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Froese, Duane G., Derald G. Smith, John A. Westgate, Thomas A. Ager, Shari J. Preece, Amanjit Sandhu, Randolph J. Enkin e Florence Weber. "Recurring middle Pleistocene outburst floods in east-central Alaska". Quaternary Research 60, n.º 1 (julho de 2003): 50–62. http://dx.doi.org/10.1016/s0033-5894(03)00090-5.
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AbstractRecurring glacial outburst floods from the Yukon-Tanana Upland are inferred from sediments exposed along the Yukon River near the mouth of Charley River in east-central Alaska. Deposits range from imbricate gravel and granules indicating flow locally extending up the Yukon valley, to more distal sediments consisting of at least 10 couplets of planar sands, granules, and climbing ripples with up-valley paleocurrent indicators overlain by massive silt. An interglacial organic silt, occurring within the sequence, indicates at least two flood events are associated with an earlier glaciation, and at least three flood events are associated with a later glaciation which postdates the organic silt. A minimum age for the floods is provided by a glass fission track age of 560,000 ± 80,000 yr on the GI tephra, which occurs 8 m above the flood beds. A maximum age of 780,000 yr for the floods is based on normal magnetic polarity of the sediments. These age constraints allow us to correlate the flood events to the early-middle Pleistocene. And further, the outburst floods indicate extensive glaciation of the Yukon-Tanana Upland during the early-middle Pleistocene, likely representing the most extensive Pleistocene glaciation of the area.
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Gourbesville, Philippe, e Masoud Ghulami. "Which models for extreme flood events in Mediterranean catchments?" IOP Conference Series: Earth and Environmental Science 1136, n.º 1 (1 de janeiro de 2023): 012017. http://dx.doi.org/10.1088/1755-1315/1136/1/012017.
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Abstract Over the last years, most of the Mediterranean countries have been affected by catastrophic flood events generated by never observed before extreme rainfalls. Those events are frequently convective and stationary for several hours. The recorded intensities have frequently values exceeding 100 mm/hour and can last for several hours. Under those specific conditions as during the storm ALEX of October 2020, the runoff processes are particularly intense and can generate massive floods. Mitigation strategies should be developed and based on modeling that can support the understanding of the processes and the forecast the magnitude of the flood events and the associated impacts. The choice of the relevant hydrological modeling tools is a key element. The selected ones should be able to provide the relevant information, on time and with the relevant accuracy for the decision makers. The hydrological deterministic distributed models have reached a sufficient maturity to provide an accurate representation of the processes. The storm ALEX was generating more than 500 mm in less than 6 hours and producing a devastating flood within the Vésubie valley (France) in October 2020. The analysis of the event has demonstrated the difficulty to obtain consistent field observations and the limitations of many stochastic hydrological tools. The application of the AquaVar approach, combining several distributed deterministic models, has demonstrated its capacity to generate meaningful hydrographs and to quantify process with the catchment. The proposed solution is currently implemented within a real-time decision support system and can be used in real-time.
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Fadaeifard, Mostafa, e Mohammad Danesh-Yazdi. "Lessons Learned from Flood Management in Iran". E3S Web of Conferences 346 (2022): 02012. http://dx.doi.org/10.1051/e3sconf/202234602012.
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Iran has a longstanding challenge in supplying water during prolonged drought periods. This has drawn considerable attention towards the dam industry over the past four decades, leading to the study, construction and operation of several large dams. These dams played a critical role in controlling the massive floods of 2019 and 2020, among others. Nevertheless, due to the increased intensity and frequency of extreme events because of climate change, the downstream regions of these large storage dams still face significant damages. This is mainly attributed to the insufficient dredging of rivers and tributaries, lack of rule curve and operation guideline for some storage dams, inaccurate prediction of flood volume, violation of land-use and water management action plans, promotion of industries with high water need, and floodplain encroachment. In this study, we aim to evaluate the performance of several large dams in the Karkheh and Karoon river basin, located in southwestern Iran, in managing the floods took place in the aforementioned periods. We also discuss the challenges and the lessons learned, with suggestions for improving the flood management in the country.
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Dougherty, Erin, e Kristen L. Rasmussen. "Changes in Future Flash Flood–Producing Storms in the United States". Journal of Hydrometeorology 21, n.º 10 (1 de outubro de 2020): 2221–36. http://dx.doi.org/10.1175/jhm-d-20-0014.1.
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AbstractFlash floods are high-impact events that can result in massive destruction, such as the May 2010 flash floods in the south-central United States that resulted in over $2 billion of damage. While floods in the current climate are already destructive, future flood risk is projected to increase based on work using global climate models. However, global climate models struggle to resolve precipitation structure, intensity, and duration, which motivated the use of convection-permitting climate models that more accurately depict these precipitation processes on a regional scale due to explicit representation of convection. These high-resolution convection-permitting simulations have been used to examine future changes to rainfall, but not explicitly floods. This study aims to fill this gap by examining future changes to rainfall characteristics and runoff in flash flood–producing storms over the United States using convection-permitting models under a pseudo–global warming framework. Flash flood accumulated rainfall increases on average by 21% over the United States in a future climate. Storm-generated runoff increases by 50% on average, suggesting increased runoff efficiency in future flash flood–producing storms. In addition to changes in nonmeteorological factors, which were not explored in this study, increased future runoff is possible due to the 7.5% K−1 increase in future hourly maximum rain rates. Though this median change in rain rates is consistent with Clausius–Clapeyron theory, some storms exhibit increased future rain rates well above this, likely associated with storm dynamics. Overall, results suggest that U.S. cities might need to prepare for more intense flash flood–producing storms in a future climate.
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Rustan, Irpan Chumaedi e Linda Handayani. "SIMULASI KERUNTUHAN BENDUNGAN BILI-BILI KABUPATEN GOWA PROVINSI SULAWESI SELATAN". JOURNAL ONLINE OF PHYSICS 5, n.º 1 (19 de dezembro de 2019): 24–28. http://dx.doi.org/10.22437/jop.v5i1.8117.
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The extreme weather that occurred on January 22-24, 2019 in the Makassar city and surrounding areas caused massive flooding in the downstream area of the Bili-Bili DAM which covered 5 districts and cities, namely Gowa Regency, Makassar City, Jeneponto Regency, Maros Regency, and Selayar Regency. There 6757 people were displaced and tens of hectares of rice fields and housing were inundated. As a form of evaluation in the context of disaster mitigation efforts if similar or larger events occur in the future, it is very important to do a floods simulation to mapping which areas will be affected by flood inundation if the Bili-Bili DAM collapses. The software used to simulate flooding in this study is HEC-RAS 2D. The object of research is focused in the city of Makassar which is a densely populated city center and other vital objects. The parameters analyzed are the distribution of flood inundation area and the depth of flood inundation. Simulation results that have been calibrated will be used as a reference for disaster mitigation planning.
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Jacka, Jerry K., e Amelia Moore. "Flood and Fire". Environment and Society 14, n.º 1 (1 de setembro de 2023): 1–3. http://dx.doi.org/10.3167/ares.2023.140101.
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The intensifying warming of the planet over the past several decades is a manifestation of centuries of uneven and inequitable extractive economies. This warming is well known to be the main force driving shifts in climatological conditions and extreme weather events leading to increasingly severe impacts on planetary systems. Every year, more locations on earth are experiencing heat waves, intense droughts, longer and larger fire seasons, increased tropical storm intensity, and sea level rise at rates that would have been unthinkable a generation ago while near daily news reports document the increasing toll that this changing climate plays in exacerbating social and ecological vulnerabilities. Just this year, at the start of the Northern Hemisphere summer of 2023, a massive tropical cyclone has killed over 145 people in Bangladesh and Myanmar, western Canada has already seen as much forest burned in a few days as it does in an entire summer, drastically diminishing air quality over half a continent, the Po River Valley in Italy has been ravaged by floods after experiencing two years of extreme drought, and California has experienced deadly and pervasive atmospheric rivers after years of record-setting fire seasons and water shortages. In this special issue, rather than prioritizing benign and depoliticized notions of adaptive capacity and resilience, as is far too common within mainstream discussions of climate change, we highlight the theme of flood and fire to examine these events as compounding contemporary crises and responses to phenomena that are devastating, transforming, and reformulating communities, ecologies, and governing processes around the planet.
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Leulmi, Lamia, Youcef Lazri, Brahim Abdelkebir e Sofiane Bensehla. "Assessment of the effect of land use and land cover (LULC) change on depth runoff: Case study of Skikda floods event". Glasnik Srpskog geografskog drustva 103, n.º 2 (2023): 145–60. http://dx.doi.org/10.2298/gsgd2302145l.
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Land use and land cover changes in coastal cities can influence drainage sys-tems in ways that affect surface overflows and the infiltration potential of a land surface, making flooding one of the drivers. This research aims to demonstrate the spatiotemporal dynamics of LULC and their combined impact on rainfall and flood height in Skikda, Algeria. The research uses remote sensing (RS) and geographic information systems (GIS) to determine the type and location of LULC changes in Skikda. The supervised classification methodology used the maximum likelihood technique (MCL). Changes were identified in five categories: built-up areas, green spaces, bodies of water, agriculture, and vacant land. In Q-GIS 3.28.2, Landsat 4-5 (TM) data from 1984 and 2004 and Landsat 8-9 (OLI)/TIRS data from 2019 were used based on the United States Geological Survey (USGS). The results show that the impervious built-up area has changed significantly (44.01%) due to massive urbanization and rapid industrialization, which would affect heavy rainfall activity and increase flood height due to the intense imperviousness of the affected soil (from 27% to 44%). The precipitation and flood height were examined and compared with observations to investigate the impact of the LULC model modification during the flood. The comparison of three flood events (1984, 2004, and 2019) revealed that the change in the LULC model is the main factor increasing flood risk in the study area. This study demonstrates the importance of considering temporal changes in land use, land cover, rainfall, and flood height when mapping floods in urban cities.
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Putra, M. H. Z., D. Sarah, I. A. Sadisun, E. Soebowo, A. N. Aulia e Sukristiyanti. "Modeling and mapping the environmental impact of debris flow hazard on alluvial fans for sustainable development in Bangga and Poi Villages, Sigi, Central Sulawesi". IOP Conference Series: Earth and Environmental Science 1201, n.º 1 (1 de junho de 2023): 012028. http://dx.doi.org/10.1088/1755-1315/1201/1/012028.
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Abstract On September 28, 2018, an Mw 7.5 Palu earthquake triggered massive landslides upstream, followed by 24 debris flood events that spread to 15 villages in Sigi from September 2018 to December 2021. Debris flow and flash floods on alluvial fans inundated lowland communities, causing severe property destruction and structural damage to bridges and roadways and resulting in an estimated 900 damaged houses. Understanding their historical occurrence is essential to sustainable fan development and minimizing their threat to infrastructure and human life due to their severe geohazard potential. Poi and Bangga Villages were affected by the disastrous debris flood in Sigi Regency, Central Sulawesi. This study aimed to create a landslide inventory map, a back-analysis model, and a damage and loss assessment (DaLAs) to evaluate the potential hazard and environmental impacts of debris flow on Sigi’s alluvial fans. The result of landslide mapping showed more than 400 mapped landslides within Bangga Village in various sizes and a massive landslide within Poi Village were digitized. Then, the back-analysis model overpredicted flow direction due to vegetation, infrastructure, and road information not covered by the digital elevation model (DEM). Finally, DaLAs shows the losses caused by damaged buildings were estimated at around 65.7 and 7.4 billion rupiah in Bangga and Poi Villages, respectively.
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Makinano-Santillan, M., J. R. Santillan, E. M. O. Morales, L. C. S. Asube, A. M. Amora, L. C. Cutamora e R. M. Makinano. "ACADEME-LOCAL GOVERNMENT PARTNERSHIP TOWARDS EFFECTIVE APPLICATION OF GEOSPATIAL TECHNOLOGIES FOR SMARTER FLOOD DISASTER MANAGEMENT AT THE LOCAL LEVEL: AN EXAMPLE FROM MINDANAO, PHILIPPINES". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (22 de junho de 2016): 109–15. http://dx.doi.org/10.5194/isprs-archives-xli-b8-109-2016.
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In this paper, we discuss how an academe-local government partnership can lead the way for the effective use of geospatial technologies for smarter and geospatially-informed decision making before, during, and after a flood disaster. In Jabonga municipality, in the province of Agusan del Norte, in Mindanao, Philippines, two significant flooding events occurred in the year 2014 which were caused by overflowing water bodies due to continuous heavy rains. These flood events inundated populated areas, caused massive evacuation, made roads un-passable, and greatly damaged sources of incomes such as croplands and other agricultural areas. The partnership between Caraga State University and the local government of Jabonga attempts to improve localized flood disaster management through the development of web-based Near-real Time Flood Event Visualization and Damage Estimations (Flood EViDEns) application. Flood EViDENs utilizes LiDAR-derived elevation and information products as well as other elevation datasets, water level records by monitoring stations, flood simulation models, flood hazard maps, and socio-economic datasets (population, household information, etc.), in order to visualize in near-real time the current and future extent of flooding, to disseminate early warnings, and to provide maps and statistics of areas and communities affected and to be affected by flooding. The development of Flood EViDEns as the main product of the partnership is an important application of geospatial technologies that will allow smarter and geospatially-informed decision making before, during, and after a flood disaster in Jabonga.
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Makinano-Santillan, M., J. R. Santillan, E. M. O. Morales, L. C. S. Asube, A. M. Amora, L. C. Cutamora e R. M. Makinano. "ACADEME-LOCAL GOVERNMENT PARTNERSHIP TOWARDS EFFECTIVE APPLICATION OF GEOSPATIAL TECHNOLOGIES FOR SMARTER FLOOD DISASTER MANAGEMENT AT THE LOCAL LEVEL: AN EXAMPLE FROM MINDANAO, PHILIPPINES". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (22 de junho de 2016): 109–15. http://dx.doi.org/10.5194/isprsarchives-xli-b8-109-2016.
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In this paper, we discuss how an academe-local government partnership can lead the way for the effective use of geospatial technologies for smarter and geospatially-informed decision making before, during, and after a flood disaster. In Jabonga municipality, in the province of Agusan del Norte, in Mindanao, Philippines, two significant flooding events occurred in the year 2014 which were caused by overflowing water bodies due to continuous heavy rains. These flood events inundated populated areas, caused massive evacuation, made roads un-passable, and greatly damaged sources of incomes such as croplands and other agricultural areas. The partnership between Caraga State University and the local government of Jabonga attempts to improve localized flood disaster management through the development of web-based Near-real Time Flood Event Visualization and Damage Estimations (Flood EViDEns) application. Flood EViDENs utilizes LiDAR-derived elevation and information products as well as other elevation datasets, water level records by monitoring stations, flood simulation models, flood hazard maps, and socio-economic datasets (population, household information, etc.), in order to visualize in near-real time the current and future extent of flooding, to disseminate early warnings, and to provide maps and statistics of areas and communities affected and to be affected by flooding. The development of Flood EViDEns as the main product of the partnership is an important application of geospatial technologies that will allow smarter and geospatially-informed decision making before, during, and after a flood disaster in Jabonga.
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Yang, Zhongkang, Jinbing Wei, Jianhui Deng, Yunjian Gao, Siyuan Zhao e Zhiliang He. "Mapping Outburst Floods Using a Collaborative Learning Method Based on Temporally Dense Optical and SAR Data: A Case Study with the Baige Landslide Dam on the Jinsha River, Tibet". Remote Sensing 13, n.º 11 (4 de junho de 2021): 2205. http://dx.doi.org/10.3390/rs13112205.
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Outburst floods resulting from giant landslide dams can cause devastating damage to hundreds or thousands of kilometres of a river. Accurate and timely delineation of flood inundated areas is essential for disaster assessment and mitigation. There have been significant advances in flood mapping using remote sensing images in recent years, but little attention has been devoted to outburst flood mapping. The short-duration nature of these events and observation constraints from cloud cover have significantly challenged outburst flood mapping. This study used the outburst flood of the Baige landslide dam on the Jinsha River on 3 November 2018 as an example to propose a new flood mapping method that combines optical images from Sentinel-2, synthetic aperture radar (SAR) images from Sentinel-1 and a Digital Elevation Model (DEM). First, in the cloud-free region, a comparison of four spectral indexes calculated from time series of Sentinel-2 images indicated that the normalized difference vegetation index (NDVI) with the threshold of 0.15 provided the best separation flooded area. Subsequently, in the cloud-covered region, an analysis of dual-polarization RGB false color composites images and backscattering coefficient differences of Sentinel-1 SAR data were found an apparent response to ground roughness’s changes caused by the flood. We carried out the flood range prediction model based on the random forest algorithm. Training samples consisted of 13 feature vectors obtained from the Hue-Saturation-Value color space, backscattering coefficient differences/ratio, DEM data, and a label set from the flood range prepared from Sentinel-2 images. Finally, a field investigation and confusion matrix tested the prediction accuracy of the end-of-flood map. The overall accuracy and Kappa coefficient were 92.3%, 0.89 respectively. The full extent of the outburst floods was successfully obtained within five days of its occurrence. The multi-source data merging framework and the massive sample preparation method with SAR images proposed in this paper, provide a practical demonstration for similar machine learning applications using remote sensing.
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Liu, Yang, Rui Li, Shunli Wang, Huayi Wu e Zhipeng Gui. "Deducing Flood Development Process Using Social Media: An Event-Based and Multi-Level Modeling Approach". ISPRS International Journal of Geo-Information 11, n.º 5 (10 de maio de 2022): 306. http://dx.doi.org/10.3390/ijgi11050306.
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Social media is increasingly being used to obtain timely flood information to assist flood disaster management and situational awareness. However, since data in social media are massive, redundant, and unstructured, it is tricky to intuitively and clearly obtain effective information. To automatically obtain clear flood information and deduce flood development processes from social media, the authors of this paper propose an event-based and multi-level modeling approach including a data model and two methods. Through the hierarchical division of events (division into spatial object, phase, and attribute status), the flood information structure (including time, space, topic, emotion, and disaster condition) is defined. We built an entity construction method and a development process deduction method to achieve the automatic transition from cluttered data to orderly flood development processes. Taking the flooding event of the Yangtze and Huai Rivers in 2020 as an example, we successfully obtained true flood information and development process from social media data, which verified the effectiveness of the model and methods. Meanwhile, spatiotemporal pattern mining was carried out by using entities from different levels. The results showed that the flood was from west to east and the damage level was positively correlated with the number of flood-related social media texts, especially emotional texts. In summary, through the model and methods in this paper, clear flood information and dynamic development processes can be quickly and automatically obtained, and the spatiotemporal patterns of flood entities can be examined. It is beneficial to extract timely flood information and public sentiments towards flood events in order to perform better disaster relief and post-disaster management.
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Bakker, Marloes H. N. "Transboundary river floods: examining countries, international river basins and continents". Water Policy 11, n.º 3 (1 de junho de 2009): 269–88. http://dx.doi.org/10.2166/wp.2009.041.
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The objectives of this study were (1) to quantify river floods shared by more than one country, that is, transboundary river floods and (2) to grasp more fully the degree of vulnerability of people to such events on a global, international river basin (IRB) and country level. To these ends, publicly available data were combined to identify such events and the resultant losses of life, flood-related affected individuals and financial damage statistics were related to national levels of development. It was determined that in the period 1985–2005, some 175 of the 1,760 river floods were transboundary, but globally accounted for 32% of all casualties and almost 60% of all affected individuals, illustrating the massive impact of shared floods. This database of transboundary floods was then merged with socio-economic and biophysical data, enabling analyses that revealed the degree of vulnerability of people to transboundary floods from a global to a country level. Selecting one country, continent or IRB most vulnerable to transboundary floods proofed to be unfeasible since the answer heavily depended upon the specific definition of vulnerability, illustrating the complexity of this phenomenon. However, together, the results significantly increased our current knowledge of shared floods which could aid policy-makers in identifying and evaluating potential vulnerability to transboundary river floods.
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Choo, Jo, Yun e Lee. "A Study on the Improvement of Flood Forecasting Techniques in Urban Areas by Considering Rainfall Intensity and Duration". Water 11, n.º 9 (10 de setembro de 2019): 1883. http://dx.doi.org/10.3390/w11091883.
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Frequent localized torrential rains, excessive population density in urban areas, and increased impervious areas have led to massive flood damage that has been causing overloading of drainage systems (watersheds, reservoirs, drainage pump sites, etc.). Flood concerns are raised around the world in the events of rain. Flood forecasting, a typical nonstructural measure, was developed to help prevent repetitive flood damage. However, it is difficult to apply flood prediction techniques using training processes because training needs to be applied at every usage. Other techniques that use predicted rainfall data are also not appropriate for small watershed, such as single drainage area. Thus, in this paper, a flood prediction method is proposed by improving four criteria (50% water level, 70% water level, 100% water level, and first flooding of water pipes) in an attempt to reduce flooding in urban areas. The four criteria nodes are generated using a rainfall runoff simulation with synthetic rainfall at various durations. When applying real-time rainfall data, these nodes have the advantage of simple application. The improved flood nomograph made in this way is expected to help predict and prepare for rainstorms that can potentially cause flood damage.
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Alrajhi, Muhamad, Mudasir Khan, Mohammad Afroz Khan e Abdalla Alobeid. "INFLUENCE OF DEM IN WATERSHED MANAGEMENT AS FLOOD ZONATION MAPPING". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (22 de junho de 2016): 3–10. http://dx.doi.org/10.5194/isprs-archives-xli-b8-3-2016.
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Despite of valuable efforts from working groups and research organizations towards flood hazard reduction through its program, still minimal diminution from these hazards has been realized. This is mainly due to the fact that with rapid increase in population and urbanization coupled with climate change, flood hazards are becoming increasingly catastrophic. Therefore there is a need to understand and access flood hazards and develop means to deal with it through proper preparations, and preventive measures. To achieve this aim, Geographical Information System (GIS), geospatial and hydrological models were used as tools to tackle with influence of flash floods in the Kingdom of Saudi Arabia due to existence of large valleys (Wadis) which is a matter of great concern. In this research paper, Digital Elevation Models (DEMs) of different resolution (30m, 20m,10m and 5m) have been used, which have proven to be valuable tool for the topographic parameterization of hydrological models which are the basis for any flood modelling process. The DEM was used as input for performing spatial analysis and obtaining derivative products and delineate watershed characteristics of the study area using ArcGIS desktop and its Arc Hydro extension tools to check comparability of different elevation models for flood Zonation mapping. The derived drainage patterns have been overlaid over aerial imagery of study area, to check influence of greater amount of precipitation which can turn into massive destructions. The flow accumulation maps derived provide zones of highest accumulation and possible flow directions. This approach provide simplified means of predicting extent of inundation during flood events for emergency action especially for large areas because of large coverage area of the remotely sensed data.
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Manfreda, Salvatore, Caterina Samela, Alberto Refice, Valerio Tramutoli e Fernando Nardi. "Advances in Large-Scale Flood Monitoring and Detection". Hydrology 5, n.º 3 (3 de setembro de 2018): 49. http://dx.doi.org/10.3390/hydrology5030049.
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The last decades have seen a massive advance in technologies for Earth observation (EO) and environmental monitoring, which provided scientists and engineers with valuable spatial information for studying hydrologic processes. At the same time, the power of computers and newly developed algorithms have grown sharply. Such advances have extended the range of possibilities for hydrologists, who are trying to exploit these potentials the most, updating and re-inventing the way hydrologic and hydraulic analyses are carried out. A variety of research fields have progressed significantly, ranging from the evaluation of water features, to the classification of land-cover, the identification of river morphology, and the monitoring of extreme flood events. The description of flood processes may particularly benefit from the integrated use of recent algorithms and monitoring techniques. In fact, flood exposure and risk over large areas and in scarce data environments have always been challenging topics due to the limited information available on river basin hydrology, basin morphology, land cover, and the resulting model uncertainty. The ability of new tools to carry out intensive analyses over huge datasets allows us to produce flood studies over large extents and with a growing level of detail. The present Special Issue aims to describe the state-of-the-art on flood assessment, monitoring, and management using new algorithms, new measurement systems and EO data. More specifically, we collected a number of contributions dealing with: (1) the impact of climate change on floods; (2) real time flood forecasting systems; (3) applications of EO data for hazard, vulnerability, risk mapping, and post-disaster recovery phase; and (4) development of tools and platforms for assessment and validation of hazard/risk models.
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Alrajhi, Muhamad, Mudasir Khan, Mohammad Afroz Khan e Abdalla Alobeid. "INFLUENCE OF DEM IN WATERSHED MANAGEMENT AS FLOOD ZONATION MAPPING". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (22 de junho de 2016): 3–10. http://dx.doi.org/10.5194/isprsarchives-xli-b8-3-2016.
Texto completo da fonteResumo:
Despite of valuable efforts from working groups and research organizations towards flood hazard reduction through its program, still minimal diminution from these hazards has been realized. This is mainly due to the fact that with rapid increase in population and urbanization coupled with climate change, flood hazards are becoming increasingly catastrophic. Therefore there is a need to understand and access flood hazards and develop means to deal with it through proper preparations, and preventive measures. To achieve this aim, Geographical Information System (GIS), geospatial and hydrological models were used as tools to tackle with influence of flash floods in the Kingdom of Saudi Arabia due to existence of large valleys (Wadis) which is a matter of great concern. In this research paper, Digital Elevation Models (DEMs) of different resolution (30m, 20m,10m and 5m) have been used, which have proven to be valuable tool for the topographic parameterization of hydrological models which are the basis for any flood modelling process. The DEM was used as input for performing spatial analysis and obtaining derivative products and delineate watershed characteristics of the study area using ArcGIS desktop and its Arc Hydro extension tools to check comparability of different elevation models for flood Zonation mapping. The derived drainage patterns have been overlaid over aerial imagery of study area, to check influence of greater amount of precipitation which can turn into massive destructions. The flow accumulation maps derived provide zones of highest accumulation and possible flow directions. This approach provide simplified means of predicting extent of inundation during flood events for emergency action especially for large areas because of large coverage area of the remotely sensed data.
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Namwade, Gangadhar, M. M. Trivedi, Mukesh Kumar Tiwari e G. R. Patel. "Rainfall-Runoff Modelling Using HEC-HMS Model, Remote Sensing and GIS in Middle Gujarat, India". International Journal of Environment and Climate Change 13, n.º 9 (11 de julho de 2023): 952–62. http://dx.doi.org/10.9734/ijecc/2023/v13i92317.
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Hydrological modeling is a widely used approach for estimating the hydrological response of a basin to precipitation. Floods are among the most catastrophic natural disasters in small urban watersheds, inflicting loss of life, massive property destruction, and a severe danger to the economy. As a result, appropriate modeling can be a useful tool in preventing and mitigating such flood hazards. Despite this, flash flood prediction remains one of the challenges of hydrological modeling in ungauged basins due to a lack of runoff observations. This study aims to calibrate and validate the rainfall-runoff transformation model for Hathmati river sub watershed in the Sabarmati River basin using HEC-HMS (Hydrologic Engineering Centre Hydrology Modeling System). For the loss rate, SCS Curve Number method was selected while Clark Unit Hydrograph and SCS unit hydrograph was used for the transform method. The model is calibrated and verified using two rainfall-runoff events from 2006 and 2007 year The model calibration and validation efficiency were verified for both methods using the Nash-Sutcliffe efficiency (NSE), The coefficient of determination (R2), and the Percent Bias (PBIAS) As a result, the model calibration and validation were found to be satisfactory with the acceptable value of NSE between 0.869 to 0.914, with R2 0.901 to 0.947 and PBIAS from 9.76 to 14.8. it is observed that the model shows a very good correlation between simulated flow and observed flow. As a result, the model can be used to forecast river flow and aid in flood mitigation efforts to lessen their effects and associated costs. Additionally, the findings of this study can serve as guidelines for future assessments of the flood risk in the study area.
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AbdelAziz, Nabil M., Hassan H. Mohammed e Khalid A. Eldrandaly. "An effective Decision making model through Fusion Optimization and risk associated with flash flood hazards: A case study Asyut, Egypt". Fusion: Practice and Applications 12, n.º 1 (2023): 64–94. http://dx.doi.org/10.54216/fpa.120105.
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One of the most dangerous natural disasters, which causes massive damage all over the world, is flash floods. Therefore, the assessment of flash floods disasters is considered increasingly urgent and important. The widely used techniques for studying and analyzing the causes and impact of natural hazards are multi-criteria techniques. Several researchers used traditional multi-criteria decision-making techniques in the estimation process of flash floods problems as the analytical hierarchy process, decision making trial and evaluation laboratory and analytic network process. The main disadvantage of these traditional models is the incapability of simulating and reflecting uncertain human thoughts. Since neutrosophic logic has a great ability for simulating human’s thoughts and increase the flexibility of expert's preferences in real world problems, we applied it in this study. There are different locations in Egypt that are at a serious risk of flooding, especially in Upper Egypt. Asyut has suffered from frequent flash floods, with some flood events that lead to mortality, damages, and economic losses in the last decades. The intensity of floods in Egypt varies from year to year, according to several climatic and hydrological variables. This study focuses on using a Neutrosophic Decision making trial and evaluation laboratory (N-DEMATEL) technique with remotely sensed data and geographical information system (GIS) for producing a flash floods hazard map. The N-DEMATEL technique is applied to determine the weights of various factors that related to flash flooding, including elevation, slope, topographic wetness index, distance from the stream, flow accumulation, aspect, flow direction, soil, land cover, watershed, curvature, drainage density , total population , population density and precipitation. The obtained weight of selected criteria used then to produce the flood hazard map (FHM) using a raster calculator tool in geographic information system.
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Wahalathantri, Buddhi, Weena Lokuge, Warna Karunasena e Sujeeva Setunge. "Quantitative assessment of flood discharges and floodway failures through cross-cultivation of advancement in knowledge and traditional practices". International Journal of Disaster Resilience in the Built Environment 9, n.º 4/5 (16 de novembro de 2018): 435–56. http://dx.doi.org/10.1108/ijdrbe-09-2017-0051.
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Purpose The 2011 and 2013 Queensland, Australia flood events caused massive infrastructure damage for low-level stream crossings such as floodways and culverts in regional Queensland. Failures of newly built floodways during the 2013 Queensland flood event in the Lockyer Valley Regional Council area raised significant concerns with respect to floodway design practices adopted in Australia and attracted significant research interest to enhance the resilience of floodways. Review of existing floodway design guidelines indicates that floodway design process is closely related to hydraulic and hydrological aspects. However, conducting a hydrological analysis is a challenging in rural areas, mainly owing to information scarcity. Floodways in rural areas often require a simple and economical solution contrast to more detailed hydrological analysis approaches adopted in urbanised areas. This paper aims to identify and apply the rational method to estimate maximum flood discharges at selected floodway locations in the Lockyer Valley Regional Council area. The paper further attempts to provide the first insight of flood characteristics during the 2011 and 2013 Queensland flood events at three catchment outputs across the selected case study area. It also highlights modern day challenges for practising engineers and researchers when estimating flood characteristics in rural areas. The paper shows that cross-cultivation of advancement in engineering practices and traditional approaches can promote quantitative approaches when assessing floodway damage in regional areas. Design/methodology/approach The research identifies limitations when assessing flood impact in rural regions in collaboration with experience from industry partners and authors themselves. The authors developed a framework to overcome those limitations arising from information scarcity to minimise the trial and error design approaches utilised in the current design practices for floodways. Findings This paper developed a simple and effective hydrological method with minimum inputs. It also provides an example on collating available but scattered resources and traditional method to quantitatively assess flood discharges of a rural catchment in Australia. Flood discharges at three catchment outlets along the Left-Hand Branch Road in the Lockyer Valley Region during both 2011 and 2013 Queensland flood events are estimated for the first time. The findings highlight the impact of flood discharges and flooded period on floodway failures. Research limitations/implications The current research is based on a selected case study area in Australia. However, similar challenges are expected all across the world, due to the scarcity of rainfall and flood measurement gauges. Practical implications Floodway designers can apply similar framework to estimate the flood discharges instead of current practice of trial and error process. This will provide more scientific and reliable estimation and assessment process. Social implications One of the social impacts identified in the broader research is the community outrages and disagreement between floodway design engineers and the community. Following the developed framework in the manuscript, design engineers will be able to justify their assumptions and design work. Originality/value The paper presents a novel framework on collating different and scattered information towards estimating flood discharges in rural areas. The manuscript presents the first insights on estimated flood discharges in the selected case study area during the 2011 and 2013 Queensland flood events. This will enable further research to be performed in a quantitative manner rather than the present approach of qualitative manner.
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Pelletier, Émilien, Bruno Deflandre, Christian Nozais, Guglielmo Tita, Gaston Desrosiers, Jean-Pierre Gagné e Alfonso Mucci. "Crue éclair de juillet 1996 dans la région du Saguenay (Québec). 2. Impacts sur les sédiments et le biote de la baie des Ha! Ha! et du fjord du Saguenay". Canadian Journal of Fisheries and Aquatic Sciences 56, n.º 11 (1 de novembro de 1999): 2136–47. http://dx.doi.org/10.1139/f99-143.
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Several million tons of sediments and various debris were transported to the north arm of the Saguenay Fjord and the Baie des Ha! Ha! following the torrential rains and accompanying flash flood of July 1996 in the Saguenay region (Québec). The flood deposits covered the indigenous sediments and buried the benthic community. The objective of this work is to determine the best chemical and biological indicators of the changes that occurred in the benthic habitat of the fjord. The new sediment layer is poor in organic matter but rich in detrital carbonates and contains low mercury and lead concentrations reflecting the absence of industrial contamination. Ongoing geological processes leading to the re-establishment of steady-state conditions were evidenced by measurements of porosity, redox potential (Eh), and salinity of interstitial waters taken a few weeks and a few months after the events. The meiofauna were severely affected with a massive reduction of the average density of organisms relative to values recorded before the flood, but recolonisation was already in progress 1 year after the flood. Important losses of macrobenthic species were recorded in 1997 relative to 1996. However, the abundance and the diversity of the polycheate taxa were higher in 1997, indicating a recolonisation of the new sediment layer by pioneer species.
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James, Harold. "Introduction". World Politics 55, n.º 1 (outubro de 2002): 1–3. http://dx.doi.org/10.1353/wp.2003.0005.
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The tragic events of September 11, 2001, came as a terrible surprise, except of course to those who perpetrated them. The four aircraft hijackings, the use of the seized and fully fueled large aircraft as incendiary bombs directed against the perceived centers of American financial, military, and legislative life (on the assumption that the fourth jet was to have been targeted at the U.S. Capitol), and the massive loss of life shattered all assumptions. The terror immediately produced a flood of analysis, instant commentary, articles, books, and gradually also a smaller tide of semiacademic and academic analysis.
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Ferreira, Eva, Stanley Nmor, Eric Viollier, Bruno Lansard, Bruno Bombled, Edouard Regnier, Gaël Monvoisin, Christian Grenz, Pieter van Beek e Christophe Rabouille. "Characterization of the benthic biogeochemical dynamics after flood events in the Rhône River prodelta: a data–model approach". Biogeosciences 21, n.º 3 (8 de fevereiro de 2024): 711–29. http://dx.doi.org/10.5194/bg-21-711-2024.
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Abstract. At the land–sea interface, the benthic carbon cycle is strongly influenced by the export of terrigenous particulate material across the river–ocean continuum. Episodic flood events delivering massive sedimentary materials can occur, but their short-term impact on carbon cycling is poorly understood. In this paper, we use a coupled data–model approach to estimate the temporal variations in sediment–water fluxes, biogeochemical pathways and their reaction rates during these abrupt phenomena. We studied one episodic depositional event in the vicinity of the Rhône River mouth (NW Mediterranean Sea) during the fall–winter of 2021/22. The distributions of dissolved inorganic carbon (DIC), sulfate (SO42-) and methane (CH4) were measured in sediment porewaters collected every 2 weeks before and after the deposition of a 25 cm sediment layer during the main winter flood event. Significant changes in the distribution of DIC, SO42- and CH4 concentrations were observed in the sediment porewaters. The use of an early diagenetic model (FESDIA) to calculate biogeochemical reaction rates and fluxes revealed that this type of flood event can increase the total organic carbon mineralization rate in the sediment by 75 % a few days after deposition. In this period, sulfate reduction is the main process contributing to the increase in total mineralization relative to non-flood deposition. The model predicts a short-term decrease in the DIC flux out of the sediment from 100 to 55 mmolm-2d-1 after the deposition of the new sediment layer with a longer-term increase by 4 %, therefore implying an initial internal storage of DIC in the newly deposited layer and a slow release over relaxation of the system. Furthermore, examination of the stoichiometric ratios of DIC and SO42- as well as model output over this 5-month window shows a decoupling between the two modes of sulfate reduction following the deposition – organoclastic sulfate reduction (OSR) intensified in the newly deposited layer below the sediment surface, whereas anaerobic oxidation of methane (AOM) intensified at depth below the former buried surface. The bifurcation depth of sulfate reduction pathways, i.e., the sulfate–methane transition zone (SMTZ), is shifted deeper by 25 cm in the sediment column following the flood deposition. Our findings highlight the significance of short-term transient biogeochemical processes at the seafloor and provide new insights into the benthic carbon cycle in the coastal ocean.
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Pulcinella, Joshua A., Arne M. E. Winguth, Diane Jones Allen e Niveditha Dasa Gangadhar. "Analysis of Flood Vulnerability and Transit Availability with a Changing Climate in Harris County, Texas". Transportation Research Record: Journal of the Transportation Research Board 2673, n.º 6 (22 de abril de 2019): 258–66. http://dx.doi.org/10.1177/0361198119839346.
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Hurricanes and other extreme precipitation events can have devastating effects on population and infrastructure that can create problems for emergency responses and evacuation. Projected climate change and associated global warming may lead to an increase in extreme weather events that results in greater inundation from storm surges or massive precipitation. For example, record flooding during Hurricane Katrina or, more recently, during Hurricane Harvey in 2017, led to many people being cut off from aid and unable to evacuate. This study focuses on the impact of severe weather under climate change for areas of Harris County, TX that are susceptible to flooding either by storm surge or extreme rainfall and evaluates the transit demand and availability in those areas. Future risk of flooding in Harris County was assessed by GIS mapping of the 100-year and 500-year FEMA floodplains and most extreme category 5 storm tide and global sea level rise. The flood maps have been overlaid with population demographics and transit accessibility to determine vulnerable populations in need of transit during a disaster. It was calculated that 70% of densely populated census block groups are located within the floodplains, including a disproportional amount of low-income block groups. The results also show a lack of transit availability in many areas susceptible to extreme storm surge exaggerated with sea level rise. Further study of these areas to improve transit infrastructure and evacuation strategies will improve the outcomes of extreme weather events in the future.
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Simonneau, A., E. Chapron, B. Vannière, S. B. Wirth, A. Gilli, C. Di Giovanni, F. S. Anselmetti, M. Desmet e M. Magny. "Multidisciplinary distinction of mass-movement and flood-induced deposits in lacustrine environments: implications for Holocene palaeohydrology and natural hazards (Lake Ledro, Southern Alps, Italy)". Climate of the Past Discussions 8, n.º 4 (3 de agosto de 2012): 3205–49. http://dx.doi.org/10.5194/cpd-8-3205-2012.
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Abstract. High-resolution seismic profiles and sediment cores from Lake Ledro combined with soil and river-bed samples from the lake's catchment area are used to assess the recurrence of natural hazards (earthquakes and flood events) in the southern Italian Alps during the Holocene. Two well-developed deltas and a flat central basin are identified on seismic profiles in Lake Ledro. Lake sediments are finely laminated in the basin since 9000 cal. yr BP and frequently interrupted by two types of sedimentary events: light-coloured massive layers and dark-coloured graded beds. Optical analysis (quantitative organic petrography) of the organic matter occurring in soils, river beds and lacustrine samples together with lake-sediment bulk density and grain-size analysis illustrate that light-coloured layers consist of a mixture of lacustrine sediments and mainly contain algal particles similar to the ones observed in background sediments. Light-coloured layers thicker than 1.5 cm in the main basin of Lake Ledro are dense and synchronous to numerous coeval mass-wasting deposits remoulding the slopes of the basin. They are interpreted as subaquatic mass movements triggered by historical and pre-historical regional earthquakes dated to 2005 AD, 1891 AD, 1045 AD and 1260, 2545, 2595, 3350, 3815, 4740, 7190, 9185 and 11495 cal. yr BP. Dark-coloured sedimentary event are dense and develop high-amplitude reflections in front of the deltas and in the deep central basin. These beds are mainly made of terrestrial organic matter (soils and ligno-cellulosic debris) and are interpreted as resulting from intense hyperpycnal flood events. Mapping and quantifying the amount of soil material accumulated in the Holocene hyperpycnal flood deposits of the sequence and applying the De Ploey erosion model allow estimating that the equivalent soil thickness eroded over the catchment area reached up to 4 mm during the largest Holocene flood events. Such significant soil erosion is interpreted as resulting from the combination of heavy rainfall and snowmelt. The recurrence of flash-flood events during the Holocene was however not high enough to affect pedogenesis processes and highlight several wet regional periods during the Holocene. The Holocene period is divided into four phases of environmental evolution. Over the first half of the Holocene, a progressive stabilization of the soils present through the catchment of Lake Ledro was associated with a progressive reforestation of the area and only interrupted during the wetter 8.2 event when the soil destabilization was particularly important. Lower soil erosion was recorded during the Mid-Holocene climatic optimum (8000–4200 cal. yr BP) and associated with higher algal production. Between 4200 and 3100 cal. yr BP, both wetter climate and human activities within the drainage basin drastically increased soil erosion rates. Finally, from 3100 cal. yr BP to the present-day, results suggest increasing and changing human land-use.
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Al-Suhili, Rafea, Cheila Cullen e Reza Khanbilvardi. "An Urban Flash Flood Alert Tool for Megacities—Application for Manhattan, New York City, USA". Hydrology 6, n.º 2 (24 de junho de 2019): 56. http://dx.doi.org/10.3390/hydrology6020056.
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Urban flooding is a frequent problem affecting cities all over the world. The problem is more significant now that the climate is changing and urbanization trends are increasing. Various, physical hydrological models such as the Environmental Protection Agency Storm Water Management Model (EPA SWMM), MIKE URBAN-II and others, have been developed to simulate flooding events in cities. However, they require high accuracy mapping and a simulation of the underground storm drainage system. Sadly, this capability is usually not available for older or larger so-called megacities. Other hydrological model types are classified in the semi-physical category, like Cellular Automata (CA), require the incorporation of very fine resolution data. These types of data, in turn, demand massive computer power and time for analysis. Furthermore, available forecasting systems provide a way to determine total rainfall during extreme events, but they do not tell us what areas will be flooded. This work introduces an urban flooding tool that couples a rainfall-runoff model with a flood map database to expedite the alert process and estimate flooded areas. A 0.30-m Lidar Digital Elevation Model (DEM) of the study area (in this case Manhattan, New York City) is divided into 140 sub-basins. Several flood maps for each sub-basin are generated and organized into a database. For any forecasted extreme rainfall event, the rainfall-runoff model predicts the expected runoff volume at different times during the storm interval. The system rapidly searches for the corresponding flood map that delineates the expected flood area. The sensitivity analysis of parameters in the model show that the effect of storm inlet flow head is approximately linear while the effects of the threshold infiltration rate, the number of storm inlets, and the storm inlet flow reduction factor are non-linear. The reduction factor variation is found to exhibit a high non-linearity variation, hence requiring further detailed investigation.
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Emtehani, Sobhan, Victor Jetten, Cees van van Westen e Dhruba Pikha Shrestha. "Quantifying Sediment Deposition Volume in Vegetated Areas with UAV Data". Remote Sensing 13, n.º 12 (18 de junho de 2021): 2391. http://dx.doi.org/10.3390/rs13122391.
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Floods are frequent hydro-meteorological hazards which cause losses in many parts of the world. In hilly and mountainous environments, floods often contain sediments which are derived from mass movements and soil erosion. The deposited sediments cause significant direct damage, and indirect costs of clean-up and sediment removal. The quantification of these sediment-related costs is still a major challenge and few multi-hazard risk studies take this into account. This research is an attempt to quantify sediment deposition caused by extreme weather events in tropical regions. The research was carried out on the heavily forested volcanic island of Dominica, which was impacted by Hurricane Maria in September 2017. The intense rainfall caused soil erosion, landslides, debris flows, and flash floods resulting in a massive amount of sediments being deposited in the river channels and alluvial fan, where most settlements are located. The overall damages and losses were approximately USD 1.3 billion, USD 92 million of which relates to the cost for removing sediments. The deposition height and extent were determined by calculating the difference in elevation using pre- and post-event Unmanned Aerial Vehicle (UAV) data and additional Light Detection and Raging (LiDAR) data. This provided deposition volumes of approximately 41 and 21 (103 m3) for the two study sites. For verification, the maximum flood level was simulated using trend interpolation of the flood margins and the Digital Terrain Model (DTM) was subtracted from it to obtain flooding depth, which indicates the maximum deposition height. The sediment deposition height was also measured in the field for a number of points for verification. The methods were applied in two sites and the results were compared. We investigated the strengths and weaknesses of direct sediment observations, and analyzed the uncertainty of sediment volume estimates by DTM/DSM differencing. The study concludes that the use of pre- and post-event UAV data in heavily vegetated tropical areas leads to a high level of uncertainty in the estimated volume of sediments.
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Mazzoglio, Paola, Francesco Laio, Constantin Sandu e Piero Boccardo. "Assessment of an Extreme Rainfall Detection System for Flood Prediction over Queensland (Australia)". Proceedings 18, n.º 1 (23 de maio de 2019): 1. http://dx.doi.org/10.3390/ecrs-3-06187.
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Flood events represent some of the most catastrophic natural disasters, especially in localities where appropriate measurement instruments and early warning systems are not available. Remotely sensed data can often help to obtain near real-time rainfall information with a global spatial coverage without the limitations that characterize other instruments. In order to achieve this goal, a freely accessible Extreme Rainfall Detection System (ERDS—erds.ithacaweb.org) was developed and implemented by ITHACA with the aim of monitoring and forecasting exceptional rainfall events and providing information in an understandable way for researchers as well as non-specialized users. The near real-time rainfall monitoring is performed by taking advantage of NASA GPM (Global Precipitation Measurement) IMERG (Integrated Multi-satellite Retrievals for GPM) half-hourly data (one of the most advanced rainfall measurements provided by satellite). This study aims to evaluate ERDS performance in the detection of the extreme rainfall that led to a massive flood event in Queensland (Australia) between January and February 2019. Due to the impressive amount of rainfall that affected the area, Flinders River (one of the longest Australian rivers) overflowed, expanding to a width of tens of kilometers. Several cities were also partially affected and Copernicus Emergency Management Service was activated with the aim of providing an assessment of the impact of the event. In this research, ERDS outputs were validated using both in situ and open source remotely sensed data. Specifically, taking advantage of both NASA MODIS (Moderate-resolution Imaging Spectroradiometer) and Copernicus Sentinel datasets, it was possible to gain a clear look at the full extent of the flood event. GPM data proved to be a reliable source of rainfall information for the evaluation of areas affected by heavy rainfall. By merging these data, it was possible to recreate the dynamics of the event.
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Mazzoglio, Paola, Francesco Laio, Constantin Sandu e Piero Boccardo. "Assessment of an Extreme Rainfall Detection System for Flood Prediction over Queensland (Australia)". Proceedings 18, n.º 1 (23 de maio de 2019): 1. http://dx.doi.org/10.3390/proceedings2019018001.
Texto completo da fonteResumo:
Flood events represent some of the most catastrophic natural disasters, especially in localities where appropriate measurement instruments and early warning systems are not available. Remotely sensed data can often help to obtain near real-time rainfall information with a global spatial coverage without the limitations that characterize other instruments. In order to achieve this goal, a freely accessible Extreme Rainfall Detection System (ERDS—erds.ithacaweb.org) was developed and implemented by ITHACA with the aim of monitoring and forecasting exceptional rainfall events and providing information in an understandable way for researchers as well as non-specialized users. The near real-time rainfall monitoring is performed by taking advantage of NASA GPM (Global Precipitation Measurement) IMERG (Integrated Multi-satellite Retrievals for GPM) half-hourly data (one of the most advanced rainfall measurements provided by satellite). This study aims to evaluate ERDS performance in the detection of the extreme rainfall that led to a massive flood event in Queensland (Australia) between January and February 2019. Due to the impressive amount of rainfall that affected the area, Flinders River (one of the longest Australian rivers) overflowed, expanding to a width of tens of kilometers. Several cities were also partially affected and Copernicus Emergency Management Service was activated with the aim of providing an assessment of the impact of the event. In this research, ERDS outputs were validated using both in situ and open source remotely sensed data. Specifically, taking advantage of both NASA MODIS (Moderate-resolution Imaging Spectroradiometer) and Copernicus Sentinel datasets, it was possible to gain a clear look at the full extent of the flood event. GPM data proved to be a reliable source of rainfall information for the evaluation of areas affected by heavy rainfall. By merging these data, it was possible to recreate the dynamics of the event.
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Simonneau, A., E. Chapron, B. Vannière, S. B. Wirth, A. Gilli, C. Di Giovanni, F. S. Anselmetti, M. Desmet e M. Magny. "Mass-movement and flood-induced deposits in Lake Ledro, southern Alps, Italy: implications for Holocene palaeohydrology and natural hazards". Climate of the Past 9, n.º 2 (21 de março de 2013): 825–40. http://dx.doi.org/10.5194/cp-9-825-2013.
Texto completo da fonteResumo:
Abstract. High-resolution seismic profiles and sediment cores from Lake Ledro combined with soil and riverbed samples from the lake's catchment area are used to assess the recurrence of natural hazards (earthquakes and flood events) in the southern Italian Alps during the Holocene. Two well-developed deltas and a flat central basin are identified on seismic profiles in Lake Ledro. Lake sediments have been finely laminated in the basin since 9000 cal. yr BP and frequently interrupted by two types of sedimentary events (SEs): light-coloured massive layers and dark-coloured graded beds. Optical analysis (quantitative organic petrography) of the organic matter present in soil, riverbed and lacustrine samples together with lake sediment bulk density and grain-size analysis illustrate that light-coloured layers consist of a mixture of lacustrine sediments and mainly contain algal particles similar to the ones observed in background sediments. Light-coloured layers thicker than 1.5 cm in the main basin of Lake Ledro are synchronous to numerous coeval mass-wasting deposits remoulding the slopes of the basin. They are interpreted as subaquatic mass-movements triggered by historical and pre-historical regional earthquakes dated to AD 2005, AD 1891, AD 1045 and 1260, 2545, 2595, 3350, 3815, 4740, 7190, 9185 and 11 495 cal. yr BP. Dark-coloured SEs develop high-amplitude reflections in front of the deltas and in the deep central basin. These beds are mainly made of terrestrial organic matter (soils and lignocellulosic debris) and are interpreted as resulting from intense hyperpycnal flood event. Mapping and quantifying the amount of soil material accumulated in the Holocene hyperpycnal flood deposits of the sequence allow estimating that the equivalent soil thickness eroded over the catchment area reached up to 5 mm during the largest Holocene flood events. Such significant soil erosion is interpreted as resulting from the combination of heavy rainfall and snowmelt. The recurrence of flash flood events during the Holocene was, however, not high enough to affect pedogenesis processes and highlight several wet regional periods during the Holocene. The Holocene period is divided into four phases of environmental evolution. Over the first half of the Holocene, a progressive stabilization of the soils present through the catchment of Lake Ledro was associated with a progressive reforestation of the area and only interrupted during the wet 8.2 event when the soil destabilization was particularly important. Lower soil erosion was recorded during the mid-Holocene climatic optimum (8000–4200 cal. yr BP) and associated with higher algal production. Between 4200 and 3100 cal. yr BP, both wetter climate and human activities within the drainage basin drastically increased soil erosion rates. Finally, from 3100 cal. yr BP to the present-day, data suggest increasing and changing human land use.
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Pietrafesa, L. J., K. Kelleher, T. Karl, M. Davidson, M. Peng, S. Bao, D. Dickey, L. Xie, H. Liu e M. Xia. "A New Architecture for Coastal Inundation and Flood Warning Prediction". Marine Technology Society Journal 40, n.º 4 (1 de dezembro de 2006): 71–77. http://dx.doi.org/10.4031/002533206787353205.
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The marine atmosphere, coastal ocean, estuary, harbor and river water systems constitute a physically coupled system. While these systems have always been heavily impacted by coastal storms, increases in population density, infrastructure, and personal and business merchandise have exacerbated the economic and personal impacts of these events over the past half century. As such there has been increased focus on the need for more timely and accurate forecasts of impending events. Traditionally model forecast architectures for coastal storm surge, flooding and inundation of coastal and inland areas have taken the approach of dealing with each system separately: rivers, estuaries, harbors and offshore facing areas. However, given advances in coupled modeling and the availability of real-time data, the ability to accurately predict and project coastal, estuary and inland flooding related to the passage of high energy and wet atmospheric events is rapidly emerging and requires a new paradigm in system architecture. No longer do monthly averaged winds or river discharge or water levels have to be invoked in developing hindcasts for planning purposes or for real-time forecasts. In 1999 a hurricane associated flood on the North Carolina coast took 56 lives and caused more than $6 billion in economic impacts. None of the models existing at that time were able to properly forecast the massive flooding and clearly called for a new model paradigm. Here we propose a model system that couples atmospheric information to fully three dimensional, non-linear time dependent ocean basin, coastal and estuary hydrodynamic models coupled to interactive river models with input of real or modeled winds, observed or modeled precipitation, measured and modeled water levels, and streamflow. The river and estuarine components must both be capable of going into modes of storage or accelerated discharge. Spatial scales must downscale in the horizontal from thousands to tens meters and in the vertical from hundreds to several centimeters. Topography and elevation data should be of the highest resolution available, necessary for highly accurate predictions of the timing and location of the inundation and retreat of flood waters. Precipitation information must be derived from the optimal mix of direct radar, satellite and ground-based observations. Creating the capability described above will advance the modernization of hydrologic services provided by the National Oceanic & Atmospheric Administration and provide more accurate and timely forecasts and climatologies of coastal and estuary flooding. The goal of these climatologies and improved forecasts is to provide better information to local and regional planners, emergency managers, highway patrols and to improve the capacity of coastal communities to mitigate against the impacts of coastal flooding.
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Kontar, Y. Y., U. S. Bhatt, S. D. Lindsey, E. W. Plumb e R. L. Thoman. "Interdisciplinary approach to hydrological hazard mitigation and disaster response and effects of climate change on the occurrence of flood severity in central Alaska". Proceedings of the International Association of Hydrological Sciences 369 (11 de junho de 2015): 13–17. http://dx.doi.org/10.5194/piahs-369-13-2015.
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Abstract. In May 2013, a massive ice jam on the Yukon River caused flooding that destroyed much of the infrastructure in the Interior Alaska village of Galena and forced the long-term evacuation of nearly 70% of its residents. This case study compares the communication efforts of the out-of-state emergency response agents with those of the Alaska River Watch program, a state-operated flood preparedness and community outreach initiative. For over 50 years, the River Watch program has been fostering long-lasting, open, and reciprocal communication with flood prone communities, as well as local emergency management and tribal officials. By taking into account cultural, ethnic, and socioeconomic features of rural Alaskan communities, the River Watch program was able to establish and maintain a sense of partnership and reliable communication patterns with communities at risk. As a result, officials and residents in these communities are open to information and guidance from the River Watch during the time of a flood, and thus are poised to take prompt actions. By informing communities of existing ice conditions and flood threats on a regular basis, the River Watch provides effective mitigation efforts in terms of ice jam flood effects reduction. Although other ice jam mitigation attempts had been made throughout US and Alaskan history, the majority proved to be futile and/or cost-ineffective. Galena, along with other rural riverine Alaskan communities, has to rely primarily on disaster response and recovery strategies to withstand the shock of disasters. Significant government funds are spent on these challenging efforts and these expenses might be reduced through an improved understanding of both the physical and climatological principals behind river ice breakup and risk mitigation. This study finds that long term dialogue is critical for effective disaster response and recovery during extreme hydrological events connected to changing climate, timing of river ice breakup, and flood occurrence in rural communities of the Far North.
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Ghodoosipour, Stolle, Nistor, Mohammadian e Goseberg. "Experimental Study on Extreme Hydrodynamic Loading on Pipelines. Part 1: Flow Hydrodynamics". Journal of Marine Science and Engineering 7, n.º 8 (31 de julho de 2019): 251. http://dx.doi.org/10.3390/jmse7080251.
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Over the past two decades, extreme flood events generated by tsunamis or hurricanes have caused massive damage to nearshore infrastructures and coastal communities. Utility pipelines are part of such infrastructure and need to be protected against potential extreme hydrodynamic loading. Therefore, to address the uncertainties and parameters involved in extreme hydrodynamic loading on pipelines, a comprehensive experimental program was performed using an experimental facility which is capable of generating significant hydraulic forcing, such as dam-break waves. The study presented herein examines the dam-break flow characteristics and influence of the presence of pipelines on flow conditions. To simulate conditions of coastal flooding under tsunami-induced inundation, experiments were performed on both dry and wet bed conditions to assess the influence of different impoundment depths and still water levels on the hydrodynamic features.
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Esherick, Joseph W., e Jeffrey N. Wasserstrom. "Acting Out Democracy: Political Theater in Modern China". Journal of Asian Studies 49, n.º 4 (novembro de 1990): 835–65. http://dx.doi.org/10.2307/2058238.
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For two and a half months in the spring of 1989, China's student actors dominated the world stage of modern telecommunications. Their massive demonstrations, the hunger strike during Gorbachev's visit, and the dramatic appearance of the Goddess of Democracy captured the attention of an audience that spanned the globe. As we write in mid-1990, the movement and its bloody suppression have already produced an enormous body of literature—from eyewitness accounts by journalists (Morrison 1989; Zhaoqiang, Gejing and Siyuan 1989) and special issues of scholarly journals (Australian Journal of Chinese Affairs Nos. 23, 24; The Fletcher Forum of World Affairs 14.4), to pictorial histories (Turnley and Turnley 1989) and documentary collections (Han 1990; Wu 1989), and, most recently, textbook chapters (Spence 1990) and analytical works (Feigon 1990; Nathan 1990)—tracing the development of China's crisis. Despite a flood of material too massive to review in the present context, we still lack a convincing interpretive framework that places the events within the context of China's modern political evolution, and also provides a way to compare China's experience to that of Eastern Europe. Such an interpretation should help us to understand why massive public demonstrations spurred an evolution toward democratic governance in Eastern Europe, but in China led only to the massacre of June 3–4 and the present era of political repression.
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Sakuna-Schwartz, D., P. Feldens, K. Schwarzer, S. Khokiattiwong e K. Stattegger. "Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash-flood deposits". Natural Hazards and Earth System Sciences 15, n.º 6 (12 de junho de 2015): 1181–99. http://dx.doi.org/10.5194/nhess-15-1181-2015.
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Abstract. Tsunami, storm and flash-flood event layers, which have been deposited over the last century on the shelf offshore Khao Lak (Thailand, Andaman Sea), are identified in sediment cores based on sedimentary structures, grain size compositions, Ti / Ca ratios and 210Pb activity. Individual offshore tsunami deposits are 12 to 30 cm in thickness and originate from the 2004 Indian Ocean Tsunami. They are characterized by (1) the appearance of sand layers enriched in shells and shell debris and (2) the appearance of mud and sand clasts. Storm deposits found in core depths between 5 and 82 cm could be attributed to recent storm events by using 210Pb profiles in conjunction with historical data of typhoons and tropical storms. Massive sand layers enriched in shells and shell debris characterize storm deposits. The last classified type of event layer represents reworked flash-flood deposits, which are characterized by a fining-upward sequence of muddy sediment. The most distinct difference between storm and tsunami deposits is the lack of mud and sand clasts, mud content and terrigenous material within storm deposits. Terrigenous material transported offshore during the tsunami backwash is therefore an important indicator to distinguish between storm and tsunami deposits in offshore environments.
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Hughes, D. B., e B. G. Clarke. "The River Aire slope failure at the St. Aidans Extension Opencast Coal Site, West Yorkshire, United Kingdom". Canadian Geotechnical Journal 38, n.º 2 (1 de abril de 2001): 239–59. http://dx.doi.org/10.1139/t00-091.
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The St. Aidans Extension Opencast Coal Site is located in the flood plain of the River Aire 10 km southeast of Leeds, United Kingdom. In March 1988, a massive (600 000 m3) slope failure caused a breach of the riverbanks and flood-protection levee, and so connected the river to the opencast void, resulting in flooding of the site. A lake of about 100 ha and up to 70 m depth was created, and coal winning operations had to be suspended for 10 years. The causes of this slope failure included the effects of previous underground coal mining beneath those seams which were being surface mined, resulting in large tensile strains (up to 10 mm/m) in a heavily faulted zone that lay beneath the river bed and an adjacent navigation canal. The fracturing and opening of existing faults and joints greatly increased the permeability beneath the river, which then acted as a source of continuous recharge as the failed mass moved towards the opencast void. Subsequent remedial and recovery works (costing £20 million) have included the rerouting of the River Aire together with the canal, and pumping the flood water from the void and restarting opencast mining operations (tender sum £36 million) with a new box cut. This paper details the ground conditions and the history of events and discusses the probable mode of failure.Key words: opencast mining, slope failure, flooding, mining subsidence, ground strains, faulting.
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Bhardwaj, Anshuman, e Lydia Sam. "Reconstruction and Characterisation of Past and the Most Recent Slope Failure Events at the 2021 Rock-Ice Avalanche Site in Chamoli, Indian Himalaya". Remote Sensing 14, n.º 4 (16 de fevereiro de 2022): 949. http://dx.doi.org/10.3390/rs14040949.
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Frequent ice avalanche events are being reported across the globe in recent years. On the 7 February 2021, a flash flood triggered by a rock-ice avalanche with an unusually long runout distance, caused significant damage of life and property in the Tapovan region of the Indian Himalaya. Using multi-temporal satellite datasets, digital terrain models (DTMs) and simulations, here we report the pre-event and during-event flow characteristics of two large-scale avalanches within a 5-year interval at the slope failure site. Prior to both the events, we observed short-term and long-term changes in surface velocity (SV) with maximum SVs increasing up to over 5 times the normal values. We further simulated the events to understand their mechanical characteristics leading to long runouts. In addition to its massive volume, the extraordinary magnitude of the 2021 event can partly be attributed to the possible remobilisation and entrainment of the colluvial deposits from previous ice and snow avalanches. The anomalous SVs should be explored further for their suitability as a possible remotely observable precursor of ice avalanches from hanging glaciers. This sequence of events highlights that there is a need to take into account the antecedent conditions, while making a holistic assessment of the hazard.
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Bracco, Fabrizio, Cinzia Modafferi e Luca Ferraris. "The role of media in community resilience: Hindsight bias in media narratives after the 2014 Genoa flood". Geopolitical, Social Security and Freedom Journal 1, n.º 1 (1 de novembro de 2018): 128–51. http://dx.doi.org/10.2478/gssfj-2018-0007.
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Abstract Aim: A massive flood due to exceptional rainfalls devastated the town of Genoa on 9 October 2014. Media reports focused on the disaster, its causes and the political accountabilities. Reading facts after the event is commonly biased by the hindsight perspective and the aim of the paper is to investigate the amount and the potential effects of hindsight bias in terms of citizens risk perception and community resilience. Method: We performed a qualitative analysis of the narratives in the national and local news reports during the aftermath to investigate occurrences of a blaming attitude and cognitive biases. Results: The results showed a considerable amount of sentences that were focused on blaming the forecasters, the Civil Protection System, and the local administration. Many narratives were affected by hindsight bias and described the events as simple and linear chain reactions. This led to counterfactual biases, assuming that a simple intervention on a single factor could have prevented the tragic outcome. Conclusion: We claim that the biased nature of the media narratives could affect the citizens’ risk perception and their attitude towards the institutions, increasing their exposure to future flood-related threats. We propose the appropriate language would generate correct cognitive frames and, therefore, safer behaviour.
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Piton, Guillaume, Firmin Fontaine, Hervé Bellot, Frédéric Liébault, Coraline Bel, Alain Recking e Thérèse Hugerot. "Direct field observations of massive bedload and debris-flow depositions in open check dams". E3S Web of Conferences 40 (2018): 03003. http://dx.doi.org/10.1051/e3sconf/20184003003.
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Sediment detention basins, also called SABO dams, are key facilities in flood protection systems of mountain catchments, specifically in torrents prone to massive bedload transport or debris flows. A better understanding of the processes generating sediment trapping is required to optimize their functioning. Two monitoring stations have been implemented in the French Alps on two torrents: the Manival (Saint-Nazaire-Les-Eymes) and the Claret (Saint-Julien-Mont-Denis). Time-lapse photos show an event depositing 10,000 m3of debris flow in a basin in less than six minutes and several events partially filling the other basin with gravel, impairing its capacity to store debris flows later. After a presentation of the catchments, this paper qualitatively analyzes the dynamics of the depositions. It highlights and stresses the consistency and differences between bedload and debris-flow deposition. Overall, despite clear differences of geomorphic activity, deposits tend to fill the trap basins just enough to enable the sediment transport continuity reestablishment through the basin. The open check dams thus play a role only provided that this continuity precondition is completed. These observations enhance our comprehension of massive sediment trapping in torrents and our capacity to better adjust trap maintenance and design to the objective sought in each site.
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Ramsewak, D., e B. Maharaj. "EXTENT MAPPING OF A MAJOR FLOODING EVENT ON THE ISLAND OF TRINIDAD USING SPACE-BORNE SYNTHETIC APERTURE RADAR". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W16 (1 de outubro de 2019): 527–30. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w16-527-2019.
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Abstract. Flooding events around the world have been increasing both in their occurrence and their intensities within recent decades. Studies have shown that this is most likely linked to climate change effects and anthropogenic activities that lead to pollution. Irrespective of the cause, floods incur massive economic and human losses. Synoptic data on flooding events help to support the planning and management efforts during this disaster event. Remotely sensed data, particularly from satellites is useful for mapping and monitoring large scale flooding events. More specifically, synthetic aperture radar (SAR) allows for data acquisition despite the interference of clouds and other atmospheric elements such as fog, light rain and mist. This study utilized SAR data from the Sentinel–1 satellite to map a major flooding event on the island of Trinidad which occurred during October 18–21, 2018. The peak of the flooding was estimated to have occurred on October 20, 2018. The SAR images were first calibrated then geometrically corrected and filtered. A threshold method was then applied to extract the inundated areas. A proprietary algorithm implemented by Geospatial Enabling Technologies (GET) and based on SNAP software, was used for processing Sentinel-1 imagery to separate the open water and non-water (land) areas from the images. Outputs were then integrated into ArcGIS 10.6 mapping software and the extents of the flooded areas were delineated based on the available data. By applying this method to a Sentinel–1 image captured on October 19, 2018 it was revealed that the total flooded area on that date was 9.94 square kilometres. This study provides a brief illustration of the value of SAR data for flood delineation and mapping but also highlights some of the limitations that can be involved when using such technology.
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Larsen, Guðrún, Maria H. Janebo e Magnús Tumi Gudmundsson. "The explosive basaltic Katla eruption in 1918, south Iceland I: Course of events, tephra fall and flood routes". Jökull 71, n.º 71 (8 de dezembro de 2021): 1–20. http://dx.doi.org/10.33799/jokull2021.71.001.
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The 23-day long eruption of the ice-covered Katla volcano in 1918 began on October 12 and was over by November 4. Seismicity preceding and accompanying the onset had already started by 11:30 on October 12, while the eruption broke through the glacier around 3 PM. The plume rose to 14–15 km on the first day. The eruption caused widespread tephra fall, accompanied by lightning and thunder. Tephra fall from the intense first phase (October 12–14) was reported from Höfn, 200 km east of Katla, Reykjavík, 150 km to the west and Akureyri, 240 km to the north. The initial phase was followed by more sporadic activity for a week, and a second intense phase (October 22–24), with heavy tephra fall in populated areas east and south of the volcano. Skaftártunga (25–35 km east of Katla), was the worst hit farming district, with reported tephra thickness of 6.5–10 cm in total, collecting into drifts tens of cm thick. The Vík village suffered almost continuous tephra fall for 13 hours on October 24 and 25, leaving a 2 to 4 cm thick tephra layer on the ground. Tephra reached Reykjavík four times but minor tephra fallout («1 mm) occurred. Tephra also reached northern, western and eastern Iceland. In addition to producing the 0.9–1.0 km3 tephra layer, which may as freshly fallen have been 1.1–1.2 km3 , the eruption was accompanied by a jökulhlaup that flooded the Mýrdalssandur plain and neighbouring areas. The jökulhlaup on October 12 had two separate phases. The first phase is considered to have flowed supraglacially down the lower parts of the Kötlujökull outlet glacier into the Leirá, Hólmsá and Skálm rivers (northern fork), and the Sandvatn and Múlakvísl rivers (southern fork). It was much more widespread than the second phase which emerged from below the glacier snout and was confined to the western part of Mýrdalssandur. That phase carried huge icebergs and massive sediment load onto the sandur plain.
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Deivendran P, Et al. "Machine Learning based IoT Flood Rediction Using Data Modeling and Decision Support System". International Journal on Recent and Innovation Trends in Computing and Communication 11, n.º 9 (5 de novembro de 2023): 2489–99. http://dx.doi.org/10.17762/ijritcc.v11i9.9318.
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An essential step in supplying data for climate impact studies and evaluations of hydrological processes is rainfall prediction. However, rainfall events are complex phenomenon’s that continue to be difficult to forecast. In this paper , we present unique hybrid models for the prediction of monthly precipitation that include Seasonal Artificial Neural Networks and Discrete wavelet transforms are two pre-processing methods, together with Artificial Neural Networks have two feed forward neural networks. The temporal series of observed monthly rainfall from Vietnam’s Ca Mau hydrological station were decomposed into three subsets by seasonal decomposition and five sub signals and four levels by wavelet analysis. The methods for predicting rainfall that use feed forward artificial neural networks (ANN) and seasonal artificial neural network (SANN) were fed with the processed data. The classic genetic method and simulated annealing method backed by using an integrated moving average and autoregressive moving was contrasted with the predicted models for model evaluation. The results showed that non-stationary regarding issues with non-linear time series, such forecasting rainfall could be satisfactorily simulated. The SANN model was integrated with the wavelet transform and seasonal decomposition are both used. Techniques, however the wavelet transform method produced the most accurate monthly rainfall data, Predictions. Due to the effects of climate change, nations including the Japan, China, the United States of America, and Taiwan, etc., have recently experienced severe and devastating natural disasters. One of the biggest causes of the destruction in Asian nations like china, India, Bangladesh, Sri Lanka, etc. is the flood. The danger of fatality from these floods is increased by 78% as information technology advances; there is a demand for simple access to massive amounts of cloud storage and computing capacity.
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Guo, Xiaohua, Jiuchuan Wei, Yudong Lu, Zhaojun Song e Huimin Liu. "Geomorphic Effects of a Dammed Pleistocene Lake Formed by Landslides along the Upper Yellow River". Water 12, n.º 5 (9 de maio de 2020): 1350. http://dx.doi.org/10.3390/w12051350.
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In a previous study two pairs of paleo-landslides within an 8 km reach of the upper Yellow River were studied and dated back to ca. 80 ka, however the relationship between these two pairs of paleo-landslides were not explored. This study inferred that the initial pair of landslides (Dehenglong and Suozi) appearing contiguously and forming an upstream 46 km-long lake along the river may be triggered by earthquake events from nearby capable faults. Subsequently, backwater inundating the valley floor as the dammed lake formed may cause shear stress of sediments lowered on steep slopes adjacent to the River, and eventually induce the other two additional landslides (Xiazangtan and Kangyang) ~8 km upstream. This could be inferred from two optically stimulated luminescence (OSL) samples yielding ca. 80 ka also, which were collected from asymmetric folds 10 to 30 cm in amplitude within the bedding plane between lake/lakeshore sediment and landslide mass at the front lobes of the two additional landslides. We estimated the maximum volume of this dammed lake was 38 km3 and may generate an outburst flood with an estimated peak discharge of 6.1 × 105 m3/s, which may cause massive geomorphic effects and potential disasters upstream and downstream. It is important to better understand the geomorphic process of this damming event in mountainous area with respect to reflecting tectonic uplift, paleoclimatic change and forecast and mitigate hazards on the northeast Tibetan Plateau.
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Crane, Kelsey, Allison Bohanon, Jonathan Rich, Leta McCullough e Desiree' Cunningham. "Flash flooding on Mars could be linked to large fault slip events". Leading Edge 41, n.º 10 (outubro de 2022): 709–17. http://dx.doi.org/10.1190/tle41100709.1.
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Studies of Martian fault-related landform morphology have noted an interesting phenomenon associated with large thrusts — isolated channels that run from the crests of these landforms down their slopes. One such example is Ogygis Rupes, an east-verging, 180 km long thrust-fault-related landform located near 55°W, 33°S. Geometric modeling efforts have indicated the fault underlying this landform has experienced approximately 2850 m of slip, and a large anticlinal fold has grown above the fault. We mapped 72 channels on back and front slopes of this massive landform at 1:24,000 scale on 10 mosaiced Context Camera images (6 m/pixel) and one High-Resolution Imaging Experiment image (2.5 m/pixel). The morphology of these channels indicates that they formed through flash flood events that originated near the hinge of the fold. We propose that these flooding events were due to the melting of subsurface ice during fault slip. We apply a thermodynamic model for heat generation along the fault surface during slip events of various magnitudes to estimate the volumes of water produced during each hypothetical event. By comparing these estimates to channel discharge values estimated from channel morphologies, we resolve fault slip magnitudes that could produce the channels. We find that slip events of approximately 28 m produce enough heat to melt the ice associated with channel flow (4.867 × 109 m3). This estimate is based on slip within a 1 m basaltic fault zone, with a friction coefficient of 0.6 where all pore space is occupied by water ice. Results indicate that only mature faults with well-developed, fractured hinges are capable of both (1) melting enough subsurface ice and (2) transporting the water to the surface to result in flooding, explaining why this impressive phenomenon remains a rare but important hazard of which to be aware during planning of the exploration and settlement of Mars.
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Adhikari, Madhav, e Bharat Bhandari. "River channel dynamics and flooding: A case of motorable bridge collapse due to abrupt flood in Chhabdi Khola, Tanahun, Nepal". Nepal Journal of Environmental Science 11, n.º 2 (21 de dezembro de 2023): 9–22. http://dx.doi.org/10.3126/njes.v11i2.60015.
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The monsoon season in Nepal brings calamitous events like riverbank erosion, toe cutting, and the structural failure of bridges due to floods. In July 2021, a motorable bridge in Bhadgaun, Tanahun district, Nepal, collapsed during a massive flood in Chhabdi Khola. The study aims to comprehensively document the aftermath, specifically focusing on the causal factors that led to the damage of the Chhabdi Khola Dovan Bridge. The study delves into an in-depth analysis of the stream's channel morphology, with the 5.85 kilometers Chhabdi Khola partitioned into 28 distinct segments, each spanning approximately 200 meters. These segments, sequentially labeled from Site 1 to Site 28, encompass the area extending from the upstream at Chhabdi Barah temple to the downstream at bridge’s location. Rigorous measurements of length, breadth, and depth at each site form the basis for volumetric assessments of the stream. The study revolves around contrasting paleo channel attributes with contemporary alterations within the Chhabdi Khola catchment. The analysis leverages precipitation data sourced from the Department of Hydrology and Meteorology (DHM) to discern precipitation trends within the Chhabdi Khola catchment area. The hydrographic data underwent trend analysis utilizing Mann-Kendall and Sen's slope method through R software (version 4.3.2). The collapse of the Chhabdi Khola Dovan Bridge resulted from intense water flow and debris due to heavy rainfall and a narrow outlet near the bridge, impacting the local population and land users facing the enduring aftermath of a catastrophic monsoon event. The study highlights the significance of understanding river dynamics in small streams and advocates for proactive disaster preparedness measures, even in seemingly small river channels.
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Sakuna-Schwartz, D., P. Feldens, K. Schwarzer, S. Khokiattiwong e K. Stattegger. "Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash flood deposits". Natural Hazards and Earth System Sciences Discussions 2, n.º 12 (1 de dezembro de 2014): 7225–67. http://dx.doi.org/10.5194/nhessd-2-7225-2014.
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Abstract. Tsunami, storm and flash event layers, which have been deposited over the last century on the shelf offshore from Khao Lak (Thailand, Andaman Sea), are identified in sediment cores based on sedimentary structures, grain size compositions, Ti / Ca ratios and 210Pb activity. Individual offshore tsunami deposits are 12 to 30 cm in thickness and originate from the 2004 Indian Ocean tsunami. They are characterized by (1) the appearance of sand layers enriched in shells and shell debris, (2) cross lamination and (3) the appearance of rip-up clasts. Storm deposits found in core depths between 5 and 82 cm could be attributed to individual storm events by using 210Pb dating in conjunction with historical data of typhoons and tropical storms and could thus be securely differentiated from tsunami deposits. Massive sand layers enriched in shells and shell debris characterize the storm deposits. The last classified type of event layer represents flash floods, which is characterized by a fining-upward sequence of muddy sediment. The most distinct difference between the storm and tsunami deposits is the lack of rip-up clasts, mud, and terrigenous material within the storm deposits. Terrigenous material transported offshore during the tsunami backwash is therefore an important indicator to distinguish between offshore storm and tsunami deposits.
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Pérez-Martín, Miguel Ángel. "Understanding Nutrient Loads from Catchment and Eutrophication in a Salt Lagoon: The Mar Menor Case". Water 15, n.º 20 (12 de outubro de 2023): 3569. http://dx.doi.org/10.3390/w15203569.
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Eutrophication is a significant threat to aquatic ecosystems worldwide, and the Mar Menor hypersaline lagoon exemplifies a coastal lagoon at risk of algal blooms due to excessive nutrient loads, nitrogen, and phosphorus. These nutrients originate from various sources within the lagoon’s catchment area, including urban, agricultural, and livestock activities. Regular and occasional loads—during flood events—produce algal blooms that can significantly reduce the water oxygen content and cause massive mortalities, as observed in recent years. A daily algal growth model (Mmag) was developed to better understand the processes and determine key elements such as the phosphorus water–sediment interchange and deep water plants that effect the entire ecosystem and algal growth. The analysis developed can be applied in other wetlands around the world facing similar challenges. In the Mar Menor, both nitrogen and phosphorus have high relevance depending on the period of the year and the phosphorus legacy in the sediments. Floods are the main phosphorus input to the lagoon (80–90%), which goes to the sediment and is released after during the warm months in the following years. At the end of summer, phosphorus released from the sediment and the regular nitrate inputs to the lagoon increase the algal bloom risk. The good status of deep water plants, which reduces the phosphorus release in summer, is a key element to reduce the algal bloom risk. An integrated set of measures is required to reduce the mean chlorophyll to levels under 1 or 0.5 µgChla/L that can make the Mar Menor more robust and resilient.
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Cho, Hyeonu, e Seungyong Choi. "Investment Priorities of the Budgets for Disaster and Safety Management Projects Based on Euclidean Distance with AHP". Journal of the Korean Society of Hazard Mitigation 21, n.º 3 (30 de junho de 2021): 23–37. http://dx.doi.org/10.9798/kosham.2021.21.3.23.
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The object of this study is to determine investment priorities for various types of disasters and accidents in order to promote the investment efficiency of disaster and safety management budgets. To this end, data were collected on 35 types of disasters and accidents and damage statistics for the five most recent years (2014-2018) from 43 disaster and safety management projects budgets. Factors are (ｉ) the damage status of overall disasters and accidents: annual average number of occurrences, human casualties, and property losses, and (ⅱ) the characteristics of large-scale events: occurrence cycle, human casualties per disaster, and property losses per disaster. Investment priority was determined using Euclidean distance with weights determined by the AHP (Analytical Hierarchy Process) to represent the current status of damage caused by disasters and accidents. As a result, storm⋅flood and maritime accidents were found to have greatest investment priority. Heat waves, heavy snows (including cold waves), infectious diseases, suicides, fires (including explosions), and accidents in vulnerable social groups show a higher ranking of investment priority. Massive investment in disaster and safety management focusing on these types is necessary.
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Knapp, Sibylle, Michael Schwenk e Michael Krautblatter. "Geophysical evidence of massive hyperconcentrated push waves with embedded toma hills caused by the Flims rockslide, Switzerland". Earth Surface Dynamics 10, n.º 6 (21 de novembro de 2022): 1185–93. http://dx.doi.org/10.5194/esurf-10-1185-2022.
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Abstract. Rockslides and rock avalanches are amongst the most destructive natural hazards in the alpine environment. The Flims rockslide is the largest known rock-slope failure in the Alps, which provides excellent outcrops and has fascinated researchers since the early 20th century. The postulated impact of the Flims rockslide on Lake Bonaduz caused intensely fluidized rock material, which formed the Bonaduz Formation and toma hills, probably accompanied by a catastrophic impact wave. So far, this hypothesized sequence of events is based only on sedimentological and geomorphic analyses. We present electrical resistivity tomography (ERT) profiles, which we correlated with the sedimentological information obtained from outcrops and drill logs. Here, geophysical evidence on a metre and decametre scale complements prior outcrop and sample intervals with much smaller representativeness. Our study provides new insights into the distribution, thickness, and internal structure of the Bonaduz Formation and the toma hills as well as other flood deposits around the Ils Aults, where we studied the sediment to a depth of up to 160 m. There is geophysical evidence that the Bonaduz Formation formed an onlap onto the Ils Aults and is thus the stratigraphically younger unit. The toma hills consist of blocky cores with an agglomeration of smaller mixed sediments, which drift and override the toma core, causing their smoothly shaped top. We consider simultaneous transport of the hills within the Bonaduz Formation but a slightly slower movement at the front due to a bulldozing effect. This study contributes to an improved understanding of (i) the complex stratigraphical context of the Tamins and Flims deposits, (ii) water-rich entrainment in rock avalanches, and (iii) the genesis and transport of toma hills.
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Brodie, Jon, Thomas Schroeder, Ken Rohde, John Faithful, Bronwyn Masters, Arnold Dekker, Vittorio Brando e Mirjam Maughan. "Dispersal of suspended sediments and nutrients in the Great Barrier Reef lagoon during river-discharge events: conclusions from satellite remote sensing and concurrent flood-plume sampling". Marine and Freshwater Research 61, n.º 6 (2010): 651. http://dx.doi.org/10.1071/mf08030.
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Intense wet-season rainfall in January 2005 caused rivers in the Mackay–Whitsunday region of Queensland, Australia, to produce large discharges to the Great Barrier Reef (GBR) lagoon. The regional land use is dominated by sugarcane cultivation, beef grazing and urban uses. The high nutrient (nitrogen and phosphorus) fluxes from these land uses via river runoff produced a massive phytoplankton bloom in the GBR lagoon, which, after 9 days, had spread 150 km offshore. The plume and algal bloom surrounded inner-shelf reefs of the GBR such as Brampton Island Reef and its spread was tracked with a variety of satellite sensors including MODIS, SeaWiFS and Landsat over the 9-day period. The ability to be able to access imagery from a large number of satellite sensors allowed almost daily estimates of the extent of plume to be made, despite periods of cloud. Analysis of water samples from the plume revealed elevated (2–50 times higher) concentrations of Chlorophyll a (and hence phytoplankton biomass), up to 50 times higher than in non-flood conditions, nutrients (2–100 times higher) and herbicide residues (10–100 times higher) compared with GBR lagoon waters in non-discharge conditions. The concentration data from the samples and estimated exposure periods from the satellite images allowed estimates of the exposure of GBR marine ecosystems (coral reefs, the pelagic community, seagrass beds and mangrove forests) to the terrestrial contaminants to be made.