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1.
The production of flood hazard assessment maps is an important component of flood risk assessment. This study analyses flood hazard using flood mark data. The chosen case study is the 2013 flood event in Quang Nam, Vietnam. The impacts of this event included 17 deaths, 230 injuries, 91,739 flooded properties, 11,530 ha of submerged and damaged agricultural land, 85,080 animals killed and widespread damage to roads, canals, dykes and embankments. The flood mark data include flood depth and flood duration. Analytic hierarchy process method is used to assess the criteria and sub-criteria of the flood hazard. The weights of criteria and sub-criteria are generated based on the judgements of decision-makers using this method. This assessment is combined into a single map using weighted linear combination, integrated with GIS to produce a flood hazard map. Previous research has usually not considered flood duration in flood hazard assessment maps. This factor has a rather strong influence on the livelihood of local communities in Quang Nam, with most agricultural land within the floodplain. A more comprehensive flood hazard assessment mapping process, with the additional consideration of flood duration, can make a significant contribution to flood risk management activities in Vietnam. 相似文献
2.
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
3.
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
4.
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
5.
In the middle of 2007, a severe flood affected the People’s Republic of Bangladesh. This is a natural disaster that takes
people’s lives, destroys livestock, infrastructures and communication systems and, damages crops and fish ponds. Despite many
adverse impacts, the flood situation is an accepted phenomenon to the citizens of Bangladesh, due to the immense increase
of soil fertility due to the flood, plus, the recharge of aquifer, ecosystem and fish. The flood of 2007 was the 5th major
flood of the last 20 years when more than thirty-five percent of the area of the country was inundated with flood water. As
in the past, the flood of 2007 had its own significance. The geography of the country contains a floodplain delta of three
major river basins: the Ganges, the Brahmaputra and the Meghna (GBM). The mean monthly rainfall plot from the TRMM satellite
data has shown that for both the Meghna and Brahmaputra basins, the rainfall was higher during July 2007 than any other months
of the last 2 years. This excess rainfall had accumulated in the Brahmaputra and Meghna rivers and carried downstream to Bangladesh.
This was the main cause of the flooding in 2007. The first crossing above the danger level of the river waters was observed
at Durgapur station of the Someswari and at Sunamganj station of the Surma on the nineteenth of July, 2007 inside Bangladesh.
In terms of magnitude of the peak and duration of the flood, the Brahmaputra was higher in 2007 than during 2004. However,
the Ganges river water level never crossed the danger level during flood of 2007. The Meghna was lower during the flood peak
for the duration of the flood in 2007. The year–to-year variability in both the magnitude and duration of the flood suggests
changes in rainfall and landuse pattern of the catchment. 相似文献
6.
Existing methods of evaluating the hazard posed by moraine-dammed lakes are unsystematic, subjective, and depend on the expertise
and biases of the geoscientist. In this paper, we provide a framework for making objective preliminary assessments of outburst
flood hazard in southwestern British Columbia. Our procedure relies on remote sensing methods and requires only limited knowledge
of glacial processes so that evaluations of outburst flood hazard can be incorporated into routine hazard assessments of glaciated
regions. We describe objective approaches, which incorporate existing empirical relations applicable to the study region,
for estimating outburst peak discharge, maximum volume, maximum travel distance, maximum area of inundation, and probability.
Outburst flood hazard is greatest for moderately large lakes that are impounded by large, narrow, ice-free moraine dams composed
of sedimentary rock debris and drain into steep, sediment-filled gullies above major river valleys. We demonstrate the application
of the procedure using three case studies and show that flood hazard varies, especially with major changes in lake level.
Our assessment scheme yields reproducible results and enables engineers and geoscientists to prioritize potentially hazardous
lakes for more detailed field investigation. 相似文献
7.
Ibidun O. Adelekan 《Natural Hazards》2011,56(1):215-231
The paper presents the result of a vulnerability assessment of urban dwellers to a major flood hazard in Abeokuta, southwestern
Nigeria in July 2007. This was achieved by means of questionnaire survey administered to 248 flood area residents. Flood vulnerability
was assessed by examining exposure, susceptibility, and coping indicators in the study area. Findings of the study show that
although about 50% of respondents had experienced floods, in Abeokuta or elsewhere in the past, majority (66%) did not anticipate
a flood event of such magnitude to occur despite its location on a flood plain and, therefore, were unprepared for such hazard.
Pre-warning of the flood event was generally lacking among flood area residents as only 8% of respondents indicated pre-warning,
which was based on personal observations. Response to the flood hazard was mainly reactive for both private and public agents
as flood risk reduction measures were not in place. 相似文献
8.
Harun Rasid 《Natural Hazards》1993,8(1):39-57
Based on a systematic sample survey among the residents of two contrasting floodplain environments - the Tista floodplain (a shallow flood area) and the Ganges-Brahmaputra floodplain (a deep flood area) - this study tests a central hypothesis that the floodplain residents of Bangladesh preferred regulation of flood levels as the main flood alleviation measure. The study found that, despite significant differences in property setting, flood hazard experience and the nature of indigenous adjustments to floods between the two sample areas, an overwhelming 95% of the respondents from each area preferred regulation of flood levels within a range of 0.3 to 2.0 m. The study attempts to provide an explanation for the popularity of regulated flood levels in the context of indigenous adjustments of floodplain crops and infrastructures tonormal flood levels in Bangladesh, which coincided with the respondents' preferred range of flood levels. The study points out that the objective of the UNDP/World Bank-sponsored embankment compartmentalization projects also coincides with this goal of regulating flood levels. However, to test the physical limitations of regulating water levels between neighbouring compartments and to assess the environmental impacts of the proposed projects, the study stresses the need for initiating environmental baseline surveys on the pilot compartmentalization project, which is located on the left bank of the Brahmaputra. 相似文献
9.
Flood is among the deadliest disasters in India, and the frequency of floods and extreme precipitation events is projected to increase under the warming climate. The frequency of floods in India varies geographically as some regions are more prone to floods than the others. The Kerala flood of 2018 caused enormous economic damage, affected millions of people, and resulted in the death of more than 400 people. Here we provide a hydroclimatological perspective on the Kerala flood of 2018. Using the observations and model simulations from the Variable Infiltration Capacity (VIC) model, we show that the 2018 extreme precipitation and runoff conditions that caused flooding were unprecedented in the record of the past 66 years (1951–2017). Our results show that mean monsoon precipitation has significantly declined while air temperature has significantly increased during 1951–2017 in Kerala. The drying and warming trends during the monsoon season resulted in a declined total runoff in large part of the state in the last 66 years. Apart from the mean hydroclimatic conditions, extreme precipitation, and extreme total runoff have also declined from 1951 to 2017. However, 1 and 2-day extreme precipitation and extreme runoff conditions in August 2018 exceeded substantially from the long-term 95th percentiles recorded during 1951–2017. Since there is no increase in mean and extreme precipitation in Kerala over the last six decades, the extreme event during August 2018 is likely to be driven by anomalous atmospheric conditions due to climate variability rather anthropogenic climate warming. The severity of the Kerala flood of 2018 and the damage caused might be affected by several factors including land use/land cover change, antecedent hydrologic conditions, reservoir storage and operations, encroachment of flood plains, and other natural factors. The impacts of key drivers (anthropogenic and natural) on flood severity need to be established to improve our understanding of floods and associated damage. 相似文献
10.
Bangladesh is a country that comprises much of the world’s largest delta, formed from the Ganges, Brahmaputra, and Meghna (GBM) rivers and their tributaries. Flooding is a fact of life in Bangladesh where up to two-thirds of the country is flooded annually from combined monsoonal rains and Himalayan snowmelt. For this reason, understanding flood dynamics on both local and regional scales is critical. However, flood hazard studies to date typically rely on single flooding events to create flood maps and to evaluate flood hazards using satellite imagery. Here we use geographic information systems to analyze weekly water level data from 304 river gauges and over 1200 groundwater gauges from the Bangladesh Water Development Board to determine the spatial and temporal changes in flood depth and extent. These data cover an eight year period from 2002 to 2010 and provide a temporal resolution that match or are better than that of available satellite imagery. Country-wide ground and surface water levels and corresponding annual flooding events were determined along with groundwater level, flooding, and precipitation trends in Bangladesh at multiple scales. We find that while precipitation within the GBM basin has steadily increased through the time series, the average country-wide inundation depth and absolute water level has been decreasing. These respective trends could be attributed to improved flood management strategies in Bangladesh and surrounding countries that are within the GBM basin, as well as fluctuating weather patterns, declining volume of Himalayan snowmelt runoff, dam construction upriver from the GBD both within and outside the Bangladesh border, and increased groundwater abstraction of shallow groundwater aquifers for sustaining life in the eighth most populous country in the world. 相似文献
11.
Flood monitoring, mapping and assessing capabilities using RADARSAT remote sensing, GIS and ground data for Bangladesh 总被引：3，自引：1，他引：2
Remote sensing is the most practical method available to managers of flood-prone areas for quantifying and mapping flood impacts. This study explored large inundation areas in the Maghna River Basin, around the northeastern Bangladesh, as determined from passive sensor LANDSAT data and the cloud-penetrating capabilities of the active sensors of the remote imaging microwave RADARSAT. This study also used passive sensor LANDSAT wet and dry images for the year 2000. Spatial resolution was 30 m by 30 m for comparisons of the inundation area with RADARSAT images. RADARSAT images with spatial resolution of 50 m by 50 m were used for frequency analysis of floods from 2000 to 2004. Time series images for 2004 were also used. RADARSAT remote sensing data, GIS data, and ground data were used for the purpose of flood monitoring, mapping and assessing. A supervised classification technique was used for this processing. They were processed for creating a maximum water extent map and for estimating inundation areas. The results of this study indicated that the maximum extent of the inundation area as estimated using RADARSAT satellite imaging was about 29, 900.72 km2 in 2004, which corresponded well with the heavy rainfall around northeast region, as seen at the Bhairab Bazar station and with the highest water level of the Ganges–Brahmaputra–Meghna (GBM) Rivers. A composite of 5 years of RADARSAT inundation maps from 2000 to 2004, GIS data, and damage data, was used to create unique flood hazard maps. Using the damage data for 2004 and the GIS data, a set of damage maps was also created. These maps are expected to be useful for future planning and flood disaster management. Thus, it has been demonstrated that RADARSAT imaging data acquired over the Bangladesh have the ability to precisely assess and clarify inundation areas allowing for successful flood monitoring, mapping and disaster management. 相似文献
12.
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
13.
The purpose of this research was to identify social, culturaland psychological aspects of riverbank erosion-induced displacement in the flood plainsof Bangladesh. Although considerable research has examined the social and economicimpacts of riverine hazards in Bangladesh, there has been a general neglect of associatedpsychosocial implications. The specific objectives of the study were to: (1) assess hazardawareness in relation to riverbank erosion, (2) determine the magnitude of psychologicaldistress associated with displacement, and (3) identify patterns of psychosocial copingand adaptation common to displaced persons in Bangladesh. Although displacees were foundto have a significantly higher level of distress than non-displacees, this was relatedprimarily to socioeconomic deprivation rather than to displacement per se. The findingsof this study showed that the constant threat of riverbank erosion has contributed to asubstantial disaster subculture in the riverine zones of Bangladesh. The commonly hypothesized factorssuch as loss of land and frequency and duration of displacement were notsignificantly associated with distress levels.The need to integrate into hazard analysis and mitigation studiesa social, cultural and psychological context is recommended. In Bangladesh, the poor copewith hardship and problems by relying on religion, which in turn significantlyinfluences how they perceive and interpret natural calamities. It is argued that the capacityof people to respond to environmental threats is a function of not only the physicalforces which affect them, but of indigenous social and cultural belief systems which influencehow people interpret and organize their activities. Hazard analysis and mitigation wouldbe most effective when it takes into account psychological and socio-cultural aspects ofdisasters, due to the fact that psychological distress impacts the capacity of people toachieve livelihoods, but also important social and psychological processes determine the waypeople perceive and adapt to natural hazards. 相似文献
14.
Decision support system based on the history of flood and flash flood events in Romania 总被引：1，自引：0，他引：1
Victor Stefanescu 《Natural Hazards》2013,65(3):2331-2352
A lightweight decision support system is presented, oriented also to statistics, useful for assisting weather forecasters and other parties interested in hazard assessment associated with extreme weather. The system can be used in enhancing the warning procedures, ahead of a flood or a flash flood whose probability of occurrence is based on the history of such events in a particular region. A software application has been built that integrates meteorological data with Geographical Information Systems procedures, in a unified informational aggregate. This system stores various types of data related to flood and flash flood events, so it is able to provide the user with any piece of information related to a documented event. It also catalogues any information that users provide it with, to further document a past, or an ongoing event. The system can be used to raise awareness of forecasters over a particular context, before a possibly hazardous situation, and it can also offer automatic warnings and suggestions to those interested in disaster mitigation. 相似文献
15.
Sajjad Asif Lu Jianzhong Chen Xiaoling Chisenga Chikondi Mazhar Nausheen Nadeem Basit 《Natural Hazards》2022,110(3):2207-2226
The Multan district is mainly prone to riverine floods but has remained understudied. Chenab flood-2014 was the worst flood that this district experienced in recorded history. This study applies remote sensing (RS) techniques to estimate the extent, calculate duration, assess the major causes and resulting impacts of the flood-2014, using Landsat-8 OLI images. These images were obtained for pre-flood, during-flood and post-flood instances. Secondary data of flood causing factors were obtained for comprehensive analysis. Spatially trained and validated datasets were obtained through Google Earth platform and Global positioning system. The supervised classification with maximum likelihood algorithm was used to classify land use and land cover of the study area. The Modified Normalized Difference Water Index was utilized to detect flood inundation extent and duration, and Normalized Difference Vegetation Index was utilized to monitor vegetation coverage and changes. The analysis allowed us to assess flood causes, and calculate the extent of the flooded areas with duration and recession, as well as damages to standing crops and built-up areas. The results revealed that the flood-2014 occurred due to heavy rains in early September in upper Chenab catchment. The flood inundation continued for around two months, which heavily affected agriculture and built-up areas. The present study introduces practical use of RS techniques to provide basis for effective flood inundation mapping and impact assessment, as an application for early flood response and recovery in the world.
相似文献16.
Mapping Disastrous Natural Hazards Using Global Datasets 总被引：3，自引：0，他引：3
The increased interest for categorising countries at risk calls for an improved methodology allowing comparison of natural hazard impacts at a global level. A disaster is the intersection between a hazardous event, the elements at risk (population, infrastructures) and their vulnerability. In order to associate reported impacts with affected elements and socio-economic or geophysical contextual parameters, geographical location and extent of hazards is needed. The scope of this paper is to present improved automated procedures for a rapid mapping of large disastrous hazard events (floods, earthquakes, cyclones and volcanoes) using Geographical Information Systems (GIS) and available global datasets. Up to 82% of the events and 88% of the reported victims could be geo-referenced and the results highlight both the potentialities and limitations of the methods applied. 相似文献
17.
Bangladesh is known to behighly vulnerable to floods. Frequent floods have put enormous constraints on its development potential. Unfortunately, the frequency of high intensity floods is on the rise. So far the country has struggled to put a sizeable infrastructure in place to prevent flooding in may parts of the country with limited success. In recent times, it was found that losses of lives and valuable assets could be significantly minimized by implementing non-structural measures including the improvement of flood forecasting and warning system. The existing flood forecasting and warning capacity of Bangladesh could be more effective if real-timedata could be acquired from upstreamareas within the Ganges-Brahmaputra-Meghna (GBM) catchment, where runoff is generated. In order to do so, Bangladesh needs to foster an effective regional cooperationwith the other GBM regional countries of India, Nepal, and Bhutan. This article examines how GBM regional cooperation could be useful towards managing floods in Bangladesh in particularand the region in general. 相似文献
18.
Flash floods are among the most severe hazards which have disastrous environmental, human, and economic impacts. This study is interested in the characterization of flood hazard in Gabes Catchment (southeastern Tunisia), considered as an important step for flood management in the region. Analytical hierarchy process (AHP) and geographic information system are applied to delineate and characterize flood areas. A spatial database was developed based on geological map, digital elevation model, land use, and rainfall data in order to evaluate the different factors susceptible to affect flood analysis. However, the uncertainties that are associated with AHP techniques may significantly impact the results. Flood susceptibility is analyzed as a function of weights using Monte Carlo (MC) simulation and Global sensitivity analysis. AHP and MC–AHP models gave similar results. However, compared to AHP approach, MC–AHP confidence intervals (95%) of the overall scores had small overlaps. Results obtained were validated by remote sensing data for the zones that showed very high flood hazard during the extreme rainfall event of June 2014 that hit the study basin. 相似文献
19.
Tidal inundation mapping under enhanced land subsidence in Semarang,Central Java Indonesia 总被引：3，自引：0，他引：3
Tidal inundation by high tide under enhanced land subsidence is a damaging phenomenon and a major threat to the Semarang urban
area in Indonesia. It impacts on economic activities, as well as the cost of an emergency program and causes interruption
of pubic services, danger of infectious diseases and injury to human lives. This study examines a spatial analysis tool on
the GIS-raster system for the tidal inundation mapping based on the subsidence-benchmark data and modified detail digital
elevation model. Neighborhood operation and iteration model as a spatial analysis tool have been applied in order to calculate
the encroachment of the tidal inundation on the coastal area. The resulting map shows that the tidal flood spreads to the
lowland area and causes the inundation of coastal settlement, infrastructure, as well as productive agricultural land, i.e.,
the fish-pond area. The monitoring of the vulnerable area due to the tidal inundation under the scenario of extended land
subsidence plays an important role in long-term coastal zone management in Semarang. 相似文献
20.
Watershed urbanization and changing flood behavior across the Los Angeles metropolitan region 总被引：3，自引：0，他引：3
This article examines the effects of watershed urbanization on stream flood behavior in the Los Angeles metropolitan region.
Stream gauge data, spatially distributed rainfall data, land use/land cover, and census population data were used to quantify
change in flood behavior and urbanization in multiple watersheds. Increase in flood discharge started at the very early stage
of the urbanization when the population density was relatively low but the rate of increase of flood discharge varied across
watersheds depending on the distribution of the imperviousness surface and flood mitigation practices. This spatial variability
in rainfall–runoff indices and the increasing flood risk across the metropolitan region has posed a challenge to the conventional
flood emergency management, which usually responds to flood damages rather than being concerned with the broader issues of
land use, land cover, and planning. This study pointed out that alternative land use planning and flood management practices
could be mitigating the urban flood implemented hazard. 相似文献