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1.
Grid system for flood extent extraction from satellite images 总被引：4，自引：2，他引：2
Floods are among the most devastating natural hazards in the world, affecting more people and causing more property damage than any other natural phenomena. One of the important problems associated with flood monitoring is a flood extent extraction from satellite imagery, since it is impractical to acquire the flood area through field observations. This paper presents a new method to the flood extent extraction from synthetic-aperture radar (SAR) images that is based on intelligent computations. In particular, we apply artificial neural networks, self-organizing Kohonen’s maps (SOMs), for SAR image segmentation and classification. We implemented our approach in a Grid system that was used to process data from three different satellite sensors: ERS-2/SAR during the flooding on the river Tisza, Ukraine and Hungary (2001), ENVISAT/ASAR WSM (Wide Swath Mode) and RADARSAT-1 during the flooding on the river Huaihe, China (2007). 相似文献
2.
Marcin Szwagrzyk Dominik Kaim Bronwyn Price Agnieszka Wypych Ewa Grabska Jacek Kozak 《Natural Hazards》2018,94(1):227-240
Flooding is a major environmental hazard in Poland with risks that are likely to increase in the future. Land use and land cover (LULC) have a strong influencing on flood risk. In the Polish Carpathians, the two main projected land use change processes are forest expansion and urbanization. These processes have a contradictory impact on flood risk, which makes the future impact of LULC changes on flooding in the Carpathians hard to estimate. In this paper, we investigate the impact of the projected LULC changes on future flood risk in the Polish Carpathians for the test area of Ropa river basin. We used three models of spatially explicit future LULC scenarios for the year 2060. We conduct hydrological simulations for the current state and for the three projected land use scenarios (trend extrapolation, ‘liberalization’ and ‘self-sufficiency’). In addition, we calculated the amount of flood-related monetary losses, based on the current flood plain area and both actual and projected land use maps under each of the three scenarios. The results show that in the Ropa river, depending on scenario, either peak discharge decreases due to the forest expansion or the peak discharge remains constant—the impact of LULC changes on the hydrology of such mountainous basins is relatively low. However, the peak discharges are very diverse across sub-catchments within the modeling area. Despite the overall decrease of peak discharge, there are areas of flow increase and there is a substantial projected increase in flood-related monetary losses within the already flood-prone areas, related to the projected degree of urbanization. 相似文献
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4.
Forecasting flood risk in the Indus River system using hydrological parameters and its damage assessment 总被引：1，自引：1，他引：0
Hydrological parameters are among the widely used parameters in assessing flood risk. On the other hand, anticipated flood damages, in case of flooding, are estimated with the help of expected losses in areas nearer to the watercourse. The major source of almost every-year flooding in Pakistan is the Indus River system that comprises the major rivers of Pakistan. We first use observed data to construct simulated data models based on various probability distributions namely normal, lognormal, Weibull, largest extreme value, gamma-3, and log-Pearson type-3 distributions and thereby compute probable maximum flood. Secondly, we perform log-Pearson type-3 analysis with and without historic adjustment on the observed data series of 17 years to forecast floods with return periods T of 2, 5, 10, 25, 50, 100, and 200 years. We also categorize the river structures based on the risk of flooding. Lastly, we estimate risk of flood damages in terms of expected losses based on observed data. The present study reveals that the log-Pearson type-3 distribution is relatively better for estimating probable maximum flood. We use exceedence probability to assess the risk of flooding in the various structures of the said rivers. The analysis shows that flood damages in Pakistan may be reduced by increasing the design capacity of the structures and also by giving awareness to people about the flood-generating factors. 相似文献
5.
A flood vulnerability index for coastal cities and its use in assessing climate change impacts 总被引：4，自引：2，他引：2
Worldwide, there is a need to enhance our understanding of vulnerability and to develop methodologies and tools to assess vulnerability. One of the most important goals of assessing coastal flood vulnerability, in particular, is to create a readily understandable link between the theoretical concepts of flood vulnerability and the day-to-day decision-making process and to encapsulate this link in an easily accessible tool. This article focuses on developing a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding. It is applied to nine cities around the world, each with different kinds of exposure. With the aid of this index, it is demonstrated which cities are most vulnerable to coastal flooding with regard to the system??s components, that is, hydro-geological, socio-economic and politico-administrative. The index gives a number from 0 to 1, indicating comparatively low or high coastal flood vulnerability, which shows which cities are most in need of further, more detailed investigation for decision-makers. Once its use to compare the vulnerability of a range of cities under current conditions has been demonstrated, it is used to study the impact of climate change on the vulnerability of these cities over a longer timescale. The results show that CCFVI provides a means of obtaining a broad overview of flood vulnerability and the effect of possible adaptation options. This, in turn, will allow for the direction of resources to more in-depth investigation of the most promising strategies. 相似文献
6.
Large-scale assessment of flood risk and the effects of mitigation measures along the Elbe River 总被引：2，自引：1，他引：1
The downstream effects of flood risk mitigation measures and the necessity to develop flood risk management strategies that
are effective on a basin scale call for a flood risk assessment methodology that can be applied at the scale of a large river.
We present an example of a rapid flood risk assessment methodology for the Elbe River. A 1D hydraulic routing model is extended
by including the effect of planned (regulated and unregulated) and unintended retention (dike breaches) on the peak water
levels. We further add an inundation model for dike breaches due to dike overtopping and a macroscale economic approach to
assess the flood damage. The flexible approach to model the effects of measures by means of volume storage functions allows
for rapid assessment of combinations of retention measures of various proposed dimensions and at multiple locations. The method
allows for the comparison of the flood risk at the scale of the main river trajectory, which has not been possible for the
Elbe River to date. The model is applied to a series of exemplary flood risk mitigation measures to show the downstream effects
and the additive effects of combinations of measures on the flood risk along the river. We further demonstrate the increase
in the downstream flood risk resulting from unilateral decisions to increase the dike height at upstream locations. As expected,
the results underline the potential effectiveness of increased retention along the river. The effects of controlled retention
at the most upstream possible location and largest possible extent generate the most pronounced reduction of average annual
damage. As expected, the effect of uncontrolled retention with dike relocations is significantly lower. 相似文献
7.
The 4th IPCC report highlights the increased vulnerability of the coastal areas from floods due to sea-level rise (SLR).
The existing coastal flood control structures in Bangladesh are not adequate to adapt these changes and new measures are urgently
necessary. It is important to determine the impacts of SLR on flooding to analyse the performance of the existing structures
and corresponding impact to plan for suitable adaptation and mitigation measures to reduce the impacts of floods on coastal
zone. The study aims to develop a comprehensive understanding of the possible effects of SLR on floods in the coastal zone
of Bangladesh. A hydrodynamic model, which is a combination of surface and river parts, was utilized for flood simulation.
The tool was applied under a range of future scenarios, and results indicate both spatial variability of risk and changes
in flood characteristics between now and under SLR. Estimated impact on population, infrastructure and transportation is also
exposed. These types of impact estimation would be of value to flood plain management authorities to minimize the socio-economic
impact. 相似文献
8.
Intense rainstorms in 2008 resulted in wide-spread flooding across the Midwestern United States. In Wisconsin, floodwater inundated a 17.7-km2 area on an outwash terrace, 7.5 m above the mapped floodplain of the Wisconsin River. Surface-water runoff initiated the flooding, but results of field investigation and modeling indicate that rapid water-table rise and groundwater inundation caused the long-lasting flood far from the riparian floodplain. Local geologic and geomorphic features of the landscape lead to spatial variability in runoff and recharge to the unconfined sand and gravel aquifer, and regional hydrogeologic conditions increased groundwater discharge from the deep bedrock aquifer to the river valley. Although reports of extreme cases of groundwater flooding are uncommon, this occurrence had significant economic and social costs. Local, state and federal officials required hydrologic analysis to support emergency management and long-term flood mitigation strategies. Rapid, sustained water-table rise and the resultant flooding of this high-permeability aquifer illustrate a significant aspect of groundwater system response to an extreme precipitation event. Comprehensive land-use planning should encompass the potential for water-table rise and groundwater flooding in a variety of hydrogeologic settings, as future changes in climate may impact recharge and the water-table elevation. 相似文献
9.
Quantitative methods for estimating flood fatalities: towards the introduction of loss-of-life estimation in the assessment of flood risk 总被引：1，自引：0，他引：1
Risk, including flood risk, can be defined as ??the combination of the probability of an event and its consequences??. Assessing and managing the risk from flooding should explicitly include the estimation of impacts to people. Extensive research is currently ongoing looking at both quantitative and qualitative approaches for assessing flood impacts on people. Although there is some literature available on such approaches, examples of methodological and routinely applications of these methodologies as part of flood risk assessments are rare. This paper focuses on quantitative approaches for estimating impacts of flooding to people, notably on methods for assessing fatality numbers associated with flooding. Three methods for assessing losses of life are discussed in detail. The methods discussed here constitute the forefront of research in Canada, UK and The Netherlands. These methods provide an assessment of the physical consequences of flooding on people and can be used to introduce the impacts to people as quantitative metric for the assessment of flood risk. In this paper, the three methodologies are discussed and applied in a UK case study reproducing the 1953 East Coast flood event. This study aims to provide a comprehensive comparison on both the reliability and the applicability of the methods. We analyse possible added values on using of these methods in systematic analyses, aiming to provide guidelines for applying these methods for flood fatality risk assessment. 相似文献
10.
The authors investigated geomorphological features on the central plain of Thailand utilizing satellite remote sensing data and made geomorphological land classification map showing flood-stricken area. Land classification maps showing flood-striken area tell us former flood inundation area, such as inundation depth, inundation width, flood flow course and flood direction, as well as estimating of the features of flooding. Thus map is useful for planning of flood control works.We classified land form units in the central plain of Thailand as following; delta, tidal flat, lagoon, mud spit, back marsh, natural levee, fan and former river course and so on. After that, the principal component analysis is applied to Landsat TM data and gives good results for photo interpretation of land form units and we transfer geomorphological land classification map to make zoning map of flood risk for the purpose of evaluating the flood damages. 相似文献
11.
Participatory modelling of vulnerability and adaptive capacity in flood risk management 总被引：1，自引：1，他引：0
Dagmar Haase 《Natural Hazards》2013,67(1):77-97
Being part of the EU-project NeWater on adaptive water resources management, the Ukrainian Tisa river basin is presented as an example for a participatory study dealing with flood risk, vulnerability and adaptive capacity. The Tisa valley is regularly and increasingly faced with hazardous floods at very limited local budgets and high poverty rates. In order to make flood risk management more resilient and better adapted to climate change, scientists and stakeholders applied a set of qualitative and quantitative modelling approaches to characterise prevailing flood risk management, to discover respective vulnerabilities and to identify barriers and options of adaptive capacity. The former were found in the defensive mentality paradigm and the inert and hierarchical structure of present institutions, the latter in, firstly, an enormous potential to link the knowledge of different stakeholders in the region, secondly, a better integration of the individual flood preparedness of households and thirdly, the active involvement of the Church as institution in local flood risk management. 相似文献
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13.
很多城市缺乏洪灾灾情资料,导致缺少洪灾损失量化的有效手段。为满足城市洪涝日益严峻的风险管理需求,亟需缺灾情资料城市的洪灾损失定量评估方法。提出了"因子变异-动态比拟-目标驱动-情景拟合"的缺灾情资料洪灾损失率函数构建方法:借鉴等比例替代思想,采用多引用对象和多特征指标构建变异比拟因子;建立以变差系数最小为目标的动态比拟方法,形成移植样本矩阵;以Beta分布概率最大为驱动目标,确定水深-损失率拟合序列;设置多拟合情景,以拟合相关系数最大为准则,优选洪灾损失率函数。以郑州市为例,模拟4种土地利用类型的洪灾损失率函数,结果表明,本文提出的缺资料城市洪灾损失率函数构建方法可行,特征组合指标呈现动态变化性,多种函数组合拟合效果最优。 相似文献
14.
P. J. Ward M. A. Marfai F. Yulianto D. R. Hizbaron J. C. J. H. Aerts 《Natural Hazards》2011,56(3):899-916
Coastal flooding poses serious threats to coastal areas, and the vulnerability of coastal communities and economic sectors
to flooding will increase in the coming decades due to environmental and socioeconomic changes. It is increasingly recognised
that estimates of the vulnerability of cities are essential for planning adaptation measures. Jakarta is a case in point,
since parts of the city are subjected to regular flooding on a near-monthly basis. In order to assess the current and future
coastal flood hazard, we set up a GIS-based flood model of northern Jakarta to simulate inundated area and value of exposed
assets. Under current conditions, estimated damage exposure to extreme coastal flood events with return periods of 100 and
1,000 years is high (€4.0 and €5.2 billion, respectively). Under the scenario for 2100, damage exposure associated with these
events increases by a factor 4–5, with little difference between low/high sea-level rise scenarios. This increase is mainly
due to rapid land subsidence and excludes socioeconomic developments. We also develop a detemporalised inundation scenario
for assessing impacts associated with any coastal flood scenario. This allows for the identification of critical points above
which large increases in damage exposure can be expected and also for the assessment of adaptation options against hypothetical
user-defined levels of change, rather than being bound to a discrete set of a priori scenarios. The study highlights the need
for urgent attention to the land subsidence problem; a continuation of the current rate would result in catastrophic increases
in damage exposure. 相似文献
15.
James Andrew Griffiths Fangfang Zhu Faith Ka Shun Chan David Laurence Higgitt 《地学前缘(英文版)》2019,10(2):363-372
Urban drainage systems in coastal cities in SE China are characterized by often complex canal and sluicegate systems that are designed to safely drain pluvial flooding whilst preventing tidal inundation.However, the risk of coastal flooding in the region is expected to increase over the next 50-100 years, as urban areas continue to expand and sea-levels are expected to rise. To assess the impact of projected sealevel rise on this type of urban drainage system, a one-dimensional model and decision support tool was developed. The model indicated that although sea-level rise represents a significant challenge, flood probability will continue to be most influenced by rainfall. Events that are significant enough to cause flooding will most likely be minimally impacted by changes to the tidal frame. However, it was found that a sea-level rise of up to 1.2 m by 2010 would result in increased drainage times and higher volumes of over-topping when flooding occurs. 相似文献
16.
Preliminary flood risk assessment: the case of Athens 总被引：3，自引：2，他引：1
Flood mapping, especially in urban areas, is a demanding task requiring substantial (and usually unavailable) data. However,
with the recent introduction of the EU Floods Directive (2007/60/EC), the need for reliable, but cost effective, risk mapping
at the regional scale is rising in the policy agenda. Methods are therefore required to allow for efficiently undertaking
what the Directive terms “preliminary flood risk assessment,” in other words a screening of areas that could potentially be
at risk of flooding and that consequently merit more detailed attention and analysis. Such methods cannot rely on modeling,
as this would require more data and effort that is reasonable for this high-level, screening phase. This is especially true
in urban areas, where modeling requires knowledge of the detailed urban terrain, the drainage networks, and their interactions.
A GIS-based multicriteria flood risk assessment methodology was therefore developed and applied for the mapping of flood risk
in urban areas. This approach quantifies the spatial distribution of flood risk and is able to deal with uncertainties in
criteria values and to examine their influence on the overall flood risk assessment. It can further assess the spatially variable
reliability of the resulting maps on the basis of the choice of method used to develop the maps. The approach is applied to
the Greater Athens area and validated for its central and most urban part. A GIS database of economic, social, and environmental
criteria contributing to flood risk was created. Three different multicriteria decision rules (Analytical Hierarchy Process,
Weighted Linear Combination and Ordered Weighting Averaging) were applied, to produce the overall flood risk map of the area.
To implement this methodology, the IDRISI Andes GIS software was customized and used. It is concluded that the results of
the analysis are a reasonable representation of actual flood risk, on the basis of their comparison with historical flood
events. 相似文献
17.
This article evaluates some of the factors which limit the human benefits of hazard warnings, with specific reference to flood
warnings, and we conclude by suggesting ways of enhancing these benefits. We focus mainly upon the economic benefits generated
by flood damage savings by households that warnings facilitate; health effects of flooding and flood warnings; and the effects
of warnings on loss of life and physical injury. Our results, based partly upon surveys of flooded households, reveal that
economic benefits are currently more limited than we previously thought, but that for several reasons these benefits are likely
to be under-estimated. We argue that the intangible benefits to public health, safety and security must also be taken into
account in decisions about investment in flood warnings. In England and Wales, the public’s response to flood warnings is
currently low and is a key benefit-limiting factor which could begin to undermine a recent major shift in national flood risk
management policy towards a more people-centred, portfolio approach in which changing human behaviour is viewed as important.
Using a trans-disciplinary approach, we discuss the evidence and literature surrounding this poor response, and suggest a
number of ways in which the issue may be addressed in future. 相似文献
18.
Analysis of flood causes and associated socio-economic damages in the Hindukush region 总被引：1，自引：0，他引：1
Pakistan is exposed to numerous hazards, but the problem of recurrent floods has been causing massive losses to lives and
other properties. Swat valley is no exception to it. In this paper, an attempt has been made to analyse the causes and associated
socio-economic impacts of floods on the Swat valley, Pakistan. Swat valley falls in the Hindukush region, North-west-Pakistan.
The valley has been studied with special reference to its physical and socio-economic environment. Similarly, three-sample
villages were also randomly selected from the active floodplain for micro-level analysis. The sample villages include Ningolai,
Delay and Ghureijo. All the three-sample communities are located on the right bank of river Swat. This area is located in
the active flood zone of Swat valley. The analysis revealed that in the study area, floods occur during summer season, which
is mainly caused by heavy rainfall as well as rapid melting of snow and glacier. Besides these, there are some floods intensifying
factors, which accelerate intensity of floods and enhance resultant damages in the valley. It was found that during flood
season, water overflows the natural levees and trigger tremendous loses to housing, agricultural land, standing crops and
other properties. The flood-related Government Departments have only implemented limited structural mitigation measures. However,
in addition to structural measure, land-use zoning and flood abatement strategies would largely help in reducing the adverse
consequences of this recurrent phenomenon. 相似文献
19.
The territory of Transbaikalia (Russia) is subject to occasional large-scale flooding. One of the most significant events in terms of scale and consequences is the historical flood that occurred in August 1897. In this article, we have tried to reconstruct the flood event. For this purpose, we have used all available historical sources (official statistical data, newspaper publications). The flood was observed almost simultaneously in two river basins (the Selenga and Shilka rivers). The main cause of the catastrophic flood was the abnormally intensive rainfall in the Hentey Mountains (Mongolia) and in Chikokonsky Ridge (southern Transbaikalia) in summer 1897. We have singled out four flood stages on the basis of the dates of flooding in different settlements. The flooding was accompanied by silting of considerable areas, and formation of new channels in local places. The flood in August 1897 in Transbaikalia, Russia, clearly demonstrated the vulnerability of both the environment and society to such catastrophic events. 相似文献
20.
Shigeko Haruyama 《GeoJournal》1993,31(4):327-334
The author has investigated the micro-geomorphology of the area flooded by the Chao Phraya river, in the central plain of Thailand. The hydrological condition of the Chao Phraya river which occurs throughout most of this plain has changed considerably over the last five decades due to the construction of artificial structures, such as embankments, multi-purpose dams, storing reservoirs, barrages, irrigation ditches and drainage canals. This report describes a recent transformation in flooding in the plain.The geomorphological units in the central plain of Thailand are classified as follows: 3 types of fans, higher and lower natural levees, 3 types of back marshes, 4 types of deltas, higher and lower mud spits and lagoons, tidal flats and former river courses. The geomorphological units correspond with flood conditions. The most serious flood damage to this point has occurred in deep back marshes and lagoons. The depth of the back marshes is greater than 3 m, and in some cases as much as 6 m. The depth of flood waters ranges from 50 cm to 1 m, and the period of submergence of the lagoonal area is more than 3 months. 相似文献