and bridges. The traditional transportation network may not always help people to make a right decision for evacuation. In order to provide dynamic road information needed for flood rescue, we...... to retrieve the shortest and safest route in Fredericton road network during flood event. It enables users to make a timely decision for flood rescue. We are using Oracle Spatial to deal with emergency situations that can be applied to other constrained network applications as well....

  1. Evaporation dynamics of completely wetting drops on geometrically textured surfaces (United States)

    Mekhitarian, Loucine; Sobac, Benjamin; Dehaeck, Sam; Haut, Benoît; Colinet, Pierre


    This study deals with the evaporation dynamics of completely wetting and highly volatile drops deposited on geometrically textured but chemically homogeneous surfaces. The texturation consists in a cylindrical pillars array with a square pitch. The triple line dynamics and the drop shape are characterized by an interferometric method. A parametric study is realized by varying the radius and the height of the pillars (at fixed interpillar distance), allowing to distinguish three types of dynamics: i) an evaporation-dominated regime with a receding triple line; ii) a spreading-dominated regime with an initially advancing triple line; iii) a cross-over region with strong pinning effects. The overall picture is in qualitative agreement with a mathematical model showing that the selected regime mostly depends on the value of a dimensionless parameter comparing the time scales for evaporation and spreading into the substrate texture.

  2. Dynamic Surface Control and Its Application to Lateral Vehicle Control

    Directory of Open Access Journals (Sweden)

    Bongsob Song


    Full Text Available This paper extends the design and analysis methodology of dynamic surface control (DSC in Song and Hedrick, 2011, for a more general class of nonlinear systems. When rotational mechanical systems such as lateral vehicle control and robot control are considered for applications, sinusoidal functions are easily included in the equation of motions. If such a sinusoidal function is used as a forcing term for DSC, the stability analysis faces the difficulty due to highly nonlinear functions resulting from the low-pass filter dynamics. With modification of input variables to the filter dynamics, the burden of mathematical analysis can be reduced and stability conditions in linear matrix inequality form to guarantee the quadratic stability via DSC are derived for the given class of nonlinear systems. Finally, the proposed design and analysis approach are applied to lateral vehicle control for forward automated driving and backward parallel parking at a low speed as well as an illustrative example.

  3. Dynamics and Instabilities of Free Surface and Vortex Flows

    DEFF Research Database (Denmark)

    Tophøj, Laust Emil Hjerrild


    This PhD thesis consists of two main parts. The first part describes the dynamics of an ideal fluid on a stationary free surface of a given shape. It turns out that one can formulate a set of self-contained equations of momentum conservation for the tangential flow, with no reference to the flow ......)]. Finally, an experimental work on elastic collisions of wet spheres is briefly discussed....

  4. Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces. (United States)

    Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli


    Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.

  5. The European Continent : Surface Expression of Upper Mantle Dynamics (United States)

    Tondi, M. R.; Schivardi, R.; Molinari, I.; Morelli, A.


    The surface topography of Europe shows important variations, most of which are relatively well explained by isostatic compensation of density contrasts within the crust and lithosphere. However, not all of the density contrasts leading to topography reside within the lithosphere. The crucial problem is how to detect the extra topography signal, in addition to that associated with both crustal and lithospheric anomalies. Forte and Perry, 2000 estimate the amplitude of the dynamic topography by removal of the crustal isostatic topography signal from the surface of the Earth. Faccenna and Becker, 2010 infer the equivalent dynamic topography from the normal stress generated at the surface by mantle viscous flow driven by thermal anomalies. Here we consider the correlation between residual topography and mantle residual gravity anomalies. As shown by Pekeris, 1935 and Hager et al., 1985, the viscous mantle flow that is driven by the thermal density contrasts is responsible for the long-wavelength gravity anomalies observed at the surface. They have demonstrated that the gravitational effects of surface deformation caused by the flow is opposite in sign and comparable in magnitude to that of the driving density contrast. The 1°x1° recently assembled European crustal model, EPCrust (Molinari and Morelli, 2011) is used to estimate the effects of the isostatic crust and the mantle residual gravity anomalies. We calculate the correlation matrix between the residual topography and the mantle residual gravity anomalies and we define the regions where the sublithospheric mantle density, below the European continent, contributes to surface topography. To recover the residual topography, the effects of the isostatic crust is estimated with the Panasyuk and Hager (2000) algorithm and subtracted from the observed elevation (ETOPO-1). The mantle residual gravity anomalies are estimated as the differences between the produced gravity field of EPCrust and the observations. 3-D

  6. Biofilm attachment reduction on bioinspired, dynamic, micro-wrinkling surfaces

    International Nuclear Information System (INIS)

    Epstein, Alexander K; Hong, Donggyoon; Kim, Philseok; Aizenberg, Joanna


    Most bacteria live in multicellular communities known as biofilms that are adherent to surfaces in our environment, from sea beds to plumbing systems. Biofilms are often associated with clinical infections, nosocomial deaths and industrial damage such as bio-corrosion and clogging of pipes. As mature biofilms are extremely challenging to eradicate once formed, prevention is advantageous over treatment. However, conventional surface chemistry strategies are either generally transient, due to chemical masking, or toxic, as in the case of leaching marine antifouling paints. Inspired by the nonfouling skins of echinoderms and other marine organisms, which possess highly dynamic surface structures that mechanically frustrate bio-attachment, we have developed and tested a synthetic platform based on both uniaxial mechanical strain and buckling-induced elastomer microtopography. Bacterial biofilm attachment to the dynamic substrates was studied under an array of parameters, including strain amplitude and timescale (1–100 mm s −1 ), surface wrinkle length scale, bacterial species and cell geometry, and growth time. The optimal conditions for achieving up to ∼ 80% Pseudomonas aeruginosa biofilm reduction after 24 h growth and ∼ 60% reduction after 48 h were combinatorially elucidated to occur at 20% strain amplitude, a timescale of less than ∼ 5 min between strain cycles and a topography length scale corresponding to the cell dimension of ∼ 1 μm. Divergent effects on the attachment of P. aeruginosa, Staphylococcus aureus and Escherichia coli biofilms showed that the dynamic substrate also provides a new means of species-specific biofilm inhibition, or inversely, selection for a desired type of bacteria, without reliance on any toxic or transient surface chemical treatments. (paper)

  7. Biofilm attachment reduction on bioinspired, dynamic, micro-wrinkling surfaces (United States)

    Epstein, Alexander K.; Hong, Donggyoon; Kim, Philseok; Aizenberg, Joanna


    Most bacteria live in multicellular communities known as biofilms that are adherent to surfaces in our environment, from sea beds to plumbing systems. Biofilms are often associated with clinical infections, nosocomial deaths and industrial damage such as bio-corrosion and clogging of pipes. As mature biofilms are extremely challenging to eradicate once formed, prevention is advantageous over treatment. However, conventional surface chemistry strategies are either generally transient, due to chemical masking, or toxic, as in the case of leaching marine antifouling paints. Inspired by the nonfouling skins of echinoderms and other marine organisms, which possess highly dynamic surface structures that mechanically frustrate bio-attachment, we have developed and tested a synthetic platform based on both uniaxial mechanical strain and buckling-induced elastomer microtopography. Bacterial biofilm attachment to the dynamic substrates was studied under an array of parameters, including strain amplitude and timescale (1-100 mm s-1), surface wrinkle length scale, bacterial species and cell geometry, and growth time. The optimal conditions for achieving up to ˜ 80% Pseudomonas aeruginosa biofilm reduction after 24 h growth and ˜ 60% reduction after 48 h were combinatorially elucidated to occur at 20% strain amplitude, a timescale of less than ˜ 5 min between strain cycles and a topography length scale corresponding to the cell dimension of ˜ 1 μm. Divergent effects on the attachment of P. aeruginosa, Staphylococcus aureus and Escherichia coli biofilms showed that the dynamic substrate also provides a new means of species-specific biofilm inhibition, or inversely, selection for a desired type of bacteria, without reliance on any toxic or transient surface chemical treatments.

  8. City-scale accessibility of emergency responders operating during flood events (United States)

    Green, Daniel; Yu, Dapeng; Pattison, Ian; Wilby, Robert; Bosher, Lee; Patel, Ramila; Thompson, Philip; Trowell, Keith; Draycon, Julia; Halse, Martin; Yang, Lili; Ryley, Tim


    Emergency responders often have to operate and respond to emergency situations during dynamic weather conditions, including floods. This paper demonstrates a novel method using existing tools and datasets to evaluate emergency responder accessibility during flood events within the city of Leicester, UK. Accessibility was quantified using the 8 and 10 min legislative targets for emergency provision for the ambulance and fire and rescue services respectively under "normal" no-flood conditions, as well as flood scenarios of various magnitudes (1 in 20-year, 1 in 100-year and 1 in 1000-year recurrence intervals), with both surface water and fluvial flood conditions considered. Flood restrictions were processed based on previous hydrodynamic inundation modelling undertaken and inputted into a Network Analysis framework as restrictions for surface water and fluvial flood events. Surface water flooding was shown to cause more disruption to emergency responders operating within the city due to its widespread and spatially distributed footprint when compared to fluvial flood events of comparable magnitude. Fire and rescue 10 min accessibility was shown to decrease from 100, 66.5, 39.8 and 26.2 % under the no-flood, 1 in 20-year, 1 in 100-year and 1 in 1000-year surface water flood scenarios respectively. Furthermore, total inaccessibility was shown to increase with flood magnitude from 6.0 % under the 1 in 20-year scenario to 31.0 % under the 1 in 100-year flood scenario. Additionally, the evolution of emergency service accessibility throughout a surface water flood event is outlined, demonstrating the rapid impact on emergency service accessibility within the first 15 min of the surface water flood event, with a reduction in service coverage and overlap being observed for the ambulance service during a 1 in 100-year flood event. The study provides evidence to guide strategic planning for decision makers prior to and during emergency response to flood events at the city

  9. Manipulating dynamic drops using a hybrid superhydrophobic/hydrophilic surface (United States)

    Guo, Yunhe; Song, Dong; Song, Baowei; Hu, Haibao


    A hybrid surface composed of superhydrophobic patterns on hydrophilic substrate was fabricated by selective painting. The impingement of a water drop on this surface was investigated using lattice Boltzmann simulation. When a drop impinged on the boundary line between the superhydrophobic and hydrophilic area, the drop would spread preferentially to the hydrophilic area while the spreading at the superhydrophobic area was highly impeded. The maximum spreading diameters as well as the spreading time, which are extremely important for the heat transfer on solid surfaces, were analyzed in detail. By adjusting the distance between the landing point and the boundary line of the superhydrophobic/hydrophilic area, the maximum spreading diameter and spreading time could be altered precisely. The impinging velocity has been found to be important on the manipulation of the dynamic droplet as well.

  10. DNSC08 mean sea surface and mean dynamic topography models

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Knudsen, Per


    -2004. It is the first global MSS without a polar gap including all of the Arctic Ocean by including laser altimetry from the ICESat mission. The mean dynamic topography (MDT) is the quantity that bridges the geoid and the mean sea surface constraining large-scale ocean circulation. Here we present a new high...... models. This way a consistent modeling of the interannual sea level variability is carried out before different MSS and MDT models are compared. Altimetric derived physical MSS can be converted into an "inverse barometer corrected MSS'' by correcting the altimeter range for the inverse barometer effect......The Danish National Space Center data set DNSC08 mean sea surface (MSS) is a new enhanced mapping of the mean sea surface height of the worlds oceans, derived from a combination of 12 years of satellite altimetry from a total of eight different satellites covering the period 1993...

  11. Investigating the temporal dynamics of suspended sediment during flood events with 7Be and 210Pbxs measurements in a drained lowland catchment (United States)

    Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Manière, Louis; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie


    Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. High suspended sediment loads, often generated from eroding agricultural landscapes, are known to degrade downstream environments. Accordingly, there is a need to understand soil erosion dynamics during flood events. Suspended sediment was therefore sampled in the river network and at tile drain outlets during five flood events in a lowland drained catchment in France. Source and sediment fallout radionuclide concentrations (7Be, 210Pbxs) were measured to quantify both the fraction of recently eroded particles transported during flood events and their residence time. Results indicate that the mean fraction of recently eroded sediment, estimated for the entire Louroux catchment, increased from 45 ± 20% to 80 ± 20% between December 2013 and February 2014, and from 65 ± 20% to 80 ± 20% in January 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel before the increasing supply of sediment recently eroded from the hillslopes during subsequent events. This research highlights the utility of coupling continuous river monitoring and fallout radionuclide measurements to increase our understanding of sediment dynamics and improve the management of soil and water resources in agricultural catchments.

  12. Adaptive integral dynamic surface control of a hypersonic flight vehicle (United States)

    Aslam Butt, Waseem; Yan, Lin; Amezquita S., Kendrick


    In this article, non-linear adaptive dynamic surface air speed and flight path angle control designs are presented for the longitudinal dynamics of a flexible hypersonic flight vehicle. The tracking performance of the control design is enhanced by introducing a novel integral term that caters to avoiding a large initial control signal. To ensure feasibility, the design scheme incorporates magnitude and rate constraints on the actuator commands. The uncertain non-linear functions are approximated by an efficient use of the neural networks to reduce the computational load. A detailed stability analysis shows that all closed-loop signals are uniformly ultimately bounded and the ? tracking performance is guaranteed. The robustness of the design scheme is verified through numerical simulations of the flexible flight vehicle model.

  13. Dynamic surface fault tolerant control for underwater remotely operated vehicles. (United States)

    Baldini, Alessandro; Ciabattoni, Lucio; Felicetti, Riccardo; Ferracuti, Francesco; Freddi, Alessandro; Monteriù, Andrea


    In this paper, we present a two stages actuator Fault Tolerant Control (FTC) strategy for the trajectory tracking of a Remotely Operated Vehicle (ROV). Dynamic Surface Control (DSC) is used to generate the moment and forces required by the vehicle to perform the desired motion. In the second stage of the control system, a fault tolerant thruster allocation policy is employed to distribute moment and forces among the thrusters. Exhaustive simulations have been carried out in order to compare the performance of the proposed solution with respect to different control techniques (i.e., PID, backstepping and sliding mode approaches). Saturations, actuator dynamics, sensor noises and time discretization are considered, in fault-free and faulty conditions. Furthermore, in order to provide a fair and exhaustive comparison of the control techniques, the same meta-heuristic approach, namely Artificial Bee Colony algorithm (ABC), has been employed to tune the controllers parameters. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  14. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva


    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  15. Probabilistic mapping of flood-induced backscatter changes in SAR time series (United States)

    Schlaffer, Stefan; Chini, Marco; Giustarini, Laura; Matgen, Patrick


    The information content of flood extent maps can be increased considerably by including information on the uncertainty of the flood area delineation. This additional information can be of benefit in flood forecasting and monitoring. Furthermore, flood probability maps can be converted to binary maps showing flooded and non-flooded areas by applying a threshold probability value pF = 0.5. In this study, a probabilistic change detection approach for flood mapping based on synthetic aperture radar (SAR) time series is proposed. For this purpose, conditional probability density functions (PDFs) for land and open water surfaces were estimated from ENVISAT ASAR Wide Swath (WS) time series containing >600 images using a reference mask of permanent water bodies. A pixel-wise harmonic model was used to account for seasonality in backscatter from land areas caused by soil moisture and vegetation dynamics. The approach was evaluated for a large-scale flood event along the River Severn, United Kingdom. The retrieved flood probability maps were compared to a reference flood mask derived from high-resolution aerial imagery by means of reliability diagrams. The obtained performance measures indicate both high reliability and confidence although there was a slight under-estimation of the flood extent, which may in part be attributed to topographically induced radar shadows along the edges of the floodplain. Furthermore, the results highlight the importance of local incidence angle for the separability between flooded and non-flooded areas as specular reflection properties of open water surfaces increase with a more oblique viewing geometry.

  16. The Community Surface Dynamics Modeling System: Experiences on Building a Collaborative Modeling Platform (United States)

    Overeem, I.; Hutton, E.; Kettner, A.; Peckham, S. D.; Syvitski, J. P.


    The Community Surface Dynamics Modeling System - CSDMS- develops a software platform with shared and coupled modules for modeling earth surface processes as a community resource. The framework allows prediction of water, sediment and nutrient transport through the landscape and seacape. The underlying paradigm is that the Earth surface we live on is a dynamic system; topography changes with seasons, with landslides and earthquakes, with erosion and deposition. The Earth Surface changes due to storms and floods, and important boundaries, like the coast, are ever-moving features. CSDMS sets out to make better predictions of these changes. Earth surface process modeling bridges the terrestrial, coastal and marine domains and requires understanding of the system over a range of time scales, which inherently needs interdisciplinarity. Members of CSDMS (~830 in July 2012) are largely from academic institutions (˜75%), followed by federal agencies (˜17%), and oil and gas companies (˜5%). Members and governmental bodies meet once annually and rely additionally on web-based information for communication. As an organization that relies on volunteer participation, CSDMS faces challenges to scientific collaboration. Encouraging volunteerism among its members to provide and adapt metadata and model code to be sufficiently standardized for coupling is crucial to building an integrated community modeling system. We here present CSDMS strategies aimed at providing the appropriate technical tools and cyberinfrastructure to support a variety of user types, ranging from advanced to novice modelers. Application of these advances in science is key, both into the educational realm and for managers and decision-makers. We discuss some of the implemented ideas to further organizational transparency and user engagement in small-scale governance, such as advanced trackers and voting systems for model development prioritization through the CSDMS wiki. We analyzed data on community

  17. Electrokinetics of nanochannels and porous membranes with dynamic surface charges

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo

    interesting because it relies on capillary filling, so it avoids the use of external forcing such as electric fields. Basically, during the filling of nanochannels by capillary action, the advancing electrolyte is titrated by deprotonation from the surface. This is observed using the pH-sensitive fluorescent....... Notably, we find that the conductance minimum is mainly caused by hydronium ions, and in our case almost exclusively due to carbonic acid generated from the dissolution of CO2 from the atmosphere. We carry out delicate experiments and measure the conductance of silica nanochannels as a function...... in the literature. Fourth, we use our model to predict a novel phenomenon called currentinduced membrane discharge (CIMD) to explain over-limiting current in ionexchange membranes. The model is based on dynamic surface charges in the membrane in equilibrium with the buffer. However, here we take the next step...

  18. Poly(lactic acid) Polymer Brushes as Dynamic Surfaces (United States)

    Xu, Le Bo

    Degradable Poly(lactic acid), PLA, polymer brushes, were prepared to use as a temporary protective layer on a substrate. The PLA brushes degraded under basic conditions, which distinguished from bulk PLA, as well as PLA oligomer. The underlying substrate was able to be exposed with the removal of PLA brushes, resulting in a dynamic behavior. PLA brushes were grafted from silicon and gold substrates through surface initiated ring opening polymerization, ROP, of lactide catalyzed by tin octoate. The surface silanol groups on silicon and hydroxyl-terminated thiol self-assembled monolayers, SAMs, on gold were used as immobilized initiators for the surface initiated polymerization. The surface silanol groups worked equally well as the alcohol species to serve as initiator for the ROP of lactide. Synthesis conditions, such as temperature, monomer concentration and the type of catalyst and solvent, were explored to pursue the maximum brush thickness and well controlled growth on the surface. It was highlighted the different optimized synthesis conditions between the ROP in solution and the surface initiated ROP due to the equilibrium behavior of ROP. Both molecular weight and monomer conversion were considered in solution ROP. However, monomer conversion was not that important for surface ROP given merely trace amount of polymer was grafted on the surface as brushes. It was also demonstrated that the thickness of PLA brush could be tuned by varying either growth time or grafting density. The PLA brushes with a gradient thickness were prepared by gradually filling a reaction container with reactive solution. PLA brushes were able to be removed by immersing them in basic aqueous solution. The degradation of PLA brushes was found to be unique. Bulk PLA degraded under acidic conditions. The degradation of PLA oligomer occurred under both acidic and basic conditions. While the PLA brushes only degraded under basic conditions. The base-catalyzed degradation suggests the

  19. Pseudospectral Gaussian quantum dynamics: Efficient sampling of potential energy surfaces. (United States)

    Heaps, Charles W; Mazziotti, David A


    Trajectory-based Gaussian basis sets have been tremendously successful in describing high-dimensional quantum molecular dynamics. In this paper, we introduce a pseudospectral Gaussian-based method that achieves accurate quantum dynamics using efficient, real-space sampling of the time-dependent basis set. As in other Gaussian basis methods, we begin with a basis set expansion using time-dependent Gaussian basis functions guided by classical mechanics. Unlike other Gaussian methods but characteristic of the pseudospectral and collocation methods, the basis set is tested with N Dirac delta functions, where N is the number of basis functions, rather than using the basis function as test functions. As a result, the integration for matrix elements is reduced to function evaluation. Pseudospectral Gaussian dynamics only requires O(N) potential energy calculations, in contrast to O(N(2)) evaluations in a variational calculation. The classical trajectories allow small basis sets to sample high-dimensional potentials. Applications are made to diatomic oscillations in a Morse potential and a generalized version of the Henon-Heiles potential in two, four, and six dimensions. Comparisons are drawn to full analytical evaluation of potential energy integrals (variational) and the bra-ket averaged Taylor (BAT) expansion, an O(N) approximation used in Gaussian-based dynamics. In all cases, the pseudospectral Gaussian method is competitive with full variational calculations that require a global, analytical, and integrable potential energy surface. Additionally, the BAT breaks down when quantum mechanical coherence is particularly strong (i.e., barrier reflection in the Morse oscillator). The ability to obtain variational accuracy using only the potential energy at discrete points makes the pseudospectral Gaussian method a promising avenue for on-the-fly dynamics, where electronic structure calculations become computationally significant.

  20. Dynamic growth of slip surfaces in catastrophic landslides. (United States)

    Germanovich, Leonid N; Kim, Sihyun; Puzrin, Alexander M


    This work considers a landslide caused by the shear band that emerges along the potential slip (rupture) surface. The material above the band slides downwards, causing the band to grow along the slope. This growth may first be stable (progressive), but eventually becomes dynamic (catastrophic). The landslide body acquires a finite velocity before it separates from the substrata. The corresponding initial-boundary value problem for a dynamic shear band is formulated within the framework of Palmer & Rice's ( Proc. R. Soc. Lond. A 332 , 527-548. (doi:10.1098/rspa.1973.0040)) approach, which is generalized to the dynamic case. We obtain the exact, closed-form solution for the band velocity and slip rate. This solution assesses when the slope fails owing to a limiting condition near the propagating tip of the shear band. Our results are applicable to both submarine and subaerial landslides of this type. It appears that neglecting dynamic (inertia) effects can lead to a significant underestimation of the slide size, and that the volumes of catastrophic slides can exceed the volumes of progressive slides by nearly a factor of 2. As examples, we consider the Gaviota and Humboldt slides offshore of California, and discuss landslides in normally consolidated sediments and sensitive clays. In particular, it is conceivable that Humboldt slide is unfinished and may still displace a large volume of sediments, which could generate a considerable tsunami. We show that in the case of submarine slides, the effect of water resistance on the shear band dynamics may frequently be limited during the slope failure stage. For a varying slope angle, we formulate a condition of slide cessation.

  1. Dynamic and reversible surface topography influences cell morphology. (United States)

    Kiang, Jennifer D; Wen, Jessica H; del Álamo, Juan C; Engler, Adam J


    Microscale and nanoscale surface topography changes can influence cell functions, including morphology. Although in vitro responses to static topography are novel, cells in vivo constantly remodel topography. To better understand how cells respond to changes in topography over time, we developed a soft polyacrylamide hydrogel with magnetic nickel microwires randomly oriented in the surface of the material. Varying the magnetic field around the microwires reversibly induced their alignment with the direction of the field, causing the smooth hydrogel surface to develop small wrinkles; changes in surface roughness, ΔRRMS , ranged from 0.05 to 0.70 μm and could be oscillated without hydrogel creep. Vascular smooth muscle cell morphology was assessed when exposed to acute and dynamic topography changes. Area and shape changes occurred when an acute topographical change was imposed for substrates exceeding roughness of 0.2 μm, but longer-term oscillating topography did not produce significant changes in morphology irrespective of wire stiffness. These data imply that cells may be able to use topography changes to transmit signals as they respond immediately to changes in roughness. Copyright © 2013 Wiley Periodicals, Inc.

  2. Molecular Dynamics Simulations of Slip on Curved Surfaces

    Directory of Open Access Journals (Sweden)

    Ross D.A.


    Full Text Available We present Molecular Dynamics (MD simulations of liquid water confined within nanoscale geometries, including slit-like and cylindrical graphitic pores. These equilibrium results are used for calculating friction coefficients, which in turn can be used to calculate slip lengths. The slip length is a material property independent of the fluid flow rate. It is therefore a better quantity for study than the fluid velocity at the wall, also known as the slip velocity. Once the slip length has been found as a function of surface curvature, it can be used to parameterise Lattice Boltzmann (LB simulations. These larger scale simulations are able to tell us about how fluid transport is affected by slip in complex geometries; not just limited to single pores. Applications include flow and transport in nano-porous engine valve deposits and gas shales. The friction coefficient is found to be a function of curvature and is higher for fluid on convex surfaces and lower for concave surfaces. Both concave and convex surfaces approach the same value of the friction coefficient, which is constant above some critical radius of curvature, here found to be 7.4 ± 2.9 nm. The constant value of the friction coefficient is 10,000 ± 600 kg m−2 s−1, which is equivalent to a slip length of approximately 67 ± 4 nm.

  3. Can foot anthropometric measurements predict dynamic plantar surface contact area?

    Directory of Open Access Journals (Sweden)

    Collins Natalie


    Full Text Available Abstract Background Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Methods Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years. The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. Results A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p R2 = 0.76, p Conclusion The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

  4. Reaction dynamics of small molecules at metal surfaces

    CERN Document Server

    Samson, P A


    directed angular distributions suggest the influence of a trapping mechanism, recombining molecules scattering through a molecularly adsorbed state, with a transition state of large d sub N sub N responsible for the product vibrational excitation. Although N sub 2 dissociation on Fe(100) forms a simple overlayer structure, on Fe(110), molecular chemisorption does not occur at or above room temperature and the sticking is extremely small (approx 10 sup - sup 6 to 10 sup - sup 7). Activated nitrogen bombardment can be used to prepare a 'surface nitride' with a structure related to the geometry of bulk Fe sub 4 N. Scanning tunnelling microscopy yields atomic scale features that cannot be explained by simple overlayers. It is proposed that the uppermost iron layer reconstructs to generate quasi-octahedral sites between the top two layers, with sub-surface nitrogen in these sites forming a model for the 'surface nitride' structure. The dissociation-desorption dynamics of D sub 2 upon the Sn/Pt(111) surface alloy a...

  5. Application of the dynamic bounds method in the safety assessment of flood defences, a case study: 17th Street flood wall, New Orleans

    NARCIS (Netherlands)

    Rajabali Nejad, Mohammadreza; van Gelder, P.H.A.J.M.; Demirbilek, Zeki; Mahdi, Tew-Fik; Vrijling, J.K.


    In this paper we provide a computational framework for evaluation of reliability and safety assessment of infrastructures. It is based on the combined application of the dynamic bounds (DB) method and a probabilistic finite element model (FEM). The DB improves the computational efficiency of the FEM

  6. Coffee-stain growth dynamics on dry and wet surfaces (United States)

    Boulogne, François; Ingremeau, François; Stone, Howard A.


    The drying of a drop containing particles often results in the accumulation of the particles at the contact line. In this work, we investigate the drying of an aqueous colloidal drop surrounded by a hydrogel that is also evaporating. We combine theoretical and experimental studies to understand how the surrounding vapor concentration affects the particle deposit during the constant radius evaporation mode. In addition to the common case of evaporation on an otherwise dry surface, we show that in a configuration where liquid is evaporating from a flat surface around the drop, the singularity of the evaporative flux at the contact line is suppressed and the drop evaporation is homogeneous. For both conditions, we derive the velocity field and we establish the temporal evolution of the number of particles accumulated at the contact line. We predict the growth dynamics of the stain and the drying timescales. Thus, dry and wet conditions are compared with experimental results and we highlight that only the dynamics is modified by the evaporation conditions, not the final accumulation at the contact line.

  7. Nanostructures and dynamics of macromolecules bound to attractive filler surfaces (United States)

    Koga, Tad; Barkley, Deborah; Jiang, Naisheng; Endoh, Maya; Masui, Tomomi; Kishimoto, Hiroyuki; Nagao, Michihiro; Satija, Sushil; Taniguchi, Takashi

    We report in-situ nanostructures and dynamics of polybutadiene (PB) chains bound to carbon black (CB) fillers (the so-called ``bound polymer layer (BPL)'') in a good solvent. The BPL on the CB fillers were extracted by solvent leaching of a CB-filled PB compound and subsequently dispersed in deuterated toluene to label the BPL for small-angle neutron scattering and neutron spin echo techniques. Intriguingly, the results demonstrate that the BPL is composed of two regions regardless of molecular weights of PB: the inner unswollen region of ~ 0.5 nm thick and outer swollen region where the polymer chains display a parabolic profile with a diffuse tail. This two-layer formation on the filler surface is similar to that reported for polymer chains adsorbed on planar substrates from melts. In addition, the results show that the dynamics of the swollen bound chains can be explained by the so-called ``breathing mode'' and is generalized with the thickness of the swollen BPL. Furthermore, we will discuss how the breathing collective dynamics is affected by the presence of polymer chains in a matrix solution. We acknowledge the financial support from NSF Grant No. CMMI-1332499.

  8. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions (United States)

    Biswas, Rajib; Bagchi, Biman


    In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water–surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface–water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of

  9. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo


    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  10. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    Energy Technology Data Exchange (ETDEWEB)

    Abuzairi, Tomy [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Electrical Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424 (Indonesia); Okada, Mitsuru [Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Bhattacharjee, Sudeep [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India); Nagatsu, Masaaki, E-mail: [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Department of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Research Institute of Electronics, Shizuoka University, Hamamatsu 432-8561 (Japan)


    Highlights: • Spatio-temporal behaviors of capillary APPJs are studied for various substrates. • Plasma irradiation area depended on the substrate conductivity and permittivity. • Surface irradiation area was significantly broadened in polymer-like substrate. • Effect of applying a substrate bias on the APPJ irradiation area was investigated. - Abstract: An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5–4.2 km/s and 2–7 × 10{sup 17} m{sup −3}. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from −900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  11. Geochemistry, water dynamics and metals: Major, trace elements, Pb and Sr isotope constraints on their origins and movements in a small anthropized catchment over a flood

    International Nuclear Information System (INIS)

    Luck, J.M.; Othman, D.B.


    Major, trace elements and Sr-Pb isotope data on the dissolved and particulate phases are reported for water samples taken regularly over the September flood of a Mediterranean river (S France). This river drains runoff from a small, carbonate, karstified watershed with Miocene and Jurassic lithologies, and characterized by agricultural, urban and road network activities. The objective is to combine all the data into a dynamic model for constraining the origin(s) and movements of waters and of their loads. Furthermore, for metals, it becomes then feasible to know their fate and bioavailability downstream

  12. Effect of permafrost thaw on the dynamics of lakes recharged by ice-jam floods: case study in Yukon Flats, Alaska (United States)

    Steve M. Jepsen,; Walvoord, Michelle Ann; Voss, Clifford I.; Rover, Jennifer R.


    Large river floods are a key water source for many lakes in fluvial periglacial settings. Where permeable sediments occur, the distribution of permafrost may play an important role in the routing of floodwaters across a floodplain. This relationship is explored for lakes in the discontinuous permafrost of Yukon Flats, interior Alaska, using an analysis that integrates satellite-derived gradients in water surface elevation, knowledge of hydrogeology, and hydrologic modeling. We observed gradients in water surface elevation between neighboring lakes ranging from 0.001 to 0.004. These high gradients, despite a ubiquitous layer of continuous shallow gravel across the flats, are consistent with limited groundwater flow across lake basins resulting from the presence of permafrost. Permafrost impedes the propagation of floodwaters in the shallow subsurface and constrains transmission to “fill-and-spill” over topographic depressions (surface sills), as we observed for the Twelvemile-Buddy Lake pair following a May 2013 ice-jam flood on the Yukon River. Model results indicate that permafrost table deepening of 1–11 m in gravel, depending on watershed geometry and subsurface properties, could shift important routing of floodwater to lakes from overland flow (fill-and-spill) to shallow groundwater flow (“fill-and-seep”). Such a shift is possible in the next several hundred years of ground surface warming, and may bring about more synchronous water level changes between neighboring lakes following large flood events. This relationship offers a potentially useful tool, well-suited to remote sensing, for identifying long-term changes in shallow groundwater flow resulting from thawing of permafrost.

  13. Regional downscaling of temporal resolution in near-surface wind from statistically downscaled Global Climate Models (GCMs) for use in San Francisco Bay coastal flood modeling (United States)

    O'Neill, A.; Erikson, L. H.; Barnard, P.


    While Global Climate Models (GCMs) provide useful projections of near-surface wind vectors into the 21st century, resolution is not sufficient enough for use in regional wave modeling. Statistically downscaled GCM projections from Multivariate Adaptive Constructed Analogues (MACA) provide daily near-surface winds at an appropriate spatial resolution for wave modeling within San Francisco Bay. Using 30 years (1975-2004) of climatological data from four representative stations around San Francisco Bay, a library of example daily wind conditions for four corresponding over-water sub-regions is constructed. Empirical cumulative distribution functions (ECDFs) of station conditions are compared to MACA GFDL hindcasts to create correction factors, which are then applied to 21st century MACA wind projections. For each projection day, a best match example is identified via least squares error among all stations from the library. The best match's daily variation in velocity components (u/v) is used as an analogue of representative wind variation and is applied at 3-hour increments about the corresponding sub-region's projected u/v values. High temporal resolution reconstructions using this methodology on hindcast MACA fields from 1975-2004 accurately recreate extreme wind values within the San Francisco Bay, and because these extremes in wind forcing are of key importance in wave and subsequent coastal flood modeling, this represents a valuable method of generating near-surface wind vectors for use in coastal flood modeling.

  14. Comparison of tool life and surface roughness with MQL, flood cooling, and dry cutting conditions with P20 and D2 steel (United States)

    Senevirathne, S. W. M. A. I.; Punchihewa, H. K. G.


    Minimum quantity lubrication (MQL) is a cutting fluid (CF) application method that has given promising results in improving machining performances. It has shown that, the performance of cutting systems, depends on the work and tool materials used. AISI P20, and D2 are popular in tool making industry. However, the applicability of MQL in machining these two steels has not been studied previously. This experimental study is focused on evaluating performances of MQL compared to dry cutting, and conventional flood cooling method. Trials were carried out with P20, and D2 steels, using coated carbides as tool material, emulsion cutting oil as the CF. Tool nose wear, and arithmetic average surface roughness (Ra) were taken as response variables. Results were statistically analysed for differences in response variables. Although many past literature has suggested that MQL causes improvements in tool wear, and surface finish, this study has found contradicting results. MQL has caused nearly 200% increase in tool nose wear, and nearly 11-13% increase in surface roughness compared flood cooling method with both P20 and D2. Therefore, this study concludes that MQL affects adversely in machining P20, and D2 steels.

  15. Real-time forecasts of flood hazard and impact: some UK experiences

    Directory of Open Access Journals (Sweden)

    Cole Steven J.


    Full Text Available Major UK floods over the last decade have motivated significant technological and scientific advances in operational flood forecasting and warning. New joint forecasting centres between the national hydrological and meteorological operating agencies have been formed that issue a daily, national Flood Guidance Statement (FGS to the emergency response community. The FGS is based on a Flood Risk Matrix approach that is a function of potential impact severity and likelihood. It has driven an increased demand for robust, accurate and timely forecast and alert information on fluvial and surface water flooding along with impact assessments. The Grid-to-Grid (G2G distributed hydrological model has been employed across Britain at a 1km resolution to support the FGS. Novel methods for linking dynamic gridded estimates of river flow and surface runoff with more detailed offline flood risk maps have been developed to obtain real-time probabilistic forecasts of potential impacts, leading to operational trials. Examples of the national-scale G2G application are provided along with case studies of forecast flood impact from (i an operational Surface Water Flooding (SWF trial during the Glasgow 2014 Commonwealth Games, (ii SWF developments under the Natural Hazards Partnership over England & Wales, and (iii fluvial applications in Scotland.

  16. Dynamics of fibronectin adsorption on TiO2 surfaces. (United States)

    Sousa, S R; Brás, M Manuela; Moradas-Ferreira, P; Barbosa, M A


    In the present work we analyze the dynamics of fibronectin (FN) adsorption on two different stable titanium oxides, with varied surface roughness, and chemically similar to those used in clinical practice. The two types of titanium oxide surfaces used were TiO2 sputtered on Si (TiO2 sp) and TiO2 formed on commercially pure titanium after immersion in H2O2 (TiO2 cp). Surface characterization was previously carried out using different techniques (Sousa, S. R.; Moradas-Ferreira, P.; Melo, L. V.; Saramago, B.; Barbosa, M. A. Langmuir 2004, 20 (22), 9745-9754). Imaging and roughness analysis before and after FN adsorption used atomic force microscopy (AFM) in tapping mode, in air, and in magnetic alternating current mode, in liquid (water). FN adsorption as a function of time was followed by X-ray photoelectron spectroscopy (XPS), by radiolabeling of FN with 125I (125I-FN), and by ellipsometry. Exchangeability studies were performed using FN and HSA. AFM roughness analysis revealed that, before FN adsorption, both TiO2 surfaces exhibited a lower root-mean-square (Rq) and maximum peak with the depth of the maximum valley (Rmax) roughness in air than in water, due to TiO2 hydration. After protein adsorption, the same behavior was observed for the TiO2 sp substrate, while Rq and Rmax roughness values in air and in water were similar in the case of the TiO2 cp substrate, for the higher FN concentration used. Surface roughness was always significantly higher on the TiO2 cp surfaces. AFM led to direct visualization of adsorbed FN on both surfaces tested, indicating that after 10 min of FN incubation the TiO2 sp surface was partially covered by FN. The adsorbed protein seems to form globular aggregates or ellipsoids, and FN aggregates coalesce, forming clusters as the time of adsorption and the concentration increase. Radiolabeling of FN revealed that a rapid adsorption occurs on both surfaces and the amount adsorbed increased with time, reaching a maximum after 60 min of

  17. Immobilizing live Escherichia coli for AFM studies of surface dynamics

    International Nuclear Information System (INIS)

    Lonergan, N.E.; Britt, L.D.; Sullivan, C.J.


    Atomic force microscopy (AFM) is a probe-based technique that permits high resolution imaging of live bacterial cells. However, stably immobilizing cells to withstand the probe-based lateral forces remains an obstacle in AFM mediated studies, especially those of live, rod shaped bacteria in nutrient media. Consequently, AFM has been under-utilized in the research of bacterial surface dynamics. The aim of the current study was to immobilize a less adherent Escherichia coli strain in a method that both facilitates AFM imaging in nutrient broth and preserves overall cell viability. Immobilization reagents and buffers were systematically evaluated and the cell membrane integrity was monitored in all sample preparations. As expected, the biocompatible gelatin coated surfaces facilitated stable cell attachment in lower ionic strength buffers, yet poorly immobilized cells in higher ionic strength buffers. In comparison, poly-L-lysine surfaces bound cells in both low and high ionic strength buffers. The benefit of the poly-L-lysine binding capacity was offset by the compromised membrane integrity exhibited by cells on poly-L-lysine surfaces. However, the addition of divalent cations and glucose to the immobilization buffer was found to mitigate this unfavorable effect. Ultimately, immobilization of E. coli cells on poly-L-lysine surfaces in a lower ionic strength buffer supplemented with Mg 2+ and Ca 2+ was determined to provide optimal cell attachment without compromising the overall cell viability. Cells immobilized in this method were stably imaged in media through multiple division cycles. Furthermore, permeability assays indicated that E. coli cells recover from the hypoosmotic stress caused by immobilization in low ionic strength buffers. Taken together, this data suggests that stable immobilization of viable cells on poly-L-lysine surfaces can be accomplished in lower ionic strength buffers that are supplemented with divalent cations for membrane stabilization while

  18. Real-time dynamic control of the Three Gorges Reservoir by coupling numerical weather rainfall prediction and flood forecasting

    DEFF Research Database (Denmark)

    Wang, Y.; Chen, H.; Rosbjerg, Dan


    In reservoir operation improvement of the accuracy of forecast flood inflow and extension of forecast lead-time can effectively be achieved by using rainfall forecasts from numerical weather predictions with a hydrological catchment model. In this study, the Regional Spectrum Model (RSM), which i...

  19. Spatial and temporal dynamics of water in the root environment of potted plants on a flooded bench fertigation system

    NARCIS (Netherlands)

    Otten, W.; Raats, P.A.C.; Baas, R.; Challa, H.; Kabat, P.


    The relationship between evapotranspiration of potted Ficus benjamina plants on a flooded bench fertigation system and the distribution of water in the root zone was studied in detail for a range of fertigation schedules. The physical characteristics of the peat-based potting medium were described

  20. Underground- and surface technologies for joint flooding of gas caves; Unter- und Uebertagetechnik als Einheit zur Flutung von Gaskavernen

    Energy Technology Data Exchange (ETDEWEB)

    Raudonus, K.; Miersch, D. [UGS GmbH, Mittenwalde (Germany); Haensler, G. [Verbundnetz Gas AG, Leipzig (Germany)


    After 20 years of operation the oldes caves in the Bernburg storage VNG AG had to repair the facilities. This required flooding of the caves from the start. At the same time geomechanical reserves which were reevaluated on the basis of redimensioning could be used by deepening. Flooding and relocation of the displaced gas should not disturb gas storage and brine extraction. As one of the caves was filled with gas for the first time it was possible to use the brine. Flooding and gas filling were coupled. [Deutsch] Nach mehr als 20jaehriger Betriebszeit der aeltesten Kavernen auf dem Speicher Bernburg stand fuer die VNG AG die Aufgabe der Reparatur. Der Umfang der Arbeiten machte von Anfang an das vollstaendige Fluten der Kavernen erforderlich. Gleicheitig ergab sich dabei die Moeglichkeit, seinerzeit verbliebene geomechanische Reserven, die auf Basis einer auf aktuelle Erkenntnisse beruhenden Neudimensionierung bewertet wurden, durch Nachsolung auszuschoepfen. Die Heranfuehrung des Flutmediums und die Umlagerung des verdraengten Gases sollten ohne nachteilige Rueckwirkung auf den Gasspeicher- und Solegewinnungsbetrieb erfolgen. Da zu diesem Zeitpunkt eine Kaverne in der Phase der Gaserstbefuellung stand, konnte die ausgetragene Sole genutzt werden. Flutprozess und Gaserstbefuellung wurden somit im direkt gekoppelten Betrieb durchgefuehrt. (orig./MSK)

  1. Adaptive Dynamic Surface Control for Generator Excitation Control System

    Directory of Open Access Journals (Sweden)

    Zhang Xiu-yu


    Full Text Available For the generator excitation control system which is equipped with static var compensator (SVC and unknown parameters, a novel adaptive dynamic surface control scheme is proposed based on neural network and tracking error transformed function with the following features: (1 the transformation of the excitation generator model to the linear systems is omitted; (2 the prespecified performance of the tracking error can be guaranteed by combining with the tracking error transformed function; (3 the computational burden is greatly reduced by estimating the norm of the weighted vector of neural network instead of the weighted vector itself; therefore, it is more suitable for the real time control; and (4 the explosion of complicity problem inherent in the backstepping control can be eliminated. It is proved that the new scheme can make the system semiglobally uniformly ultimately bounded. Simulation results show the effectiveness of this control scheme.

  2. Molecular Dynamics Simulations of Water Nanodroplets on Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.


    and DNA microarrays technologies.4,5,6,7,8 Although extensive experimental, theoretical and computational work has been devoted to study the nature of the interaction between silica and water,2,9-16 at the molecular level a complete understanding of silica-water systems has not been reached. Contact angle...... computations of water droplets on silica surfaces offers a useful fundamental and quantitative measurement in order to study chemical and physical properties of water-silica systems.3,16,17,18 For hydrophobic systems the static and dynamic properties of the fluid-solid interface are influenced by the presence...... of air. Hence, nanobubles have been observed and proposed as the origin of long range ``hydrophobic'' forces19-30 even for hydrophilic silica-water interfaces unusual phenomena related to nanobubbles have been observed.31-33 In this work we study the role of air on the wetting of amorphous silica...

  3. Molecular Dynamics Simulations of Water Droplets On Hydrophilic Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.


    of water droplets on silica surfaces offers a useful fundamental and quantitative measurement in order to study chemical and physical properties of water-silica systems. For hydrophobic systems the static and dynamic properties of the fluid-solid interface are influenced by the presence of air. Hence......Wetting is essential and ubiquitous in a variety of natural and technological processes. Silicon dioxides-water systems are abundant in nature and play fundamental roles in a vast variety of novel science and engineering activities such as silicon based devices, nanoscale lab on a chip systems...... and DNA microarrays technologies.Although extensive experimental, theoretical and computational work has been devoted to study the nature of the interaction between silica and water, at the molecular level a complete understanding of silica-water systems has not been reached. Contact angle computations...

  4. Dynamic characterisation of the specific surface area for fracture networks (United States)

    Cvetkovic, V.


    One important application of chemical transport is geological disposal of high-level nuclear waste for which crystalline rock is a prime candidate for instance in Scandinavia. Interconnected heterogeneous fractures of sparsely fractured rock such as granite, act as conduits for transport of dissolved tracers. Fluid flow is known to be highly channelized in such rocks. Channels imply narrow flow paths, adjacent to essentially stagnant water in the fracture and/or the rock matrix. Tracers are transported along channelised flow paths and retained by minerals and/or stagnant water, depending on their sorption properties; this mechanism is critical for rocks to act as a barrier and ultimately provide safety for a geological repository. The sorbing tracers are retained by diffusion and sorption on mineral surfaces, whereas non-sorbing tracers can be retained only by diffusion into stagnant water of fractures. The retention and transport properties of a sparsely fractured rock will primarily depend on the specific surface area (SSA) of the fracture network which is determined by the heterogeneous structure and flow. The main challenge when characterising SSA on the field-scale is its dependence on the flow dynamics. We first define SSA as a physical quantity and clarify its importance for chemical transport. A methodology for dynamic characterisation of SSA in fracture networks is proposed that relies on three sets of data: i) Flow rate data as obtained by a flow logging procedure; ii) transmissivity data as obtained by pumping tests; iii) fracture network data as obtained from outcrop and geophysical observations. The proposed methodology utilises these data directly as well as indirectly through flow and particle tracking simulations in three-dimensional discrete fracture networks. The methodology is exemplified using specific data from the Swedish site Laxemar. The potential impact of uncertainties is of particular significance and is illustrated for radionuclide

  5. He atom surface scattering: Surface dynamics of insulators, overlayers and crystal growth

    International Nuclear Information System (INIS)


    Investigations have focused primarily on surface structure and dynamics of ionic insulators, epitaxial growth onto alkali halide crystals and multiphoton studies. The surface dynamics of RbCl has been re-examined. We have developed a simple force constant model which provides insight into the dynamics of KBr overlayers on NaCl(001), a system with a large lattice mismatch. The KBr/NaCl(001) results are compared to Na/Cu(001) and NaCl/Ge(001). We have completed epitaxial growth experiments for KBr onto RbCl(001). Slab dynamics calculations using a shell model for this system with very small lattice mismatch are being carried out in collaboration with Professor Manson of Clemson University and with Professor Schroeder in Regensburg, Germany. Extensive experiments on multiphoton scattering of helium atoms onto NaCl and, particularly, LiF have been carried out and the theory has been developed to a rather advanced stage by Professor Manson. This work will permit the extraction of more information from time-of-flight spectra. It is shown that the theoretical model provides a very good description of the multiphoton scattering from organic films. Work has started on self-assembling organic films on gold (alkyl thiols/Au(111)). We have begun to prepare and characterize the gold crystal; one of the group members has spent two weeks at the Oak Ridge National Laboratory learning the proper Au(111) preparation techniques. One of our students has carried out neutron scattering experiments on NiO, measuring both bulk phonon and magnon dispersion curves

  6. Holographic otoscope for nanodisplacement measurements of surfaces under dynamic excitation. (United States)

    Flores-Moreno, J M; Furlong, Cosme; Rosowski, John J; Harrington, Ellery; Cheng, Jeffrey T; Scarpino, C; Santoyo, F Mendoza


    We describe a novel holographic otoscope system for measuring nanodisplacements of objects subjected to dynamic excitation. Such measurements are necessary to quantify the mechanical deformation of surfaces in mechanics, acoustics, electronics, biology, and many other fields. In particular, we are interested in measuring the sound-induced motion of biological samples, such as an eardrum. Our holographic otoscope system consists of laser illumination delivery (IS), optical head (OH), and image processing computer (IP) systems. The IS delivers the object beam (OB) and the reference beam (RB) to the OH. The backscattered light coming from the object illuminated by the OB interferes with the RB at the camera sensor plane to be digitally recorded as a hologram. The hologram is processed by the IP using the Fresnel numerical reconstruction algorithm, where the focal plane can be selected freely. Our holographic otoscope system is currently deployed in a clinic, and is packaged in a custom design. It is mounted in a mechatronic positioning system to increase its maneuverability degrees to be conveniently positioned in front of the object to be measured. We present representative results highlighting the versatility of our system to measure deformations of complex elastic surfaces in the wavelength scale including a copper foil membrane and postmortem tympanic membrane. SCANNING 33: 342-352, 2011. © 2011 Wiley Periodicals, Inc. Copyright © 2011 Wiley Periodicals, Inc.

  7. He atom-surface scattering: Surface dynamics of insulators, overlayers and crystal growth

    International Nuclear Information System (INIS)


    Investigations in this laboratory have focused on the surface structure and dynamics of ionic insulators and on epitaxial growth onto alkali halide crystals. In the later the homoepitaxial growth of NaCl/NaCl(001) and the heteroepitaxial growth of KBr/NaCl(001), NaCl/KBr(001) and KBr/RbCl(001) have been studied by monitoring the specular He scattering as a function of the coverage and by measuring the angular and energy distributions of the scattered He atoms. These data provide information on the surface structure, defect densities, island sizes and surface strain during the layer-by-layer growth. The temperature dependence of these measurements also provides information on the mobilities of the admolecules. He atom scattering is unique among surface probes because the low-energy, inert atoms are sensitive only to the electronic structure of the topmost surface layer and are equally applicable to all crystalline materials. It is proposed for the next year to exploit further the variety of combinations possible with the alkali halides in order to carry out a definitive study of epitaxial growth in the ionic insulators. The work completed so far, including measurements of the Bragg diffraction and surface dispersion at various stages of growth, appears to be exceptionally rich in detail, which is particularly promising for theoretical modeling. In addition, because epitaxial growth conditions over a wide range of lattice mismatches is possible with these materials, size effects in growth processes can be explored in great depth. Further, as some of the alkali halides have the CsCl structure instead of the NaCl structure, we can investigate the effects of the heteroepitaxy with materials having different lattice preferences. Finally, by using co-deposition of different alkali halides, one can investigate the formation and stability of alloys and even alkali halide superlattices

  8. Applications of granular-dynamics numerical simulations to asteroid surfaces (United States)

    Richardson, D. C.; Michel, P.; Schwartz, S. R.; Yu, Y.; Ballouz, R.-L.; Matsumura, S.


    Spacecraft images and indirect observations including thermal inertia measurements indicate most small bodies have surface regolith. Evidence of granular flow is also apparent in the images. This material motion occurs in very low gravity, therefore in a totally different gravitational environment than on the Earth. Upcoming sample-return missions to small bodies, and possible future manned missions, will involve interaction with the surface regolith, so it is important to develop tools to predict the surface response. We have added new capabilities to the N-body gravity tree code pkdgrav [1,2] that permit the simulation of granular dynamics, including multi-contact physics and friction forces, using the soft-sphere discrete-element method [3]. The numerical approach has been validated through comparison with laboratory experiments (e.g., [3,4]). (1) We carried out impacts into granular materials using different projectile shapes under Earth's gravity [5] and compared the results to laboratory experiments [6] in support of JAXA's Hayabusa 2 asteroid sample-return mission. We tested different projectile shapes and confirmed that the 90-degree cone was the most efficient at excavating mass when impacting 5-mm-diameter glass beads. Results are sensitive to the normal coefficient of restitution and the coefficient of static friction. Preliminary experiments in micro-gravity for similar impact conditions show both the amount of ejected mass and the timescale of the impact process increase, as expected. (2) It has been found (e.g., [7,8]) that ''fresh'' (unreddened) Q-class asteroids have a high probability of recent planetary encounters (˜1 Myr; also see [9]), suggesting that surface refreshening may have occurred due to tidal effects. As an application of the potential effect of tidal interactions, we carried out simulations of Apophis' predicted 2029 encounter with the Earth to see whether regolith motion might occur, using a range of plausible material parameters

  9. Spatial and Temporal Flood Risk Assessment for Decision Making Approach (United States)

    Azizat, Nazirah; Omar, Wan-Mohd-Sabki Wan


    Heavy rainfall, adversely impacting inundation areas, depends on the magnitude of the flood. Significantly, location of settlements, infrastructure and facilities in floodplains result in many regions facing flooding risks. A problem faced by the decision maker in an assessment of flood vulnerability and evaluation of adaptation measures is recurrent flooding in the same areas. Identification of recurrent flooding areas and frequency of floods should be priorities for flood risk management. However, spatial and temporal variability become major factors of uncertainty in flood risk management. Therefore, dynamic and spatial characteristics of these changes in flood impact assessment are important in making decisions about the future of infrastructure development and community life. System dynamics (SD) simulation and hydrodynamic modelling are presented as tools for modelling the dynamic characteristics of flood risk and spatial variability. This paper discusses the integration between spatial and temporal information that is required by the decision maker for the identification of multi-criteria decision problems involving multiple stakeholders.

  10. He-atom surface scattering apparatus for studies of crystalline surface dynamics. Progress report, May 1, 1985-April 30, 1986

    International Nuclear Information System (INIS)


    The primary goal of this grant is the construction of a state-of-the-art He atom-crystal surface scattering apparatus which will be capable of measuring both elastic and inelastic scattering of He atoms from crystal surfaces of metals, semiconductors and insulators. First, the apparatus will be constructed and characterized, after which a program of studies on the surface dynamics of a variety of crystal surfaces will be started. 6 refs., 2 figs

  11. Flood Deposition Analysis of Northern California's Eel River (Flood- DANCER) (United States)

    Ahlgren, S.; Bauman, P. D.; Dillon, R. J.; Gallagher, N.; Jamison, M. E.; King, A.; Lee, J.; Siwicke, K. A.; Harris, C. K.; Wheatcroft, R. A.; Borgeld, J. C.; Goldthwait, S. A.


    Characterizing and quantifying the fate of river born sediment is critical to our understanding of sediment supply and erosion in impacted coastal areas. Strata deposited in coastal zones provide an invaluable record of recent and historical environmental events. The Eel River in northern California has one of the highest sediment yields of any North American river and has preserved evidence of the impact of recent flood events. Previous research has documented sediment deposits associated with Eel River flood events in January 1995, March 1995, and January 1997. These deposits were found north of the river mouth on the mid shelf in water depths from 50-100 m. Sediment strata were up to 5-10 cm thick and were composed of fine to very fine grained silts and clays. Until recently, no model had been able to correctly reproduce the sediment deposits associated with these floods. In 2005, Harris et al. developed a model that accurately represents the volume and location of the flood deposit associated with the January 1997 event. However, rigorous assessment of the predictive capability of this model requires that a new flood of the Eel River be used as a test case. During the winter of 2005-06 the Eel River rose above flood stage reaching discharge similar to the flood of January 1995 which resulted in flood sedimentation on the Eel River shelf. A flood-related deposit 1-5 cm thick was found in water depths of 60-90 m approximately 20-35 km north of the river mouth. Flood deposits were recognized in box cores collected in the months following the flood. As in previously studied events, flood- related strata near the sediment surface were recognized in core x-radiographs, resistivity and porosity profiles, and were composed of fine to very fine grained silts and clays. In addition, surface flood sediments were associated with lower concentrations of benthic foraminifera compared with deeper sediments. The January 2006 flood deposit was similar in thickness to the

  12. Surface Ocean Circulation and Dynamics in the Philippine Archipelago Region (United States)

    Han, W.; Moore, A. M.; Levin, J.; Zhang, B.; Arango, H. G.; Curchitser, E.; di Lorenzo, E.; Gordon, A. L.; Lin, J.


    The dynamics of the seasonal surface circulation in the Philippine Archipelago (117E-128E, 0N-14N) are investigated using a high-resolution Regional Ocean Modeling System (ROMS) for the period of 2004 - March 2008. Three experiments are performed to estimate the relative importance of local, remote and tidal forcing. On annual mean, circulation in the Sulu Sea is dominated by the inflow from the South China Sea at the Mindoro and Balabac Straits, outflow into the Sulawesi Sea at the Sibutu Passage, and cyclonic circulation in the Sulu basin. A strong jet forms in the northeast Sulu Sea when currents from the Mindoro and Tablas Straits converge. Within the Archipelago, strong westward currents in the Bohol Sea carry the western Pacific (WP) Water from the Surigao Strait into the Sulu Sea via the Dipolog Strait. In the Sibuyan Sea, currents flow westward, which carry part of the WP water from the San Bernardino Strait into the Sulu Sea via the Tablas Strait. The surface circulations exhibit strong seasonal variations or reversals from winter to summer. The variations of volume transports above 40m at the Mindoro Strait, Balabac Strait and Sibutu Passage of the Sulu Sea and at the Verde Island Passage are dominated by remote forcing, although local forcing can be large sometimes. At the Tablas and Dipolog Straits, variations of transports result from both remote and local forcing. The cyclonic (anticyclonic) gyres during winter (summer) in the Sulu Sea and seasonally reversing currents in the Archipelago result mainly from local forcing. Nonlinear rectification of tides acts to reduce the mean transports at the Surigao, San Bernardino and Dipolog Straits, and it also affects the Sulu Sea circulation perhaps by tidal mixing and shifting the locations of jets and eddies.

  13. The hydrophobic effect: Molecular dynamics simulations of water confined between extended hydrophobic and hydrophilic surfaces

    DEFF Research Database (Denmark)

    Jensen, Morten Østergaard; Mouritsen, Ole G.; Peters, Günther H.J.


    Structural and dynamic properties of water confined between two parallel, extended, either hydrophobic or hydrophilic crystalline surfaces of n-alkane C36H74 or n-alcohol C35H71OH, are studied by molecular dynamics simulations. Electron density profiles, directly compared with corresponding...... at both surfaces. The ordering is characteristically different between the surfaces and of longer range at the hydrophilic surface. Furthermore, the dynamic properties of water are different at the two surfaces and different from the bulk behavior. In particular, at the hydrophobic surface, time......-correlation functions reveal that water molecules have characteristic diffusive behavior and orientational ordering due to the lack of hydrogen bonding interactions with the surface. These observations suggest that the altered dynamical properties of water in contact with extended hydrophobic surfaces together...

  14. Classification of mechanisms, climatic context, areal scaling, and synchronization of floods: the hydroclimatology of floods in the Upper Paraná River basin, Brazil

    Directory of Open Access Journals (Sweden)

    C. H. R. Lima


    Full Text Available Floods are the main natural disaster in Brazil, causing substantial economic damage and loss of life. Studies suggest that some extreme floods result from a causal climate chain. Exceptional rain and floods are determined by large-scale anomalies and persistent patterns in the atmospheric and oceanic circulations, which influence the magnitude, extent, and duration of these extremes. Moreover, floods can result from different generating mechanisms. These factors contradict the assumptions of homogeneity, and often stationarity, in flood frequency analysis. Here we outline a methodological framework based on clustering using self-organizing maps (SOMs that allows the linkage of large-scale processes to local-scale observations. The methodology is applied to flood data from several sites in the flood-prone Upper Paraná River basin (UPRB in southern Brazil. The SOM clustering approach is employed to classify the 6-day rainfall field over the UPRB into four categories, which are then used to classify floods into four types based on the spatiotemporal dynamics of the rainfall field prior to the observed flood events. An analysis of the vertically integrated moisture fluxes, vorticity, and high-level atmospheric circulation revealed that these four clusters are related to known tropical and extratropical processes, including the South American low-level jet (SALLJ; extratropical cyclones; and the South Atlantic Convergence Zone (SACZ. Persistent anomalies in the sea surface temperature fields in the Pacific and Atlantic oceans are also found to be associated with these processes. Floods associated with each cluster present different patterns in terms of frequency, magnitude, spatial variability, scaling, and synchronization of events across the sites and subbasins. These insights suggest new directions for flood risk assessment, forecasting, and management.

  15. Classification of mechanisms, climatic context, areal scaling, and synchronization of floods: the hydroclimatology of floods in the Upper Paraná River basin, Brazil (United States)

    Lima, Carlos H. R.; AghaKouchak, Amir; Lall, Upmanu


    Floods are the main natural disaster in Brazil, causing substantial economic damage and loss of life. Studies suggest that some extreme floods result from a causal climate chain. Exceptional rain and floods are determined by large-scale anomalies and persistent patterns in the atmospheric and oceanic circulations, which influence the magnitude, extent, and duration of these extremes. Moreover, floods can result from different generating mechanisms. These factors contradict the assumptions of homogeneity, and often stationarity, in flood frequency analysis. Here we outline a methodological framework based on clustering using self-organizing maps (SOMs) that allows the linkage of large-scale processes to local-scale observations. The methodology is applied to flood data from several sites in the flood-prone Upper Paraná River basin (UPRB) in southern Brazil. The SOM clustering approach is employed to classify the 6-day rainfall field over the UPRB into four categories, which are then used to classify floods into four types based on the spatiotemporal dynamics of the rainfall field prior to the observed flood events. An analysis of the vertically integrated moisture fluxes, vorticity, and high-level atmospheric circulation revealed that these four clusters are related to known tropical and extratropical processes, including the South American low-level jet (SALLJ); extratropical cyclones; and the South Atlantic Convergence Zone (SACZ). Persistent anomalies in the sea surface temperature fields in the Pacific and Atlantic oceans are also found to be associated with these processes. Floods associated with each cluster present different patterns in terms of frequency, magnitude, spatial variability, scaling, and synchronization of events across the sites and subbasins. These insights suggest new directions for flood risk assessment, forecasting, and management.

  16. Optodynamics: dynamic aspects of laser beam-surface interaction

    International Nuclear Information System (INIS)

    Možina, J; Diaci, J


    This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.

  17. Nonlinear dynamics and breakup of free-surface flows

    International Nuclear Information System (INIS)

    Eggers, J.


    Surface-tension-driven flows and, in particular, their tendency to decay spontaneously into drops have long fascinated naturalists, the earliest systematic experiments dating back to the beginning of the 19th century. Linear stability theory governs the onset of breakup and was developed by Rayleigh, Plateau, and Maxwell. However, only recently has attention turned to the nonlinear behavior in the vicinity of the singular point where a drop separates. The increased attention is due to a number of recent and increasingly refined experiments, as well as to a host of technological applications, ranging from printing to mixing and fiber spinning. The description of drop separation becomes possible because jet motion turns out to be effectively governed by one-dimensional equations, which still contain most of the richness of the original dynamics. In addition, an attraction for physicists lies in the fact that the separation singularity is governed by universal scaling laws, which constitute an asymptotic solution of the Navier-Stokes equation before and after breakup. The Navier-Stokes equation is thus continued uniquely through the singularity. At high viscosities, a series of noise-driven instabilities has been observed, which are a nested superposition of singularities of the same universal form. At low viscosities, there is rich scaling behavior in addition to aesthetically pleasing breakup patterns driven by capillary waves. The author reviews the theoretical development of this field alongside recent experimental work, and outlines unsolved problems. copyright 1997 The American Physical Society

  18. NAA: metals in surface waters, margin sediments, forage and cattle hair in flood plains of the Rio Doce basin, Minas Gerais, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Maria Adelaide R.V., E-mail: [Universidade Fundacao Mineira de Educacao e Cultura (FUMEC), Belo Horizonte, MG (Brazil). Mestrado em Construcao Civil, Meio Ambiente; Barbosa, Ana Flavia S.; Ruckert, Gabriela V., E-mail: [Centro Universitario do Leste de Minas Gerais (UnilesteMG), Coronel Fabriciano, MG (Brazil). Mestrado em Engenharia Industrial; Menezes, Maria Angela B.C.; Silva, Maria Aparecida, E-mail:, E-mail: [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Arno H. de, E-mail: [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Nuclear Belo Horizonte, MG (Brazil)


    Metals are toxic and can cause damage to human health when they accumulate in the food chain. The aim of this study was to determine Al, As, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hg, K, Mg, Mn, Na, Rb, Sb, Sc, Ta, Th, Ti, U, V and Zn in different samples: surface waters, margin sediments, forages and cattle hairs in the region of the Rio Doce basin. The metals were analyzed by Neutron Activation Analysis - NAA at the Centre for Development of Nuclear Technology of the National Commission of Nuclear Energy - CDTN / CNEN. The sampling sites were taken at two points: P1- (Pingo D'agua - city, Ponte Queimada, in a no industrial area) and P2 - (Santana do Paraiso city, industrial and pasture areas, subject to frequent floods). The samples were collected in different seasons: July 2009 (dry season - winter) and February 2010 (rainy season - summer). These points were strategically chosen because P1 is located into the Parque Estadual do Rio Doce, considered a no industrial pollution region. Contrariwise, P2 is located in a region of high concentration of industries. In (P2) the Doce River receives its most polluted affluent upstream the Piracicaba River which is charged of several pollutants of industries of Steel Valley region, Brazil. In general, the results showed higher concentrations of the elements in P2 riverside area of livestock production and subject to flood. (author)

  19. NAA: metals in surface waters, margin sediments, forage and cattle hair in flood plains of the Rio Doce basin, Minas Gerais, Brazil

    International Nuclear Information System (INIS)

    Vasconcelos, Maria Adelaide R.V.; Oliveira, Arno H. de


    Metals are toxic and can cause damage to human health when they accumulate in the food chain. The aim of this study was to determine Al, As, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hg, K, Mg, Mn, Na, Rb, Sb, Sc, Ta, Th, Ti, U, V and Zn in different samples: surface waters, margin sediments, forages and cattle hairs in the region of the Rio Doce basin. The metals were analyzed by Neutron Activation Analysis - NAA at the Centre for Development of Nuclear Technology of the National Commission of Nuclear Energy - CDTN / CNEN. The sampling sites were taken at two points: P1- (Pingo D'agua - city, Ponte Queimada, in a no industrial area) and P2 - (Santana do Paraiso city, industrial and pasture areas, subject to frequent floods). The samples were collected in different seasons: July 2009 (dry season - winter) and February 2010 (rainy season - summer). These points were strategically chosen because P1 is located into the Parque Estadual do Rio Doce, considered a no industrial pollution region. Contrariwise, P2 is located in a region of high concentration of industries. In (P2) the Doce River receives its most polluted affluent upstream the Piracicaba River which is charged of several pollutants of industries of Steel Valley region, Brazil. In general, the results showed higher concentrations of the elements in P2 riverside area of livestock production and subject to flood. (author)

  20. An European historical reconstruction of sea surface dynamics (waves and storm surge) for coastal impact studies (United States)

    Menendez, Melisa; Perez, Jorge; Cid, Alba; Castanedo, Sonia; Losada, Inigo; Medina, Raul; Mendez, Fernando


    Despite their outstanding relevance in coastal processes, a study of the sea surface dynamics due to atmospheric wind and pressure variations are rather limited in comparison with the mean sea level rise. Data of waves and surges along the European region are scarce and in-homogeneous, not only in terms of spatial coverage but also in terms of temporal coverage. This study presents two databases focused on a historical reconstruction of: (i) the wind-generated waves (GOW) and (ii) the meteorological sea level component (GOS). The GOW and GOS datasets cover the whole European coast (North Atlantic, North Sea, Baltic Sea, Mediterranean Sea and Black Sea) at high-spatial resolution from 1979 to present. The meteorological sea level component (storm surge) has been generated by the Regional Ocean Model System (ROMS). To take into account non-linear interactions between tides and surges, both dynamics were simulated jointly. Final results of meteorological component of sea level were obtained by subtracting the astronomical tide from the simulated sea surface. The model was set-up for Europe using an orthogonal grid, with a horizontal resolution ranging between 3.5 to 11 km. A spatial domain of approximately 5 km was used for the Black Sea. Local coastal waves can be the integrated result of the ocean surface over a large region of influence. GOW-Europe is designed from a multigrid approach based on the overlapping of two-way nested domains. The coarser spatial resolution along the European coast of GOW is 15 km. The generation and propagation of the sea surface waves of GOW-Europe are simulated with the model WAVEWATCH III v4.18. Effects of non-linear wave-wave interactions, whitecapping and depth-induced refraction are considered in the propagation model. In order to validate GOW and GOS over Europe with available observations, an exhaustive comparison with in-situ and remote measurements was developed. In-situ buoys and tide-gauges are used to compare hourly time

  1. Drivers of flood damage on event level

    DEFF Research Database (Denmark)

    Kreibich, H.; Aerts, J. C. J. H.; Apel, H.


    Flood risk is dynamic and influenced by many processes related to hazard, exposure and vulnerability. Flood damage increased significantly over the past decades, however, resulting overall economic loss per event is an aggregated indicator and it is difficult to attribute causes to this increasing...... trend. Much has been learned about damaging processes during floods at the micro-scale, e.g. building level. However, little is known about the main factors determining the amount of flood damage on event level. Thus, we analyse and compare paired flood events, i.e. consecutive, similar damaging floods...... that occurred in the same area. In analogy to ’Paired catchment studies’ - a well-established method in hydrology to understand how changes in land use affect streamflow – we will investigate how and why resulting flood damage in a region differed between the first and second consecutive flood events. One...

  2. Drivers of flood damage on event level

    DEFF Research Database (Denmark)

    Kreibich, H.; Aerts, J. C. J. H.; Apel, H.


    -level mitigation measures, 3) more effective early warning and improved coordination of disaster response and 4) a more targeted maintenance of flood defence systems and their deliberate relocation. Thus, despite higher hydrological severity damage due to the 2013 flood was significantly lower than in 2002. In our......Flood risk is dynamic and influenced by many processes related to hazard, exposure and vulnerability. Flood damage increased significantly over the past decades, however, resulting overall economic loss per event is an aggregated indicator and it is difficult to attribute causes to this increasing...... trend. Much has been learned about damaging processes during floods at the micro-scale, e.g. building level. However, little is known about the main factors determining the amount of flood damage on event level. Thus, we analyse and compare paired flood events, i.e. consecutive, similar damaging floods...

  3. Evaluating road surface conditions using dynamic tire pressure sensor (United States)

    Zhao, Yubo; Wu, H. Felix; McDaniel, J. Gregory; Wang, Ming L.


    In order to best prioritize road maintenance, the level of deterioration must be known for all roads in a city's network. Pavement Condition Index (PCI) and International Roughness Index (IRI) are two standard methods for obtaining this information. However, IRI is substantially easier to measure. Significant time and money could be saved if a method were developed to estimate PCI from IRI. This research introduces a new method to estimate IRI and correlate IRI with PCI. A vehicle-mounted dynamic tire pressure sensor (DTPS) system is used. The DTPS measures the signals generated from the tire/road interaction while driving. The tire/road interaction excites surface waves that travel through the road. DTPS, which is mounted on the tire's valve stem, measures tire/road interaction by analyzing the pressure change inside the tire due to the road vibration, road geometry and tire wall vibration. The road conditions are sensible to sensors in a similar way to human beings in a car. When driving on a smooth road, tire pressure stays almost constant and there are minimal changes in the DTPS data. When driving on a rough road, DTPS data changes drastically. IRI is estimated from the reconstructed road profile using DTPS data. In order to correlate IRI with PCI, field tests were conducted on roads with known PCI values in the city of Brockton, MA. Results show a high correlation between the estimated IRI values and the known PCI values, which suggests that DTPS-based IRI can provide accurate predictions of PCI.

  4. Estimation of flood environmental effects using flood zone mapping techniques in Halilrood Kerman, Iran


    Boudaghpour, Siamak; Bagheri, Majid; Bagheri, Zahra


    High flood occurrences with large environmental damages have a growing trend in Iran. Dynamic movements of water during a flood cause different environmental damages in geographical areas with different characteristics such as topographic conditions. In general, environmental effects and damages caused by a flood in an area can be investigated from different points of view. The current essay is aiming at detecting environmental effects of flood occurrences in Halilrood catchment area of Kerma...

  5. A large-scale simulation of climate change effects on flood regime - A case study for the Alabama-Coosa-Tallapoosa River Basin (United States)

    Dullo, T. T.; Gangrade, S.; Marshall, R.; Islam, S. R.; Ghafoor, S. K.; Kao, S. C.; Kalyanapu, A. J.


    The damage and cost of flooding are continuously increasing due to climate change and variability, which compels the development and advance of global flood hazard models. However, due to computational expensiveness, evaluation of large-scale and high-resolution flood regime remains a challenge. The objective of this research is to use a coupled modeling framework that consists of a dynamically downscaled suite of eleven Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models, a distributed hydrologic model called DHSVM, and a computational-efficient 2-dimensional hydraulic model called Flood2D-GPU to study the impacts of climate change on flood regime in the Alabama-Coosa-Tallapoosa (ACT) River Basin. Downscaled meteorologic forcings for 40 years in the historical period (1966-2005) and 40 years in the future period (2011-2050) were used as inputs to drive the calibrated DHSVM to generate annual maximum flood hydrographs. These flood hydrographs along with 30-m resolution digital elevation and estimated surface roughness were then used by Flood2D-GPU to estimate high-resolution flood depth, velocities, duration, and regime. Preliminary results for the Conasauga river basin (an upper subbasin within ACT) indicate that seven of the eleven climate projections show an average increase of 25 km2 in flooded area (between historic and future projections). Future work will focus on illustrating the effects of climate change on flood duration and area for the entire ACT basin.

  6. Tropical stormwater floods: a sustainable solution (United States)

    Molinie, Jack; Bade, Francois; Nagau, Jimmy; Nuiro, Paul


    Stormwater management is one of the most difficult problem of urban and suburban area. The urban runoff volume related to rain intensity and surfaces properties can lead to flood. Thereby, urban flooding creates considerable infrastructure problem, economics and human damages. In tropical countries, burgeoning human population coupled with unplanned urbanization altered the natural drainage. Consequently, classical intense rain around 100 cm/h produces frequent street flooding. In our case, we study the management of intense tropical rain, by using a network of individual rain storage tanks. The study area is economical and industrial zone installed in a coastal plain , with seventy per cent of impermeable surface (roads, parking lots, building roof, …) and thirty per cent of wetland (mangrove, …). Our solution is to delay the routes and parking lots runoff to the roof one. We propose sustainable individual water storage and a real time dynamical management, which permit to control the roof water arrival in the stormwater culvert. During the remaining time, the stored rainwater can be used for domestic activities instead of the use of drinking water.

  7. 2011 Dynamics at Surfaces Gordon Research Conference (August 7-12, 2011, Salve Regina University, Newport, Rhode Island)

    Energy Technology Data Exchange (ETDEWEB)

    Greg Sitz


    The 2011 Gordon Conference on Dynamics at Surfaces is the 32nd anniversary of a meeting held every two years that is attended by leading researchers in the area of experimental and theoretical dynamics at liquid and solid surfaces. The conference focuses on the dynamics of the interaction of molecules with either liquid or solid surfaces, the dynamics of the outermost layer of liquid and solid surfaces and the dynamics at the liquid-solid interface. Specific topics that are featured include state-to-state scattering dynamics, chemical reaction dynamics, non-adiabatic effects in reactive and inelastic scattering of molecules from surfaces, single molecule dynamics at surfaces, surface photochemistry, ultrafast dynamics at surfaces, and dynamics at water interfaces. The conference brings together investigators from a variety of scientific disciplines including chemistry, physics, materials science, geology, biophysics, and astronomy.

  8. Assessing land-use changes driven by river dynamics in chronically flood affected Upper Brahmaputra plains, India, using RS-GIS techniques

    Directory of Open Access Journals (Sweden)

    Nabajit Hazarika


    Full Text Available This work documents land-use changes driven by river dynamics along two tributaries in the chronically flood affected Upper Brahmaputra floodplain which supports a population of more than half a million. Planform changes for a period of 40 years are documented using topographical map and Landsat data, and the associated land-use change is assessed by utilising hybrid classification in GIS environment. Quantification of bankline migration shows that the river courses are unstable. A reversal in the rate of erosion and deposition is also observed. Hybrid classification of Landsat images yielded a higher level of accuracy as evident from the confusion matrixes. Overall, the accuracy of land-use classification ranged between 88.5% and 96.25%. Land-use change shows that there is an increase in settlement and agriculture and a decrease in the grassland. The area affected by erosion–deposition and river migration comprises primarily of the agricultural land. Effect of river dynamics on settlements is also evident. Loss of agricultural land and homestead led to the loss of livelihood and internal migration in the floodplains. The observed pattern of river dynamics and the consequent land-use change in the recent decades have thrown newer environmental challenges at a pace and magnitude way beyond the coping capabilities of the dwellers.

  9. Socio-hydrological flood models (United States)

    Barendrecht, Marlies; Viglione, Alberto; Blöschl, Günter


    Long-term feedbacks between humans and floods may lead to complex phenomena such as coping strategies, levee effects, call effects, adaptation effects, and poverty traps. Such phenomena cannot be represented by traditional flood risk approaches that are based on scenarios. Instead, dynamic models of the coupled human-flood interactions are needed. These types of models should include both social and hydrological variables as well as other relevant variables, such as economic, environmental, political or technical, in order to adequately represent the feedbacks and processes that are of importance in human-flood systems. These socio-hydrological models may play an important role in integrated flood risk management by exploring a wider range of possible futures, including unexpected phenomena, than is possible by creating and studying scenarios. New insights might come to light about the long term effects of certain measures on society and the natural system. Here we discuss a dynamic framework for flood risk and review the models that are presented in literature. We propose a way forward for socio-hydrological modelling of the human-flood system.

  10. Atomistic interactions of clusters on surfaces using molecular dynamics and hyper molecular dynamics

    International Nuclear Information System (INIS)

    Sanz-Navarro, Carlos F.


    The work presented in this thesis describes the results of Molecular Dynamics (MD) simulations applied to the interaction of silver clusters with graphite surfaces and some numerical and theoretical methods concerning the extension of MD simulations to longer time scales (hyper-MD). The first part of this thesis studies the implantation of clusters at normal incidence onto a graphite surface in order to determine the scaling of the penetration depth (PD) against the impact energy. A comparison with experimental results is made with good agreement. The main physical observations of the impact process are described and analysed. It is shown that there is a threshold impact velocity above which the linear dependence on PD on impact energy changes to a linear dependence on velocity. Implantation of silver clusters at oblique incidence is also considered. The second part of this work analyses the validity and feasibility of the three minimisation methods for the hyper-MD simulation method whereby time scales of an MD simulation can be extended. A correct mathematical basis for the iterative method is derived. It is found that one of the iterative methods, upon which hyper-lD is based, is very likely to fail in high-dimensional situations because it requires a too expensive convergence. Two new approximations to the hyper-MD approach are proposed, which reduce the computational effort considerably. Both approaches, although not exact, can help to search for some of the most likely transitions in the system. Some examples are given to illustrate this. (author)

  11. Critical Zone Co-dynamics: Quantifying Interactions between Subsurface, Land Surface, and Vegetation Properties Using UAV and Geophysical Approaches (United States)

    Dafflon, B.; Leger, E.; Peterson, J.; Falco, N.; Wainwright, H. M.; Wu, Y.; Tran, A. P.; Brodie, E.; Williams, K. H.; Versteeg, R.; Hubbard, S. S.


    Improving understanding and modelling of terrestrial systems requires advances in measuring and quantifying interactions among subsurface, land surface and vegetation processes over relevant spatiotemporal scales. Such advances are important to quantify natural and managed ecosystem behaviors, as well as to predict how watershed systems respond to increasingly frequent hydrological perturbations, such as droughts, floods and early snowmelt. Our study focuses on the joint use of UAV-based multi-spectral aerial imaging, ground-based geophysical tomographic monitoring (incl., electrical and electromagnetic imaging) and point-scale sensing (soil moisture sensors and soil sampling) to quantify interactions between above and below ground compartments of the East River Watershed in the Upper Colorado River Basin. We evaluate linkages between physical properties (incl. soil composition, soil electrical conductivity, soil water content), metrics extracted from digital surface and terrain elevation models (incl., slope, wetness index) and vegetation properties (incl., greenness, plant type) in a 500 x 500 m hillslope-floodplain subsystem of the watershed. Data integration and analysis is supported by numerical approaches that simulate the control of soil and geomorphic characteristic on hydrological processes. Results provide an unprecedented window into critical zone interactions, revealing significant below- and above-ground co-dynamics. Baseline geophysical datasets provide lithological structure along the hillslope, which includes a surface soil horizon, underlain by a saprolite layer and the fractured Mancos shale. Time-lapse geophysical data show very different moisture dynamics in various compartments and locations during the winter and growing season. Integration with aerial imaging reveals a significant linkage between plant growth and the subsurface wetness, soil characteristics and the topographic gradient. The obtained information about the organization and

  12. Simulation of surface dynamics during dissolution as a function of the surface orientation: Implications for non-constant dissolution rates (United States)

    Godinho, J. R. A.; Piazolo, S.; Evans, L.


    An important problem in geochemistry is the understanding of how changes occurring on a surface during dissolution affect the variability of measured dissolution rates. In this study a new approach to study the effect of surface dynamics on dissolution rates is tested by coupling experimental data with a numerical model that simulates the retreat of surface profiles during dissolution. We present specific results from the simulation of dissolution of fluorite surfaces. The equations that determine the retreat of a surface are based on experimentally obtained equations that relate the retreat rate of a surface to a single variable, the crystallographic orientation of the surface. Our results show that depending on the starting orientation, different types of topography are developed, similar to those observed experimentally. During the initial dissolution phase, changes of topography are rapid and associated with fast dissolution rates. The progressively slower dissolution rates are coupled with the development of surface segments with orientations that dissolve at a slower rate. Consequently, the overall retreat rate of a profile decreases during the simulation, and tends to a near-constant value. The results show a close relationship between dissolution rates, surface orientation and surface dynamics, which suggests that the dissolution rate of a specific mineral phase is not constant but varies with dissolution time and surface structure. This variability needs to be considered in the evaluation of experimentally derived dissolution rates, future dissolution experiments, and predictive kinetic models of dissolution.

  13. Mapping Carrier Dynamics on Material Surfaces in Space and Time using Scanning Ultrafast Electron Microscopy

    KAUST Repository

    Sun, Jingya


    Selectively capturing the ultrafast dynamics of charge carriers on materials surfaces and at interfaces is crucial to the design of solar cells and optoelectronic devices. Despite extensive research efforts over the past few decades, information and understanding about surface-dynamical processes, including carrier trapping and recombination remains extremely limited. A key challenge is to selectively map such dynamic processes, a capability that is hitherto impractical by time-resolved laser techniques, which are limited by the laser’s relatively large penetration depth and consequently they record mainly bulk information. Such surface dynamics can only be mapped in real space and time by applying four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM), which records snapshots of materials surfaces with nanometer spatial and sub-picosecond temporal resolutions. In this method, the secondary electron (SE) signal emitted from the sample’s surface is extremely sensitive to the surface dynamics and is detected in real time. In several unique applications, we spatially and temporally visualize the SE energy gain and loss, the charge carrier dynamics on the surface of InGaN nanowires and CdSe single crystals and its powder film. We also provide the mechanisms for the observed dynamics, which will be the foundation for future potential applications of S-UEM to a wide range of studies on material surfaces and device interfaces.

  14. Effects of flooding-induced N2O production, consumption and emission dynamics on the annual N2O emission budget in wetland soil

    DEFF Research Database (Denmark)

    Jørgensen, Christian Juncher; Elberling, Bo


    during mid-summer when the WL was at its seasonally lowest counterbalancing ~6.4% of the total annual net N2O emission budget. Main surface emission periods of N2O were observed when the water level and associated peaks in subsurface N2O concentrations were gradually decreasing to soil depths down to 40...... production and consumption capacities where >500 nmol N2O cm-3 were sequentially produced and consumed in less than 24 hrs. It is concluded that a higher future frequency of flooding induced N2O emissions will have a very limited effect on the net annual N2O emission budget as long as NO3- availability...

  15. Using LiDAR surveys to document floods: A case study of the 2008 Iowa flood (United States)

    Chen, Bo; Krajewski, Witold F.; Goska, Radek; Young, Nathan


    Can we use Light Detection and Ranging (LiDAR), an emergent remote sensing technology with wide applications, to document floods with high accuracy? To explore the feasibility of this application, we propose a method to extract distributed inundation depths from a LiDAR survey conducted during flooding. This method consists of three steps: (1) collecting LiDAR data during flooding; (2) classifying the LiDAR observational points as flooded water surface points and non-flooded points, and generating a floodwater surface elevation model; and (3) subtracting the bare earth Digital Terrain Model (DTM) from the flood surface elevation model to obtain a flood depth map. We applied this method to the 2008 Iowa flood in the United States and evaluated the results using the high-water mark measurements, flood extent extracted from SPOT (Small Programmable Object Technology) imagery, and the near-simultaneously acquired aerial photography. The root mean squared error of the LiDAR-derived floodwater surface profile to high-water marks was 30 cm, the consistency between the two flooded areas derived from LiDAR and SPOT imagery was 72% (81% if suspicious isolated ponds in the SPOT-derived extent were removed), and LiDAR-derived flood extent had a horizontal resolution of ∼3 m. This work demonstrates that LiDAR technology has the potential to provide calibration and validation reference data with appreciable accuracy for improved flood inundation modeling.

  16. Developing a Malaysia flood model (United States)

    Haseldine, Lucy; Baxter, Stephen; Wheeler, Phil; Thomson, Tina


    Faced with growing exposures in Malaysia, insurers have a need for models to help them assess their exposure to flood losses. The need for an improved management of flood risks has been further highlighted by the 2011 floods in Thailand and recent events in Malaysia. The increasing demand for loss accumulation tools in Malaysia has lead to the development of the first nationwide probabilistic Malaysia flood model, which we present here. The model is multi-peril, including river flooding for thousands of kilometres of river and rainfall-driven surface water flooding in major cities, which may cause losses equivalent to river flood in some high-density urban areas. The underlying hazard maps are based on a 30m digital surface model (DSM) and 1D/2D hydraulic modelling in JFlow and RFlow. Key mitigation schemes such as the SMART tunnel and drainage capacities are also considered in the model. The probabilistic element of the model is driven by a stochastic event set based on rainfall data, hence enabling per-event and annual figures to be calculated for a specific insurance portfolio and a range of return periods. Losses are estimated via depth-damage vulnerability functions which link the insured damage to water depths for different property types in Malaysia. The model provides a unique insight into Malaysian flood risk profiles and provides insurers with return period estimates of flood damage and loss to property portfolios through loss exceedance curve outputs. It has been successfully validated against historic flood events in Malaysia and is now being successfully used by insurance companies in the Malaysian market to obtain reinsurance cover.

  17. Assessment of hyporheic zone, flood-plain, soil-gas, soil, and surface-water contamination at the Old Incinerator Area, Fort Gordon, Georgia, 2009-2010 (United States)

    Guimaraes, Wladmir B.; Falls, W. Fred; Caldwell, Andral W.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.


    The U.S. Geological Survey, in cooperation with the U.S. Department of the Army Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon, Georgia, assessed the hyporheic zone, flood plain, soil gas, soil, and surface-water for contaminants at the Old Incinerator Area at Fort Gordon, from October 2009 to September 2010. The assessment included the detection of organic contaminants in the hyporheic zone, flood plain, soil gas, and surface water. In addition, the organic contaminant assessment included the analysis of explosives and chemical agents in selected areas. Inorganic contaminants were assessed in soil and surface-water samples. The assessment was conducted to provide environmental contamination data to the U.S. Army at Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Total petroleum hydrocarbons were detected above the method detection level in all 13 samplers deployed in the hyporheic zone and flood plain of an unnamed tributary to Spirit Creek. The combined concentrations of benzene, toluene, ethylbenzene, and total xylene were detected at 3 of the 13 samplers. Other organic compounds detected in one sampler included octane and trichloroethylene. In the passive soil-gas survey, 28 of the 60 samplers detected total petroleum hydrocarbons above the method detection level. Additionally, 11 of the 60 samplers detected the combined masses of benzene, toluene, ethylbenzene, and total xylene above the method detection level. Other compounds detected above the method detection level in the passive soil-gas survey included octane, trimethylbenzene, perchlorethylene, and chloroform. Subsequent to the passive soil-gas survey, six areas determined to have relatively high contaminant mass were selected, and soil-gas samplers were deployed, collected, and analyzed for explosives and chemical agents. No explosives or chemical agents were detected above

  18. Flood resilience urban territories. Flood resilience urban territories. (United States)

    Beraud, Hélène; Barroca, Bruno; Hubert, Gilles


    The flood's impact during the last twenty years on French territory reveals our lack of preparation towards large-extended floods which might cause the stopping of companies' activity, services, or lead to housing unavailability during several months. New Orleans' case has to exemplify us: four years after the disaster, the city still couldn't get back its dynamism. In France, more than 300 towns are flood-exposed. While these towns are the mainspring of territory's development, it is likely that the majority of them couldn't get up quickly after a large-extended flood. Therefore, to understand and improve the urban territory's resilience facing floods is a real stake for territory's development. Urban technical networks supply, unify and irrigate all urban territories' constituents. Characterizing their flood resilience can be interesting to understand better urban resilience. In this context, waste management during and after floods is completely crucial. During a flood, the waste management network can become dysfunctional (roads cut, waste storage installations or waste treatment flooded). How can the mayor respect his obligation to guarantee salubrity and security in his city? In post flood the question is even more problematic. The waste management network presents a real stake for territory's restart. After a flood, building materials, lopped-of branches, furniture, business stocks, farm stocks, mud, rubbles, animal cadavers are wet, mixed, even polluted by hydrocarbons or toxic substances. The waste's volume can be significant. Sanitary and environmental risks can be crucial. In view of this situation, waste's management in post crisis period raises a real problem. What to make of this waste? How to collect it? Where to stock it? How to process it? Who is responsible? Answering these questions is all the more strategic since this waste is the mark of disaster. Thus, cleaning will be the first population's and local actor's reflex in order to forget the

  19. Nuclear Dynamics and Electronic Effects of Hydrogen on Solid Surfaces. (United States)

    Fukutani, K; Wilde, M; Ogura, S


    Hydrogen is involved in a variety of chemical processes on surfaces. While hydrogen exhibits vibrational and rotational dynamics in its adsorption state, it in some cases undergoes diffusion into the substrate as well as on the surface, and participates in chemical reactions. Furthermore, hydrogen exchanges an electron with surfaces having a significant effect on the surface electronic structure. In this personal account, we review our recent studies on surface nuclear dynamics of hydrogen, hydrogen transport across surfaces, catalytic hydrogenation/isotope exchange reactions, and charge transfer between the surface and hydrogen by using a depth-resolved technique of nuclear reaction analysis and a quantum-state-selective detection of resonance enhanced multiphoton ionization in combination with surface science techniques. As a future prospect, we refer to ultraslow μ spin rotation spectroscopy for a direct probe of the hydrogen charge state at surfaces. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The shape, stability and dynamics of elastic surfaces (United States)

    Mahadevan, L.


    Bending a thin sheet is easier than stretching it, an observation which has its roots in geometry. We will use this fact to explain some unusual problems in biology, physics and geology. At the everyday scale, I will discuss the morphology of avascular algal blades, the dynamics of defects in an elastic ribbon, and the dynamics of prey capture by certain carnivorous plants. At the geological scale, I will try to explain the shape of island arcs on our planet. Finally, time permitting, I will discuss how we might extend these ideas to the macromolecular scale, to derive a mechanical model for the dynamic instability of a growing microtubule.

  1. Application of VRML to dynamic display of three dimension geologic surface

    Energy Technology Data Exchange (ETDEWEB)

    Rui, X.; Yu, Z.; Xu, Y. [China University of Mining and Technology, Xuzhou (China). College of Resource and Environment Technology


    The basic concept of Virtual Reality and VRML is introduced. According to the actual condition of the geologic surface, the virtual space to display dynamically the three-dimensional geologic surface is constructed by using GRID file and Elevation Grid node. The application of this method to coalfield geologic surface has achieved very good visual effect. 7 refs., 1 fig.

  2. Population dynamics of the migratory fish Prochilodus lineatus in a neotropical river: the relationships with river discharge, flood pulse, El Niño and fluvial megafan behaviour

    Directory of Open Access Journals (Sweden)

    Marinke J. M. Stassen


    Full Text Available The relative importance of flood pulse dynamics and megafan behaviour for the Sábalo (Prochilodus lineatus catches in the neotropical Pilcomayo River is studied. The Sábalo catches can mainly be explained by decreased river discharges in the preceding years resulting in smaller inundated areas during rainy season floods and thereby in a decreased area of feeding grounds for the fishes. The decreased river discharges and the related decline of Sábalo catches in the 1990's can be linked to the 90-95 El Niño event. In 2007 the Sábalo catches were comparable to the catches before the "El Niño" event. The connectivity (continuity between the main river and flood plain areas, which is influenced by sedimentation processes, is also of great importance and very probably plays a more important role since the late 1990's.Se ha estudiado la importancia relativa de la dinámica del pulso de inundación y el comportamiento del sistema megafan para las capturas del Sábalo (Prochilodus lineatus en el río Pilcomayo. Las capturas del Sábalo puede explicarse fundamentalmente por los bajos caudales del río en los años anteriores, resultando en menores superficies de las zonas inundadas durante la temporada de lluvia y por lo tanto en una área menor de alimentación para los peces. La disminución del caudal del río y la declinación relativa de capturas de Sábalo en los años 1990 pueden estar relacionadas con el 90-95 evento de El Niño. En 2007, la captura de Sábalo fue comparable a las capturas antes del evento de "El Niño". La conectividad (continuidad entre el río principal y las llanuras aluviales, que son influenciadas por los procesos de sedimentación, son también de gran importancia y muy probablemente juegan un papel muy importante desde finales de los años '90.

  3. Challenges of flood monitoring in the Senegal river valley using multi-temporal data (United States)

    Bruckmann, Laurent; Delbart, Nicolas


    In Sub-Saharan Africa, floodplains wetlands play an important role for livelihoods and economy, especially for agriculture and fishing. However, tropical rivers flows are increasingly modified by climate change and dam regulation. In the Senegal river valley, the annual flood, from August to November, is an important water resources creating ecosystems services for people. Senegal river basin face to hydrological changes, due to rainfall diminution during the 1970's and building of large dams during 1980's to secure water resources. Water management and development of irrigation have modified the floodplain functioning. Flood recession agriculture, grazing and fishing are now confronted to a high uncertainty about floods level, duration and extension. Thus, spatiotemporal information of flood extension and duration are important for local communities and stakeholders to ensure food security and ecosystems services. Multi-temporal satellite data demonstrates an important applicability for flood mapping. Aims of this work is to present potentiality of using multi-temporal data from MODIS and new satellite Sentinel-2 for flood monitoring in a Sahelian context. It will also discuss the potential of flood mapping for the analysis of the dynamics of riparian vegetation and flood recession agriculture. This study uses two datasets to explore flood monitoring in Senegal river valley. Firstly, MODIS 8-days data (MOD09A) are first used, because of its temporal resolution of 8 days covering the period from 2000 to 2016. However, MODIS data are limited due to a low spatial resolution, that's why we also use Sentinel-2 data, available since summer 2015. The data were processed by constructing NDWI time-series (NDWI threshold is empirically defined) and extracting NDWI values for each inundated pixel during flood. First results demonstrate that using MODIS on a large scale is enough for analyze interannual variability of the flooded surfaces. We present here maps of flood

  4. Disinfection byproduct precursor dynamics and water treatability during an extreme flooding event in a coastal blackwater river in southeastern United States. (United States)

    Ruecker, A; Uzun, H; Karanfil, T; Tsui, M T K; Chow, A T


    Coastal blackwater rivers, characterized by high concentrations of natural organic matter, are source water for millions of people in the southeastern US. In October 2015, large areas of coastal South Carolina were flooded by Hurricane Joaquin. This so-called "thousand-year" rainfall mobilized and flushed large amounts of terrestrial organic matter and associated pollutants (e.g. mercury) into source water, affecting water quality and safety of municipal water supply. To understand the dynamics of water quality and water treatability during this extreme flood, water samples were collected from Waccamaw River (a typical blackwater river in the southeastern US) during rising limb, peak discharge, falling limb, and base flow. Despite decreasing water flow after peak discharge, dissolved organic carbon (DOC) levels (increased by up to 125%), and formation potentials of trihalomethanes and haloacetic acids (increased by up to 150%) remained high for an extended period of time (>eight weeks after peak discharge), while variation in the N-nitrosodimethylamine (NDMA) FP was negligible. Coagulation with alum and ferric at optimal dosage significantly reduced concentrations of DOC by 51-76%, but up to 10 mg/L of DOC still remained in treated waters. For an extended period of time, elevated levels of THMs (71-448 μg/L) and HAAs (88-406 μg/L) were quantified in laboratory chlorination experiments under uniform formation conditions (UFC), exceeding the United States Environmental Protection Agency's (USEPA) maximum contaminant level of 80 and 60 μg/L, respectively. Results demonstrated that populations in coastal cities are at high risk with disinfection by-products (DBPs) under the changing climate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Friction and diffusion dynamics of adsorbates at surfaces

    NARCIS (Netherlands)

    Fusco, C.


    A theoretical study of the motion of adsorbates (e. g. atoms, molecules or clusters) on solid surfaces is presented, with a focus on surface diffusion and atomic-scale friction. These two phenomena are inextricably linked, because when an atomic or molecular adsorbate diffuses, or is pulled, it

  6. A tri-objective, dynamic weapon assignment model for surface ...

    African Journals Online (AJOL)


    May 11, 2015 ... of available surface-based weapon systems to engage aerial threats in an attempt to protect defended surface ...... time stages to include in the fixed mean calculation in (2) be fixed to the minimum length of a FW. ... to solve the model in 139 seconds on an Intel Core i7-4770 processor with 8GB of random.

  7. Dynamics of phenanthrenequinone on carbon nano-onion surfaces probed by quasielastic neutron scattering. (United States)

    Chathoth, Suresh M; Anjos, Daniela M; Mamontov, Eugene; Brown, Gilbert M; Overbury, Steven H


    We used quasielastic neutron scattering (QENS) to study the dynamics of phenanthrenequinone (PQ) on the surface of onion-like carbon (OLC), or so-called carbon onions, as a function of surface coverage and temperature. For both the high- and low-coverage samples, we observed two diffusion processes; a faster process and nearly an order of magnitude slower process. On the high-coverage surface, the slow diffusion process is of long-range translational character, whereas the fast diffusion process is spatially localized on the length scale of ∼4.7 Å. On the low-coverage surface, both diffusion processes are spatially localized; on the same length scale of ∼4.7 Å for the fast diffusion and a somewhat larger length scale for the slow diffusion. Arrhenius temperature dependence is observed except for the long-range diffusion on the high-coverage surface. We attribute the fast diffusion process to the generic localized in-cage dynamics of PQ molecules, and the slow diffusion process to the long-range translational dynamics of PQ molecules, which, depending on the coverage, may be either spatially restricted or long-range. On the low-coverage surface, uniform surface coverage is not attained, and the PQ molecules experience the effect of spatial constraints on their long-range translational dynamics. Unexpectedly, the dynamics of PQ molecules on OLC as a function of temperature and surface coverage bears qualitative resemblance to the dynamics of water molecules on oxide surfaces, including practically temperature-independent residence times for the low-coverage surface. The dynamics features that we observed may be universal across different classes of surface adsorbates.

  8. Dynamics of Phenanthrenequinone on Carbon Nano-Onion Surfaces Probed by Quasielastic Neutron Scattering

    International Nuclear Information System (INIS)

    Mamontov, Eugene; Brown, Gilbert M.; Overbury, Steven H.; Mavila Chathoth, Suresh


    We used quasielastic neutron scattering (QENS) to study the dynamics of phenanthrenequinone (PQ) on the surface of onion-like carbon (OLC), or so called carbon onions, as a function of surface coverage and temperature. For both the high- and low-coverage samples, we observed two diffusion processes; a faster process and nearly an order of magnitude slower process. On the high-coverage surface, the slow diffusion process is of long-range translational character, whereas the fast diffusion process is spatially localized on the length scale of ∼ 4.7. On the low-coverage surface, both diffusion processes are spatially localized; on the same length scale of ∼ 4.7 for the fast diffusion and a somewhat larger length scale for the slow diffusion. Arrhenius temperature dependence is observed except for the long-range diffusion on the high-coverage surface. We attribute the fast diffusion process to the generic localized in-cage dynamics of PQ molecules, and the slow diffusion process to the long-range translational dynamics of PQ molecules, which, depending on the coverage, may be either spatially restricted, or long-range. On the low-coverage surface, uniform surface coverage is not attained, and the PQ molecules experience the effect of spatial constraints on their long-range translational dynamics. Unexpectedly, the dynamics of PQ molecules on OLC as a function of temperature and surface coverage bears qualitative resemblance to the dynamics of water molecules on oxide surfaces, including practically temperature-independent residence times for the low-coverage surface. The dynamics features that we observed may be universal across different classes of surface adsorbates.

  9. Liquid surface dynamics: a quantum-resolved scattering study (United States)

    Kenyon, A. J.; McCaffery, A. J.; Quintella, C. M.; Zidan, M. D.


    Results are presented from a preliminary study of molecular scattering from liquid surfaces. Cold iodine molecules have been scattered off the surface of a methylated poly-siloxane oil and liquid gallium. Energy transfer at the liquid surface has been probed via the laser-induced fluorescence spectrum of the scattered molecules from which the vibrational and rotational state populations are accessible. We have been able to follow energy transfer via two separate channels; impulsive scattering and trapping-desorption, and have made a brief study of changes in the degree of vibrational and rotational accommodation at and around the melting point of gallium.

  10. Molecular dynamics calculation of the surface tension of aluminum nanodrops

    International Nuclear Information System (INIS)

    Gubin, A.S.; Botyachkova, A.I.; Dubrovskij, A.V.


    A method has been proposed for calculating the surface tension coefficient of liquid drops. The density and normal and tangential components of the stress tensor have been calculated as functions of the distance to the center of a nanodrop [ru

  11. Dynamics of hydration water and coupled protein sidechains around a polymerase protein surface (United States)

    Qin, Yangzhong; Yang, Yi; Wang, Lijuan; Zhong, Dongping


    Water-protein coupled interactions are essential to the protein structural stability, flexibility and dynamic functions. The ultimate effects of the hydration dynamics on the protein fluctuations remain substantially unexplored. Here, we investigated the dynamics of both hydration water and protein sidechains at 13 different sites around the polymerase β protein surface using a tryptophan scan with femtosecond spectroscopy. Three types of hydration-water relaxations and two types of protein sidechain motions were determined, reflecting a highly dynamic water-protein interactions fluctuating on the picosecond time scales. The hydration-water dynamics dominate the coupled interactions with higher flexibility.

  12. Oscillon dynamics and rogue wave generation in Faraday surface ripples. (United States)

    Xia, H; Maimbourg, T; Punzmann, H; Shats, M


    We report new experimental results which suggest that the generation of extreme wave events in the Faraday surface ripples is related to the increase in the horizontal mobility of oscillating solitons (oscillons). The analysis of the oscillon trajectories in a horizontal plane shows that at higher vertical acceleration, oscillons move chaotically, merge and form enclosed areas on the water surface. The probability of the formation of such craters, which precede large wave events, increases with the increase in horizontal mobility.

  13. Dynamic superhydrophobic behavior in scalable random textured polymeric surfaces (United States)

    Moreira, David; Park, Sung-hoon; Lee, Sangeui; Verma, Neil; Bandaru, Prabhakar R.


    Superhydrophobic (SH) surfaces, created from hydrophobic materials with micro- or nano- roughness, trap air pockets in the interstices of the roughness, leading, in fluid flow conditions, to shear-free regions with finite interfacial fluid velocity and reduced resistance to flow. Significant attention has been given to SH conditions on ordered, periodic surfaces. However, in practical terms, random surfaces are more applicable due to their relative ease of fabrication. We investigate SH behavior on a novel durable polymeric rough surface created through a scalable roll-coating process with varying micro-scale roughness through velocity and pressure drop measurements. We introduce a new method to construct the velocity profile over SH surfaces with significant roughness in microchannels. Slip length was measured as a function of differing roughness and interstitial air conditions, with roughness and air fraction parameters obtained through direct visualization. The slip length was matched to scaling laws with good agreement. Roughness at high air fractions led to a reduced pressure drop and higher velocities, demonstrating the effectiveness of the considered surface in terms of reduced resistance to flow. We conclude that the observed air fraction under flow conditions is the primary factor determining the response in fluid flow. Such behavior correlated well with the hydrophobic or superhydrophobic response, indicating significant potential for practical use in enhancing fluid flow efficiency.

  14. Comparison of dynamic isotope power systems for distributed planetary surface applications

    International Nuclear Information System (INIS)

    Bents, D.J.; McKissock, B.I.; Withrow, C.A.; Hanlon, J.C.; Schmitz, P.C.


    To support the Space Exploration Initiative, a study was performed to investigate and characterize dynamic isotope power system (DIPS) alternatives for the surface mission elements associated with a lunar base and subsequent manned Mars expedition

  15. Quantum Nuclear Extension of Electron Nuclear Dynamics on Folded Effective-Potential Surfaces

    DEFF Research Database (Denmark)

    Hall, B.; Deumens, E.; Ohrn, Y.


    A perennial problem in quantum scattering calculations is accurate theoretical treatment of low energy collisions. We propose a method of extracting a folded, nonadiabatic, effective potential energy surface from electron nuclear dynamics (END) trajectories; we then perform nuclear wave packet...

  16. Artificial surface-mounted molecular rotors: Molecular dynamics simulations

    Czech Academy of Sciences Publication Activity Database

    Vacek, Jaroslav; Michl, Josef


    Roč. 17, č. 5 (2007), s. 730-739 ISSN 1616-301X R&D Projects: GA AV ČR IAA400550616; GA MŠk ME 857 Institutional research plan: CEZ:AV0Z40550506 Keywords : molecular dynamics * molecular machines * nanomaterials Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.496, year: 2007

  17. Stochastic dynamic stiffness of surface footing for offshore wind turbines

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammadjavad; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo


    Highlights •This study concerns the stochastic dynamic stiffness of foundations for large offshore wind turbines. •A simple model of wind turbine structure with equivalent coupled springs at the base is utilized. •The level of uncertainties is quantified through a sensitivity analysis. •Estimatio...... of rare events of first natural frequency applying subset simulation is discussed....

  18. Effect of surface modification and hybridization on dynamic ...

    Indian Academy of Sciences (India)

    Storage and loss modulus values increased after treatments with simultaneous decrease in tan values. Roystonea regia and glass fibres were used together with varying proportions as reinforcement in epoxy matrix to study the hybridization effect on dynamic mechanical properties. Storage and loss modulus values ...

  19. A tri-objective, dynamic weapon assignment model for surface ...

    African Journals Online (AJOL)

    In this paper, a tri-objective, dynamic weapon assignment model is proposed by modelling the weapon assignment problem as a multi-objective variation of the celebrated vehicle routing problem with time windows. A multi-objective, evolutionary metaheuristic for solving the vehicle routing problem with time windows is ...

  20. Importance of surface structure on dissolution of fluorite: Implications for surface dynamics and dissolution rates (United States)

    Godinho, J. R. A.; Piazolo, S.; Balic-Zunic, T.


    Dissolution rates are usually calculated as a function of surface area, which is assumed to remain constant ignoring the changes occurring on the surface during dissolution. Here we present a study of how topography of natural fluorite surfaces with different orientation changes during up to 3200 h of dissolution. Results are analyzed in terms of changes in surface area, surface reactivity and dissolution rates. All surfaces studied present fast changes in topography during the initial 200 h of dissolution. The controlling factors that cause the development of topography are the stability of the step edges forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces continue to present significant changes in topography, while for others the topography tends to remain approximately constant. The observed variation of dissolution rates are attributed to a decrease of the density of step edges on the surface and the continuous increase in exposure of more stable surfaces. Calculations of dissolution rates, which assume that dissolution rates are directly proportional to surface area, are not valid for the type of surfaces studied. Instead, to develop accurate kinetic dissolution models and more realistic stochastic dissolution simulations the surface reactivity, determined by the relative stability of the planes and type of edges that constitute a surface needs to be considered. Significant differences between dissolution rates calculated based on surface area alone, and based on surface reactivity are expected for materials with the fluorite structure.

  1. Assessing river regime alteration due to flood detention structures in dry and semi-dry regions (United States)

    Yaraghi, Navid; Torabihaghighi, Ali; Ronkanen, Anna-Kaisa; Fazel, Nasim; Rossi, Pekka. M.; Klöve, Björn


    In dry and semi-dry climate, flood detention structures are used for flood control and managed aquifer recharge. These damps basin runoff response decreasing the maximum flows and increasing the runoff duration through wet seasons. In this study, a framework to quantify the role of flood detention dams in headwater tributaries on total water balance of major basin and alteration of flow pattern in the main river has been presented. The study contains four main subroutines: rainfall-runoff model, reservoir flood routing, river analysis system and seepage analysis. The flood hydrographs with different return periods are estimated based on the climatic data and geomorphology of headwater basin. River flow analysis below the flood detention structure is carried out for two unsteady flow scenarios, first with the hydrographs of natural system (as pre-impact: quick flood with significant peak flow) and second the routed hydrographs due to detention process in the reservoir (as post-impact: damped flood lower peak with longer duration time). Two sets of dynamic water surface along the river (from the location of detention structure (x=0) to the confluence point with main river (x=L) are developed based on two hydrologic conditions as results of river analysis system. The results of framework define the impact of flood detention structure by comparing the timing, magnitude and variability of flow. The Kamal Abad artificial groundwater recharge in Mahrloo Lake basin in Southern Iran was selected as case study to demonstrate the application of the created framework. Through the probability analysis, the return period for hydrological drought would be compared in pre and post impact condition. The results clearly showed how embankments influence floods in tributaries and in some cases the flow reduced significantly and disappears in tributaries.

  2. Molecular dynamics simulation of uranium compound adsorption on solid surface

    International Nuclear Information System (INIS)

    Omori, Yuki; Takizawa, Yuji; Okamoto, Tsuyoshi


    Particles mixed in the UF6 gas have the property of accumulating on the inside of piping or units. This type of accumulation will cause material unaccounted for (MUF) in the UF6 gas processing facilities. Development of a calculation model for estimating the accumulation rate of uranium compounds has been expected. And predicting possible part of the units where uranium compounds adsorb will contribute to design an effective detection system. The purpose of this study is to take the basic knowledge of the particle's adsorption mechanism from the microscopic point of view. In simulation analysis, UF5 model particle is produced, then two types of solid surfaces are prepared; one is a solid surface at rest and the other is a moving solid surface. The result obtained by the code 'PABS' showed that when the solid surface moves at a lower velocity, the particle's adsorption process dominates over the particle's breakup one. Besides the velocity of the solid surface, other principal factors affecting an adsorption ratio were also discussed. (author)

  3. Nonlinear friction dynamics on polymer surface under accelerated movement

    Directory of Open Access Journals (Sweden)

    Yuuki Aita


    Full Text Available Nonlinear phenomena on the soft material surface are one of the most exciting topics of chemical physics. However, only a few reports exist on the friction phenomena under accelerated movement, because friction between two solid surfaces is considered a linear phenomenon in many cases. We aim to investigate how nonlinear accelerated motion affects friction on solid surfaces. In the present study, we evaluate the frictional forces between two polytetrafluoroethylene (PTFE resins using an advanced friction evaluation system. On PTFE surfaces, the normalized delay time δ, which is the time lag in the response of the friction force to the accelerated movement, is observed in the pre-sliding friction process. Under high-velocity conditions, kinetic friction increases with velocity. Based on these experimental results, we propose a two-phase nonlinear model including a pre-sliding process (from the beginning of sliding of a contact probe to the establishment of static friction and a kinetic friction process. The present model consists of several factors including velocity, acceleration, stiffness, viscosity, and vertical force. The findings reflecting the viscoelastic properties of soft material is useful for various fields such as in the fabrication of clothes, cosmetics, automotive materials, and virtual reality systems as well as for understanding friction phenomena on soft material surfaces.

  4. Development of a dynamic model for cleaning ultra filtration membranes fouled by surface water

    NARCIS (Netherlands)

    Zondervan, E.; Betlem, Bernardus H.L.; Roffel, B.


    In this paper, a dynamic model for cleaning ultra filtration membranes fouled by surface water is proposed. A model that captures the dynamics well is valuable for the optimization of the cleaning process. The proposed model is based on component balances and contains three parameters that can be

  5. Accelerating solving the dynamic multi-objective nework design problem using response surface methods

    NARCIS (Netherlands)

    Wismans, Luc Johannes Josephus; van Berkum, Eric C.; Bliemer, Michiel C.J.; Viti, F.; Immers, B.; Tampere, C.


    Multi objective optimization of externalities of traffic solving a network design problem in which Dynamic Traffic Management measures are used, is time consuming while heuristics are needed and solving the lower level requires solving the dynamic user equilibrium problem. Use of response surface

  6. Remote sensing estimates of impervious surfaces for hydrological modelling of changes in flood risk during high-intensity rainfall events

    DEFF Research Database (Denmark)

    Kaspersen, Per Skougaard; Fensholt, Rasmus; Drews, Martin

    areas at different geographical locations within Europe, and to be applicable for cities with diverse morphologies and dissimilar climatic and vegetative conditions. Detailed data on urban land cover changes can be used to examine the diverse environmental impacts of past and present urbanisation......This paper addresses the accuracy and applicability of medium resolution (MR) remote sensing estimates of impervious surfaces (IS) for urban land cover change analysis. Landsat-based vegetation indices (VI) are found to provide fairly accurate measurements of sub-pixel imperviousness for urban......, including the importance of such changes for the exposure of cities towards the occurrence and impacts of climate extremes like high-intensity rainfall events....

  7. Remote sensing estimates of impervious surfaces for hydrological modelling of changes in flood risk during high-intensity rainfall events

    DEFF Research Database (Denmark)

    Kaspersen, Per Skougaard; Fensholt, Rasmus; Drews, Martin

    This paper addresses the accuracy and applicability of medium resolution (MR) remote sensing estimates of impervious surfaces (IS) for urban land cover change analysis. Landsat-based vegetation indices (VI) are found to provide fairly accurate measurements of sub-pixel imperviousness for urban...... areas at different geographical locations within Europe, and to be applicable for cities with diverse morphologies and dissimilar climatic and vegetative conditions. Detailed data on urban land cover changes can be used to examine the diverse environmental impacts of past and present urbanisation...

  8. Dynamical structure of the turbulent boundary layer on rough surface

    Czech Academy of Sciences Publication Activity Database

    Uruba, Václav; Jonáš, Pavel; Hladík, Ondřej


    Roč. 11, č. 1 (2011), s. 603-604 ISSN 1617-7061 R&D Projects: GA ČR GA101/08/1112; GA ČR GAP101/10/1230 Institutional research plan: CEZ:AV0Z20760514 Keywords : turbulent boundary layer * rough wall * hairpin vortex Subject RIV: BK - Fluid Dynamics

  9. Control and dynamics study for the satellite power system. Volume 1: MPTS/SPS collector dynamic analysis and surface deformation (United States)

    Wang, S. J.


    The basic dynamic properties and performance characteristics of the microwave power transmission satellite antenna were analyzed in an effort to develop criteria, requirements, and constraints for the control and structure design. The vibrational properties, the surface deformation, and the corresponding scan loss under the influence of disturbances are considered.

  10. Global drivers of future river flood risk

    NARCIS (Netherlands)

    Winsemius, H.C.; Aerts, J.C.J.H.; Van Beek, L.P.H.; Bierkens, M.F.P.; Bouwman, A.; Jongman, B.; Kwadijk, J.; Ligtvoet, W.; Lucas, P.L.; Van Vuuren, D.P.; Ward, P.J.


    Understanding global future river flood risk is a prerequisite for the quantification of climate change impacts and planning effective adaptation strategies. Existing global flood risk projections fail to integrate the combined dynamics of expected socio-economic development and climate change. We

  11. Global drivers of future river flood risk

    NARCIS (Netherlands)

    Winsemius, Hessel C.; Aerts, Jeroen C. J. H.; van Beek, Ludovicus P. H.|info:eu-repo/dai/nl/14749799X; Bierkens, Marc F. P.|info:eu-repo/dai/nl/125022794; Bouwman, Arno; Jongman, Brenden; Kwadijk, Jaap C. J.; Ligtvoet, Willem; Lucas, Paul L.|info:eu-repo/dai/nl/272607444; van Vuuren, Detlef P.|info:eu-repo/dai/nl/11522016X; Ward, Philip J.

    Understanding global future river flood risk is a prerequisite for the quantification of climate change impacts and planning effective adaptation strategies1. Existing global flood risk projections fail to integrate the combined dynamics of expected socio-economic development and climate change. We

  12. Dynamic and Impure Perovskite Structured Metal Oxide Surfaces

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Norrman, Kion; Traulsen, Marie Lund


    on the electrode surfaces. An experimental test of the suggestion that the segregation might happen in the vacuum in the analysis equipment gave a negative result. Formation of particles containing significant amounts of S and Cr from segregation of the trace impurities in the acquired powders were observed...

  13. Topological Fluid Dynamics For Free and Viscous Surfaces

    DEFF Research Database (Denmark)

    Balci, Adnan

    In an incompressible fluid flow, streamline patterns and their bifurcations are investigated close to wall for two-dimensional system and close to free and viscous surfaces in three-dimensional system. Expanding the velocity field in a Taylor series, we conduct a local analysis at the given...

  14. Body surface adaptations to boundary-layer dynamics

    NARCIS (Netherlands)

    Videler, J.J.


    Evolutionary processes have adapted nektonic animals to interact efficiently with the water that surrounds them. Not all these adaptations serve the same purpose. This paper concentrates on reduction of drag due to friction in the boundary layer close to the body surface. Mucus, compliant skins,

  15. Modified Contact Line Dynamics about a Surface-Piercing Hydrofoil (United States)

    Grivel, Morgane; Jeon, David; Gharib, Morteza


    The contact line around a surface-piercing hydrofoil is modified by introducing alternating hydrophobic and hydrophilic bands along one side of the body. These bands are either aligned perpendicular or parallel to the flow direction. The other side of the hydrofoil is un-patterned and retains its original, uniformly hydrophilic properties. The hydrofoil is mounted onto air bearings, such that it can freely move side-to-side in the water tunnel. A force sensor is attached to the setup via a universal joint in order to measure the forces acting on the body for several Reynolds numbers (ranging from 104 to 105) and angles of attack (ranging from -10o to 10o) . Cameras are also used to record the resulting flow structures and free surface elevation. The generation of wave trains and an altered free-surface elevation (also associated with the generation of surface waves) are observed over a wide range flow conditions. Force measurements elucidate how introducing these flow features impacts the forces acting on the hydrofoil, specifically with regards to the generation of lateral forces due to the asymmetric wetting conditions on either side of the hydrofoil. Work is funded by ONR Grant N00014-11-1-0031 and NSF GRFP Grant DGE-1144469.

  16. Droplet evaporation dynamics on a superhydrophobic surface with negligible hysteresis. (United States)

    Dash, Susmita; Garimella, Suresh V


    We report on experiments of droplet evaporation on a structured superhydrophobic surface that displays very high contact angle (CA ∼ 160 deg), and negligible contact angle hysteresis (evaporation is observed to occur in a constant-contact-angle mode, with contact radius shrinking for almost the entire duration of evaporation. Experiments conducted on Teflon-coated smooth surface (CA ∼ 120 deg) as a baseline also support an evaporation process that is dominated by a constant-contact-angle mode. The experimental results are compared with an isothermal diffusion model for droplet evaporation from the literature. Good agreement is observed for the Teflon-coated smooth surface between the analytical expression and experimental results in terms of the total time for evaporation, transient volume, contact angle, and contact radius. However, for the structured superhydrophobic surface, the experiments indicate that the time taken for complete evaporation of the droplet is greater than the predicted time, across all droplet volumes. This disparity is attributed primarily to the evaporative cooling at the droplet interface due to the high aspect ratio of the droplet and also the lower effective thermal conductivity of the substrate due to the presence of air gaps. This hypothesis is verified by numerically evaluating the temperature distribution along the droplet interface. We propose a generalized relation for predicting the instantaneous volume of droplets with initial CA > 90 deg, irrespective of the mode of evaporation.

  17. Vortex-Surface Interactions: Vortex Dynamics and Instabilities (United States)


    Crow instability (see for example Leweke & Williamson, 2012). (b) Short-wave cooperative elliptic instability (Leweke & Williamson 1998). (c...vortex generators. Of interest in such studies would be the formation of secondary vorticity from the surface, the downstream vortex trajectories , and

  18. Dynamic modeling method of the bolted joint with uneven distribution of joint surface pressure (United States)

    Li, Shichao; Gao, Hongli; Liu, Qi; Liu, Bokai


    The dynamic characteristics of the bolted joints have a significant influence on the dynamic characteristics of the machine tool. Therefore, establishing a reasonable bolted joint dynamics model is helpful to improve the accuracy of machine tool dynamics model. Because the pressure distribution on the joint surface is uneven under the concentrated force of bolts, a dynamic modeling method based on the uneven pressure distribution of the joint surface is presented in this paper to improve the dynamic modeling accuracy of the machine tool. The analytic formulas between the normal, tangential stiffness per unit area and the surface pressure on the joint surface can be deduced based on the Hertz contact theory, and the pressure distribution on the joint surface can be obtained by the finite element software. Futhermore, the normal and tangential stiffness distribution on the joint surface can be obtained by the analytic formula and the pressure distribution on the joint surface, and assigning it into the finite element model of the joint. Qualitatively compared the theoretical mode shapes and the experimental mode shapes, as well as quantitatively compared the theoretical modal frequencies and the experimental modal frequencies. The comparison results show that the relative error between the first four-order theoretical modal frequencies and the first four-order experimental modal frequencies is 0.2% to 4.2%. Besides, the first four-order theoretical mode shapes and the first four-order experimental mode shapes are similar and one-to-one correspondence. Therefore, the validity of the theoretical model is verified. The dynamic modeling method proposed in this paper can provide a theoretical basis for the accurate dynamic modeling of the bolted joint in machine tools.

  19. Formation of Surface Nanobubbles and the Universality of Their Contact Angles: A Molecular Dynamics Approach

    NARCIS (Netherlands)

    Weijs, Joost; Snoeijer, Jacobus Hendrikus; Lohse, Detlef


    We study surface nanobubbles using molecular dynamics simulation of ternary (gas, liquid, solid) systems of Lennard-Jones fluids. They form for a sufficiently low gas solubility in the liquid, i.e., for a large relative gas concentration. For a strong enough gas-solid attraction, the surface

  20. Molecular dynamics simulation of temperature effects on CF3+ etching of Si surface

    NARCIS (Netherlands)

    Ning, J. P.; Lu, X. D.; Zhao, C. L.; Qin, Y. M.; He, P. N.; Bogaerts, A.; Gou, F. J.


    Molecular dynamics method was employed to investigate the effects of the reaction layer formed near the surface region on CF3+ etching of Si at different temperatures. The simulation results show that the coverages of F and C are sensitive to the surface temperature. With increasing temperature, the

  1. Post-fire surface fuel dynamics in California forests across three burn severity classes (United States)

    Bianca N. I. Eskelson; Vicente J. Monleon


    Forest wildfires consume fuel and are followed by post-fire fuel accumulation. This study examines post-fire surface fuel dynamics over 9 years across a wide range of conditions characteristic of California fires in dry conifer and hardwood forests. We estimated post-fire surface fuel loadings (Mg ha _1) from 191 repeatedly measured United States...

  2. Non-equilibrium dynamics of single polymer adsorption to solid surfaces

    NARCIS (Netherlands)

    Panja, D.; Barkema, G.T.; Kolomeisky, A.B.


    The adsorption of polymers to surfaces is crucial for understanding many fundamental processes in nature. Recent experimental studies indicate that the adsorption dynamics is dominated by non-equilibrium effects. We investigate the adsorption of a single polymer of length N to a planar solid surface

  3. Trapped between institutions and politics : The role of politics and social dynamics in institutional performance for flood defense management in Jakarta, Indonesia

    NARCIS (Netherlands)

    Simanjuntak, I.; Frantzeskaki, N.; Enserink, B.; Ravesteijn, W.


    Flood defense management in Jakarta is a critical governmental activity given that Jakarta is a low-lying delta metropolis and trade center which relies on its safety for the continuity of the economic activities. Despite the urgency for action flood defense policy implementation was a lengthy and

  4. Dynamical models for sand ripples beneath surface waves

    DEFF Research Database (Denmark)

    Andersen, Ken Haste; Chabanol, M.-L.; v. Hecke, M.


    We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass...... transport function, our models predict the existence of a stable band of wave numbers limited by secondary instabilities. Small ripples coarsen in our models and this process leads to a sharply selected final wave number, in agreement with experimental observations....

  5. The Dynamic Stiffness of Surface Footings for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammadjavad; Andersen, Lars; Clausen, Johan


    of the turbine structure are subject to relatively small uncertainties compared to the properties of the subsoil. Thus, the seabed is not a homogeneous half-space but contains layers of sand, clay, silt, etc. with depths that vary from one position to another. The depth of the top layer may even change over time...... due to sediment transportation. Further, the stiffness and density of the materials within a single layer is subject to uncertainties. This leads to uncertainties of the dynamic stiffness of the foundation and therefore the natural frequencies. The aim of the study is to quantify the level...

  6. Experimental studies of photon-surface interaction dynamics in the alkali halides

    International Nuclear Information System (INIS)

    Haglund, R.F. Jr.; Tolk, N.H.


    We describe recent measurements which have provided, in unprecedented detail, insights into the electronic mechanisms through which energy carried into a material by photon irradiation is absorbed, localized and rechanneled to produce desorption, surface modification, erosion and damage. The specific object of these studies has been desorption induced by electronic transition in alkali halide crystals, with particular emphasis on the dynamics of changes in the surface and near-surface regions. In our experiments, the irradiating ultraviolet photons are provided by a synchrotron storage ring, and the dynamical information about desorption products is obtained from optical measurements of the quantum states, yields and velocity distributions of neutral ground-state and excited-state atoms ejected from the surface of the irradiating material. These studies have shown that the dominant exit channels in photon-induced particle emission are those producing ground-state and excited-state neutral atoms. Using dynamical information about these desorbing neutral species, obtained, for example, by laser-induced fluorescence and laser Doppler spectroscopy, we are generating an increasingly comprehensive picture of the dynamics of electronic energy flow into and out of pure crystalline surfaces in these prototypical dielectrics. We are also beginning to be able to relate desorption dynamics to specific materials properties, and to discriminate between pure surface and near-surface effects in these materials. Applications of these techniques to the problem of photon-induced surface damage and to analysis of surface dynamics in dielectric materials are discussed, and the relationships between these nearly ideal model materials and the non-crystalline, covalently bonded materials more typical of real optical elements are pointed out. 19 refs., 13 figs

  7. Effect of surface topography upon micro-impact dynamics

    International Nuclear Information System (INIS)

    Mohammadpour, M; Morris, N J; Leighton, M; Rahnejat, H


    Often the effect of interactions at nano-scale determines the tribological performance of load bearing contacts. This is particularly the case for lightly loaded conjunctions where a plethora of short range kinetic interactions occur. It is also true of larger load bearing conjunctions where boundary interactions become dominant. At the diminutive scale of fairly smooth surface topography the cumulative discrete interactions give rise to the dominance of boundary effects rather than the bulk micro-scale phenomena, based on continuum mechanics. The integration of the manifold localized discrete interactions into a continuum is the pre-requisite to the understanding of characteristic boundary effects, which transcend the physical length scales and affect the key observed system attributes. These are energy efficiency and vibration refinement. This paper strives to present such an approach. It is shown that boundary and near boundary interactions can be adequately described by surface topographical measures, as well the thermodynamic conditions. (paper)

  8. Molecular dynamics simulations on surface properties of silicon dioxide melts

    CERN Document Server

    Röder, A


    In the present thesis the surface properties of a silicon dioxide melt were studied. As first systems drops (i.e. sytems without periodic boundary conditions) of N=432, 1536, as well as 4608 atoms were considered. The second analyzed geometry corresponds to that of a thin film, i. e. periodic boundary conditions in x- and y-direction were present, while in z-direction one had a free surface. In this case a system of N=1152 atoms was considered. As model potential the two-body potential proposed by Beest, Kramer, and van Santen was applied. For both geometries five temperatures were considered, which lied in the range of 3000 K

  9. Dynamics of radon-222 near below ground surface

    International Nuclear Information System (INIS)

    Fukui, Masami; Katsurayama, Kousuke; Nishimura, Susumu.


    The concentrations and variation of 222 Rn were investigated both in unconfined groundwater and in the aerated zone to obtain information as to the behavior of Rn close to ground surface. The Rn concentrations in unconfined groundwater near the surface were depletive by the extent of about 50 % compared with that of lower part in a borehole, then the continuous extraction of groundwater causes pronounced increase of the concentration. The method, which monitors continuously the Rn concentration in such surroundings, was developed, where the unconfined groundwater extracted was injected into another borehole and sprayed gas was measured using an ionization chamber. The read-out values of this system well followed the variation of concentrations caused by the meteorological parameter, especially infiltrating water. The increase of 222 Rn concentration in the aerated zone above the water level was clearly observed following the ascendant of groundwater level caused by the infiltrating water, whereas the change of concentration in soil air just below the ground surface obeyed mainly to the wetness of soil and unconfined groundwater level rather than atmospheric pressure. (author)

  10. Multi-Decadal Surface Water Dynamics in North American Tundra (United States)

    Carroll, Mark L.; Loboda, Tatiana V.


    Over the last several decades, warming in the Arctic has outpaced the already impressive increases in global mean temperatures. The impact of these increases in temperature has been observed in a multitude of ecological changes in North American tundra including changes in vegetative cover, depth of active layer, and surface water extent. The low topographic relief and continuous permafrost create an ideal environment for the formation of small water bodies - a definitive feature of tundra surface. In this study, water bodies in Nunavut territory in northern Canada were mapped using a long-term record of remotely sensed observations at 30 meters spatial resolution from the Landsat suite of instruments. The temporal trajectories of water extent between 1985 and 2015 were assessed. Over 675,000 water bodies have been identified over the 31-year study period with over 168,000 showing a significant (probability is less than 0.05) trend in surface area. Approximately 55 percent of water bodies with a significant trend were increasing in size while the remaining 45 percent were decreasing in size. The overall net trend for water bodies with a significant trend is 0.009 hectares per year per water body.

  11. Using impulses to control the convergence toward invariant surfaces of continuous dynamical systems

    International Nuclear Information System (INIS)

    Marão, José; Liu Xinzhi; Figueiredo, Annibal


    Let us consider a smooth invariant surface S of a given ordinary differential equations system. In this work we develop an impulsive control method in order to assure that the trajectories of the controlled system converge toward the surface S. The method approach is based on a property of a certain class of invariant surfaces whose the dynamics associated to their transverse directions can be described by a non-autonomous linear system. This fact allows to define an impulsive system which drives the trajectories toward the surface S. Also, we set up a definition of local stability exponents which can be associated to such kind of invariant surface.

  12. Path integral molecular dynamics with surface hopping for thermal equilibrium sampling of nonadiabatic systems. (United States)

    Lu, Jianfeng; Zhou, Zhennan


    In this work, a novel ring polymer representation for a multi-level quantum system is proposed for thermal average calculations. The proposed representation keeps the discreteness of the electronic states: besides position and momentum, each bead in the ring polymer is also characterized by a surface index indicating the electronic energy surface. A path integral molecular dynamics with surface hopping (PIMD-SH) dynamics is also developed to sample the equilibrium distribution of the ring polymer configurational space. The PIMD-SH sampling method is validated theoretically and by numerical examples.

  13. Dynamics of intramolecular spin exchange interaction of a nitronyl nitroxide diradical in solution and on surfaces


    Lloveras Montserrat, Vega; Badetti, Elena; Veciana Miró, Jaume; Vidal-Gancedo, José


    In this paper we report the study of the dynamics of a thermally modulated intramolecular spin exchange interaction of a novel diradical nitronyl nitroxide-substituted disulfide in solution and when it is grafted on a gold surface. The structure of this diradical was designed to have flexible chains leading to intramolecular collisions and hence spin exchange interaction, and with an appropriate binding group to be grafted on the gold surface to study its behavior on the surface. In solution,...

  14. Remote sensing for mapping wetland floods in Kafue Flats, Zambia ...

    African Journals Online (AJOL)

    Monitoring huge and dynamic floodplains such as the Kafue Flats in Zambia is critical to its sustainable use. This requires among other things accurate, past and current geo-referenced flood maps. The aim of this study was, therefore, to use remotely sensed data to generate flood maps for Kafue Flats. Flood maps were ...

  15. Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin, E-mail:


    The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

  16. Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu (United States)

    Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin


    The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

  17. The control of mesenchymal stem cell differentiation using dynamically tunable surface microgrooves. (United States)

    Gong, Tao; Zhao, Kun; Yang, Guang; Li, Jinrong; Chen, Hongmei; Chen, Yuping; Zhou, Shaobing


    Many studies have demonstrated the potential to modulate stem cell differentiation by using static material substrate surfaces. However, cells actually grow in a dynamically diverse microenvironment in vivo. The regulated signals to the differentiation provided by these materials should not be passive or static but be active and dynamic. To mimic the endogenous cell culture microenvironment, a novel system is designed to realize the dynamic change of the surface geometries as well as a resultant mechanical force using a thermally activated four-stage shape memory polymer. The parallel microgroove surface patterns are fabricated via thermal embossing lithography on the polymer substrate surface. The dynamic microgroove surfaces accompanying with the mechanical force can effectively and significantly regulate the shape and the cytoskeletal arrangement of rBMSC compared with the static patterned and non-patterned surfaces. Cellular and molecular analyses reveal that the spatiotemporally programmed regulation of cell shape is more viable to coax lineage-specific differentiation of stem cell in contrast to the general reports with the static surfaces. Therefore, this study provides a facile strategy in designing and manufacturing an artificial substrate with a mimic natural cellular environment to precisely direct the cell differentiation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Probing Ultrafast Electron Dynamics at Surfaces Using Soft X-Ray Transient Reflectivity Spectroscopy (United States)

    Baker, L. Robert; Husek, Jakub; Biswas, Somnath; Cirri, Anthony

    The ability to probe electron dynamics with surface sensitivity on the ultrafast time scale is critical for understanding processes such as charge separation, injection, and surface trapping that mediate efficiency in catalytic and energy conversion materials. Toward this goal, we have developed a high harmonic generation (HHG) light source for femtosecond soft x-ray reflectivity. Using this light source we investigated the ultrafast carrier dynamics at the surface of single crystalline α-Fe2O3, polycrystalline α-Fe2O3, and the mixed metal oxide, CuFeO2. We have recently demonstrated that CuFeO2 in particular is a selective catalyst for photo-electrochemical CO2 reduction to acetate; however, the role of electronic structure and charge carrier dynamics in mediating catalytic selectivity has not been well understood. Soft x-ray reflectivity measurements probe the M2,3, edges of the 3d transition metals, which provide oxidation and spin state resolution with element specificity. In addition to chemical state specificity, these measurements are also surface sensitive, and by independently simulating the contributions of the real and imaginary components of the complex refractive index, we can differentiate between surface and sub-surface contributions to the excited state spectrum. Accordingly, this work demonstrates the ability to probe ultrafast carrier dynamics in catalytic materials with element and chemical state specificity and with surface sensitivity.

  19. Dynamics of formation of the Exclusion Zone near hydrophilic surfaces (United States)

    De Ninno, Antonella


    EZ water is unable to host solutes, what provides the root of the name Exclusion Zone, and its formation law points towards a diffusive process. These peculiarities have attracted the interest of scientists because it challenges all the theories which have tried to describe the structure of liquid water. The mixture of H-bond stable and H-bond distorted structures envisaged by very recent experimental findings, cannot account for the long-lived hexagonal configuration observed near the Nafion surface. A theoretical account for the phenomenology of H-bond is provided which looks able to explain many among the most striking feature of this water.

  20. 1D and 2D urban dam-break flood modelling in Istanbul, Turkey (United States)

    Ozdemir, Hasan; Neal, Jeffrey; Bates, Paul; Döker, Fatih


    Urban flood events are increasing in frequency and severity as a consequence of several factors such as reduced infiltration capacities due to continued watershed development, increased construction in flood prone areas due to population growth, the possible amplification of rainfall intensity due to climate change, sea level rise which threatens coastal development, and poorly engineered flood control infrastructure (Gallegos et al., 2009). These factors will contribute to increased urban flood risk in the future, and as a result improved modelling of urban flooding according to different causative factor has been identified as a research priority (Gallegos et al., 2009; Ozdemir et al. 2013). The flooding disaster caused by dam failures is always a threat against lives and properties especially in urban environments. Therefore, the prediction of dynamics of dam-break flows plays a vital role in the forecast and evaluation of flooding disasters, and is of long-standing interest for researchers. Flooding occurred on the Ayamama River (Istanbul-Turkey) due to high intensity rainfall and dam-breaching of Ata Pond in 9th September 2009. The settlements, industrial areas and transportation system on the floodplain of the Ayamama River were inundated. Therefore, 32 people were dead and millions of Euros economic loses were occurred. The aim of this study is 1 and 2-Dimensional flood modelling of the Ata Pond breaching using HEC-RAS and LISFLOOD-Roe models and comparison of the model results using the real flood extent. The HEC-RAS model solves the full 1-D Saint Venant equations for unsteady open channel flow whereas LISFLOOD-Roe is the 2-D shallow water model which calculates the flow according to the complete Saint Venant formulation (Villanueva and Wright, 2006; Neal et al., 2011). The model consists a shock capturing Godunov-type scheme based on the Roe Riemann solver (Roe, 1981). 3 m high resolution Digital Surface Model (DSM), natural characteristics of the pond

  1. Visual Sensing for Urban Flood Monitoring (United States)

    Lo, Shi-Wei; Wu, Jyh-Horng; Lin, Fang-Pang; Hsu, Ching-Han


    With the increasing climatic extremes, the frequency and severity of urban flood events have intensified worldwide. In this study, image-based automated monitoring of flood formation and analyses of water level fluctuation were proposed as value-added intelligent sensing applications to turn a passive monitoring camera into a visual sensor. Combined with the proposed visual sensing method, traditional hydrological monitoring cameras have the ability to sense and analyze the local situation of flood events. This can solve the current problem that image-based flood monitoring heavily relies on continuous manned monitoring. Conventional sensing networks can only offer one-dimensional physical parameters measured by gauge sensors, whereas visual sensors can acquire dynamic image information of monitored sites and provide disaster prevention agencies with actual field information for decision-making to relieve flood hazards. The visual sensing method established in this study provides spatiotemporal information that can be used for automated remote analysis for monitoring urban floods. This paper focuses on the determination of flood formation based on image-processing techniques. The experimental results suggest that the visual sensing approach may be a reliable way for determining the water fluctuation and measuring its elevation and flood intrusion with respect to real-world coordinates. The performance of the proposed method has been confirmed; it has the capability to monitor and analyze the flood status, and therefore, it can serve as an active flood warning system. PMID:26287201

  2. 2010: Why is it flooding everywhere this year? Coincidence or a predictable climate phenomenon, and how can we respond? (Invited) (United States)

    Lall, U.


    There are always droughts and floods. Sometimes, drought in a region begets a flood. Sometimes floods in a region reliably coincide with a drought in another specific region. In 2010, as floods unfolded simultaneously and sequentially in one region after another of the world, the media has asked whether there is a common cause, pointing the finger at anthropogenic climate change. Will floods end our civilization as climate changes? Or merely erase the Indus Valley civilization yet again? Floods have traditionally been considered the consequence of extreme, random, weather extremes, and much of the prediction effort has focused on near real term meteorological and land surface hydrological forecasting. While very useful, these typically offer a relatively short lead time. Exceptions are floods in large rivers such as the Mississippi, the Indus and the Yangtze that have long transit times to the outlet. Today, climatic aspects of floods, specifically, the spatial structure of fields of droughts and floods, the associated ocean-atmosphere circulation conditions and precursors, as well as the recurrence characteristics of these precursors are beginning to be understood. I offer an early review of how these analyses are emerging, and of examples of selected regions in the world where an empirical flood risk analysis that is climate informed is feasible in both a correlative and a predictive mode. Novel risk management products, that combine organizational planning, infrastructure and financial risk management tools at a variety of institutional and spatial scales are also emerging. Potential global socio-economic impacts of unmitigated concurrent floods/droughts are highlighted. A framework for how these can be applied to effect dynamic risk management and adaptation in a changing world is presented.

  3. Integrated remote sensing imagery and two-dimensional hydraulic modeling approach for impact evaluation of flood on crop yields (United States)

    Chen, Huili; Liang, Zhongyao; Liu, Yong; Liang, Qiuhua; Xie, Shuguang


    The projected frequent occurrences of extreme flood events will cause significant losses to crops and will threaten food security. To reduce the potential risk and provide support for agricultural flood management, prevention, and mitigation, it is important to account for flood damage to crop production and to understand the relationship between flood characteristics and crop losses. A quantitative and effective evaluation tool is therefore essential to explore what and how flood characteristics will affect the associated crop loss, based on accurately understanding the spatiotemporal dynamics of flood evolution and crop growth. Current evaluation methods are generally integrally or qualitatively based on statistic data or ex-post survey with less diagnosis into the process and dynamics of historical flood events. Therefore, a quantitative and spatial evaluation framework is presented in this study that integrates remote sensing imagery and hydraulic model simulation to facilitate the identification of historical flood characteristics that influence crop losses. Remote sensing imagery can capture the spatial variation of crop yields and yield losses from floods on a grid scale over large areas; however, it is incapable of providing spatial information regarding flood progress. Two-dimensional hydraulic model can simulate the dynamics of surface runoff and accomplish spatial and temporal quantification of flood characteristics on a grid scale over watersheds, i.e., flow velocity and flood duration. The methodological framework developed herein includes the following: (a) Vegetation indices for the critical period of crop growth from mid-high temporal and spatial remote sensing imagery in association with agricultural statistics data were used to develop empirical models to monitor the crop yield and evaluate yield losses from flood; (b) The two-dimensional hydraulic model coupled with the SCS-CN hydrologic model was employed to simulate the flood evolution process

  4. Adaptive Dynamic Surface Control is designed for Twin Rotor unmanned helicopter in three-dimensional space

    Directory of Open Access Journals (Sweden)

    Amir Reza Moadeli


    Full Text Available In this paper, the system control design problem twin rotors helicopters Unmanned Aerial Vehicles (UAV in three dimensional space Without uncertainty based on the dynamic adaptive control is studied. the adaptive Dynamic surface control approach complexity explosion problem in non-linear control step back or backstepping method [45] using the First-order filters removed. The first helicopter dynamic equations and functions are examined. Then, the Dynamic surface control techniques by compare non-linear control technique back stepping [45] is checked and the system is simulation by both techniques adaptive Dynamic surface control and nonlinear control back stepping method. The proposed adaptive dynamics surface nonlinear control method approach is able to guarantees that all the signals in the closed-loop system are asymptotically stable for all initial conditions and you can also choose appropriate design parameters of the system output converges to a small neighborhood of origin ensured . Finally, simulation results are presented, showing the effectiveness of control methods are given.

  5. Surface Ozone Dynamics in the Kola Peninsula Region (United States)

    Beloglazov, M. I.; Karpechko, A. Yu.; Nikulin, G. N.; Roumjantsev, S. A.

    Measurements of surface ozone from the centre of the Murmansk Region (Apatity, Kola peninsula) and its southern part (Kovda, White Sea coast) give a picture of the behaviour of this air component on the Kola peninsula and surrounding vicinity. Simultaneous measurements in Apatity and Kovda have shown that the ozone concentration in Apatity is roughly twice as much as in Kovda. This fact may be explained by the local wind circulation and the presence of bromine near the coast of the Kola Peninsula. An inverse correlation is found between the ozone and nitrogen oxide concentrations from observations near motorways in Apatity. A decrease of nitrogen oxide concentration accompanies the growth of ozone on average. Thus, Apatity is a northern city in which the air pollution by traffic emissions decreases the ozone content.

  6. Surface and step dynamics of a semi-infinite insulating antiferromagnet system

    CERN Document Server

    Tamine, M


    We have carried out a theoretical study of the localized spin-wave modes near the surface step of the insulating Heisenberg antiferromagnet. In this work, we study the full magnetic problem arising from the absence of translational symmetry due to the presence of a magnetic surface and step. The calculation concerns in particular the spin fluctuation dynamics and employs the matching procedure in the random-phase approximation. Only the nearest neighbours exchange interactions are considered between the spins in the model. The analytical formalism presented here determines the bulk and evanescent spin fluctuation fields in the two-dimensional plane normal to the surface and step regions. The results are used to calculate the localized modes of magnons associated with the step and surface terraces. The present model may be generalized to treat the spin fluctuations dynamics of other extended surface imperfections or nanostructures, provided they preserve the translation symmetry of the ordered spins along a di...

  7. Programmable Active Matter: Dynamics of active filaments on patterned surfaces (United States)

    Yadav, Vikrant; Todd, Daniel; Milas, Peker; Ruijgrok, Paul; Bryant, Zev; Ross, Jennifer

    Interfaces are ubiquitous in biology. For a sub-cellular component moving inside the cell, any change in its local environment across an interface whether chemical concentration, density, or any other physical variables can produce novel dynamics. Recent advances in bioengineering allow us to control motor proteins' velocities when prompted by an optical trigger. Using an optical diaphragm and a gear-shifting myosin XI construct containing a photoactive LOV domain, we can spatially pattern light to create interfaces across which speed of a gliding actin filament can differ by as much as a factor of two. We observe that when a gliding actin filament crosses an interface that has a discontinuous velocity jump, it buckles and changes its angle of orientation due to the velocity mismatch. Our preliminary data suggests that for small angels of incidence, the angle of emergence increases linearly. If we increase the angle of incidence further we observe that the angle of emergence saturates. For some actin filaments approaching the interface near-tangentially we observe total internal reflection as they fail to crossover the boundary. We have modeled our system using Cytosim software package and find excellent agreement with experimental data.

  8. Splash Dynamics of Watercolors on Dry, Wet, and Cooled Surfaces (United States)

    Baron, David; Vaidya, Ashwin; Su, Haiyan


    In his classic study in 1908, A.M. Worthington gave a thorough account of splashes and their formation through visualization experiments. In more recent times, there has been renewed interest in this subject, and much of the underlying physics behind Worthington's experiments has now been clarified. One specific set of such recent studies, which motivates this paper, concerns the fluid dynamics behind Jackson Pollock's drip paintings. The physical processes and the mathematical structures hidden in his works have received serious attention and made the scientific pursuit of art a compelling area of exploration. Our work explores the interaction of watercolors with watercolor paper. Specifically, we conduct experiments to analyze the settling patterns of droplets of watercolor paint on wet and frozen paper. Variations in paint viscosity, paper roughness, paper temperature, and the height of a released droplet are examined from time of impact, through its transient stages, until its final, dry state. Observable phenomena such as paint splashing, spreading, fingering, branching, rheological deposition, and fractal patterns are studied in detail and classified in terms of the control parameters.

  9. Measuring and modeling surface sorption dynamics of organophosphate flame retardants on impervious surfaces (United States)

    U.S. Environmental Protection Agency — The data presented in this data file is a product of a journal publication. The dataset contains measured and model predicted OPFRs gas-phase and surface-phase...

  10. Design basis flood for nuclear power plants on coastal sites

    International Nuclear Information System (INIS)


    This Guide discusses the phenomena causing coastal floods (storm surge, seiche, tsunami and wind-wave) and gives a general description of the methods used and the critical factors involved in the evaluation of such floods and of their associated effects. In addition, some treatment is presented of the possible combinations of two or more of these phenomena to produce a DBF. Methods are also provided for evaluating the reference water levels, taking into account the effect of tides, sea level anomalies and changes in lake level and river flow. Sites vulnerable to coastal flooding are located on open coastal regions, semi-enclosed bodies of water and enclosed bodies of water. Open coastal regions are those portions of land directly exposed to and having a shore on a major body of water. Semi-enclosed bodies of water are lagoons, river estuaries, gulfs, fjords and rias. Enclosed bodies of water are lakes and reservoirs. The phenomena of the lowering of the water level at coastal sites caused by offshore winds, low tides, wave effects or of drawdown caused by tsunamis are discussed. The static and dynamic effects of floods resulting from the various combinations (independent and interdependent) of surface waves of varying frequency are also discussed. Consideration is also given to shoreline instabilities and to the effects of erosion. Estimated flood levels and related effects on the nuclear power plant, which will vary according to the method of analysis and the type of flooding considered, shall be compared with available historical data where this is relevant, to check the conservativeness of the evaluated results

  11. Advancing flood risk analysis by integrating adaptive behaviour in large-scale flood risk assessments (United States)

    Haer, T.; Botzen, W.; Aerts, J.


    In the last four decades the global population living in the 1/100 year-flood zone has doubled from approximately 500 million to a little less than 1 billion people. Urbanization in low lying -flood prone- cities further increases the exposed assets, such as buildings and infrastructure. Moreover, climate change will further exacerbate flood risk in the future. Accurate flood risk assessments are important to inform policy-makers and society on current- and future flood risk levels. However, these assessment suffer from a major flaw in the way they estimate flood vulnerability and adaptive behaviour of individuals and governments. Current flood risk projections commonly assume that either vulnerability remains constant, or try to mimic vulnerability through incorporating an external scenario. Such a static approach leads to a misrepresentation of future flood risk, as humans respond adaptively to flood events, flood risk communication, and incentives to reduce risk. In our study, we integrate adaptive behaviour in a large-scale European flood risk framework through an agent-based modelling approach. This allows for the inclusion of heterogeneous agents, which dynamically respond to each other and a changing environment. We integrate state-of-the-art flood risk maps based on climate scenarios (RCP's), and socio-economic scenarios (SSP's), with government and household agents, which behave autonomously based on (micro-)economic behaviour rules. We show for the first time that excluding adaptive behaviour leads to a major misrepresentation of future flood risk. The methodology is applied to flood risk, but has similar implications for other research in the field of natural hazards. While more research is needed, this multi-disciplinary study advances our understanding of how future flood risk will develop.

  12. Dynamics of Surface Exchange Reactions Between Au and Pt for HER and HOR

    DEFF Research Database (Denmark)

    Abrams, Billie; Vesborg, Peter Christian Kjærgaard; Bonde, Jacob Lindner


    Cyclic voltammetric analysis of the Pt-on-Au system for hydrogen evolution and oxidation reactions (HER/HOR) indicates that dynamic surface exchange reactions occur between Pt and Au. HER/HOR activities depend on the dominant surface species present, which is controllable by the potential applied...... to the system. Bulk Au is not very active for HER/HOR; however, when Pt is deposited onto the Au surface, the system becomes active. The Pt-on-Au system can subsequently be deactivated by cycling to potentials cathodic of the OH-adsorption and Pt-dissolution potentials (~+1.18 V vs normal hydrogen electrode...... reaction is attributed to the lower surface energy of Au relative to Pt causing Au to migrate to the surface. When the system is deactivated, Au is present at the surface. However, Pt migrates back to the surface at higher positive potentials, where PtOx/PtOHx is formed, leading to adsorbate...

  13. Calculation of surface potentials at the silica-water interface using molecular dynamics: Challenges and opportunities (United States)

    Lowe, Benjamin M.; Skylaris, Chris-Kriton; Green, Nicolas G.; Shibuta, Yasushi; Sakata, Toshiya


    Continuum-based methods are important in calculating electrostatic properties of interfacial systems such as the electric field and surface potential but are incapable of providing sufficient insight into a range of fundamentally and technologically important phenomena which occur at atomistic length-scales. In this work a molecular dynamics methodology is presented for interfacial electric field and potential calculations. The silica-water interface was chosen as an example system, which is highly relevant for understanding the response of field-effect transistors sensors (FET sensors). Detailed validation work is presented, followed by the simulated surface charge/surface potential relationship. This showed good agreement with experiment at low surface charge density but at high surface charge density the results highlighted challenges presented by an atomistic definition of the surface potential. This methodology will be used to investigate the effect of surface morphology and biomolecule addition; both factors which are challenging using conventional continuum models.

  14. Molecular dynamics study on mechanism of preformed particle gel transporting through nanopores: Surface chemistry and heterogeneity (United States)

    Cui, Peng; Zhang, Heng; Ma, Ying; Hao, Qingquan; Liu, Gang; Sun, Jichao; Yuan, Shiling


    The translocation behavior of preformed particle gel (PPG) in porous media is crucial for its application in enhanced oil recovery. By means of non-equilibrium molecular dynamics simulation, the translocation mechanism of PPG confined in different silica nanopores were investigated. The influence of surface chemistry and chemical heterogeneity of silica nanopore on the translocation process was revealed. As the degree of surface hydroxylation increases and the heterogeneity decreases, the pulling force needed to drive PPG decreases. We infer that the nanopore's surface (i.e. surface chemistry and heterogeneity) affects the translocation of PPG indirectly by forming different hydration layers.

  15. Target surface area effects on hot electron dynamics from high intensity laser-plasma interactions (United States)

    Zulick, C.; Raymond, A.; McKelvey, A.; Chvykov, V.; Maksimchuk, A.; Thomas, A. G. R.; Willingale, L.; Yanovsky, V.; Krushelnick, K.


    Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a {K}α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Hybrid Vlasov-Fokker-Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

  16. Modeling land-surface/atmosphere dynamics for CHAMMP

    International Nuclear Information System (INIS)

    Gutowski, W.J. Jr.


    Project progress is described on a DOE CHAMP project to model the land-surface/atmosphere coupling in a heterogeneous environment. This work is a collaboration between scientists at Iowa State University and the University of New Hampshire. Work has proceeded in two areas: baseline model coupling and data base development for model validation. The core model elements (land model, atmosphere model) have been ported to the Principal Investigator's computing system and baseline coupling has commenced. The initial target data base is the set of observations from the FIFE field campaign, which is in the process of being acquired. For the remainder of the project period, additional data from the region surrounding the FIFE site and from other field campaigns will be acquired to determine how to best extrapolate results from the initial target region to the rest of the globe. In addition, variants of the coupled model will be used to perform experiments examining resolution requirements and coupling strategies for land-atmosphere coupling in a heterogeneous environment

  17. Advances in Remote Sensing of Flooding

    Directory of Open Access Journals (Sweden)

    Yong Wang


    Full Text Available With the publication of eight original research articles, four types of advances in the remote sensing of floods are achieved. The uncertainty of modeled outputs using precipitation datasets derived from in situ observations and remote sensors is further understood. With the terrestrial laser scanner and airborne light detection and ranging (LiDAR coupled with high resolution optical and radar imagery, researchers improve accuracy levels in estimating the surface water height, extent, and flow of floods. The unmanned aircraft system (UAS can be the game changer in the acquisition and application of remote sensing data. The UAS may fly everywhere and every time when a flood event occurs. With the development of urban structure maps, the flood risk and possible damage is well assessed. The flood mitigation plans and response activities become effective and efficient using geographic information system (GIS-based urban flood vulnerability and risk maps.

  18. Dynamics of surface screening charges on domains of BiFeO3 films

    Directory of Open Access Journals (Sweden)

    Jun-xing Gu


    Full Text Available The dynamics of surface screening charges on BiFeO3 films with pre-written stripe domains was studied with surface potential measurements by Kelvin Probe Force Microscopy. The screening effect decays exponentially over time, and this decay is slower in the arrays with wider domains or larger intervals of domains, indicating that the in-plane diffusion of the surface screening charges plays a major role in the decay dynamics. The good agreement between experimental data and theoretical results based on diffusion-drift model confirms the mechanism of in-plane diffusion of the screening charges in the decay dynamics. Our work could provide a pathway to control the data stability of charge storage by artificially designing the ferroelectric domains.

  19. Accelerated sampling by infinite swapping of path integral molecular dynamics with surface hopping (United States)

    Lu, Jianfeng; Zhou, Zhennan


    To accelerate the thermal equilibrium sampling of multi-level quantum systems, the infinite swapping limit of a recently proposed multi-level ring polymer representation is investigated. In the infinite swapping limit, the ring polymer evolves according to an averaged Hamiltonian with respect to all possible surface index configurations of the ring polymer and thus connects the surface hopping approach to the mean-field path-integral molecular dynamics. A multiscale integrator for the infinite swapping limit is also proposed to enable efficient sampling based on the limiting dynamics. Numerical results demonstrate the huge improvement of sampling efficiency of the infinite swapping compared with the direct simulation of path-integral molecular dynamics with surface hopping.

  20. Assessment of static flood modeling techniques: application to contrasting marshes flooded during Xynthia (western France

    Directory of Open Access Journals (Sweden)

    J. F. Breilh


    Full Text Available This study aims to assess the performance of raster-based flood modeling methods on a wide diversity of coastal marshes. These methods are applied to the flooding associated with the storm Xynthia, which severely hit the western coast of France in February 2010. Static and semi-dynamic methods are assessed using a combination of LiDAR data, post-storm delineation of flooded areas and sea levels originating from both tide gauge measurements and storm surge modeling. Static methods are applied to 27 marshes showing a wide geomorphological diversity. It appears that these methods are suitable for marshes with a small distance between the coastline and the landward boundary of the marsh, which causes these marshes to flood rapidly. On the contrary, these methods overpredict flooded areas for large marshes where the distance between the coastline and the landward boundary of the marsh is large, because the flooding cannot be considered as instantaneous. In this case, semi-dynamic methods based on surge overflowing volume calculations can improve the flooding prediction significantly. This study suggests that static and semi-dynamic flood modeling methods can be attractive and quickly deployed to rapidly produce predictive flood maps of vulnerable areas under certain conditions, particularly for small distances between the coastline and the landward boundary of the low-lying coastal area.

  1. Numerical Modeling for Flood Mapping under Climate Change Impacts: Transboundary Dniester River Study (United States)

    Zheleznyak, Mark; Kolomiets, Pavlo; Dzjuba, Natalia; Ievgen, Ievgen; Sorokin, Maxim; Denisov, Nickolai; Ischuk, Oleksiy; Koeppel, Sonja


    The Dniester river is shared by Ukraine and Moldova. Ukraine being both upstream and downstream of Moldova. The basin is especially suffering from heavy floods, often with transboundary impacts: in Ukraine, disastrous floods in July 2008, which were possibly partly caused or exacerbated by climate change. Within the UNECE | ENVSEC project "Reducing vulnerability to extreme floods and climate change in the Dniester river basin" the numerical flood risks mapping for several "hot spots" along the Dniester river was initiated Two transboundary sites: "Mohyliv Podylskiy- Ataki" and "Dubossary HPP-, Mayaki" (in the delta zone) were chosen for flood risk modelling/mapping. . Floodplain inundation at Mohyliv Podylskiy- Ataki during historical and projected extreme floods scenarios is simulated by 2D model COASTOX -UN based on the numerical solution of shallow water equations on unstructured grid. The scenario of extreme flood, July 2008 that caused hazardous flooding of the riverside areas of Mohyliv Podylskiy has been used for model verification and calibration. The floodmarks of the inundated in 2008 streets have been collected and GIS processed to be used together with the data from the city's water gage station for model testing. The comparison of the simulated dynamics of floodplain inundation during 2008 flood with the observed data show good accuracy of the model. The technologies of the flood modeling and GIS based risk assessments verified for this site are implemented for analyses of the vulnerability to extreme floods for Q=7600 m3 / sec inflow to Dniester reservoir ( 1% flood for contemporary climate assessment) and for Q=8700 m3 / sec. that is considered as projection of 1% flood maximum for XXI century The detailed flood mapping was provided for all cases and was shown that 13% increase in water elevation for future extreme flood scenario will provide at 20% increasing of flooded areas in Mohilev Podolsky. For the site Dubossary NPP in Moldova downstream till

  2. Analysis of surface and root-zone soil moisture dynamics with ERS scatterometer and the hydrometeorological model SAFRAN-ISBA-MODCOU at Grand Morin watershed (France

    Directory of Open Access Journals (Sweden)

    T. Paris Anguela


    Full Text Available Spatial and temporal variations of soil moisture strongly affect flooding, erosion, solute transport and vegetation productivity. Its characterization, offers an avenue to improve our understanding of complex land surface-atmosphere interactions. In this paper, soil moisture dynamics at soil surface (first centimeters and root-zone (up to 1.5 m depth are investigated at three spatial scales: local scale (field measurements, 8×8 km2 (hydrological model and 25×25 km2 scale (ERS scatterometer in a French watershed. This study points out the quality of surface and root-zone soil moisture data for SIM model and ERS scatterometer for a three year period. Surface soil moisture is highly variable because is more influenced by atmospheric conditions (rain, wind and solar radiation, and presents RMSE up to 0.08 m3 m−3. On the other hand, root-zone moisture presents lower variability with small RMSE (between 0.02 and 0.06 m3 m−3. These results will contribute to satellite and model verification of moisture, but also to better application of radar data for data assimilation in future.

  3. Compound simulation of fluvial floods and storm surges in a global coupled river-coast flood model: Model development and its application to 2007 Cyclone Sidr in Bangladesh (United States)

    Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip J.; Winsemius, Hessel C.; Verlaan, Martin; Kanae, Shinjiro


    Water-related disasters, such as fluvial floods and cyclonic storm surges, are a major concern in the world's mega-delta regions. Furthermore, the simultaneous occurrence of extreme discharges from rivers and storm surges could exacerbate flood risk, compared to when they occur separately. Hence, it is of great importance to assess the compound risks of fluvial and coastal floods at a large scale, including mega-deltas. However, most studies on compound fluvial and coastal flooding have been limited to relatively small scales, and global-scale or large-scale studies have not yet addressed both of them. The objectives of this study are twofold: to develop a global coupled river-coast flood model; and to conduct a simulation of compound fluvial flooding and storm surges in Asian mega-delta regions. A state-of-the-art global river routing model was modified to represent the influence of dynamic sea surface levels on river discharges and water levels. We conducted the experiments by coupling a river model with a global tide and surge reanalysis data set. Results show that water levels in deltas and estuaries are greatly affected by the interaction between river discharge, ocean tides and storm surges. The effects of storm surges on fluvial flooding are further examined from a regional perspective, focusing on the case of Cyclone Sidr in the Ganges-Brahmaputra-Meghna Delta in 2007. Modeled results demonstrate that a >3 m storm surge propagated more than 200 km inland along rivers. We show that the performance of global river routing models can be improved by including sea level dynamics.

  4. Betwixt Droughts and Floods: Flood Management Politics in Thailand

    Directory of Open Access Journals (Sweden)

    Naila Maier-Knapp


    Full Text Available Attempting to create greater understanding of the political dynamics that influence domestic disaster relief and management (DRM in Thailand, this article takes a closer look at these dynamics by outlining the main actors involved in flood-related DRM. It acknowledges the importance of international and military actors but emphasises the role of national and subnational authorities. The article then identifies the central issues of DRM governance as capacity and bureaucracy and discusses these through a chronological assessment of the flood crisis in Thailand in 2011, interweaving the colourful domestic politics with various political cleavages and dichotomies, and thereby distinguishing between three main dichotomies which it considers as the central drivers of the political dynamics and institutional development of DRM. These issues can be summarised as old versus new institutions, technocracy versus bureaucracy and centralised (but with direct people-orientation through greater channels of citizenry participation versus decentralised bureaucracy with an indirect orientation towards people.

  5. Desorption dynamics of deuterium molecules from the Si(100)-(3×1) dideuteride surface


    Niida, T; Tsurumaki, Hiroshi; Namiki, Akira


    We measured polar angle ()-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3×1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of 0.25 eV, which is mostly independent of the desorption angles for 0°30°. The observed desorption dynamics of deuterium was discussed along the principle of detailed balance to predict their adsorption dynamics onto the monohydride Si surface.

  6. Dynamics of Surface Reorganization of Poly(methyl methacrylate) in Contact with Water (United States)

    Horinouchi, Ayanobu; Atarashi, Hironori; Fujii, Yoshihisa; Tanaka, Keiji


    New tools for tailor-made diagnostics, such as DNA arrays and tips for micro-total-analysis systems, are generally made from polymers. In these applications, the polymer surface is in contact with a water phase. However, despite the importance of detailed knowledge of the fundamental interactions of polymer interfaces with liquids, such studies are very limited. As an initial benchmark for designing and constructing specialized biomedical surfaces containing polymer, aggregation states and dynamics of chains at the water interface should be systematically examined. We here apply time-resolved contact angle measurement to study the dynamics of the surface reorganization of poly(methyl methacrylate) (PMMA) in contact with water. By doing the measurements at various temperatures, it is possible to discuss the surface dynamics of PMMA based on the apparent activation energy. Also, sum-frequency generation spectroscopy revealed that the surface reorganization involves the conformational changes in the main chain part as well as the side chains. Hence, the dynamics observed here may reflect the segmental motion at the outermost region of the PMMA film, in which water plays as a plasticizer.

  7. Sea Surface Temperature Modeling using Radial Basis Function Networks With a Dynamically Weighted Particle Filter

    KAUST Repository

    Ryu, Duchwan


    The sea surface temperature (SST) is an important factor of the earth climate system. A deep understanding of SST is essential for climate monitoring and prediction. In general, SST follows a nonlinear pattern in both time and location and can be modeled by a dynamic system which changes with time and location. In this article, we propose a radial basis function network-based dynamic model which is able to catch the nonlinearity of the data and propose to use the dynamically weighted particle filter to estimate the parameters of the dynamic model. We analyze the SST observed in the Caribbean Islands area after a hurricane using the proposed dynamic model. Comparing to the traditional grid-based approach that requires a supercomputer due to its high computational demand, our approach requires much less CPU time and makes real-time forecasting of SST doable on a personal computer. Supplementary materials for this article are available online. © 2013 American Statistical Association.

  8. Flooding and Schools (United States)

    National Clearinghouse for Educational Facilities, 2011


    According to the Federal Emergency Management Agency, flooding is the nation's most common natural disaster. Some floods develop slowly during an extended period of rain or in a warming trend following a heavy snow. Flash floods can occur quickly, without any visible sign of rain. Catastrophic floods are associated with burst dams and levees,…

  9. Desorption dynamics of deuterium molecules from the Si(100)-(3x1) dideuteride surface. (United States)

    Niida, T; Tsurumaki, H; Namiki, A


    We measured polar angle (theta)-resolved time-of-flight spectra of D2 molecules desorbing from the Si(100)-(3x1) dideuteride surface. The desorbing D2 molecules exhibit a considerable translational heating with mean desorption kinetic energies of approximately 0.25 eV, which is mostly independent of the desorption angles for 0 degreesdynamics of deuterium was discussed along the principle of detailed balance to predict their adsorption dynamics onto the monohydride Si surface.

  10. NASA-VOF2D, 2-D Transient Free Surface Incompressible Fluid Dynamic

    International Nuclear Information System (INIS)

    Torrey, M.D.


    1 - Description of program or function: NASA-VOF2D is a two- dimensional, transient, free surface incompressible fluid dynamics program. It allows multiple free surfaces with surface tension and wall adhesion forces and has a partial cell treatment which allows curved boundaries and interior obstacles. 2 - Method of solution: NASA-VOF2D simulates incompressible flows with free surfaces using the volume-of-fluid (VOF) algorithm. This technique is based on the use of donor-acceptor differencing to track the free surface across an Eulerian grid. The complete Navier-Stokes equations in primitive variables for an incompressible fluid are solved by finite differences with surface tension and wall adhesion included. Optionally the pressure equation can be solved by a conjugate residual method rather than the successive over-relaxation (SOR) method

  11. Dynamic behavior of water droplets and flashover characteristics on a superhydrophobic silicone rubber surface (United States)

    Li, Yufeng; Jin, Haiyun; Nie, Shichao; Zhang, Peng; Gao, Naikui


    In this paper, a superhydrophobic surface is used to increase the flashover voltage when water droplets are present on a silicone rubber surface. The dynamic behavior of a water droplet and the associated flashover characteristics are studied on common and superhydrophobic silicone rubber surfaces under a high DC voltage. On common silicone rubber, the droplet elongates and the flashover voltage decreases with increasing droplet volume and conductivity. In contrast, the droplet slides off the superhydrophobic surface, leading to an increased flashover voltage. This droplet sliding is due to the low adhesion of the superhydrophobic surface and a sufficiently high electrostatic force provided by the DC voltage. Experimental results show that a superhydrophobic surface is effective at inhibiting flashover.

  12. Structural Origin of Enhanced Dynamics at the Surface of a Glassy Alloy (United States)

    Sun, Gang; Saw, Shibu; Douglass, Ian; Harrowell, Peter


    The enhancement of mobility at the surface of an amorphous alloy is studied using a combination of molecular dynamic simulations and normal mode analysis of the nonuniform distribution of Debye-Waller factors. The increased mobility at the surface is found to be associated with the appearance of Arrhenius temperature dependence. We show that the transverse Debye-Waller factor exhibits a peak at the surface. Over the accessible temperature range, we find that the bulk and surface diffusion coefficients obey the same empirical relationship with the respective Debye-Waller factors. Extrapolating this relationship to lower T , we argue that the observed decrease in the constraint at the surface is sufficient to account for the experimentally observed surface enhancement of mobility.

  13. INTRODUCTION: Surface Dynamics, Phonons, Adsorbate Vibrations and Diffusion (United States)

    Bruch, L. W.


    understanding of the underlying factors determining the optical quality of GaInNAs, such as composition, growth and annealing conditions. We are still far from establishing an understanding of the band structure and its dependence on composition. Fundamental electronic interactions such as electron-electron and electron-phonon scattering, dependence of effective mass on composition, strain and orientation, quantum confinement effects, effects of localized nitrogen states on high field transport and on galvanometric properties, and mechanisms for light emission in these materials, are yet to be fully understood. Nature and formation mechanisms of grown-in and processing-induced defects that are important for material quality and device performance are still unknown. Such knowledge is required in order to design strategies to efficiently control and eliminate harmful defects. For many potential applications (such as solar cells, HBTs) it is essential to get more information on the transport properties of dilute nitride materials. The mobility of minority carriers is known to be low in GaInNAs and related material. The experimental values are far from reaching the theoretical ones, due to defects and impurities introduced in the material during the growth. The role of the material inhomogeneities on the lateral carrier transport also needs further investigation. From the device's point of view most attention to date has been focused on the GaInNAs/GaAs system, mainly because of its potential for optoelectronic devices covering the 1.3-1.55 µm data and telecommunications wavelength bands. As is now widely appreciated, these GaAs-compatible structures allow monolithic integration of AlGaAs-based distributed Bragg reflector mirrors (DBRs) for vertical cavity surface-emitting lasers with low temperature sensitivity and compatibility with AlOx-based confinement techniques. In terms of conventional edge-emitting lasers (EELs), the next step is to extend the wavelength range for cw room

  14. Dynamics of a Rydberg hydrogen atom near a metal surface in the electron-extraction scheme

    Energy Technology Data Exchange (ETDEWEB)

    Iñarrea, Manuel [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Lanchares, Víctor [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Palacián, Jesús [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain); Pascual, Ana I. [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Salas, J. Pablo, E-mail: [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Yanguas, Patricia [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain)


    We study the classical dynamics of a Rydberg hydrogen atom near a metal surface in the presence of a constant electric field in the electron-extraction situation [1], e.g., when the field attracts the electron to the vacuum. From a dynamical point of view, this field configuration provides a dynamics richer than in the usual ion-extraction scheme, because, depending on the values of field and the atom–surface distance, the atom can be ionized only towards the metal surface, only to the vacuum or to the both sides. The evolution of the phase space structure as a function of the atom–surface distance is explored in the bound regime of the atom. In the high energy regime, the ionization mechanism is also investigated. We find that the classical results of this work are in good agreement with the results obtained in the wave-packet propagation study carried out by So et al. [1]. - Highlights: • We study a classical hydrogen atom near a metal surface plus a electric field. • We explore the phase space structure as a function of the field strength. • We find most of the electronic orbits are oriented along the field direction. • We study the ionization of the atom for several atom–surface distances. • This classical study is in good agreement with the quantum results.

  15. The Role of Electronic Excitations on Chemical Reaction Dynamics at Metal, Semiconductor and Nanoparticle Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tully, John C. [Yale Univ., New Haven, CT (United States)


    Chemical reactions are often facilitated and steered when carried out on solid surfaces, essential for applications such as heterogeneous catalysis, solar energy conversion, corrosion, materials processing, and many others. A critical factor that can determine the rates and pathways of chemical reactions at surfaces is the efficiency and specificity of energy transfer; how fast does energy move around and where does it go? For reactions on insulator surfaces energy transfer generally moves in and out of vibrations of the adsorbed molecule and the underlying substrate. By contrast, on metal surfaces, metallic nanoparticles and semiconductors, another pathway for energy flow opens up, excitation and de-excitation of electrons. This so-called “nonadiabatic” mechanism often dominates the transfer of energy and can directly impact the course of a chemical reaction. Conventional computational methods such as molecular dynamics simulation do not account for this nonadiabatic behavior. The current DOE-BES funded project has focused on developing the underlying theoretical foundation and the computational methodology for the prediction of nonadiabatic chemical reaction dynamics at surfaces. The research has successfully opened up new methodology and new applications for molecular simulation. In particular, over the last three years, the “Electronic Friction” theory, pioneered by the PI, has now been developed into a stable and accurate computational method that is sufficiently practical to allow first principles “on-the-fly” simulation of chemical reaction dynamics at metal surfaces.

  16. Characterization of remarkable floods in France, a transdisciplinary approach applied on generalized floods of January 1910 (United States)

    Boudou, Martin; Lang, Michel; Vinet, Freddy; Coeur, Denis


    emphasize one flood typology or one flood dynamic (for example flash floods are often over-represented than slow dynamic floods in existing databases). Thus, the selected criteria have to introduce a general overview of flooding risk in France by integrating all typologies: storm surges, torrential floods, rising groundwater level and resulting to flood, etc. The methodology developed for the evaluation grid is inspired by several scientific works related to historical hydrology (Bradzil, 2006; Benito et al., 2004) or extreme floods classification (Kundzewics et al. 2013; Garnier E., 2005). The referenced information are mainly issued from investigations realized for the PFRA (archives, local data),from internet databases on flooding disasters, and from a complementary bibliography (some scientists such as Maurice Pardé a geographer who largely documented French floods during the 20th century). The proposed classification relies on three main axes. Each axis is associated to a set of criteria, each one related to a score (from 0.5 to 4 points), and pointing out a final remarkability score. • The flood intensity characterizing the flood's hazard level. It is composed of the submersion duration, important to valorize floods with slow dynamics as flooding from groundwater, the event peak discharge's return period, and the presence of factors increasing significantly the hazard level (dykes breaks, log jam, sediment transport…) • The flood severity focuses on economic damages, social and political repercussions, media coverage of the event, fatalities number or eventual flood warning failures. Analyzing the flood consequences is essential in order to evaluate the vulnerability of society at disaster date. • The spatial extension of the flood, which contributes complementary information to the two first axes. The evaluation grid was tested and applied on the sample of 176 remarkable events. Around twenty events (from 1856 to 2010) come out with a high remarkability rate

  17. Molecular dynamics for lateral surface adhesion and peeling behavior of single-walled carbon nanotubes on gold surfaces

    International Nuclear Information System (INIS)

    Huang, Pei-Hsing


    Highlights: ► Adhesion and peeling behaviors of SWCNTs are investigated by detailed, fully atomistic MD simulations. ► Adhesion energy of SWCNTs are discussed. ► Dynamical behaviors of SWCNTs in low temperature adhesion are analyzed. ► Adhesion strengths of SWCNTs obtained from MD simulations are compared with the predictions of Hamaker theory and JKR model. - Abstract: Functional gecko-inspired adhesives have attracted a lot of research attention in the last decade. In this work, the lateral surface adhesion and normal peeling-off behavior of single-walled carbon nanotubes (SWCNTs) on gold substrates are investigated by performing detailed, fully atomistic molecular dynamics (MD) simulations. The effects of the diameter and adhered length of CNTs on the adhesive properties were systematically examined. The simulation results indicate that adhesion energies between the SWCNTs and the Au surface varied from 220 to 320 mJ m −2 over the reported chirality range. The adhesion forces on the lateral surface and the tip of the nanotubes obtained from MD simulations agree very well with the predictions of Hamaker theory and Johnson–Kendall–Roberts (JKR) model. The analyses of covalent bonds indicate that the SWCNTs exhibited excellent flexibility and extensibility when adhering at low temperatures (∼100 K). This mechanism substantially increases adhesion time compared to that obtained at higher temperatures (300–700 K), which makes SWCNTs promising for biomimetic adhesives in ultra-low temperature surroundings.

  18. Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces (United States)

    Zutz, Amelia Marie

    Detailed molecular scale interactions at the gas-liquid interface are explored with quantum state-to-state resolved scattering of a jet-cooled beam of NO(2pi1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered distributions are probed via laser-induced fluorescence methods, which yield rotational and spin-orbit state populations that elucidate the dynamics of energy transfer at the gas-liquid interface. These collision dynamics are explored as a function of incident collision energy, surface temperature, scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational, electronic and vibrational excitation of NO via collisions at the liquid surface. Rotational distributions observed reveal two distinct scattering pathways, (i) molecules that trap, thermalize and eventually desorb from the surface (trapping-desorption, TD), and (ii) those that undergo prompt recoil (impulsive scattering, IS) prior to complete equilibration with the liquid surface. Thermally desorbing NO molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities on liquid surfaces. Nitric oxide is a radical with multiple low-lying electronic states that serves as an ideal candidate for exploring nonadiabatic state-changing collision dynamics at the gas-liquid interface, which induce significant excitation from ground (2pi1/2) to excited (2pi 3/2) spin-orbit states. Molecular beam scattering of supersonically cooled NO from hot molten metals (Ga and Au, Ts = 300 - 1400 K) is also explored, which provide preliminary evidence for vibrational excitation of NO mediated by thermally populated electron-hole pairs in the hot, conducting liquid metals. The results highlight the presence of electronically nonadiabatic effects and build toward a more complete characterization of energy transfer dynamics at gas-liquid interfaces.

  19. Image-based rendering of intersecting surfaces for dynamic comparative visualization

    NARCIS (Netherlands)

    Busking, S.; Botha, C.P.; Ferrarini, L.; Milles, J.; Post, F.H.


    Nested or intersecting surfaces are proven techniques for visualizing shape differences between static 3D objects (Weigle and Taylor II, IEEE Visualization, Proceedings, pp. 503–510, 2005). In this paper we present an image-based formulation for these techniques that extends their use to dynamic

  20. New sensitive micro-measurements of dynamic surface tension and diffusion coefficients

    DEFF Research Database (Denmark)

    Kinoshita, Koji; Ortiz, Elisa Parra; Needham, David


    Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain “dead time” at initial measurement. These ...

  1. Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

    DEFF Research Database (Denmark)

    Clarkson, R B; Odintsov, B M; Ceroke, P J


    ; they can be calibrated and used for oximetry. Biological stability and low toxicity make chars good sensors for in vivo measurements. Scalar and dipolar interactions of water protons at the surfaces of chars may be utilized to produce dynamic nuclear polarization (DNP) of the nuclear spin population...

  2. Towards Dynamic Control of Wettability by Using Functionalized Altitudinal Molecular Motors on Solid Surfaces

    NARCIS (Netherlands)

    London, Gabor; Chen, Kuang-Yen; Carroll, Gregory T.; Feringa, Ben L.


    We report the synthesis of altitudinal molecular motors that contain functional groups in their rotor part. In an approach to achieve dynamic control over the properties of solid surfaces, a hydrophobic perfluorobutyl chain and a relatively hydrophilic cyano group were introduced to the rotor part

  3. Friction and Surface Dynamics of Polymers on the Nanoscale by AFM

    NARCIS (Netherlands)

    Schönherr, Holger; Schónherr, Holger; Samori, Paolo; Tocha, E.; Vancso, Gyula J.


    In this article the measurement and understanding of friction forces and surface dynamics of polymers on the one hand and the importance of molecular relaxation processes and viscoelasticity in polymers for advanced micro- and nanoscale applications on the other hand are discussed. Particular

  4. Influence of Surface Irregularities on the Dynamic Response of Minor Highway Bridges

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.; Kirkegaard, Poul Henning

    In the present paper the effect on the dynamic application factor of bridge response from the surface irregularities is investigated. A numerical 3D model has been formulated for a 48t Scania truck. Further, a characteristic minor highway bridge has been selected, and a numerical FEM-model has been...

  5. Effect of Surface Pollution on Homogeneous Ice Nucleation: A Molecular Dynamics Study

    Czech Academy of Sciences Publication Activity Database

    Pluhařová, Eva; Vrbka, L.; Jungwirth, Pavel


    Roč. 114, č. 17 (2010), s. 7831-7838 ISSN 1932-7447 R&D Projects: GA MŠk LC512 Grant - others:NSF(US) CHE0909227 Institutional research plan: CEZ:AV0Z40550506 Keywords : ice nucleation * surface contamination * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.520, year: 2010

  6. Dynamic Leidenfrost temperature on micro-textured surfaces: Acoustic wave absorption into thin vapor layer (United States)

    Jerng, Dong Wook; Kim, Dong Eok


    The dynamic Leidenfrost phenomenon is governed by three types of pressure potentials induced via vapor hydrodynamics, liquid dynamic pressure, and the water hammer effect resulting from the generation of acoustic waves at the liquid-vapor interface. The prediction of the Leidenfrost temperature for a dynamic droplet needs quantitative evaluation and definition for each of the pressure fields. In particular, the textures on a heated surface can significantly affect the vapor hydrodynamics and the water hammer pressure. We present a quantitative model for evaluating the water hammer pressure on micro-textured surfaces taking into account the absorption of acoustic waves into the thin vapor layer. The model demonstrates that the strength of the acoustic flow into the liquid droplet, which directly contributes to the water hammer pressure, depends on the magnitude of the acoustic resistance (impedance) in the droplet and the vapor region. In consequence, the micro-textures of the surface and the increased spacing between them reduce the water hammer coefficient ( kh ) defined as the ratio of the acoustic flow into the droplet to total generated flow. Aided by numerical calculations that solve the laminar Navier-Stokes equation for the vapor flow, we also predict the dynamic Leidenfrost temperature on a micro-textured surface with reliable accuracy consistent with the experimental data.

  7. Near Space Hypersonic Unmanned Aerial Vehicle Dynamic Surface Backstepping Control Design

    Directory of Open Access Journals (Sweden)

    Jinyong YU


    Full Text Available Compared with traditional aircraft, the near space hypersonic unmanned aerial vehicle control system design must deal with the extra prominent dynamics characters, which are differ from the traditional aircrafts control system design. A new robust adaptive control design method is proposed for one hypersonic unmanned aerial vehicle (HSUAV uncertain MIMO nonaffine block control system by using multilayer neural networks, feedback linearization technology, and dynamic surface backstepping. Multilayer neural networks are used to compensate the influence from the uncertain, which designs the robust terms to solve the problem from approach error. Adaptive backstepping is adopted designed to ensure control law, the dynamic surface control strategy to eliminate “the explosion of terms” by introducing a series of first order filters to obtain the differentiation of the virtual control inputs. Finally, nonlinear six-degree-of-freedom (6-DOF numerical simulation results for a HSUAV model are presented to demonstrate the effectiveness of the proposed method.

  8. Optimizing conjunctive use of surface water and groundwater resources with stochastic dynamic programming

    DEFF Research Database (Denmark)

    Davidsen, Claus; Liu, Suxia; Mo, Xinguo


    . A stochastic dynamic programming (SDP) approach is used to minimize the basin-wide total costs arising from water allocations and water curtailments. Dynamic allocation problems with inclusion of groundwater resources proved to be more complex to solve with SDP than pure surface water allocation problems due...... to head-dependent pumping costs. These dynamic pumping costs strongly affect the total costs and can lead to non-convexity of the future cost function. The water user groups (agriculture, industry, domestic) are characterized by inelastic demands and fixed water allocation and water supply curtailment...... and future costs for given surface water reservoir and groundwater aquifer end storages. The immediate cost is found by solving a simple linear allocation sub-problem, and the future costs are assessed by interpolation in the total cost matrix from the following time step. Total costs for all stages...

  9. Floods and climate: emerging perspectives for flood risk assessment and management

    DEFF Research Database (Denmark)

    Merz, B.; Aerts, J.; Arnbjerg-Nielsen, Karsten


    context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical......, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand......Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction...

  10. Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Jiaqi; Dang, Liem X.; Miller, Jan D.


    Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.

  11. Modelling and investigation of partial wetting surfaces for drop dynamics using lattice Boltzmann method (United States)

    Pravinraj, T.; Patrikar, Rajendra


    Partial wetting surfaces and its influence on the droplet movement of micro and nano scale being contemplated for many useful applications. The dynamics of the droplet usually analyzed with a multiphase lattice Boltzmann method (LBM). In this paper, the influence of partial wetting surface on the dynamics of droplet is systematically analyzed for various cases. Splitting of droplets due to chemical gradient of the surface is studied and analyses of splitting time for various widths of the strips for different Weber numbers are computed. With the proposed model one can tune the splitting volume and time by carefully choosing a strip width and droplet position. The droplet spreading on chemically heterogeneous surfaces shows that the spreading can be controlled not only by parameters of Weber number but also by tuning strip width ratio. The transportation of the droplet from hydrophobic surface to hydrophilic surface due to chemical gradient is simulated and analyzed using our hybrid thermodynamic-image processing technique. The results prove that with the progress of time the surface free energy decreases with increase in spreading area. Finally, the transportation of a droplet on microstructure gradient is demonstrated. The model explains the temporal behaviour of droplet during the spreading, recoiling and translation along with tracking of contact angle hysteresis phenomenon.

  12. Rupture and Spreading Dynamics of Lipid Membranes on a Solid Surface (United States)

    Perazzo, Antonio; Shin, Sangwoo; Colosqui, Carlos; Young, Yuan-Nan; Stone, Howard A.


    The spreading of lipid membranes on solid surfaces is a dynamic phenomenon relevant to drug delivery, endocytosis, biofouling, and the synthesis of supported lipid bilayers. Current technological developments are limited by an incomplete understanding of the spreading and adhesion dynamics of a lipid bilayer under different physicochemical conditions. Here, we present recent experimental and theoretical results for the spreading of giant unilamellar vesicles (GUVs), where the vesicle shell consists of a lipid bilayer. In particular, we study the effect of different background ion concentrations, osmolarity mismatches between the interior and the exterior of the vesicles, and different surface chemistries of the glass substrate. In all of the studied cases, we observe a delay time before a GUV in contact with the solid surface eventually ruptures. The rupture kinetics and subsequent spreading dynamics is controlled by the ionic screening within the thin film of liquid between the vesicle and the surface. Different rupture mechanisms, mobilities of the spreading vesicle, and degrees of substrate coverage are observed by varying the electrolyte concentration, solid surface charge, and osmolarity mismatch.

  13. Adsorption mechanism of ribosomal protein L2 onto a silica surface: a molecular dynamics simulation study. (United States)

    Tosaka, Ryo; Yamamoto, Hideaki; Ohdomari, Iwao; Watanabe, Takanobu


    A large-scale molecular dynamics simulation was carried out in order to investigate the adsorption mechanism of ribosomal protein L2 (RPL2) onto a silica surface at various pH values. RPL2 is a constituent protein of the 50S large ribosomal subunit, and a recent experimental report showed that it adsorbs strongly to silica surfaces and that it can be used to immobilize proteins on silica surfaces. The simulation results show that RPL2, especially domains 1 (residues 1-60) and 3 (residues 203-273), adsorbed more tightly to the silica surface above pH 7. We found that a major driving force for the adsorption of RPL2 onto the silica surface is the electrostatic interaction and that the structural flexibility of domains 1 and 3 may further contribute to the high affinity.

  14. Molecular-dynamics theory of the temperature-dependent surface phonons of W(001)

    International Nuclear Information System (INIS)

    Wang, C.Z.; Fasolino, A.; Tosatti, E.


    We study the temperature-dependent zone-boundary surface phonons across the c(2x2)→1x1 reconstruction phase transition of the clean W(001) surface. Velocity-velocity correlations and hence the phonon spectral densities are calculated by molecular dynamics for the surface atoms of a finite thickness (001) slab, with interatomic potentials established in a previous study of the surface statics. Our calculated k = (1/2,1/2)(2π/a) surface phonon are dominated by three main low-frequency modes. Of these, the longitudinal and the shear horizontal are reconstruction-related and display critical broadening and softening at the phase transition, while the third, the shear vertical, is basically unaffected. The reconstruction phase mode, shear horizontal, appears to be responsible for the phase fluctuations which destroy long-range order at the transition. (author). 30 refs, 12 figs

  15. Do floods have permanent effects? Evidence from the Netherlands

    NARCIS (Netherlands)

    Husby, T.G.; de Groot, H.L.F.; Hofkes, M.W.; Dröes, M.I.


    This study investigates the short- and long-run impact on population dynamics of the major flood in the Netherlands in 1953. A dynamic difference-in-differences analysis reveals that the flood had an immediate negative impact on population growth, but limited long-term effects. In contrast, the

  16. Do floods have permanent effects? Evidence from the Netherlands

    NARCIS (Netherlands)

    Husby, T.G.; de Groot, H.L.F.; Hofkes, M.W.; Dröes, M.I.


    This study investigates the short- and long-run impact on population dynamics of the major flood in the Netherlands in 1953. A dynamic difference-in-differences analysis reveals that the flood had an immediate negative impact on population growth, but limited long term effects. In contrast, the

  17. Ab initio potential energy surfaces and quantum dynamics for polyatomic bimolecular reactions. (United States)

    Fu, Bina; Zhang, Donghui


    There has been great progress in the development of potential energy surfaces (PESs) and quantum dynamics calculations in the gas phase. The establishment of fitting procedure for highly accurate PESs and new developments in quantum reactive scattering on reliable PESs allow accurate characterization of reaction dynamics beyond triatomic systems. This review will give the recent development in our group in constructing ab initio PESs based on the neural networks, and the time-dependent wave packet calculations for bimolecular reactions beyond three atoms. Bimolecular reactions of current interest to the community, namely, OH+H2, H+H2O, OH+CO, H+CH4 and Cl+CH4 are focused on. Quantum mechanical characterization of these reactions uncovers interesting dynamical phenomena with an unprecedented level of sophistication, and has greatly advanced our understanding of polyatomic reaction dynamics.

  18. Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops. (United States)

    Chen, Longquan; Bonaccurso, Elmar


    In this paper, we experimentally investigated the dynamic spreading of liquid drops on solid surfaces. Drop of glycerol water mixtures and pure water that have comparable surface tensions (62.3-72.8 mN/m) but different viscosities (1.0-60.1 cP) were used. The size of the drops was 0.5-1.2 mm. Solid surfaces with different lyophilic and lyophobic coatings (equilibrium contact angle θ(eq) of 0°-112°) were used to study the effect of surface wettability. We show that surface wettability and liquid viscosity influence wetting dynamics and affect either the coefficient or the exponent of the power law that describes the growth of the wetting radius. In the early inertial wetting regime, the coefficient of the wetting power law increases with surface wettability but decreases with liquid viscosity. In contrast, the exponent of the power law does only depend on surface wettability as also reported in literature. It was further found that surface wettability does not affect the duration of inertial wetting, whereas the viscosity of the liquid does. For low viscosity liquids, the duration of inertial wetting corresponds to the time of capillary wave propagation, which can be determined by Lamb's drop oscillation model for inviscid liquids. For relatively high viscosity liquids, the inertial wetting time increases with liquid viscosity, which may due to the viscous damping of the surface capillary waves. Furthermore, we observed a viscous wetting regime only on surfaces with an equilibrium contact angle θ(eq) smaller than a critical angle θ(c) depending on viscosity. A scaling analysis based on Navier-Stokes equations is presented at the end, and the predicted θ(c) matches with experimental observations without any additional fitting parameters.

  19. Beyond 'flood hotspots': Modelling emergency service accessibility during flooding in York, UK (United States)

    Coles, Daniel; Yu, Dapeng; Wilby, Robert L.; Green, Daniel; Herring, Zara


    This paper describes the development of a method that couples flood modelling with network analysis to evaluate the accessibility of city districts by emergency responders during flood events. We integrate numerical modelling of flood inundation with geographical analysis of service areas for the Ambulance Service and the Fire & Rescue Service. The method was demonstrated for two flood events in the City of York, UK to assess the vulnerability of care homes and sheltered accommodation. We determine the feasibility of emergency services gaining access within the statutory 8- and 10-min targets for high-priority, life-threatening incidents 75% of the time, during flood episodes. A hydrodynamic flood inundation model (FloodMap) simulates the 2014 pluvial and 2015 fluvial flood events. Predicted floods (with depth >25 cm and areas >100 m2) were overlain on the road network to identify sites with potentially restricted access. Accessibility of the city to emergency responders during flooding was quantified and mapped using; (i) spatial coverage from individual emergency nodes within the legislated timeframes, and; (ii) response times from individual emergency service nodes to vulnerable care homes and sheltered accommodation under flood and non-flood conditions. Results show that, during the 2015 fluvial flood, the area covered by two of the three Fire & Rescue Service stations reduced by 14% and 39% respectively, while the remaining station needed to increase its coverage by 39%. This amounts to an overall reduction of 6% and 20% for modelled and observed floods respectively. During the 2014 surface water flood, 7 out of 22 care homes (32%) and 15 out of 43 sheltered accommodation nodes (35%) had modelled response times above the 8-min threshold from any Ambulance station. Overall, modelled surface water flooding has a larger spatial footprint than fluvial flood events. Hence, accessibility of emergency services may be impacted differently depending on flood mechanism

  20. Hydrodynamic modeling of urban flooding taking into account detailed data about city infrastructure (United States)

    Belikov, Vitaly; Norin, Sergey; Aleksyuk, Andrey; Krylenko, Inna; Borisova, Natalya; Rumyantsev, Alexey


    Flood waves moving across urban areas have specific features. Thus, the linear objects of infrastructure (such as embankments, roads, dams) can change the direction of flow or block the water movement. On the contrary, paved avenues and wide streets in the cities contribute to the concentration of flood waters. Buildings create an additional resistance to the movement of water, which depends on the urban density and the type of constructions; this effect cannot be completely described by Manning's resistance law. In addition, part of the earth surface, occupied by buildings, is excluded from the flooded area, which results in a substantial (relative to undeveloped areas) increase of the depth of flooding, especially for unsteady flow conditions. An approach to numerical simulation of urban areas flooding that consists in direct allocating of all buildings and structures on the computational grid are proposed. This can be done in almost full automatic way with usage of modern software. Real geometry of all objects of infrastructure can be taken into account on the base of highly detailed digital maps and satellite images. The calculations based on two-dimensional Saint-Venant equations on irregular adaptive computational meshes, which can contain millions of cells and take into account tens of thousands of buildings and other objects of infrastructure. Flood maps, received as result of modeling, are the basis for the damage and risk assessment for urban areas. The main advantage of the developed method is high-precision calculations, realistic modeling results and appropriate graphical display of the flood dynamics and dam-break wave's propagation on urban areas. Verification of this method has been done on the experimental data and real events simulations, including catastrophic flooding of the Krymsk city in 2012 year.

  1. Groundwater flood or groundwater-induced flood?


    Robins, N.S.; Finch, J.W.


    A number of ‘groundwater flood’ events have been recorded over the Chalk aquifer in southern England since the 1994 occurrence at Chichester, Sussex. Reporting of this event and subsequent groundwater floods indicates that there are two types of groundwater flood event. Type 1 is the true groundwater flood in which the water table elevation rises above the ground elevation, and Type 2 occurs when intense groundwater discharge via bourne springs and highly permeable shallow horizons discharges...

  2. Constrained chemical dynamics of CO dissociation/hydrogenation on Rh surfaces. (United States)

    Kraus, Peter; Frank, Irmgard


    Among noble metal catalysts, rhodium (Rh) is unique in its ability to perform one step synthesis of ethanol from syngas. The first steps following adsorption of syngas on Rh surfaces are assumed to be responsible for the conversion of CO and selectivity effects between C1, C2 and oxygenated species. In the current work, we have applied constrained ab initio molecular dynamics to investigate the kinetics of CO dissociation and hydrogenation over flat and stepped Rh surfaces. The obtained barriers for the Rh(111) surface are in a good agreement with the literature. On the stepped Rh(211) surface, a large site-dependent variation in barrier height is shown, with the upper terrace exhibiting behaviour comparable to the Rh(111) surface, while the barriers over the lower terrace site are generally significantly lower. We have calculated rate constants using transition state theory for both surfaces, and successfully applied them in a microkinetic model, confirming the predicted impact on CO conversion and CH4 /C1-oxygenate/C2Hn selectivity. In addition to reporting high-accuracy energetics and rate constants for CO dissociation/hydrogenation, and presenting an updated microkinetic mechanism for Rh catalysts, we have confirmed the applicability of constrained molecular dynamics for reaction barrier calculation, and we have also highlighted sensitive pathways affecting the selectivity between formaldehyde/methanol over Rh catalysts. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Modeling surface energy fluxes and thermal dynamics of a seasonally ice-covered hydroelectric reservoir. (United States)

    Wang, Weifeng; Roulet, Nigel T; Strachan, Ian B; Tremblay, Alain


    The thermal dynamics of human created northern reservoirs (e.g., water temperatures and ice cover dynamics) influence carbon processing and air-water gas exchange. Here, we developed a process-based one-dimensional model (Snow, Ice, WAater, and Sediment: SIWAS) to simulate a full year's surface energy fluxes and thermal dynamics for a moderately large (>500km(2)) boreal hydroelectric reservoir in northern Quebec, Canada. There is a lack of climate and weather data for most of the Canadian boreal so we designed SIWAS with a minimum of inputs and with a daily time step. The modeled surface energy fluxes were consistent with six years of observations from eddy covariance measurements taken in the middle of the reservoir. The simulated water temperature profiles agreed well with observations from over 100 sites across the reservoir. The model successfully captured the observed annual trend of ice cover timing, although the model overestimated the length of ice cover period (15days). Sensitivity analysis revealed that air temperature significantly affects the ice cover duration, water and sediment temperatures, but that dissolved organic carbon concentrations have little effect on the heat fluxes, and water and sediment temperatures. We conclude that the SIWAS model is capable of simulating surface energy fluxes and thermal dynamics for boreal reservoirs in regions where high temporal resolution climate data are not available. SIWAS is suitable for integration into biogeochemical models for simulating a reservoir's carbon cycle. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Structural dynamics of surfaces by ultrafast electron crystallography: experimental and multiple scattering theory. (United States)

    Schäfer, Sascha; Liang, Wenxi; Zewail, Ahmed H


    Recent studies in ultrafast electron crystallography (UEC) using a reflection diffraction geometry have enabled the investigation of a wide range of phenomena on the femtosecond and picosecond time scales. In all these studies, the analysis of the diffraction patterns and their temporal change after excitation was performed within the kinematical scattering theory. In this contribution, we address the question, to what extent dynamical scattering effects have to be included in order to obtain quantitative information about structural dynamics. We discuss different scattering regimes and provide diffraction maps that describe all essential features of scatterings and observables. The effects are quantified by dynamical scattering simulations and examined by direct comparison to the results of ultrafast electron diffraction experiments on an in situ prepared Ni(100) surface, for which structural dynamics can be well described by a two-temperature model. We also report calculations for graphite surfaces. The theoretical framework provided here allows for further UEC studies of surfaces especially at larger penetration depths and for those of heavy-atom materials. © 2011 American Institute of Physics

  5. Study on dynamic deformation synchronized measurement technology of double-layer liquid surfaces (United States)

    Tang, Huiying; Dong, Huimin; Liu, Zhanwei


    Accurate measurement of the dynamic deformation of double-layer liquid surfaces plays an important role in many fields, such as fluid mechanics, biomechanics, petrochemical industry and aerospace engineering. It is difficult to measure dynamic deformation of double-layer liquid surfaces synchronously for traditional methods. In this paper, a novel and effective method for full-field static and dynamic deformation measurement of double-layer liquid surfaces has been developed, that is wavefront distortion of double-wavelength transmission light with geometric phase analysis (GPA) method. Double wavelength lattice patterns used here are produced by two techniques, one is by double wavelength laser, and the other is by liquid crystal display (LCD). The techniques combine the characteristics such as high transparency, low reflectivity and fluidity of liquid. Two color lattice patterns produced by laser and LCD were adjusted at a certain angle through the tested double-layer liquid surfaces simultaneously. On the basis of the refractive indexes difference of two transmitted lights, the double-layer liquid surfaces were decoupled with GPA method. Combined with the derived relationship between phase variation of transmission-lattice patterns and out-of plane heights of two surfaces, as well as considering the height curves of the liquid level, the double-layer liquid surfaces can be reconstructed successfully. Compared with the traditional measurement method, the developed method not only has the common advantages of the optical measurement methods, such as high-precision, full-field and non-contact, but also simple, low cost and easy to set up.

  6. Impact of dynamic vegetation phenology on the simulated pan-Arctic land surface state (United States)

    Teufel, Bernardo; Sushama, Laxmi; Arora, Vivek K.; Verseghy, Diana


    The pan-Arctic land surface is undergoing rapid changes in a warming climate, with near-surface permafrost projected to degrade significantly during the twenty-first century. Vegetation-related feedbacks have the potential to influence the rate of degradation of permafrost. In this study, the impact of dynamic phenology on the pan-Arctic land surface state, particularly near-surface permafrost, for the 1961-2100 period, is assessed by comparing two simulations of the Canadian Land Surface Scheme (CLASS)—one with dynamic phenology, modelled using the Canadian Terrestrial Ecosystem Model (CTEM), and the other with prescribed phenology. These simulations are forced by atmospheric data from a transient climate change simulation of the 5th generation Canadian Regional Climate Model (CRCM5) for the Representative Concentration Pathway 8.5 (RCP8.5). Comparison of the CLASS coupled to CTEM simulation to available observational estimates of plant area index, spatial distribution of permafrost and active layer thickness suggests that the model captures reasonably well the overall distribution of vegetation and permafrost. It is shown that the most important impact of dynamic phenology on the land surface occurs through albedo and it is demonstrated for the first time that vegetation control on albedo during late spring and early summer has the highest potential to impact the degradation of permafrost. While both simulations show extensive near-surface permafrost degradation by the end of the twenty-first century, the strong projected response of vegetation to climate warming and increasing CO2 concentrations in the coupled simulation results in accelerated permafrost degradation in the northernmost continuous permafrost regions.

  7. Multi-dimensional perspectives of flood risk - using a participatory framework to develop new approaches to flood risk communication (United States)

    Rollason, Edward; Bracken, Louise; Hardy, Richard; Large, Andy


    find confusing or lacking in realistic grounding. This means users do not have information they find useful to make informed decisions about how to prepare for and respond to floods. Working together with at-risk participants, the research has developed new approaches for communicating flood risk. These approaches focus on understanding flood mechanisms and dynamics, to help participants imagine their flood risk and link potential scenarios to reality, and provide forecasts of predicted flooding at a variety of scales, allowing participants to assess the significance of predicted flooding and make more informed judgments on what action to take in response. The findings presented have significant implications for the way in which flood risk is communicated, changing the focus of mapping from probabilistic future scenarios to understanding flood dynamics and mechanisms. Such ways of communicating flood risk embrace how people would like to see risk communicated, and help those at risk grow their resilience. Communicating in such a way has wider implications for flood modelling and data collection. However, these represent potential opportunities to build more effective local partnerships for assessing and managing flood risks.

  8. A new method for quantifying and modeling large scale surface water inundation dynamics and key drivers using multiple time series of Earth observation and river flow data. A case study for Australia's Murray-Darling Basin (United States)

    Heimhuber, Valentin; Tulbure, Mirela G.; Broich, Mark


    Periodically inundated surface water (SW) areas such as floodplains are hotspots of biodiversity and provide a broad range of ecosystem services but have suffered alarming declines in recent history. Large scale flooding events govern the dynamics of these areas and are a critical component of the terrestrial water cycle, but their propagation through river systems and the corresponding long term SW dynamics remain poorly quantified on continental or global scales. In this research, we used an unprecedented Landsat-based time series of SW maps (1986-2011), to develop statistical inundation models and quantify the role of driver variables across the Murray-Darling Basin (MDB) (1 million square-km), which is Australia's bread basket and subject to competing demands over limited water resources. We fitted generalized additive models (GAM) between SW extent as the dependent variable and river flow data from 68 gauges, spatial time series of rainfall (P; interpolated gauge data), evapotranspiration (ET; AWRA-L land surface model) and soil moisture (SM; active passive microwave satellite remote sensing) as predictor variables. We used a fully directed and connected river network (Australian Geofabric) in combination with ancillary data, to develop a spatial modeling framework consisting of 18,521 individual modeling units. We then fitted individual models for all modeling units, which were made up of 10x10 km grid cells split into floodplain, floodplain-lake and non-floodplain areas, depending on the type of water body and its hydrologic connectivity to a gauged river. We applied the framework to quantify flood propagation times for all major river and floodplain systems across the MDB, which were in good accordance with observed travel times. After incorporating these flow lag times into the models, average goodness of fit was high across floodplains and floodplain-lake modeling units (r-squared > 0.65), which were primarily driven by river flow, and lower for non

  9. Dynamics of competitive polymer adsorption onto planar surfaces in good solvent. (United States)

    Källrot, Niklas; Linse, Per


    Adsorption of mixed polymer solutions in good solvent containing polymers of different chain length has been studied by applying simulation techniques on a coarse-grained bead-spring polymer model. Fully flexible polymers at varying bead-surface interaction strength and different combinations of flexible, semiflexible, and stiff polymers at a single bead-surface interaction strength have been examined. Monte Carlo simulation techniques have been employed to investigate static equilibrium properties and Brownian dynamic simulations to follow the dynamics of the adsorption process. The properties examined comprise the adsorbed number of polymers, adsorbed number of beads, bead density profiles, components of the polymer radius of gyration, tail, loop, and train configurations, and nematic bond order of adsorbed beads. The adsorption involves an initially independent adsorption of the two polymer types followed by competitive adsorption. The competitive adsorption is characterized by a maximum of the adsorbed amount and a desorption of the polymer with the smallest surface affinity and a continued, but reduced, growth of the adsorbed amount of the polymer with the largest surface affinity. The surface affinity difference between the two polymer types of different length increased with increasing bead-surface interaction. Furthermore, the surface affinity of a polymer initially decreased but then largely increased at increasing stiffness. As a consequence, a stiff short polymer was found to displace a 4-fold longer flexible polymer. The spatial extension of adsorbed polymers as characterized by the radius of gyration parallel and perpendicular to the surface of a polymer of a given flexibility was independent of the flexibility of the other polymer type. The fraction of beads in tails was increased and in trains reduced as the surface affinity of the dissimilar polymer type was raised. Finally, the adsorption layer of a stiff polymer possesses a nematic bond order. In

  10. Coupled slow and fast surface dynamics in an electrocatalytic oscillator: Model and simulations

    International Nuclear Information System (INIS)

    Nascimento, Melke A.; Nagao, Raphael; Eiswirth, Markus; Varela, Hamilton


    The co-existence of disparate time scales is pervasive in many systems. In particular for surface reactions, it has been shown that the long-term evolution of the core oscillator is decisively influenced by slow surface changes, such as progressing deactivation. Here we present an in-depth numerical investigation of the coupled slow and fast surface dynamics in an electrocatalytic oscillator. The model consists of four nonlinear coupled ordinary differential equations, investigated over a wide parameter range. Besides the conventional bifurcation analysis, the system was studied by means of high-resolution period and Lyapunov diagrams. It was observed that the bifurcation diagram changes considerably as the irreversible surface poisoning evolves, and the oscillatory region shrinks. The qualitative dynamics changes accordingly and the chaotic oscillations are dramatically suppressed. Nevertheless, periodic cascades are preserved in a confined region of the resistance vs. voltage diagram. Numerical results are compared to experiments published earlier and the latter reinterpreted. Finally, the comprehensive description of the time-evolution in the period and Lyapunov diagrams suggests further experimental studies correlating the evolution of the system's dynamics with changes of the catalyst structure

  11. Coupled Motion of Contact Line on Nanoscale Chemically Heterogeneous Surfaces for Improved Bubble Dynamics in Boiling. (United States)

    Jaikumar, Arvind; Kandlikar, Satish G


    We demonstrate that the contact line (CL) motion on energetically heterogeneous solid surfaces occurs in a coupled fashion as against the traditional staggered stick-slip motion. Introducing chemical inhomogeneities at nanoscale induces a local change in dynamic contact angles which manifests as a smooth and continuous motion of the CL. Nanoscale chemically inhomogeneous surfaces comprising of gold, palladium and nickel were generated on copper substrates to demonstrate the underlying CL dynamics. The spatial variations of chemical constituents were mapped using elemental display scanning electron microscope images. Further, the coupled and stick-slip motion was confirmed for a sliding water droplet on these surfaces, and then used in studying the pool boiling bubble dynamics of a single bubble from nucleation to departure. The coupled motion was seen to increase the CL velocity thereby increasing the contribution from transient conduction heat transfer. Consequently, a ~2X increase in the boiling critical heat flux (CHF) was observed. Enhancing the pool boiling performance by introducing nanoscale surface features is an attractive approach in many applications and this work provides a framework and understanding of the CL motion induced through the chemical inhomogeneity effects.

  12. Coupled slow and fast surface dynamics in an electrocatalytic oscillator: Model and simulations (United States)

    Nascimento, Melke A.; Nagao, Raphael; Eiswirth, Markus; Varela, Hamilton


    The co-existence of disparate time scales is pervasive in many systems. In particular for surface reactions, it has been shown that the long-term evolution of the core oscillator is decisively influenced by slow surface changes, such as progressing deactivation. Here we present an in-depth numerical investigation of the coupled slow and fast surface dynamics in an electrocatalytic oscillator. The model consists of four nonlinear coupled ordinary differential equations, investigated over a wide parameter range. Besides the conventional bifurcation analysis, the system was studied by means of high-resolution period and Lyapunov diagrams. It was observed that the bifurcation diagram changes considerably as the irreversible surface poisoning evolves, and the oscillatory region shrinks. The qualitative dynamics changes accordingly and the chaotic oscillations are dramatically suppressed. Nevertheless, periodic cascades are preserved in a confined region of the resistance vs. voltage diagram. Numerical results are compared to experiments published earlier and the latter reinterpreted. Finally, the comprehensive description of the time-evolution in the period and Lyapunov diagrams suggests further experimental studies correlating the evolution of the system's dynamics with changes of the catalyst structure.

  13. Methods for dynamic investigations of surface-attached in vitro bacterial and fungal biofilms

    DEFF Research Database (Denmark)

    Sternberg, Claus; Bjarnsholt, Thomas; Shirtliff, Mark


    Three dynamic models for the investigation of in vitro biofilm formation are described in this chapter. In the 6-well plate assay presented here, the placing of the plate on a rotating platform provides shear, thereby making the system dynamic with respect to the static microtiter assay.The second...... reported model, especially suitable for harvesting high amounts of cells for transcriptomic or proteomic investigations, is based on numerous glass beads placed in a flask incubated with shaking on a rotating platform, thus increasing the surface area for biofilm formation. Finally, the flow-cell system...

  14. The impact of upper tropospheric dynamics on surface air quality over the United States (United States)

    Kollonige, Debra E.

    Monitoring air quality and source attribution at the surface requires a vast understanding of radiative and dynamical e.ects in the lower atmosphere to capture influential processes a.ecting human health, the environment, and current pollutant standards. In order to accurately determine all sources impacting lower atmospheric composition, a more thorough comprehension of the dynamical, chemical, and radiative coupling of the stratosphere and troposphere is required. Particularly significant is the transport or exchange of trace gases (i.e. ozone), both natural and anthropogenic, between the stratosphere and troposphere also known as stratosphere-troposphere exchange (STE). During previous research campaigns, STE was found to contribute to the tropospheric ozone budget. In this work, a plan was designed to determine whether or not stratosphere-to-troposphere transport (STT) was a viable mechanism for elevated ozone at the surface, particularly in cases where unhealthy air quality conditions were detected. An investigation of several case studies in which high levels of surface ozone appear to originate from the stratosphere shows that a variety of dynamical pro cesses from the boundary layer to the lower stratosphere are involved. Starting with the quasi-geostrophic equations of vertical and horizontal motion, dynamical parameters can be derived and evaluated from the North American Regional Reanalysis (NARR) meteorological fields. Reanalysis diagnostics, such as Q-vector, can locate the prevailing STT mechanism and capture the extent of vertical transport and mixing into the lower troposphere. Back trajectories from the UMBC-LT model released at the ground sites present additional support for stratospheric contribution to measured ozone levels. Along with the reanalysis dataset, a combination of satellite-retrieved and surface observations of chemical tracers were utilized to demonstrate the plausibility of a stratospheric source and to rule out anthropogenic

  15. Molecular dynamics study of room temperature ionic liquids with water at mica surface

    Directory of Open Access Journals (Sweden)

    Huanhuan Zhang


    Full Text Available Water in room temperature ionic liquids (RTILs could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood, in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces, using molecular dynamics (MD simulation. MD results showed that (1 there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K+ ions is farther from mica surface; (2 more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces. Keywords: Room temperature ionic liquids, Hydrophobicity/hydrophicility, Water content, Electrical double layer, Mica surface

  16. Observed and forecast flood-inundation mapping application-A pilot study of an eleven-mile reach of the White River, Indianapolis, Indiana (United States)

    Kim, Moon H.; Morlock, Scott E.; Arihood, Leslie D.; Kiesler, James L.


    Near-real-time and forecast flood-inundation mapping products resulted from a pilot study for an 11-mile reach of the White River in Indianapolis. The study was done by the U.S. Geological Survey (USGS), Indiana Silver Jackets hazard mitigation taskforce members, the National Weather Service (NWS), the Polis Center, and Indiana University, in cooperation with the City of Indianapolis, the Indianapolis Museum of Art, the Indiana Department of Homeland Security, and the Indiana Department of Natural Resources, Division of Water. The pilot project showed that it is technically feasible to create a flood-inundation map library by means of a two-dimensional hydraulic model, use a map from the library to quickly complete a moderately detailed local flood-loss estimate, and automatically run the hydraulic model during a flood event to provide the maps and flood-damage information through a Web graphical user interface. A library of static digital flood-inundation maps was created by means of a calibrated two-dimensional hydraulic model. Estimated water-surface elevations were developed for a range of river stages referenced to a USGS streamgage and NWS flood forecast point colocated within the study reach. These maps were made available through the Internet in several formats, including geographic information system, Keyhole Markup Language, and Portable Document Format. A flood-loss estimate was completed for part of the study reach by using one of the flood-inundation maps from the static library. The Federal Emergency Management Agency natural disaster-loss estimation program HAZUS-MH, in conjunction with local building information, was used to complete a level 2 analysis of flood-loss estimation. A Service-Oriented Architecture-based dynamic flood-inundation application was developed and was designed to start automatically during a flood, obtain near real-time and forecast data (from the colocated USGS streamgage and NWS flood forecast point within the study reach

  17. Concepts of Urban Drainage and Flood Protection

    DEFF Research Database (Denmark)

    Harremoës, Poul


    to calculate surcharging and flooding, rather than just relating to pipe capacity performance criteria; the capability of calculating long series of rain record in order to derive proper statistics on the pollutional load on the environment; and finally the capability of dynamically controlling the system...... in real time in order to decrease the pollutional load by optimization of the usage of storage at rains smaller than the design rain, without increasing the risk of floods....

  18. Molecular dynamics simulations of water on a hydrophilic silica surface at high air pressures

    DEFF Research Database (Denmark)

    Zambrano, H.A.; Walther, Jens Honore; Jaffe, R.L.


    of air in water at different pressures. Using the calibrated force field, we conduct MD simulations to study the interface between a hydrophilic silica substrate and water surrounded by air at different pressures. We find that the static water contact angle is independent of the air pressure imposed......Wepresent a force field forMolecular Dynamics (MD) simulations ofwater and air in contactwith an amorphous silica surface. We calibrate the interactions of each species present in the systemusing dedicated criteria such as the contact angle of a water droplet on a silica surface, and the solubility...... on the system. Our simulations reveal the presence of a nanometer thick layer of gas at the water–silica interface. We believe that this gas layer could promote nucleation and stabilization of surface nanobubbles at amorphous silica surfaces. © 2014 Elsevier B.V. All rights reserved....

  19. Chemical stability and surface stoichiometry of vanadium oxide phases studied by reactive molecular dynamics simulations (United States)

    Jeon, Byoungseon; Ko, Changhyun; van Duin, Adri C. T.; Ramanathan, Shriram


    Compositional stability of various vanadium oxides and oxide growth on vanadium surfaces have been studied using reactive molecular dynamics simulation methods. Vanadium dioxide (VO2), sesquioxide (V2O3), pentoxide (V2O5), and hexavanadium tridecaoxide (V6O13) are studied in bulk crystalline and thin film structures, investigating charge distribution and pair distribution functions of particle interactions. The stability is estimated to be pentoxide, hexavanadium tridecaoxide, sesquioxide, and dioxide respectively in decreasing order in thin film structures. We then analyze oxide growth kinetics on vanadium (100) and (110) surfaces. The oxidation rate, stoichiometry, charge distribution, and the effect of surface orientation on kinetic phenomena are noted. In the early stages of surface oxidation of our simulation configurations, sesquioxide is found to be the dominant component. The modeling and simulation results are compared with experiments where available.

  20. Floods in the Pampas: Insights from over a Decade of Satellite Observations (United States)

    Kuppel, S.; Houspanossian, J.; Nosetto, M. D.; Jobbagy, E. G.


    There is a general need to understand floods in very flat sedimentary regions, particularly in the context of current climate and land use changes. While most landscapes respond to extreme rainfall inputs by increasing their liquid water outputs, very flat and poorly drained ones have little capacity to do this and their most common responses include (i) increased water storage leading to rising water tables and floods, (ii) increased evaporative water losses and, only at very high levels of storage, (iii) increased liquid water losses. We explored the relative importance of these pathways in the extensive plains of the Argentine Pampas, where two significant flood episodes took place in 2000-2003 and 2012-2013. We combined a new remote sensing estimate of 8-day surface water cover (SWC, based on MODIS albedo product), monthly terrestrial water stock (TWS, based on GRACE gravity recovery data), daily precipitation (PP, based on TRMM data), evapotranspiration (ET, based on MODIS NDVI and surface temperature data). Focusing on two of the most flood-prone areas of the Argentine Pampas (60 000 km² each) we found that in 2000-2003, SWC reached 18 and 15% in each region, while the accumulated precipitation anomalies respectively approached 500 and 800 millimeters since the beginning of the flood cycle. In 2012-2013, SWC peaked at 8 and 7% after respective precipitation excesses of 420 and 250 mm. There was a direct, somewhat linear coupling between SWC and TWS in the western region during both flood events, while significant hysteresis features in the eastern region hint at a decoupling between the terrestrial water reservoir and its surface component. The relationships between yearly SWC, TWS, PP and ET point at a surface-water-balance-driven water cycle in the east, with below-ground water storage exerting a secondary and delayed control on the somewhat rapid flood dynamics. On the contrary, a groundwater-connected water cycle is suggested in the west, where

  1. Drought to flood: a comparative assessment of four parallel surface water treatments during the 2010-2012 inflows to the Murray-Darling Basin, South Australia. (United States)

    Braun, Kalan; Fabris, Rolando; Morran, Jim; Ho, Lionel; Drikas, Mary


    Four treatment processes; conventional coagulation, magnetic ion exchange (MIEX)/coagulation, with and without granular activated carbon (GAC), and membrane treatment combining microfiltration (MF) and nanofiltration (NF), were operated in parallel using the same source water from the Murray-Darling basin in South Australia. During the two year study, high levels of natural organic matter and turbidity arising from floods affecting the Murray-Darling basin in 2010-2012 challenged the four processes. The comparative study indicated that all four processes could effectively meet basic water quality guidelines of turbidity and colour despite challenging source water quality but that the more advanced treatments improved overall organic and bacterial removal. Interestingly, the high organics and turbidity arising from the floods resulted in improved treatment efficiency for all treatments incorporating coagulation to the extent that, despite flood conditions, treated water quality could remain comparatively constant provided that the process was operated and optimised effectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Base Flood Elevation (United States)

    Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

  3. Flood Hazard Boundaries (United States)

    Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

  4. Flood Control Structures (United States)

    Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

  5. Flood Hazard Area (United States)

    Earth Data Analysis Center, University of New Mexico — The National Flood Hazard Layer (NFHL) data incorporates all Digital Flood Insurance Rate Map(DFIRM) databases published by FEMA, and any Letters Of Map Revision...

  6. Interfacial layers from the protein HFBII hydrophobin: dynamic surface tension, dilatational elasticity and relaxation times. (United States)

    Alexandrov, Nikola A; Marinova, Krastanka G; Gurkov, Theodor D; Danov, Krassimir D; Kralchevsky, Peter A; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Arnaudov, Luben N; Pelan, Eddie G; Lips, Alex


    The pendant-drop method (with drop-shape analysis) and Langmuir trough are applied to investigate the characteristic relaxation times and elasticity of interfacial layers from the protein HFBII hydrophobin. Such layers undergo a transition from fluid to elastic solid films. The transition is detected as an increase in the error of the fit of the pendant-drop profile by means of the Laplace equation of capillarity. The relaxation of surface tension after interfacial expansion follows an exponential-decay law, which indicates adsorption kinetics under barrier control. The experimental data for the relaxation time suggest that the adsorption rate is determined by the balance of two opposing factors: (i) the barrier to detachment of protein molecules from bulk aggregates and (ii) the attraction of the detached molecules by the adsorption layer due to the hydrophobic surface force. The hydrophobic attraction can explain why a greater surface coverage leads to a faster adsorption. The relaxation of surface tension after interfacial compression follows a different, square-root law. Such behavior can be attributed to surface diffusion of adsorbed protein molecules that are condensing at the periphery of interfacial protein aggregates. The surface dilatational elasticity, E, is determined in experiments on quick expansion or compression of the interfacial protein layers. At lower surface pressures (<11 mN/m) the experiments on expansion, compression and oscillations give close values of E that are increasing with the rise of surface pressure. At higher surface pressures, E exhibits the opposite tendency and the data are scattered. The latter behavior can be explained with a two-dimensional condensation of adsorbed protein molecules at the higher surface pressures. The results could be important for the understanding and control of dynamic processes in foams and emulsions stabilized by hydrophobins, as well as for the modification of solid surfaces by adsorption of such

  7. Flood frequency analysis of historical flood data under stationary and non-stationary modelling (United States)

    Machado, M. J.; Botero, B. A.; López, J.; Francés, F.; Díez-Herrero, A.; Benito, G.


    Historical records are an important source of information on extreme and rare floods and fundamental to establish a reliable flood return frequency. The use of long historical records for flood frequency analysis brings in the question of flood stationarity, since climatic and land-use conditions can affect the relevance of past flooding as a predictor of future flooding. In this paper, a detailed 400 yr flood record from the Tagus River in Aranjuez (central Spain) was analysed under stationary and non-stationary flood frequency approaches, to assess their contribution within hazard studies. Historical flood records in Aranjuez were obtained from documents (Proceedings of the City Council, diaries, chronicles, memoirs, etc.), epigraphic marks, and indirect historical sources and reports. The water levels associated with different floods (derived from descriptions or epigraphic marks) were computed into discharge values using a one-dimensional hydraulic model. Secular variations in flood magnitude and frequency, found to respond to climate and environmental drivers, showed a good correlation between high values of historical flood discharges and a negative mode of the North Atlantic Oscillation (NAO) index. Over the systematic gauge record (1913-2008), an abrupt change on flood magnitude was produced in 1957 due to constructions of three major reservoirs in the Tagus headwaters (Bolarque, Entrepeñas and Buendia) controlling 80% of the watershed surface draining to Aranjuez. Two different models were used for the flood frequency analysis: (a) a stationary model estimating statistical distributions incorporating imprecise and categorical data based on maximum likelihood estimators, and (b) a time-varying model based on "generalized additive models for location, scale and shape" (GAMLSS) modelling, which incorporates external covariates related to climate variability (NAO index) and catchment hydrology factors (in this paper a reservoir index; RI). Flood frequency

  8. Flood Risk Regional Flood Defences : Technical report

    NARCIS (Netherlands)

    Kok, M.; Jonkman, S.N.; Lendering, K.T.


    Historically the Netherlands have always had to deal with the threat of flooding, both from the rivers and the sea as well as from heavy rainfall. The country consists of a large amount of polders, which are low lying areas of land protected from flooding by embankments. These polders require an

  9. Urban Land: Study of Surface Run-off Composition and Its Dynamics (United States)

    Palagin, E. D.; Gridneva, M. A.; Bykova, P. G.


    The qualitative composition of urban land surface run-off is liable to significant variations. To study surface run-off dynamics, to examine its behaviour and to discover reasons of these variations, it is relevant to use the mathematical apparatus technique of time series analysis. A seasonal decomposition procedure was applied to a temporary series of monthly dynamics with the annual frequency of seasonal variations in connection with a multiplicative model. The results of the quantitative chemical analysis of surface wastewater of the 22nd Partsjezd outlet in Samara for the period of 2004-2016 were used as basic data. As a result of the analysis, a seasonal pattern of variations in the composition of surface run-off in Samara was identified. Seasonal indices upon 15 waste-water quality indicators were defined. BOD (full), suspended materials, mineralization, chlorides, sulphates, ammonium-ion, nitrite-anion, nitrate-anion, phosphates (phosphorus), iron general, copper, zinc, aluminium, petroleum products, synthetic surfactants (anion-active). Based on the seasonal decomposition of the time series data, the contribution of trends, seasonal and accidental components of the variability of the surface run-off indicators was estimated.

  10. Estimation of Nanodiamond Surface Charge Density from Zeta Potential and Molecular Dynamics Simulations. (United States)

    Ge, Zhenpeng; Wang, Yi


    Molecular dynamics simulations of nanoparticles (NPs) are increasingly used to study their interactions with various biological macromolecules. Such simulations generally require detailed knowledge of the surface composition of the NP under investigation. Even for some well-characterized nanoparticles, however, this knowledge is not always available. An example is nanodiamond, a nanoscale diamond particle with surface dominated by oxygen-containing functional groups. In this work, we explore using the harmonic restraint method developed by Venable et al., to estimate the surface charge density (σ) of nanodiamonds. Based on the Gouy-Chapman theory, we convert the experimentally determined zeta potential of a nanodiamond to an effective charge density (σ eff ), and then use the latter to estimate σ via molecular dynamics simulations. Through scanning a series of nanodiamond models, we show that the above method provides a straightforward protocol to determine the surface charge density of relatively large (> ∼100 nm) NPs. Overall, our results suggest that despite certain limitation, the above protocol can be readily employed to guide the model construction for MD simulations, which is particularly useful when only limited experimental information on the NP surface composition is available to a modeler.

  11. Signal Processing for Determining Water Height in Steam Pipes with Dynamic Surface Conditions (United States)

    Lih, Shyh-Shiuh; Lee, Hyeong Jae; Bar-Cohen, Yoseph


    An enhanced signal processing method based on the filtered Hilbert envelope of the auto-correlation function of the wave signal has been developed to monitor the height of condensed water through the steel wall of steam pipes with dynamic surface conditions. The developed signal processing algorithm can also be used to estimate the thickness of the pipe to determine the cut-off frequency for the low pass filter frequency of the Hilbert Envelope. Testing and analysis results by using the developed technique for dynamic surface conditions are presented. A multiple array of transducers setup and methodology are proposed for both the pulse-echo and pitch-catch signals to monitor the fluctuation of the water height due to disturbance, water flow, and other anomaly conditions.

  12. SHARC: ab Initio Molecular Dynamics with Surface Hopping in the Adiabatic Representation Including Arbitrary Couplings. (United States)

    Richter, Martin; Marquetand, Philipp; González-Vázquez, Jesús; Sola, Ignacio; González, Leticia


    We present a semiclassical surface-hopping method which is able to treat arbitrary couplings in molecular systems including all degrees of freedom. A reformulation of the standard surface-hopping scheme in terms of a unitary transformation matrix allows for the description of interactions like spin-orbit coupling or transitions induced by laser fields. The accuracy of our method is demonstrated in two systems. The first one, consisting of two model electronic states, validates the semiclassical approach in the presence of an electric field. In the second one, the dynamics in the IBr molecule in the presence of spin-orbit coupling after laser excitation is investigated. Due to an avoided crossing that originates from spin-orbit coupling, IBr dissociates into two channels: I + Br((2)P3/2) and I + Br*((2)P1/2). In both systems, the obtained results are in very good agreement with those calculated from exact quantum dynamical simulations.

  13. Structure and Dynamics of Water on Aqueous Barium Ion and the {001} Barite Surface

    International Nuclear Information System (INIS)

    Stack, Andrew G.; Rustad, James R.


    The structure of water and its dynamics affect a number of fundamental properties of an interface. Yet, these properties are often inaccessible experimentally and computational studies including solvent are comparatively few. Here, we estimate the structure and kinetics of water exchange of aqueous barium ions and barium ions within the {001} barite surface using molecular dynamics and the reactive flux method. For the aqueous ion, the Ba-O distance to water in the first hydration shell was found to be 280 pm with a coordination number of 8.3, and the best estimate of the exchange rate constant is 4.8 x 10 9 s -1 , closely matching experimental estimates. For the barite surface, the first shell water distance was 282 pm, with a coordination number of 0.9 and the best estimate of the rate constant for exchange is 1.7 x 10 10 s -1 , 3.5 times faster than that of the aqueous ion.

  14. Isolated, slowly evolving, and dynamical trapping horizons: Geometry and mechanics from surface deformations

    International Nuclear Information System (INIS)

    Booth, Ivan; Fairhurst, Stephen


    We study the geometry and dynamics of both isolated and dynamical trapping horizons by considering the allowed variations of their foliating two-surfaces. This provides a common framework that may be used to consider both their possible evolutions and their deformations as well as derive the well-known flux laws. Using this framework, we unify much of what is already known about these objects as well as derive some new results. In particular we characterize and study the ''almost isolated'' trapping horizons known as slowly evolving horizons. It is for these horizons that a dynamical first law holds and this is analogous and closely related to the Hawking-Hartle formula for event horizons

  15. Surface hopping study of the photodissociation dynamics of ICN- and BrCN- (United States)

    Opoku-Agyeman, Bernice; McCoy, Anne B.


    In this work the efficacy of semi-classical surface hopping approaches is investigated through studies of the photodissociation dynamics of BrCN- and ICN-. BrCN- provides a challenging situation for semi-classical approaches as excitation to the first bright state yields both Br- + CN and Br∗ + CN- products. Further, this branching is highly sensitive to the amount of rotational energy in the CN0/- fragment. The results of semi-classical and quantum mechanical descriptions of the dynamics are compared when the classical dynamics are propagated in an adiabatic and diabatic representation. The implications of the differences between the classical and quantum treatments of J = 0 are also explored.

  16. Integrating aerodynamic surface modeling for computational fluid dynamics with computer aided structural analysis, design, and manufacturing (United States)

    Thorp, Scott A.


    This presentation will discuss the development of a NASA Geometry Exchange Specification for transferring aerodynamic surface geometry between LeRC systems and grid generation software used for computational fluid dynamics research. The proposed specification is based on a subset of the Initial Graphics Exchange Specification (IGES). The presentation will include discussion of how the NASA-IGES standard will accommodate improved computer aided design inspection methods and reverse engineering techniques currently being developed. The presentation is in viewgraph format.

  17. Dynamics at Solid State Surfaces and Interfaces, Volume 1 Current Developments

    CERN Document Server

    Bovensiepen, Uwe; Wolf, Martin


    This two-volume work covers ultrafast structural and electronic dynamics of elementary processes at solid surfaces and interfaces, presenting the current status of photoinduced processes. Providing valuable introductory information for newcomers to this booming field of research, it investigates concepts and experiments, femtosecond and attosecond time-resolved methods, as well as frequency domain techniques. The whole is rounded off by a look at future developments.

  18. Holographic otoscope for nano-displacement measurements of surfaces under dynamic excitation


    Flores-Moreno, J. M.; Furlong, Cosme; Rosowski, John J.; Harrington, Ellery; Cheng, Jeffrey T.; Scarpino, C.; Santoyo, F. Mendoza


    We describe a novel holographic otoscope system for measuring nano-displacements of objects subjected to dynamic excitation. Such measurements are necessary to quantify the mechanical deformation of surfaces in mechanics, acoustics, electronics, biology and many other fields. In particular, we are interested in measuring the sound-induced motion of biological samples, such as an eardrum. Our holographic otoscope system consists of laser illumination delivery (IS), optical head (OH), and image...

  19. Flood Wave Propagation

    Indian Academy of Sciences (India)

    I available for forecasting the propagation of the flood wave. Introduction. Among all natural disasters, floods are the most frequently occurring phenomena that affect a large section of population all over the world, every year. Throughout the last century, flood- ing has been one of the most devastating disasters both in terms.

  20. Case studies of extended model-based flood forecasting: prediction of dike strength and flood impacts (United States)

    Stuparu, Dana; Bachmann, Daniel; Bogaard, Tom; Twigt, Daniel; Verkade, Jan; de Bruijn, Karin; de Leeuw, Annemargreet


    Flood forecasts, warning and emergency response are important components in flood risk management. Most flood forecasting systems use models to translate weather predictions to forecasted discharges or water levels. However, this information is often not sufficient for real time decisions. A sound understanding of the reliability of embankments and flood dynamics is needed to react timely and reduce the negative effects of the flood. Where are the weak points in the dike system? When, how much and where the water will flow? When and where is the greatest impact expected? Model-based flood impact forecasting tries to answer these questions by adding new dimensions to the existing forecasting systems by providing forecasted information about: (a) the dike strength during the event (reliability), (b) the flood extent in case of an overflow or a dike failure (flood spread) and (c) the assets at risk (impacts). This work presents three study-cases in which such a set-up is applied. Special features are highlighted. Forecasting of dike strength. The first study-case focusses on the forecast of dike strength in the Netherlands for the river Rhine branches Waal, Nederrijn and IJssel. A so-called reliability transformation is used to translate the predicted water levels at selected dike sections into failure probabilities during a flood event. The reliability of a dike section is defined by fragility curves - a summary of the dike strength conditional to the water level. The reliability information enhances the emergency management and inspections of embankments. Ensemble forecasting. The second study-case shows the setup of a flood impact forecasting system in Dumfries, Scotland. The existing forecasting system is extended with a 2D flood spreading model in combination with the Delft-FIAT impact model. Ensemble forecasts are used to make use of the uncertainty in the precipitation forecasts, which is useful to quantify the certainty of a forecasted flood event. From global

  1. Probing the surface profile and friction behavior of heterogeneous polymers: a molecular dynamics study (United States)

    Dai, L.; Sorkin, V.; Zhang, Y. W.


    We perform molecular dynamics simulations to investigate molecular structure alternation and friction behavior of heterogeneous polymer (perfluoropolyether) surfaces using a nanoscale probing tip (tetrahedral amorphous carbon). It is found that depending on the magnitude of the applied normal force, three regimes exist: the shallow depth-sensing (SDS), deep depth-sensing (DDS), and transitional depth-sensing (TDS) regimes; TDS is between SDS and DDS. In SDS, the tip is floating on the polymer surface and there is insignificant permanent alternation in the polymer structure due to largely recoverable atomic deformations, and the surface roughness profile can be accurately measured. In DDS, the tip is plowing through the polymer surface and there is significant permanent alternation in the molecular structure. In this regime, the lateral friction force rises sharply and fluctuates violently when overcoming surface pile-ups. In SDS, the friction can be described by a modified Amonton’s law including the adhesion effect; meanwhile, in DDS, the adhesion effect is negligible but the friction coefficient is significantly higher. The underlying reason for the difference in these regimes rests upon different contributions by the repulsion and attraction forces between the tip and polymer surfaces to the friction force. Our findings here reveal important insights into lateral depth-sensing on heterogeneous polymer surfaces and may help improve the precision of depth-sensing devices.

  2. Liquid flow in surface-nanostructured channels studied by molecular dynamics simulation (United States)

    Cao, Bing-Yang; Chen, Min; Guo, Zeng-Yuan


    Molecular dynamics simulations have been carried out to investigate the fluid wetting and flow in nanochannels whose surfaces are structured by an array of nanoscale triangular modules. We find that the surface nanostructures have a dual effect on the boundary slip and friction of the liquid nanoflow. On the one hand, the nanostructures can enhance the surface hydrophilicity for a hydrophilic liquid-solid interaction, and can increase the hydrophobicity for a hydrophobic interaction due to a nanoscale lotus effect. In particular, the nanostructured surface may show superhydrophobicity and lead to the large velocity slip of the liquid flow. On the other hand, simultaneously, the nanostructures distort the nanoscale streamlines of the liquid flow near the channel surfaces and block the nanoflow directly, which decreases the apparent slip length equivalently. The dual effect of the nanostructures on the surface wettability and the hydrodynamic disturbance results in a nonmonotonic dependence of the slip length on the nanostructure size. The simulations imply that the surface nanostructures can be applied to control the friction of liquid micro- and nanoflows.

  3. Hydration water dynamics around a protein surface: a first passage time approach (United States)

    Sharma, Shivangi; Biswas, Parbati


    A stochastic noise-driven dynamic model is proposed to study the diffusion of water molecules around a protein surface, under the effect of thermal fluctuations that arise due to the collision of water molecules with the surrounding environment. The underlying dynamics of such a system may be described in the framework of the generalized Langevin equation, where the thermal fluctuations are assumed to be algebraically correlated in time, which governs the non-Markovian behavior of the system. Results of the calculations of mean-square displacement and the velocity autocorrelation function reveal that the hydration water around the protein surface follows subdiffusive dynamics at long times. Analytical expressions for the first passage time distribution, survival probability, mean residence time and mean first passage time of water molecules are derived for different boundary conditions, to analyze hydration water dynamics under the effect of thermally correlated noise. The results depict a unimodal distribution of the first passage time unlike Brownian motion. The survival probability of hydration water follows a stretched exponential decay for both boundary conditions. The mean residence time of the hydration water molecule for different initial positions increases with increase in the complexity/heterogeneity of the surrounding environment for both boundary conditions. The mean first passage time of the water molecule to reach the absorbing/reflecting boundary follows an asymptotic power law with respect to the thickness of the hydration layer, and increases with increase in the complexity/heterogeneity of the environment.

  4. Direct imaging of delayed magneto-dynamic modes induced by surface acoustic waves. (United States)

    Foerster, Michael; Macià, Ferran; Statuto, Nahuel; Finizio, Simone; Hernández-Mínguez, Alberto; Lendínez, Sergi; Santos, Paulo V; Fontcuberta, Josep; Hernàndez, Joan Manel; Kläui, Mathias; Aballe, Lucia


    The magnetoelastic effect-the change of magnetic properties caused by the elastic deformation of a magnetic material-has been proposed as an alternative approach to magnetic fields for the low-power control of magnetization states of nanoelements since it avoids charge currents, which entail ohmic losses. Here, we have studied the effect of dynamic strain accompanying a surface acoustic wave on magnetic nanostructures in thermal equilibrium. We have developed an experimental technique based on stroboscopic X-ray microscopy that provides a pathway to the quantitative study of strain waves and magnetization at the nanoscale. We have simultaneously imaged the evolution of both strain and magnetization dynamics of nanostructures at the picosecond time scale and found that magnetization modes have a delayed response to the strain modes, adjustable by the magnetic domain configuration. Our results provide fundamental insight into magnetoelastic coupling in nanostructures and have implications for the design of strain-controlled magnetostrictive nano-devices.Understanding the effects of local dynamic strain on magnetization may help the development of magnetic devices. Foerster et al. demonstrate stroboscopic imaging that allows the observation of both strain and magnetization dynamics in nickel when surface acoustic waves are driven in the substrate.

  5. Adaptive dynamic surface control for a class of MIMO nonlinear systems with actuator failures (United States)

    Amezquita S., Kendrick; Yan, Lin; Butt, Waseem A.


    In this article, an adaptive dynamic surface control scheme for a class of MIMO nonlinear systems with actuator failures and uncertainties is presented. In the proposed control scheme, the dynamic changes and disturbances induced by actuator failures are detected and isolated by means of radial basis function neural networks, which also compensate system uncertainties that arise from the mismatch between nominal model and real plant. In the presence of unknown actuation functions, the effectiveness of the control scheme is guaranteed by imposing a structural condition on the actuation matrix. Moreover, the singularity problem that arises from the approximation of unknown actuation functions is circumvented, and thus the use parameter projection is avoided. In this work, the nominal plant is transformed into a suitable form via diffeomorphism. Dynamic surface control design technique is used to develop the control laws. The closed-loop signals are proven to be uniformly ultimately bounded through Lyapunov approach, and the output tracking error is shown to be bounded within a residual set which can be made arbitrarily small by appropriately tuning the controller parameters. Finally, the proposed adaptive control scheme effectiveness is verified by simulation of the longitudinal dynamics of a twin otter aircraft undergoing actuator failures.


    Directory of Open Access Journals (Sweden)



    Full Text Available The design of the re-entry space vehicles and high-speed aircrafts requires special attention to the nonlinear thermoelastic and aerodynamic instabilities of their structural components. The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes. To contribute to the understanding of dynamic behavior of these “hot” structures, a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed. A third order Piston Theory Aerodynamics is used to evaluate the applied nonlinear unsteady aerodynamic loads. The loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered. The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams. Modelling issues as well as simulation results have been presented and pertinent conclusions outlined. It is highlighted that a serious loss of torsional stiffness may induce the dynamic instability of the lifting surfaces. The influence of various parameters such as flight condition, thickness ratio, freeplays and pitching stiffness nonlinearity are also discussed.

  7. Theory of the reaction dynamics of small molecules on metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Bret [Univ. of Massachusetts, Amherst, MA (United States)


    The objective of this project has been to develop realistic theoretical models for gas-surface interactions, with a focus on processes important in heterogeneous catalysis. The dissociative chemisorption of a molecule on a metal is a key step in many catalyzed reactions, and is often the rate-limiting step. We have explored the dissociative chemisorption of H2, H2O and CH4 on a variety of metal surfaces. Most recently, our extensive studies of methane dissociation on Ni and Pt surfaces have fully elucidated its dependence on translational energy, vibrational state and surface temperature, providing the first accurate comparisons with experimental data. We have explored Eley-Rideal and hot atom reactions of H atoms with H- and C-covered metal surfaces. H atom interactions with graphite have also been explored, including both sticking and Eley-Rideal recombination processes. Again, our methods made it possible to explain several experiments studying these reactions. The sticking of atoms on metal surfaces has also been studied. To help elucidate the experiments that study these processes, we examine how the reaction dynamics depend upon the nature of the molecule-metal interaction, as well as experimental variables such as substrate temperature, beam energy, angle of impact, and the internal states of the molecules. Electronic structure methods based on Density Functional Theory are used to compute each molecule-metal potential energy surface. Both time-dependent quantum scattering techniques and quasi-classical methods are used to examine the reaction or scattering dynamics. Much of our effort has been directed towards developing improved quantum methods that can accurately describe reactions, as well as include the effects of substrate temperature (lattice vibration).

  8. Some learnings from post-event field investigations after the june 2013 floods in the Pyrenees region in France. (United States)

    Payrastre, Olivier; Bonnifait, Laurent; Gaume, Eric; Le Boursicaut, Raphael


    In June 2013 catastrophic floods occurred in south of France in the Pyrenees mountainous area. These floods were due to the combination of a high initial discharge due to snowmelt with a significant rainfall event (up to 200mm rainfall), which effects may have been enhanced by an increase of snowmelt. Although the dynamics of this flood are not really similar, some of its features clearly remind what may be observed in the case of flash floods: significant contribution of relatively small watersheds, high solid transport, very limited information on the reality of flood magnitudes due to the small size of catchments contributing to the flood and the destruction of a significant part of the gauging network. This contribution presents the results of a post event field survey conducted in July 2013 in order to document this flood in terms of intensities of hydrologic reactions. The methods used are those described in Gaume et al. [2008, 2009], with a specific focus on the exploitation of videos from weatnesses. The dataset builded includes 31 peak discharge estimates, illustrating the relatively limited intensity of hydrologic reactions if compared to flash floods, but also providing some interesting complements for the consolidation of the methodology used for post-event field investigations: - several opportunities of comparison of the peak discharge estimates obtained from post event field investigations and from the gauging network, showing an overall good coherence - possibility of very significant flow velocities (up to 6 m/s-2) in the specific context observed here (slopes reaching up to 5%). - possibility to get information on flow surface velocities fields from videos provided by weatnesses. - significant influence of space-time rainfall distribution on the features of the flood, stressing the importance of a detailed information on the contribution of the sub-catchments. Gaume E., Borga M., 2008. Post flood field investigations after major flash floods

  9. Decision Support for Flood Event Prediction and Monitoring

    DEFF Research Database (Denmark)

    Mioc, Darka; Anton, François; Liang, Gengsheng


    In this paper the development of Web GIS based decision support system for flood events is presented. To improve flood prediction we developed the decision support system for flood prediction and monitoring that integrates hydrological modelling and CARIS GIS. We present the methodology for data...... integration, floodplain delineation, and online map interfaces. Our Web-based GIS model can dynamically display observed and predicted flood extents for decision makers and the general public. The users can access Web-based GIS that models current flood events and displays satellite imagery and digital...... elevation model integrated with flood plain area. The system can show how the flooding prediction based on the output from hydrological modeling for the next 48 hours along the lower Saint John River Valley....

  10. Extreme flood events in the Bolivian Amazon wetlands

    Directory of Open Access Journals (Sweden)

    A. Ovando


    New hydrological insights for the region: The results showed that large floods are the result of the superimposition of flood waves from major sub-basins of the region. As a previous study suggested, the dynamics of the floods are controlled by an exogenous process, created by the flood wave originating in the Andes piedmont that travels through the Mamoré River; and by an endogenous process, which is the runoff originating in the Llanos. Our study showed that the first process is evident only at the initial phase of the floods, and although important for attenuating the rising flood wave, it is of lesser importance compared to the endogenous process. We conclude that the endogenous process controls the magnitude and duration of major floods.

  11. Investigation to describe the dynamics of contamination with heavy metals and organic pollutants in relation to suspended particulate matter during flood events

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, M.; Baborowski, M.; Tuempling, W. von Jr. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Magdeburg (Germany). Sektion Gewaesserforschung


    Heavy metals and non-polar anthropogenic organic substances like polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and chloropesticides can be adsorbed on suspended particulate matter (SPM). In rivers thereby SPM can be a major carrier of such contaminants. The deposition of SPM in rivers results in an enrichment of these substances in sediments, while their resuspension leads to a pollution of river water again. Until the end of the 80{sup th} the Elbe river was contaminated with high amounts of chloropesticides and SPM by several chemical plants located in the former GDR and CSSR. Sediments in groynefields and flood plains are highly contaminated with these substances. Whether there is any recontamination of river water during flood events is a subject of several projects in our institute.

  12. Surface hopping dynamics using a locally diabatic formalism: Charge transfer in the ethylene dimer cation and excited state dynamics in the 2- pyridone dimer

    Czech Academy of Sciences Publication Activity Database

    Plasser, F.; Granucci, G.; Pittner, Jiří; Barbatti, M.; Persico, M.; Lischka, H.


    Roč. 137, č. 22 (2012), 22A514 ISSN 0021-9606 R&D Projects: GA ČR(CZ) GAP208/12/0559 Institutional support: RVO:61388955 Keywords : surface hopping dynamics * molecular dynamics * electron transfer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.164, year: 2012

  13. Novel dynamic flux chamber for measuring air-surface exchange of Hg(o) from soils. (United States)

    Lin, Che-Jen; Zhu, Wei; Li, Xianchang; Feng, Xinbin; Sommar, Jonas; Shang, Lihai


    Quantifying the air-surface exchange of Hg(o) from soils is critical to understanding the cycling of mercury in different environmental compartments. Dynamic flux chambers (DFCs) have been widely employed for Hg(o) flux measurement over soils. However, DFCs of different sizes, shapes, and sampling flow rates yield distinct measured fluxes for a soil substrate under identical environmental conditions. In this study, we performed an integrated modeling, laboratory and field study to design a DFC capable of producing a steady and uniform air flow over a flat surface. The new DFC was fabricated using polycarbonate sheets. The internal velocity field was experimentally verified against model predictions using both theoretical and computational fluid dynamics techniques, suggesting fully developed flow with velocity profiles in excellent agreement with model results. Laboratory flux measurements demonstrated that the new design improves data reproducibility as compared to a conventional DFC, and reproduces the model-predicted flux trend with increasing sampling flow. A mathematical relationship between the sampling flow rate and surface friction velocity, a variable commonly parametrized in atmospheric models, was developed for field application. For the first time, the internal shear property of a DFC can be precisely controlled using the sampling flow rate, and the flux under atmospheric condition can be inferred from the measured flux and surface shear property. The demonstrated methodology potentially bridges the gap in measured fluxes obtained by the DFC method and the micrometeorological methods.

  14. Dissolved organic matter adsorption to model surfaces: adlayer formation, properties, and dynamics at the nanoscale. (United States)

    Armanious, Antonius; Aeppli, Meret; Sander, Michael


    Adlayers of dissolved organic matter (DOM) form on many surfaces in natural and engineered systems and affect a number of important processes in these systems. Yet, the nanoscalar properties and dynamics of DOM adlayers remain poorly investigated. This work provides a systematic analysis of the properties and dynamics of adlayers formed from a diverse set of eight humic and fulvic acids, used as DOM models, on surfaces of self-assembled monolayers (SAMs) of different alkylthiols covalently bound to gold supports. DOM adsorption to positively charged amine-terminated SAMs resulted in the formation of water-rich adlayers with nanometer thicknesses that were relatively rigid, irreversibly adsorbed, and collapsed upon air drying, as demonstrated by combined quartz crystal microbalance and ellipsometry measurements. DOM adlayer thicknesses varied only slightly with solution pH from 5 to 8 but increased markedly with increasing ionic strength. Contact angle measurements revealed that the DOM adlayers were relatively polar, likely due to the high water contents of the adlayers. Comparing DOM adsorption to SAM-coated sensors that systematically differed in surface charge and polarity characteristics showed that electrostatics dominated DOM-surface interactions. Laccase adsorption to DOM adlayers on amine-terminated SAMs served to demonstrate the applicability of the presented experimental approach to study the interactions of (bio)macromolecules and (nano)particles with DOM.

  15. Dynamics and mass accommodation of HCl molecules on sulfuric acid-water surfaces. (United States)

    Behr, P; Scharfenort, U; Ataya, K; Zellner, R


    A molecular beam technique has been used to study the dynamics and mass accommodation of HCl molecules in collision with sulfuric acid-water surfaces. The experiments were performed by directing a nearly mono-energetic beam of HCl molecules onto a continuously renewed liquid film of 54-76 wt% sulfuric acid at temperatures between 213 K and 243 K. Deuterated sulfuric acid was used to separate sticking but non-reactive collisions from those that involved penetration through the phase boundary followed by dissociation and recombination with D+. The results indicate that the mass accommodation of HCl on sulfuric acid-water surfaces decreases sharply with increasing acidity over the concentration range 54-76 wt%. Using the capillary wave theory of mass accommodation this effect is explained by a change of the surface dynamics. Regarding the temperature dependence it is found that the mass accommodation of HCl increases with increasing temperature and is limited by the bulk phase viscosity and driven by the restoring forces of the surface tension. These findings imply that under atmospheric conditions the uptake of HCl from the gas phase depends crucially on the bulk phase parameters of the sulfuric acid aerosol.

  16. A dimension reduction method for flood compensation operation of multi-reservoir system (United States)

    Jia, B.; Wu, S.; Fan, Z.


    Multiple reservoirs cooperation compensation operations coping with uncontrolled flood play vital role in real-time flood mitigation. This paper come up with a reservoir flood compensation operation index (ResFCOI), which formed by elements of flood control storage, flood inflow volume, flood transmission time and cooperation operations period, then establish a flood cooperation compensation operations model of multi-reservoir system, according to the ResFCOI to determine a computational order of each reservoir, and lastly the differential evolution algorithm is implemented for computing single reservoir flood compensation optimization in turn, so that a dimension reduction method is formed to reduce computational complexity. Shiguan River Basin with two large reservoirs and an extensive uncontrolled flood area, is used as a case study, results show that (a) reservoirs' flood discharges and the uncontrolled flood are superimposed at Jiangjiaji Station, while the formed flood peak flow is as small as possible; (b) cooperation compensation operations slightly increase in usage of flood storage capacity in reservoirs, when comparing to rule-based operations; (c) it takes 50 seconds in average when computing a cooperation compensation operations scheme. The dimension reduction method to guide flood compensation operations of multi-reservoir system, can make each reservoir adjust its flood discharge strategy dynamically according to the uncontrolled flood magnitude and pattern, so as to mitigate the downstream flood disaster.

  17. Suppression of self-organized surface nanopatterning on GaSb/InAs multilayers induced by low energy oxygen ion bombardment by using simultaneously sample rotation and oxygen flooding (United States)

    Beainy, Georges; Cerba, Tiphaine; Bassani, Franck; Martin, Mickaël; Baron, Thierry; Barnes, Jean-Paul


    Time of flight secondary ion mass spectrometry (ToF-SIMS) is a well-adapted analytical method for the chemical characterization of concentration profiles in layered or multilayered materials. However, under ion beam bombardment, initially smooth material surface becomes morphologically unstable. This leads to abnormal secondary ion yields and depth profile distortions. In this contribution, we explore the surface topography and roughening evolution induced by O2+ ion bombardment on GaSb/InAs multilayers. We demonstrate the formation of nanodots and ripples patterning according to the ion beam energy. Since the latter are undesirable for ToF-SIMS analysis, we managed to totally stop their growth by using simultaneously sample rotation and oxygen flooding. This unprecedented coupling between these two latter mechanisms leads to a significant enhancement in depth profiles resolution.

  18. Evolution of flood management policies of Pakistan and causes of flooding in year 2010

    Directory of Open Access Journals (Sweden)

    Muhammad Arslan


    Full Text Available The problem of floods in Pakistan dates back to the year of independence, 1947, when first massive flood inflicted havoc in upper Pakistan. We have divided flood management policy of the region into three time periods; British colonial rule that managed surface water through construction of canals; pre-Indus basin development that achieved a breakthrough in the form of Indus water treaty; and it was during post-Indus basin development phase, in 1973, that federal flood commission and proper flood management policies were devised. However, poor implementation has made these policies ineffective in terms of risk assessment and hazard management. As a case study we discussed the flood of 2010. It was a flash flood in north but inefficient and docile management plans turned it in to a riverine flood as the rainwater receded along the lengths of River Indus, in southern areas. Despite all the obstacles, these huge rainwaters can become a source of much needed energy (electricity if adequate measures are taken. We conclude that the policies regarding flood management within the country must be revisited, and communication gaps between Pakistani and Indian water commissions must be plugged to avoid such future disasters.

  19. Effect of droplet morphology on growth dynamics and heat transfer during condensation on superhydrophobic nanostructured surfaces. (United States)

    Miljkovic, Nenad; Enright, Ryan; Wang, Evelyn N


    Condensation on superhydrophobic nanostructured surfaces offers new opportunities for enhanced energy conversion, efficient water harvesting, and high performance thermal management. These surfaces are designed to be Cassie stable and favor the formation of suspended droplets on top of the nanostructures as compared to partially wetting droplets which locally wet the base of the nanostructures. These suspended droplets promise minimal contact line pinning and promote passive droplet shedding at sizes smaller than the characteristic capillary length. However, the gas films underneath such droplets may significantly hinder the overall heat and mass transfer performance. We investigated droplet growth dynamics on superhydrophobic nanostructured surfaces to elucidate the importance of droplet morphology on heat and mass transfer. By taking advantage of well-controlled functionalized silicon nanopillars, we observed the growth and shedding behavior of suspended and partially wetting droplets on the same surface during condensation. Environmental scanning electron microscopy was used to demonstrate that initial droplet growth rates of partially wetting droplets were 6× larger than that of suspended droplets. We subsequently developed a droplet growth model to explain the experimental results and showed that partially wetting droplets had 4-6× higher heat transfer rates than that of suspended droplets. On the basis of these findings, the overall performance enhancement created by surface nanostructuring was examined in comparison to a flat hydrophobic surface. We showed these nanostructured surfaces had 56% heat flux enhancement for partially wetting droplet morphologies and 71% heat flux degradation for suspended morphologies in comparison to flat hydrophobic surfaces. This study provides insights into the previously unidentified role of droplet wetting morphology on growth rate, as well as the need to design Cassie stable nanostructured surfaces with tailored droplet

  20. The surface chemistry determines the spatio-temporal interaction dynamics of quantum dots in atherosclerotic lesions. (United States)

    Uhl, Bernd; Hirn, Stephanie; Mildner, Karina; Coletti, Raffaele; Massberg, Steffen; Reichel, Christoph A; Rehberg, Markus; Zeuschner, Dagmar; Krombach, Fritz


    To optimize the design of nanoparticles for diagnosis or therapy of vascular diseases, it is mandatory to characterize the determinants of nano-bio interactions in vascular lesions. Using ex vivo and in vivo microscopy, we analyzed the interactive behavior of quantum dots with different surface functionalizations in atherosclerotic lesions of ApoE-deficient mice. We demonstrate that quantum dots with different surface functionalizations exhibit specific interactive behaviors with distinct molecular and cellular components of the injured vessel wall. Moreover, we show a role for fibrinogen in the regulation of the spatio-temporal interaction dynamics in atherosclerotic lesions. Our findings emphasize the relevance of surface chemistry-driven nano-bio interactions on the differential in vivo behavior of nanoparticles in diseased tissue.

  1. Dynamics of Plasma-Surface Interactions using In-situ Ion Beam Analysis

    International Nuclear Information System (INIS)

    Whyte, D.G.


    The overall goal of this proposal was to develop an innovative experimental facility that would allow for the measurement of real-time response of a material surface to plasma bombardment by employing in-situ high-energy ion beam analysis. This facility was successfully developed and deployed at U. Wisconsin-Madison and was named DIONISOS (Dynamics of IONic Implantation and Sputtering on Surfaces). There were several major highlights to the DIONISOS research which we will briefly highlight below. The full technical details of the DIONISOS development, deployment and research results are contained in the Appendices which contain several peer-reviewed publications and a PhD thesis devoted to DIONISOS. The DIONISOS results on deuterium retention in molybdenum were chosen as an invited talk at the 2008 International Conference on Plasma-Surface Interactions in Toledo, Spain.

  2. Initial stages of Pt(111) electrooxidation: dynamic and structural studies by surface X-ray diffraction

    International Nuclear Information System (INIS)

    Drnec, Jakub; Ruge, Martin; Reikowski, Finn; Rahn, Björn; Carlà, Francesco; Felici, Roberto; Stettner, Jochim; Magnussen, Olaf M.; Harrington, David A.


    In-situ surface X-ray diffraction is used to characterize the surface oxides on a Pt(111) surface in 0.1 M HClO 4 . Detailed analysis at two potentials confirms that the surface restructuring in the initial oxidation stages is consistent with a place exchange process between Pt and O atoms, and the exchanged Pt atoms are located above their original positions in the Pt(111) lattice. The (1,1,1.5) reflection is used to dynamically study the surface during cyclic voltammetry. The restructuring associated with the place exchange initiates with the CV peak at 1.05 V, even though multiple cycles to 1.17 V lead to no changes in the CV. The restructuring is reversible below a critical coverage of place exchanged Pt atoms, which we estimate to be between 0.07 and 0.15 ML. Extensive cycling to potentials higher or equal to 1.17 V leads to progressive disordering of the surface.

  3. Using decadal climate prediction to characterize and manage changing drought and flood risks in Colorado (United States)

    Lazrus, H.; Done, J.; Morss, R. E.


    A new branch of climate science, known as decadal prediction, seeks to predict the time-varying trajectory of climate over the next 3-30 years and not just the longer-term trends. Decadal predictions bring climate information into the time horizon of decision makers, particularly those tasked with managing water resources and floods whose master planning is often on the timescale of decades. Information from decadal predictions may help alleviate some aspects of vulnerability by helping to inform decisions that reduce drought and flood exposure and increase adaptive capacities including preparedness, response, and recovery. This presentation will highlight an interdisciplinary project - involving atmospheric and social scientists - on the development of decadal climate information and its use in decision making. The presentation will explore the skill and utility of decadal drought and flood prediction along Colorado's Front Range, an area experiencing rapid population growth and uncertain climate variability and climate change impacts. Innovative statistical and dynamical atmospheric modeling techniques explore the extent to which Colorado precipitation can be predicted on decadal scales using remote Pacific Ocean surface temperature patterns. Concurrently, stakeholder interviews with flood managers in Colorado are being used to explore the potential utility of decadal climate information. Combining the modeling results with results from the stakeholder interviews shows that while there is still significant uncertainty surrounding precipitation on decadal time scales, relevant and well communicated decadal information has potential to be useful for drought and flood management.

  4. Modeling multi-source flooding disaster and developing simulation framework in Delta (United States)

    Liu, Y.; Cui, X.; Zhang, W.


    Most Delta regions of the world are densely populated and with advanced economies. However, due to impact of the multi-source flooding (upstream flood, rainstorm waterlogging, storm surge flood), the Delta regions is very vulnerable. The academic circles attach great importance to the multi-source flooding disaster in these areas. The Pearl River Delta urban agglomeration in south China is selected as the research area. Based on analysis of natural and environmental characteristics data of the Delta urban agglomeration(remote sensing data, land use data, topographic map, etc.), hydrological monitoring data, research of the uneven distribution and process of regional rainfall, the relationship between the underlying surface and the parameters of runoff, effect of flood storage pattern, we use an automatic or semi-automatic method for dividing spatial units to reflect the runoff characteristics in urban agglomeration, and develop an Multi-model Ensemble System in changing environment, including urban hydrologic model, parallel computational 1D&2D hydrodynamic model, storm surge forecast model and other professional models, the system will have the abilities like real-time setting a variety of boundary conditions, fast and real-time calculation, dynamic presentation of results, powerful statistical analysis function. The model could be optimized and improved by a variety of verification methods. This work was supported by the National Natural Science Foundation of China (41471427); Special Basic Research Key Fund for Central Public Scientific Research Institutes.

  5. Urban pluvial flood prediction

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Nielsen, Jesper Ellerbæk; Jensen, David Getreuer


    Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events – especially in the future climate – it is valuable to be able to simulate these events numerically both...... historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper radar data observations with different spatial and temporal resolution, radar nowcasts of 0–2 h lead time, and numerical weather models with lead times up to 24 h are used as inputs...... to an integrated flood and drainage systems model in order to investigate the relative difference between different inputs in predicting future floods. The system is tested on a small town Lystrup in Denmark, which has been flooded in 2012 and 2014. Results show it is possible to generate detailed flood maps...

  6. Flood Hazard Mapping Assessment for Lebanon (United States)

    Abdallah, Chadi; Darwich, Talal; Hamze, Mouin; Zaarour, Nathalie


    Of all natural disasters, floods affect the greatest number of people worldwide and have the greatest potential to cause damage. In fact, floods are responsible for over one third of people affected by natural disasters; almost 190 million people in more than 90 countries are exposed to catastrophic floods every year. Nowadays, with the emerging global warming phenomenon, this number is expected to increase, therefore, flood prediction and prevention has become a necessity in many places around the globe to decrease damages caused by flooding. Available evidence hints at an increasing frequency of flooding disasters being witnessed in the last 25 years in Lebanon. The consequences of such events are tragic including annual financial losses of around 15 million dollars. In this work, a hydrologic-hydraulic modeling framework for flood hazard mapping over Lebanon covering 19 watershed was introduced. Several empirical, statistical and stochastic methods to calculate the flood magnitude and its related return periods, where rainfall and river gauge data are neither continuous nor available on a long term basis with an absence of proper river sections that under estimate flows during flood events. TRMM weather satellite information, automated drainage networks, curve numbers and other geometrical characteristics for each basin was prepared using WMS-software and then exported into HMS files to implement the hydrologic modeling (rainfall-runoff) for single designed storm of uniformly distributed depth along each basin. The obtained flow hydrographs were implemented in the hydraulic model (HEC-RAS) where relative water surface profiles are calculated and flood plains are delineated. The model was calibrated using the last flood event of January 2013, field investigation, and high resolution satellite images. Flow results proved to have an accuracy ranging between 83-87% when compared to the computed statistical and stochastic methods. Results included the generation of

  7. D2 dissociative adsorption on and associative desorption from Si(100): Dynamic consequences of an ab initio potential energy surface

    DEFF Research Database (Denmark)

    Luntz, A. C.; Kratzer, Peter


    favors the symmetric one. Under the conditions of many experiments, either could dominate. The calculations show quite weak dynamic coupling to the Si lattice for both paths, i.e., weak surface temperature dependences to dissociation and small energy loss to the lattice upon desorption......Dynamical calculations are reported for D-2 dissociative chemisorption on and associative desorption from a Si(100) surface. These calculations use the dynamically relevant effective potential which is based on an ab initio potential energy surface for the ''pre-paired'' species. Three coordinates...

  8. Combined effects of surface conditions, boundary layer dynamics and chemistry on diurnal SOA evolution

    Directory of Open Access Journals (Sweden)

    R. H. H. Janssen


    Full Text Available We study the combined effects of land surface conditions, atmospheric boundary layer dynamics and chemistry on the diurnal evolution of biogenic secondary organic aerosol in the atmospheric boundary layer, using a model that contains the essentials of all these components. First, we evaluate the model for a case study in Hyytiälä, Finland, and find that it is able to satisfactorily reproduce the observed dynamics and gas-phase chemistry. We show that the exchange of organic aerosol between the free troposphere and the boundary layer (entrainment must be taken into account in order to explain the observed diurnal cycle in organic aerosol (OA concentration. An examination of the budgets of organic aerosol and terpene concentrations show that the former is dominated by entrainment, while the latter is mainly driven by emission and chemical transformation. We systematically investigate the role of the land surface, which governs both the surface energy balance partitioning and terpene emissions, and the large-scale atmospheric process of vertical subsidence. Entrainment is especially important for the dilution of organic aerosol concentrations under conditions of dry soils and low terpene emissions. Subsidence suppresses boundary layer growth while enhancing entrainment. Therefore, it influences the relationship between organic aerosol and terpene concentrations. Our findings indicate that the diurnal evolution of secondary organic aerosols (SOA in the boundary layer is the result of coupled effects of the land surface, dynamics of the atmospheric boundary layer, chemistry, and free troposphere conditions. This has potentially some consequences for the design of both field campaigns and large-scale modeling studies.

  9. Assessment of nature-based flood defences' implementation potential : development and application of a game theory based method

    NARCIS (Netherlands)

    Janssen, S.K.H.; Hermans, L.M.


    Nature-based flood defence (NBFD) by means of vegetated foreshores is an innovative flood protection strategy. In contrasts with traditional hard structures it combines nature and flood protection functions and employs natural dynamics. Introducing such an innovation into actual flood protection

  10. NASA-VOF3D, 3-D Transient, Free Surface, Incompressible Fluid Dynamic

    International Nuclear Information System (INIS)

    Torrey, M.D.


    1 - Description of program or function: NASA-VOF3D is a three- dimensional, transient, free surface, incompressible fluid dynamics program. It is specifically designed to calculate confined flows in a low gravity environment in which surface physics must be accurately treated. It allows multiple free surfaces with surface tension and wall adhesion and includes a partial cell treatment that allows curved boundaries and internal obstacles. Variable mesh spacing is permitted in all three coordinate directions. Boundary conditions available are rigid free-slip wall, rigid no-slip, wall, continuative, periodic, and specified pressure outflow boundary. 2 - Method of solution: NASA-VOF3D simulates incompressible flows with free surfaces using the volume-of-fluid (VOF) algorithm. This technique is based on the use of donor-acceptor differencing to track the free surface across an Eulerian grid. The free surfaces are treated by introducing a function defined to be unity at any point occupied by the fluid and zero elsewhere. The complete Navier- Stokes equations for an incompressible fluid are solved by finite differences with surface tension effects included. Wall adhesion may be included or neglected as a user option. The pressures (and velocities) are advanced in time throughout the computing mesh by either a conjugate residual method or the successive over-relaxation (SOR) method. The conjugate residual method is vectorized for the Cray and uses a scaled coefficient matrix. 3 - Restrictions on the complexity of the problem: NASA-VOF3D is restricted to cylindrical coordinate representation of the geometry. A three-dimensional wall-adhesion procedure is available only for straight-walled containers

  11. Influence of solid waste and topography on urban floods: The case of Mexico City. (United States)

    Zambrano, Luis; Pacheco-Muñoz, Rodrigo; Fernández, Tania


    Floods in cities are increasingly common as a consequence of multifactor watershed dynamics, including geomorphology, land-use changes and land subsidence. However, urban managers have focused on infrastructure to address floods by reducing blocked sewage infrastructure, without significant success. Using Mexico City as a case study, we generated a spatial flood risk model with geomorphology and anthropogenic variables. The results helped contrast the implications of different public policies in land use and waste disposal, and correlating them with flood hazards. Waste disposal was only related to small floods. 58% of the city has a high risk of experiencing small floods, and 24% of the city has a risk for large floods. Half of the population with the lowest income is located in the high-risk areas for large floods. These models are easy to build, generate fast results and are able to help to flood policies, by understanding flood interactions in urban areas within the watershed.

  12. Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

    CERN Document Server

    Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai


    The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

  13. Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields (United States)

    Appels, Willemijn M.; Bogaart, Patrick W.; van der Zee, Sjoerd E. A. T. M.


    In winter, saturation excess (SE) ponding is observed regularly in temperate lowland regions. Surface runoff dynamics are controlled by small topographical features that are unaccounted for in hydrological models. To better understand storage and routing effects of small-scale topography and their interaction with shallow groundwater under SE conditions, we developed a model of reduced complexity to investigate SE runoff generation, emphasizing feedbacks between shallow groundwater dynamics and mesotopography. The dynamic specific yield affected unsaturated zone water storage, causing rapid switches between negative and positive head and a flatter groundwater mound than predicted by analytical agrohydrological models. Accordingly, saturated areas were larger and local groundwater fluxes smaller than predicted, leading to surface runoff generation. Mesotopographic features routed water over larger distances, providing a feedback mechanism that amplified changes to the shape of the groundwater mound. This in turn enhanced runoff generation, but whether it also resulted in runoff events depended on the geometry and location of the depressions. Whereas conditions favorable to runoff generation may abound during winter, these feedbacks profoundly reduce the predictability of SE runoff: statistically identical rainfall series may result in completely different runoff generation. The model results indicate that waterlogged areas in any given rainfall event are larger than those predicted by current analytical groundwater models used for drainage design. This change in the groundwater mound extent has implications for crop growth and damage assessments.

  14. Quantitative Analysis of Hepatitis C NS5A Viral Protein Dynamics on the ER Surface

    KAUST Repository

    Knodel, Markus


    Exploring biophysical properties of virus-encoded components and their requirement for virus replication is an exciting new area of interdisciplinary virological research. To date, spatial resolution has only rarely been analyzed in computational/biophysical descriptions of virus replication dynamics. However, it is widely acknowledged that intracellular spatial dependence is a crucial component of virus life cycles. The hepatitis C virus-encoded NS5A protein is an endoplasmatic reticulum (ER)-anchored viral protein and an essential component of the virus replication machinery. Therefore, we simulate NS5A dynamics on realistic reconstructed, curved ER surfaces by means of surface partial differential equations (sPDE) upon unstructured grids. We match the in silico NS5A diffusion constant such that the NS5A sPDE simulation data reproduce experimental NS5A fluorescence recovery after photobleaching (FRAP) time series data. This parameter estimation yields the NS5A diffusion constant. Such parameters are needed for spatial models of HCV dynamics, which we are developing in parallel but remain qualitative at this stage. Thus, our present study likely provides the first quantitative biophysical description of the movement of a viral component. Our spatio-temporal resolved ansatz paves new ways for understanding intricate spatial-defined processes central to specfic aspects of virus life cycles.

  15. Quantitative Analysis of Hepatitis C NS5A Viral Protein Dynamics on the ER Surface

    Directory of Open Access Journals (Sweden)

    Markus M. Knodel


    Full Text Available Exploring biophysical properties of virus-encoded components and their requirement for virus replication is an exciting new area of interdisciplinary virological research. To date, spatial resolution has only rarely been analyzed in computational/biophysical descriptions of virus replication dynamics. However, it is widely acknowledged that intracellular spatial dependence is a crucial component of virus life cycles. The hepatitis C virus-encoded NS5A protein is an endoplasmatic reticulum (ER-anchored viral protein and an essential component of the virus replication machinery. Therefore, we simulate NS5A dynamics on realistic reconstructed, curved ER surfaces by means of surface partial differential equations (sPDE upon unstructured grids. We match the in silico NS5A diffusion constant such that the NS5A sPDE simulation data reproduce experimental NS5A fluorescence recovery after photobleaching (FRAP time series data. This parameter estimation yields the NS5A diffusion constant. Such parameters are needed for spatial models of HCV dynamics, which we are developing in parallel but remain qualitative at this stage. Thus, our present study likely provides the first quantitative biophysical description of the movement of a viral component. Our spatio-temporal resolved ansatz paves new ways for understanding intricate spatial-defined processes central to specfic aspects of virus life cycles.

  16. Quantitative Analysis of Hepatitis C NS5A Viral Protein Dynamics on the ER Surface. (United States)

    Knodel, Markus M; Nägel, Arne; Reiter, Sebastian; Vogel, Andreas; Targett-Adams, Paul; McLauchlan, John; Herrmann, Eva; Wittum, Gabriel


    Exploring biophysical properties of virus-encoded components and their requirement for virus replication is an exciting new area of interdisciplinary virological research. To date, spatial resolution has only rarely been analyzed in computational/biophysical descriptions of virus replication dynamics. However, it is widely acknowledged that intracellular spatial dependence is a crucial component of virus life cycles. The hepatitis C virus-encoded NS5A protein is an endoplasmatic reticulum (ER)-anchored viral protein and an essential component of the virus replication machinery. Therefore, we simulate NS5A dynamics on realistic reconstructed, curved ER surfaces by means of surface partial differential equations (sPDE) upon unstructured grids. We match the in silico NS5A diffusion constant such that the NS5A sPDE simulation data reproduce experimental NS5A fluorescence recovery after photobleaching (FRAP) time series data. This parameter estimation yields the NS5A diffusion constant. Such parameters are needed for spatial models of HCV dynamics, which we are developing in parallel but remain qualitative at this stage. Thus, our present study likely provides the first quantitative biophysical description of the movement of a viral component. Our spatio-temporal resolved ansatz paves new ways for understanding intricate spatial-defined processes central to specfic aspects of virus life cycles.

  17. Street floods in Metro Manila and possible solutions. (United States)

    Lagmay, Alfredo Mahar; Mendoza, Jerico; Cipriano, Fatima; Delmendo, Patricia Anne; Lacsamana, Micah Nieves; Moises, Marc Anthony; Pellejera, Nicanor; Punay, Kenneth Niño; Sabio, Glenn; Santos, Laurize; Serrano, Jonathan; Taniza, Herbert James; Tingin, Neil Eneri


    Urban floods from thunderstorms cause severe problems in Metro Manila due to road traffic. Using Light Detection and Ranging (LiDAR)-derived topography, flood simulations and anecdotal reports, the root of surface flood problems in Metro Manila is identified. Majority of flood-prone areas are along the intersection of creeks and streets located in topographic lows. When creeks overflow or when rapidly accumulated street flood does not drain fast enough to the nearest stream channel, the intersecting road also gets flooded. Possible solutions include the elevation of roads or construction of well-designed drainage structures leading to the creeks. Proposed solutions to the flood problem of Metro Manila may avoid paralyzing traffic problems due to short-lived rain events, which according to Japan International Cooperation Agency (JICA) cost the Philippine economy 2.4billionpesos/day. Copyright © 2017. Published by Elsevier B.V.

  18. Ultimate Cavity Dynamics of Hydrophobic Spheres Impacting on Free Water Surfaces

    KAUST Repository

    Mansoor, Mohammad M.


    Cavity formation resulting from the water-entry of solid objects has been the subject of extensive research owing to its practical relevance in naval, military, industrial, sports and biological applications. The cavity formed by an impacting hydrophobic sphere normally seals at two places, one below (deep seal) and the other above the water surface (surface seal). For Froude numbers , the air flow into the resulting cavity is strong enough to suck the splash crown above the surface and disrupt the cavity dynamics before it deep seals. In this research work we eliminate surface seals by means of a novel practice of using cone splash-guards and examine the undisturbed transient cavity dynamics by impact of hydrophobic spheres for Froude numbers ranging . This enabled the measurement of extremely accurate pinch-off heights, pinch-off times, radial cavity collapse rates, and jet speeds in an extended range of Froude numbers compared to the previous work of Duclaux et al. (2007). Results in the extended regime were in remarkable agreement with the theoretical prediction of scaled pinch-off depth, and experimentally derived pinch-off time for . Furthermore, we investigated the influence of confinement on cavity formation by varying the cross-sectional area of the tank of liquid. In conjunction with surface seal elimination we observed the formation of multiple pinch-off points where a maximum of four deep seals were obtained in a sequential order for the Froude number range investigated. The presence of an elongated cavity beneath the first pinch-off point 5 resulted in evident "kinks" primarily related to the greatly diminished air pressure at the necking region caused by supersonic air flows (Gekle et al. 2010). Such flows passing through second pinch-offs were also found to choke the cavities beneath the first pinch- off depths causing radial expansion and hence disappearance of downward jets.

  19. Surface current dynamics under sea breeze conditions observed by simultaneous HF radar, ADCP and drifter measurements (United States)

    Sentchev, Alexei; Forget, Philippe; Fraunié, Philippe


    Ocean surface boundary layer dynamics off the southern coast of France in the NW Mediterranean is investigated by using velocity observations by high-frequency (HF) radars, surface drifting buoys and a downward-looking drifting acoustic Doppler current profiler (ADCP). The analysis confirms that velocities measured by HF radars correspond to those observed by an ADCP at the effective depth z f = k -1, where k is wavenumber of the radio wave emitted by the radar. The radials provided by the radars were in a very good agreement with in situ measurements, with the relative errors of 1 and 9 % and root mean square (RMS) differences of 0.02 and 0.04 m/s for monostatic and bistatic radar, respectively. The total radar-based velocities appeared to be slightly underestimated in magnitude and somewhat biased in direction. At the end of the survey period, the difference in the surface current direction, based on HF radar and ADCP data, attained 10°. It was demonstrated that the surface boundary layer dynamics cannot be reconstructed successfully without taking into the account velocity variation with depth. A significant misalignment of ˜30° caused by the sea breeze was documented between the HF radar (HFR-derived) surface current and the background current. It was also found that the ocean response to a moderate wind forcing was confined to the 4-m-thick upper