Understanding large plastic deformation of SiC nanowires at room temperature

Tensile behaviors of SiC [111] nanowires with various possible microstructures have been investigated by molecular-dynamics simulations. The results show that the large plastic deformation in these nanowires is induced by the anti-parallel sliding of 3C grains along an ultra- thin intergranular amorphous film parallel to the (11¯1) plane and inclined at an angle of 19.47◦ with respect to the nanowire axis. The resulting large plastic deformation of SiC nanowires at room temperature is attributed to the stretching, breaking and re-forming of Si–C bonds in the intergranular amorphous film, which is also evident from the sawtooth jumps in the stress-strain response

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Flood risk analysis for metropolitan areas – a case study for Shanghai

In Shanghai, the main threat to the city’s safety is a typhoon induced storm surge in combination with a high astronomic tide in the Huangpu River. Historical flood events have shown that the weakness of the floodwall, with potential overtopping and breaching along the Huangpu River and its branches, has caused great economic damage and loss of life. In order to better understand flood risk in the city, flood risk analysis at the local city level is strongly required. With climate change, land subsidence and the rapid socio-economic development, flood risk is inevitably increasing if no measures are taken. Not only the current flood risk but also the flood risk in the future needs to be understood. Moreover, it is necessary to recommend effective risk-reduction measures to mitigate future flood risk. Therefore, the objective of this thesis is to quantify the current and future flood risk and to make recommendations on risk-reduction measures in a case study of Shanghai. It also aims to show and develop general methods for flood risk analysis in rapidly growing metropolitan areas. As a first step the Shanghai water system has been analysed. In terms of flood threats to the river, the water level is dominated by the storm tide at the mouth of the Huangpu River. The heavy precipitation mainly induces waterlogging due to an insufficient drainage capacity in the city, while not significantly increasing river runoff in the Huangpu River. Moreover, a control gate (between Tai Lake and the Huangpu River) is regulated to reduce drainage water from Tai Lake when a storm surge occurs. Therefore, a combination of a storm surge and a high astronomic tide will be the main flood threat. It is noticed that the current protection level of the floodwall is only based on the exceedance of the crest height of the floodwall by the water level and does not directly take other failure mechanisms into account. Failure mechanisms such as breaching of floodwalls and failure of the closure of floodgates would induce potential floods in Shanghai. In order to identify flood hazard in extreme events, a frequency analysis of annual maximum water levels was performed; the new frequency curves represent the relationships of water levels at three typical gauge stations along the Huangpu River with different return periods. The Generalized Extreme Value (GEV) distribution was suggested as a most suitable probability distribution for the datasets of annual maximum water levels at Wusongkou and Huangpu Park instead of a Pearson Type III distribution. With the aid of the 1D hydraulic model, water levels in each cross section of the Huangpu River were derived. The potential overtopping points were systematically identified by a comparison of the crest height of the floodwall and the water levels under different return periods (50yr, 100yr, 200yr, 500yr, 1,000yr and 10,000yr). It turned out that the current estimation of overtopping probability is 1/200 p.y. in the Huangpu River. In addition, potential breaching points and failure of floodgates were also hypothesized on both sides of the floodwall. Subsequently, inundation maps were produced by 1D2D hydrodynamic modelling (SOBEK) under different flood scenarios along the Huang-pu River. The results can be visualized on a map with information on maximum inundation depth and the extent of inundation. Firstly, a scenario without protection demonstrates the im-portant role of the floodwall and the infrastructures (e.g. floodgate) along the Huangpu River to protect Shanghai against river flooding. Secondly, various overtopping events at certain points along the floodwall were simulated. It was found that the inundation would merely oc-cur adjacent to the riverine area due to a limited flood volume under overtopping scenarios, since it only occurs during a limited period (e.g. 1 hour). Thirdly, as breach scenarios were developed to explore the worst–case flooding in Shanghai; it turned out that breaching would cause the most serious flooding along the Huangpu River, as parts of the city centre would get inundated with a maximum inundation depth of more than 3m. Lastly, the simulations of a failure of the floodgates were conducted at three selected locations. It showed that the inundation depth was a few decimeters in each scenario (40cm-80cm on average), which would pose threats to the buildings and the infrastructures adjacent to the floodgates. Ex-ante flood damage assessment plays an increasingly important role in flood risk management. Potential flood damage in cities like Shanghai can be massive due to the high rate of socio-economic development and the rapid urbanization in the near-future. Different flood scenarios result in different degrees of damage. New damage functions for various building categories were suggested in Shanghai; with the application of these functions, it was calculated that the potential damage under various breaching scenarios ranged from 88 to 440 million $USD in part of downtown area, which accounts for 1.5$USD). In the estimation of indirect flood damage on the service interruption of the subway system, two typical subway stations were selected to estimate the revenue loss due to flooding. It was calculated that the service interruption at one subway station for one week would cause approximately 1 million $USD of revenue losses in Shanghai, which implied that it would cause a huge practical inconvenience for the inhabitants during such unexpected events. Furthermore, in the discussion of the effects of components on the flood damage, the damage function has the greatest influence on the final results, and this deserves priority for future study to reduce the uncertainty of flood damage estimation. Flood risk is calculated by the occurrence/exceedance probability and its associated potential damage. In this thesis, the total risk, which accounts for expected value and standard deviation of damages on the basis of risk aversion, represents the results of flood risk analysis. The results are represented below. The probability of flooding exists in events of overtopping, breaching and failure of floodgates. 26 scenarios were simulated along the Huangpu River based on various boundary conditions of the water level as a function of return periods of 200yr., 500yr., 1,000yr., and 10,000yr. at Wusongkou, in which 8 breaching points and 3 floodgates points were selected on the west and east side of the floodwall. The total (flood) risk is calculated between 40 million$USD/yr. and 112 million $USD/yr. along the Huangpu River of Shanghai, in which the point at ~45km away from the mouth is most likely to be over-topped, and the breaching point, ~26km away from the mouth at the west side of the Huangpu River in the city centre, leads to largest potential flood damage among all the scenarios. Furthermore, it is noticed that the economic damage due to breaching is a factor of 10 higher than the damage caused by overtopping scenarios. However, in terms of the contribution to the flood risk, the failure of floodgates accounts for ~41% of the overall flood risk due to its high-er probability of failure than breaching and parts of overtopping scenarios. Economic development appears to have the greatest effect on future flood risk, which could triple flood risk in 2030 and increase six fold in 2050 if no further measures are taken. Land subsidence is the second driver of future risk, and the ‘absolute’ sea level rise has the least effect on the future flood risk. The combination of all these affected factors would raise flood risk 4 times and 16 times in total in 2030 and 2050 respectively if no further measures are taken. In order to evaluate and recommend an effective (combination of) risk-reduction measure(s) to mitigate flood risk, a comparative study between Shanghai and Rotterdam was conducted to propose potential risk-reduction measures under the threats of future climate change and economic growth. It also showed that the metropolitan cities, under similar challenging flood threats, can learn from each other. Regarding the risk-reduction measures, the potential (structural and non-structural) measures have been proposed and evaluated by the methods of cost-benefit analysis and economic optimization. Preliminary results of the cost-benefit analysis show that the construction of a storm surge barrier has a somewhat larger benefit/cost ratio than the upgrading of the floodwall. Besides, since the Shanghai Municipal Government desires to upgrade the city to the level of an international metropolis with a high quality of life, the upgrading of the floodwall will largely hinder the view of rivers and lower the attractiveness of the city. Therefore, it is expected that the construction of the storm surge barrier is a better solution to protect Shanghai in the long run. Economic optimization led to a preliminary result of a safety level of 1/4,500p.y. for the Huangpu River in Shanghai due to fast economic growth in the future (2050). It is additionally noted that, given the current relatively low protec-tion level the flood barrier boards (to protect buildings for small floods) have advantages and it is also recommended to apply this measure at the entrance of all types of buildings in case of unexpected flood events. These results show how flood risk analysis can provide rational in-formation to support decisions for risk reduction for rapidly growing mega-cities, like Shanghai.Hydraulic EngineeringCivil Engineering and Geoscience

Storm surge modelling by Delft3D FM – a case study in Shanghai area

The coupled Delft3D Flexible Mesh (D3D FM) - SWAN model with an unstructured grid has been developed recently to simulate storm surge and waves; and another open source model, Telemac-Tomawac, has been widely used for storm surge and wave propagation simulation in coastal areas for more than 20 years. However, the choice of a hydrodynamic model for a specific area in terms of cost, efficiency and accuracy is often a dilemma at the beginning of a modeling project. The objective of this research is to examine the effects of two software packages in terms of accuracy and performance with a case study in the Shanghai area of China. Model performance has been assessed based on model configuration, model calibration, grid generation and computational efficiency. Comparing measured water levels with model results, both approaches were able to accurately predict hydrodynamic conditions in a complex estuarine environment. Both models showed that it can efficiently simulate hydrodynamics in the coastal area under various scenarios for further climate adaptation research. Additionally, both models were used to simulate inundation propagation due to hypothetical failures of flood defenses in the coastal area. A comparison of inundation extent and maximum inundation depth showed that they were equally well-suited for overtopping and inundation simulation. Accepted Author ManuscriptHydraulic Structures and Flood RiskCoastal Engineerin

National estimation of societal risk of flooding in China

cd-romHydraulic Structures and Flood Ris

Inundation modelling for fluvial and pluvial flooding during typhoons: a case study in Shanghai city

The co-occurrence of storm surge, high tides and heavy precipitation increases flood probability and potential consequences compared to each hazard separately in Delta cities. The Huangpu River (HP) is a tributary of the Yangtze River in China, which drains Tai Lake to the west of Shanghai city, and meanders through downtown Shanghai. During typhoon events, storm surge reverses the river flow and pushes the water level up as far as 100km upstream. If storm surge (1-2 m above msl) co-occurs with high tide (2-3 m above msl), it poses great threats to the HP floodwall (crest level from ~3-5.5m above msl). At the same time, typhoons cause heavy precipitation (up to 70-80mm/hour) in the city, which increases urban drainage discharge in the pipeline system. In order to prevent elevated water levels in the river, stormwater drainage is ceased to effectively work in this situation. Pluvial and fluvial flooding occur simultaneously. The objective of this paper is to develop a hydrodynamic model to simulate simultaneous pluvial and fluvial flooding and to produce inundation maps due to failure of floodwalls and the urban drainage system. We apply the Delft3D FM numerical model to compound flood events in Shanghai. Results raise risk awareness for decision-makers during compound flood events and demonstrate the importance of compound flood modelling at a city scale.Accepted Author ManuscriptHydraulic Structures and Flood Ris

Flood damage estimation for downtown Shanghai sensitivity analysis

Flood damage estimation is essential to flood risk analysis. Flood hazards, values of elements at risk and vulnerability of elements determine flood damage. However, these determinants entail uncertainties. In this study, water depth, values of elements at risk and damage function are selected as three key parameters. The local sensitivity method, which changes the value of one parameter at one time, is adopted to determine the sensitivity degrees of parameters for flood damage estimation in downtown Shanghai, China. The variance of 25% for water depth as a function of different return periods of 50,100, 200,500,1000 and 10,000 years, values of elements at risk and damage functions (piecewise function and square-root function) are uniformly taken into account in the sensitivity analysis. Sensitivity value (SV) for three parameters, which stands for the influential degree to the results of flood damage, are obtained by the largest damage being divided by the smallest damage if only changing one parameter at one time separately. The results show damage function has largest influential degree among the three parameters with SV of 2.69; while parameters of values of elements at risk (SV: 2.22) and water depth (SV: 1.81) are also significant. This suggests future research to focus first on reducing uncertainties in the flood damage functions.Hydraulic EngineeringCivil Engineering and Geoscience

Frequency Analysis of Storm-Surge-Induced Flooding for the Huangpu River in Shanghai, China

Shanghai, as a coastal city, is vulnerable to various types of flooding. The floodwalls along the Huangpu River provide protection against typhoon-induced flooding. However, there is limited insight into the actual safety level of the flood defences in Shanghai, and recent failures have highlighted their vulnerability. Therefore, the aims of this paper are to derive a series of new flood frequency curves for the Huangpu River, and to evaluate the level of protection of the floodwall system. This paper analysed over 100 years (1912–2013) of annual maximum water levels for three stations at near-sea, mid-stream and inland locations along the Huangpu River. Best-fit curves were determined for a number of selected probability distributions using statistical performance indicators. As a result, new flood frequency curves of the water levels for different storm surge return periods were produced. The results showed that generalised extreme value (GEV) was identified as the most suitable probability distribution for the datasets. Analysis showed that the current design water levels correspond to exceedance probabilities of 1/500 per year at the near-sea and mid-stream stations, and no more than 1/50 per year at the inland station of the Huangpu River, whereas the intended safety standard is 1/1000 per year. A comparison of the findings with a dataset of the crest heights of the floodwalls showed that the current protection level of the floodwalls along the Huangpu River is expected to be around 1/50 per year in terms of overtopping for the lowest sections. The results of this study can be utilized to provide future recommendations for flood risk management in ShanghaiHydraulic Structures and Flood RiskSafety and Security Scienc

Flash flood early warning coupled with hydrological simulation and the rising rate of the flood stage in a mountainous small watershed in Sichuan province, China

Flash floods in mountainous areas have become more severe and frequent as a result of climate change and are a threat to public safety and social development. This study explores the application of distributed hydrological models in flash floods risk management in a small watershed in Sichuan Province, China, and aims to increase early warning lead time in mountainous areas. The Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) model was used to simulate the flash flood process and analyze the variation in flood hydrographs. First, the HEC-HMS model was established based on geospatial data and the river network shape, and eight heavy rainfall events from 2010 to 2015 were used for model calibration and validation, showing that the HEC-HMS model was effective for the simulation of mountain floods in the study area. Second, with the assumption that rainfall and flood events have the same frequency, the flood hydrographs with different frequencies (p = 1%, 2%, 5%, and 10%) were calculated by the HEC-HMS model. The rising limbs of the flood hydrographs were significantly different and can be divided into three parts (0-5 h, 6-10 h, and 11-15 h). The rising rate of the flood stage for each part of the flood hydrograph increases in multiples. According to the analysis of the flood hydrographs, two critical early warning indicators with an invention patent were determined in the study: the flood stage for immediate evacuation and the rising rate. The application of the indicators in the study shows that it is feasible to advance the time of issuing an early warning signal, and it is expected that the indicators can offer a reference for flash flood early warning in the study area and other small watersheds in mountainous areas.Hydraulic Structures and Flood Ris

Design & assessing the flood risk management paradigm shift: an interdisciplinary study of Vlissingen, the Netherlands

Mean sea level rise (SLR) could increase up to 2m by 2100, which would see damage caused by coastal flooding in Europe increase from €1.25bn per annum currently to €961bn in just over 80 years. Urban areas situated along the North Sea coastline are particularly vulnerable to extreme sea level rise (a combination of SLR, tide and storm surges). The main goal of this study is to assess the paradigm shift in flood risk management from reducing probability of the flood event to reducing its consequences in the city of Vlissingen, in the Netherlands. Two spatial adaptation strategies are modeled and compared by using spatial, climatic, and socioeconomic projections for the year 2100: the “Vlissings Model” and the “Spuikom Model”. The Vlissings Model is about increased coastal protection through the heightening of existing grey infrastructure by 3 m, which includes the dike and buildings constructed on top of it. The Spuikom Model is accepting and rerouting overtopping water towards an existing former backshore water basin. The study brings forth an interdisciplinary "Design & Assess" framework that brings together design strategies with flood damage models and cost/benefit analyses to compare the effectiveness of two paradigms in dealing with extreme SLR. Results show that raising the dike would ensure full protection from extreme events against an initial investment and maintenance cost of €215 mil. Accepting and rerouting overtopping water would, on the contrary, reduce the impact of the flood to €8,6 million damage and less than a hundred affected inhabitants, without requiring the construction of major infrastructure but of a flood retention basin integrated to the new urban development. On the other hand, the comparison between the two strategies remains complex in quantitative terms given the different cost-benefit assessment models for such interventions.Environmental Technology and DesignHydraulic Structures and Flood Ris