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1.
A sound, evidence-based hazard mapping requires the analysis of stochastic processes taking place at critical configurations
(e.g., bridges, levees) in order to reliably determine the spatial patterns of flood intensities and probabilities. Here,
we discuss an approach aiming to support an enhanced determination of flood hazard patterns by identifying within alluvial
fans and river corridors two main types of spatial domains based on the predictability of their dynamics, i.e., stochastic
and quasi-deterministic domains. The former represents critical configurations whose dynamic evolution (e.g., clogging by
large wood, failure due to breaching) cannot be realistically specified by deterministic models, whereas the latter refers
to the part of the system where the flood propagation can be computed with sufficient precision and accuracy by hydrodynamic
models. The applicability of the proposed approach is discussed on the basis of a case study in the Autonomous Province of
Bolzano (Italy). 相似文献
2.
An important issue that is not considered in most flood risk assessments in mountain villages in Spain is the transport of solids associated with the flood flow, in this case, large wood transport. The transport and deposition of this wood in urban areas may be a potentially worse hazard than the flood flow itself. Despite its importance, large wood is a key ecological element in rivers, so removing it could be an unsuccessful approach. Therefore, efforts are needed in the better understanding of wood transport and deposition in streams. To analyse this process, scenario-based 2D hydrodynamic flood modelling was carried out. Since flood risk assessment has considerable intrinsic uncertainty, probabilistic thinking was complemented by possibilistic thinking, considering worst-case scenarios. This procedure obtained a probabilistic flood map for a 500-year return period. Then, a series of scenarios was built based on wood budget to simulate wood transport and deposition. Results allowed us to identify the main infrastructures sensitive to the passing of large wood and simulate the consequences of their blockage due to wood. The potential damage was estimated as well as the preliminary social vulnerability for all scenarios (with and without wood transport). This work shows that wood transport and deposition during flooding may increase potential damage at critical stream configurations (bridges) by up to 50 % and the number of potentially exposed people nearby these areas by up to 35 %. 相似文献
3.
Historical responses to flood hazards have stimulated development in hazardous areas. Scholars recommend an alternative approach to reducing flood losses that combines flood hazard mapping with land use planning to identify and direct development away from flood-prone areas. Creating flood hazard maps to inform municipal land use planning is an expensive and complex process that can require resources not always available at the municipal government level. Senior levels of government in some countries have addressed deficiencies in municipal capacity by assuming an active role in producing municipal flood hazard maps. In other countries, however, senior governments do not contribute to municipal flood hazard mapping. Despite a large body of research on the importance of municipal land use planning for addressing flood hazards, little is known about the extent of flood hazard information that is available to municipalities that do not receive outside assistance from senior governments for flood hazard mapping. We assess the status of flood hazard maps in British Columbia, where municipalities do not receive outside assistance in creating the maps. Our analysis shows that these maps are generally outdated and/or lacking a variety of features that are critical for supporting effective land use planning. We recommend that senior levels of government play an active role in providing municipalities with (1) detailed and current information regarding flood hazards in their jurisdiction and (2) compelling incentives to utilize this information. 相似文献
4.
Floods are a major natural hazard, with vast implications over a wide range of socio-economic activities. A harmonized post-flood classification is critical for a better understanding of this hazard, by providing homogeneous flood catalogues for future research on triggering mechanisms. We apply a flood severity index (FSI) to damaging floods in Northern Portugal over a 152-year period (1865–2016) and identify the most critical areas to flood occurrences. The index is a damage-based post-event assessment tool, which includes five categories ranging from minor flooding (1) to catastrophic flooding (5). FSI is applied to a historical damaging flood database with 2318 occurrences. In Northern Portugal, serious floods (3) are the most frequent typology, while catastrophic floods are typically river floods occurring in the Douro basin. Overall, damaging flood occurrences are favoured by the positive phase of the East Atlantic pattern and by the negative phase of the North Atlantic Oscillation. Furthermore, the north-western areas reveal higher concentrations of damaging flood occurrences, mainly due to higher population density, higher precipitation values and more flood plain areas. In particular, 48% of all occurrences are concentrated in the Porto Metropolitan Area, mainly the Porto city centre and nearby riverside areas of the Douro River. High-population density and heavily urbanized areas lead to greater exposure to flood risk, whereas the most peripheral municipalities, with large agricultural/forested areas, show much lower numbers of damaging floods. FSI is tool to communicate the magnitude of the flood risk and is, therefore, of foremost relevance to civil protection and risk management. 相似文献
5.
Assessment of flood hazard,vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model 总被引：1，自引：0，他引：1
Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the
eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past
devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map
is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map
for mid-eastern Dhaka (37.16 km2) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography
Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably
changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date
of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation
was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the
maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared
according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was
prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure
of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority
for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future. 相似文献
6.
Hydrodynamic flow modeling is carried out using a coupled 1D and 2D hydrodynamic flow model in northern India where an industrial plant is proposed. Two flooding scenarios, one considering the flooding source at regional/catchment level and another considering all flooding sources at local level have been simulated. For simulating flooding scenario due to flooding of the upstream catchment, the probable maximum flood (PMF) in the main river is routed and its flooding impact at the plant site is studied, while at the local level flooding, in addition to PMF in the main river, the probable maximum precipitation at the plant site and breaches in the canals near the plant site have been considered. The flood extent, depth, level, duration and maximum flow velocity have been computed. Three parameters namely the flood depth, cross product of flood depth and velocity and flood duration have been used for assessing the flood hazard, and a flood hazard classification scheme has been proposed. Flood hazard assessment for flooding due to upstream catchment and study on local scale facilitates determination of plinth level for the plant site and helps in identifying the flood protection measures. 相似文献
7.
An evidence-based flood hazard analysis in mountain streams requires the identification and the quantitative characterisation of multiple possible processes. These processes result from specific triggering mechanisms on the hillslopes (i.e. landslides, debris flows), in-channel morphodynamic processes associated with sudden bed changes and stochastic processes taking place at critical stream configurations (e.g. occlusion of bridges, failure of levees). From a hazard assessment perspective, such possible processes are related to considerable uncertainties underlying the hydrological cause-effect chains. Overcoming these uncertainties still remains a major challenge in hazard and risk assessment and represents a necessary condition for a reliable spatial representation of process intensities and the associated probabilities. As a result of an accurate analysis of the conceptual flaws present in the procedures currently employed for hazard mapping in South Tyrol (Italy) and Carinthia (Austria), we propose a structured approach as a means to enhance the integration of hillslope, morphodynamic and stochastic processes into conventional flood hazard prediction for mountain basins. To this aim, a functional distinction is introduced between prevailing one-dimensional and two-dimensional process propagation domains, i.e., between confined and semi- to unconfined stream segments. The former domains are mostly responsible for the generation of water, sediment and wood fluxes, and the latter are where flooding of inactive channel areas (i.e. alluvial fans, floodplains) can occur. For the 1D process propagation domain, we discuss how to carry out a process routing along the stream system and how to integrate numerical models output with expert judgement in order to derive consistent event scenarios, thus providing a consistent quantification of the input variables needed for the associated 2D domains. Within these latter domains, two main types of spatial sub-domains can be identified based on the predictability of their dynamics, i.e., stochastic and quasi-deterministic. Advantages and limitations offered by this methodology are finally discussed with respect to hazard and risk assessment in mountain basins. 相似文献
8.
Bay of Bengal cyclone extreme water level estimate uncertainty 总被引：4，自引：3，他引：1
9.
Flooding in urban area is a major natural hazard causing loss of life and damage to property and infrastructure. The major causes of urban floods include increase in precipitation due to climate change effect, drastic change in land use–land cover (LULC) and related hydrological impacts. In this study, the change in LULC between the years 1966 and 2009 is estimated from the toposheets and satellite images for the catchment of Poisar River in Mumbai, India. The delineated catchment area of the Poisar River is 20.19 km2. For the study area, there is an increase in built-up area from 16.64 to 44.08% and reduction in open space from 43.09 to 7.38% with reference to total catchment area between the years 1966 and 2009. For the flood assessment, an integrated approach of Hydrological Engineering Centre-Hydrological Modeling System (HEC-HMS), HEC-GeoHMS and HEC-River analysis system (HEC-RAS) with HEC-GeoRAS has been used. These models are integrated with geographic information system (GIS) and remote sensing data to develop a regional model for the estimation of flood plain extent and flood hazard analysis. The impact of LULC change and effects of detention ponds on surface runoff as well as flood plain extent for different return periods have been analyzed, and flood plain maps are developed. From the analysis, it is observed that there is an increase in peak discharge from 2.6 to 20.9% for LULC change between the years 1966 and 2009 for the return periods of 200, 100, 50, 25, 10 and 2 years. For the LULC of year 2009, there is a decrease in peak discharge from 10.7% for 2-year return period to 34.5% for 200-year return period due to provision of detention ponds. There is also an increase in flood plain extent from 14.22 to 42.5% for return periods of 10, 25, 50 and 100 years for LULC change between the year 1966 and year 2009. There is decrease in flood extent from 4.5% for 25-year return period to 7.7% for 100-year return period and decrease in total flood hazard area by 14.9% due to provisions of detention pond for LULC of year 2009. The results indicate that for low return period rainfall events, the hydrological impacts are higher due to geographic characteristics of the region. The provision of detention ponds reduces the peak discharge as well as the extent of the flooded area, flood depth and flood hazard considerably. The flood plain maps and flood hazard maps generated in this study can be used by the Municipal Corporation for flood disaster and mitigation planning. The integration of available software models with GIS and remote sensing proves to be very effective for flood disaster and mitigation management planning and measures. 相似文献
10.
Assessment of flood hazard based on natural and anthropogenic factors using analytic hierarchy process (AHP) 总被引：5，自引：3，他引：2
Flooding is the most common natural hazard in Greece, and most of low-lying urban centers are flood-prone areas. Assessment of flood hazard zones is a necessity for rational management of watersheds. In this study, the coupling of the analytical hierarchy process and geographical information systems were used, in order to assess flood hazard, based either on natural or on anthropogenic factors. The proposed method was applied on Kassandra Peninsula, in Northern Greece. The morphometric and hydrographic characteristics of the watersheds were calculated. Moreover, the natural flood genesis factors were examined, and subsequently, the anthropogenic interventions within stream beds were recorded. On the basis of the above elements, two flood hazard indexes were defined, separately for natural and anthropogenic factors. According to the results of these indexes, the watersheds of the study area were grouped into hazard classes. At the majority of watersheds, the derived hazard class was medium (according to the classification) due to natural factors and very high due to anthropogenic. The results were found to converge to historical data of flood events revealing the realistic representation of hazard on the relating flood hazard maps. 相似文献
11.
The frequency in occurrence and severity of floods has increased globally. However, many regions around the globe, especially in developing countries, lack the necessary field monitoring data to characterize flood hazard risk. This paper puts forward methodology for developing flood hazard maps that define flood hazard risk, using a remote sensing and GIS-based flood hazard index (FHI), for the Nyamwamba watershed in western Uganda. The FHI was compiled using analytical hierarchy process and considered slope, flow accumulation, drainage network density, distance from drainage channel, geology, land use/cover and rainfall intensity as the flood causative factors. These factors were derived from Landsat, SRTM and PERSIANN remote sensing data products, except for geology that requires field data. The resultant composite FHI yielded a flood hazard map pointing out that over 11 and 18% of the study area was very highly and highly susceptible to flooding, respectively, while the remaining area ranged from medium to very low risk. The resulting flood hazard map was further verified using inundation area of a historical flood event in the study area. The proposed methodology was effective in producing a flood hazard map at the watershed local scale, in a data-scarce region, useful in devising flood mitigation measures. 相似文献
12.
Simulation-based decision support system for flood damage assessment under uncertainty using remote sensing and census block information 总被引：1，自引：0，他引：1
The level of damage of flood events does not solely depend on exposure to flood waters. Vulnerabilities due to various socio-economic
factors such as population at risk, public awareness, and presence of early warning systems, etc. should also be taken into
account. Federal and state agencies, watershed management coalitions, insurance companies, need reliable decision support
system to evaluate flood risk, to plan and design flood damage assessment and mitigation systems. In current practice, flood
damage evaluations are generally carried out based on results obtained from one dimensional (1D) numerical simulations. In
some cases, however, 1D simulation is not able to accurately capture the dynamics of the flood events. The present study describes
a decision support system, which is based on 2D flood simulation results obtained with CCHE2D-FLOOD. The 2D computational
results are complemented with information from various resources, such as census block layer, detailed survey data, and remote
sensing images, to estimate loss of life and direct damages (meso or micro scale) to property under uncertainty. Flood damage
calculations consider damages to residential, commercial, and industrial buildings in urban areas, and damages to crops in
rural areas. The decision support system takes advantage of fast raster layer operations in a GIS platform to generate flood
hazard maps based on various user-defined criteria. Monte Carlo method based on an event tree analysis is introduced to account
for uncertainties in various parameters. A case study illustrates the uses of the proposed decision support system. The results
show that the proposed decision support system allows stake holders to have a better appreciation of the consequences of the
flood. It can also be used for planning, design, and evaluation of future flood mitigation measures. 相似文献
13.
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
14.
Praveen K. Thakur Sreyasi Maiti Nanette C. Kingma V. Hari Prasad S. P. Aggarwal Ashutosh Bhardwaj 《Natural Hazards》2012,61(2):501-520
Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing
frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For
risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on
the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa,
India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were
interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural
types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood
depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage).
Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized
by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable
for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally
collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation. 相似文献
15.
This paper illustrates the development of flood hazard and risk maps in Greater Dhaka of Bangladesh using geoinformatics. Multi-temporal RADARSAT SAR and GIS data were employed to delineate flood hazard and risk areas for the 1998 historical flood. Flood-affected frequency and flood depth were estimated from multi-date SAR data and considered as hydrologic parameters for the evaluation of flood hazard. Using land-cover, gemorphic units and elevation data as thematic components, flood hazard maps were created by considering the interactive effect of flood frequency and flood water depth concurrently. Analysis revealed that a major portion of Greater Dhaka was exposed to high to very high hazard zones while a smaller portion (2.72%) was free from the potential flood hazard. Flood risk map according to administrative division showed that 75.35% of Greater Dhaka was within medium to very high risk areas of which 53.39% of areas are believed to be fully urbanized by the year 2010. 相似文献
16.
Probability-weighted hazard maps for comparing different flood risk management strategies: a case study 总被引：5，自引：1，他引：4
Giuliano Di Baldassarre Attilio Castellarin Alberto Montanari Armando Brath 《Natural Hazards》2009,50(3):479-496
The study proposes an original methodology for producing probability-weighted hazard maps based on an ensemble of numerical
simulations. These maps enable one to compare different strategies for flood risk management. The methodology was applied
over a 270-km2 flood-prone area close to the left levee system of a 28-km reach of the river Reno (Northern Central Italy). This reach is
characterised by the presence of a weir that allows controlled flooding of a large flood-prone area during major events. The
proposed probability-weighted hazard maps can be used to evaluate how a structural measure such as the mentioned weir alters
the spatial variability of flood hazard in the study area. This article shows an application by constructing two different
flood hazard maps: a first one which neglects the presence of the weir using a regular levee system instead, and a second
one that reflects the actual geometry with the weir. Flood hazard maps were generated by combining the results of several
inundation scenarios, simulated by coupling 1D- and 2D-hydrodynamic models. 相似文献
17.
Danial Amini Baghbadorani Ali-Asghar Beheshti Behzad Ataie-Ashtiani 《Natural Hazards》2017,85(2):977-1003
Flooding is the most costly natural hazard event worldwide and can severely impact communities, both through economic losses and social disruption. To predict and reduce the flood risk facing a community, a reliable model is needed to estimate the cost of repairing flood-damaged buildings. In this paper, we describe the development and assessment of two models for predicting direct economic losses for single-family residential buildings, based on the experience of the 2013 Boulder, Colorado riverine floods. The first model is based on regression analyses on empirical data from over 3000 residential building damage inspections conducted by the Federal Emergency Management Agency (FEMA). This model enables a probabilistic assessment of loss (in terms of FEMA grants paid to homeowners for post-flood repairs) as a function of key building and flood hazard parameters, considering uncertainties in structural properties, building contents, and damage characteristics at a given flood depth. The second model is an assembly-based prediction of loss considering unit prices for damaged building components to predict mean repair costs borne by the homeowner, which is based on typical Boulder construction practices and local construction and material costs. Comparison of the two proposed models illustrates benefits that arise from each of the two approaches, while also serving to validate both models. These models can be used as predictive tools in the future, in Boulder and other US communities, due to adaptability of the model for other context, and similarities in home characteristics across the country. The assembly-based model quantifies the difference between the FEMA grants and true losses, providing a quantification of out-of-pocket homeowner expenses. 相似文献
18.
In recent decades, there have been discussions and predictions regarding the impact of climate on floods, due to its socioeconomic and environmental consequences. For accurate prediction of future flood events and their impacts, it is crucial to have an improved understanding on past flood events. Lacustrine sediments have been used as a natural archive to study the past flood events. Here, we study the impact of 1954 flood event on the lacustrine environment of Bengas and Rupa Lake in central Nepal based on X-ray fluorescence spectrometry (XRF) element analysis, magnetic susceptibility (MS), total organic carbon (TOC) and the biomarker molecular compositions. Results showed that 1954 flood event had significant impacts on the two lakes in terms of detrital input, organic matter deposition and aquatic production. Before the flood event, both two studied lakes had relatively lower catchment erosion rate, lower organic matter deposition and aquatic production. During the flood event, catchment erosion and aquatic production increased in both lakes due to mass transport deposits and the increased nutrition loading attributed to flood event. Following the flood event, Begnas Lake showed the sharp increase in organic matter deposition, whereas in the Rupa Lake organic matter deposition showed minor changes. The difference in organic matter deposition in lakes during flooding event is likely due to detrital material brought and deposited by the flood activity. Overall our results suggest that lacustrine sediments are sensitive to the extreme event and would be an ideal archive for the reconstruction of flood events. 相似文献
19.
Zhu Chonghao Zhang Jianjing Liu Yang Ma Donghua Li Mengfang Xiang Bo 《Natural Hazards》2020,101(1):173-194
Communities everywhere are being subjected to a variety of natural hazard events that can result in significant disruption to critical functions. As a result, community resilience assessment in these locations is gaining popularity as a means to help better prepare for, respond to, and recover from potentially disruptive events. The objective of this study was to identify key vulnerabilities relevant to addressing rural community resilience through conducting an initial flood impact analysis, with a specific focus on emergency response and transportation network accessibility. It included a use case involving the flooding of a rural community along the US inland waterway system. Special consideration was given to impacts experienced by at-risk populations (e.g., low economic status, youth, and elderly), given their unique vulnerabilities. An important backdrop to this work is recognition that Federal Emergency Management Agency’s Hazus, a free, publicly available tool, is commonly recommended by the agency for counties, particularly those with limited resources (i.e., rural areas), to use in developing their hazard mitigation plans. The case study results, however, demonstrate that Hazus, as currently utilized, has some serious deficiencies in that it: (1) likely underestimates the flood extent boundaries for study regions in a Level 1 analysis (which solely relies upon filling digital elevation models with precipitation), (2) may be incorrectly predicting the number and location of damaged buildings due to its reliance on out-of-date census data and the assumption that buildings are evenly distributed within a census block, and (3) is incomplete in its reporting of the accessibility of socially vulnerable populations and response capabilities of essential facilities. Therefore, if counties base their flood emergency response plans solely on Hazus results, they are likely to be underprepared for future flood events of significant magnitude. An approach in which Hazus results can be augmented with additional data and analyses is proposed to provide a more risk-informed assessment of community-level flood resilience.
相似文献20.
Natural hazards in Central Java Province,Indonesia: an overview 总被引：2，自引：0，他引：2
Muh Aris Marfai Lorenz King Lalan Prasad Singh Djati Mardiatno Junun Sartohadi Danang Sri Hadmoko Anggraini Dewi 《Environmental Geology》2008,56(2):335-351
Central Java Province, Indonesia, suffers from natural hazard processes such as land subsidence, coastal inundation, flood,
volcanic eruption, earthquake, tsunami, and landslide. The occurrence of each kind of natural hazard is varied according to
the intensity of geo-processes. It is necessary to learn from the historical record of coastal inundation, flood, volcanic
eruption, earthquake, tsunami, and landslide hazards in Central Java Province to address issues of comprehensive hazard mitigation
and management action. Through the understanding about the nature and spatial distribution of natural hazards, treatments
can be done to reduce the risks. This paper presents the natural hazard phenomena in Central Java Province and provides critical
information for hazard mitigation and reduction. 相似文献