东南沿海水库下游地区基于动态模拟的洪涝风险评估

我国东南沿海地区大多为一些中小流域,这些流域上游多建有水库工程,下游则为人口稠密的平原区,流域调蓄能力小,汇流时间短.同时,随着近年来城镇化快速发展,洪涝风险不断加大.因此,迫切需要开展水库下游不同暴雨重现期下的洪涝风险评估研究,以便为防洪决策提供技术支撑.为此,本文利用遥感、GIS、水文水动力学模型等相关技术方法,建立洪涝动态模拟模型来评估洪涝危险性;采用层次分析法和因子叠加法,从洪涝危险性和洪涝易损性两方面开展洪涝风险综合评估分析.研究表明,通过多学科与多技术手段相结合方法,来模拟预测不同暴雨重现期洪水动态淹没过程,再结合相关社会经济属性,可以有效地评估研究区洪涝灾害的风险,从而为水库调度及流域防洪减灾提供有力支撑.     

城市化背景下年最大日径流演变及影响因素研究——以长江下游秦淮河流域为例

随着气候变化和人类活动的加剧,城市化地区水文过程受到较大影响,极端水文事件发生频率显著加大,探究城市化地区洪水演变和驱动机理对于防洪减灾具有重大意义。本文以长江下游快速城市化地区的秦淮河流域为例,分析了1987—2018年期间该流域年最大日径流的演变特征,构建多元线性回归模型和广义可加GAMLSS模型识别了关键驱动因子并量化其贡献作用。结果表明:(1)城市化背景下秦淮河流域年最大日径流呈现显著上升趋势,平均增长速率为14.77 m³/(s·a),并于2001年发生显著突变。(2)汛期降水量和不透水面率是年最大日径流变化的关键驱动因素,最优模型显示前者贡献率超过了70%,表明了降水改变的决定性作用,而不透水面率贡献率超过20%则表明了下垫面的改变对年最大日径流演变存在显著影响。(3)不透水面的增加对年最大日径流和汛期降水量响应关系的影响程度从突变前的6.7%增加到突变后的10.4%,快速城市化已显著改变了流域降水-径流响应过程。研究表明,随着城市发展秦淮河流域的年最大日径流受到人类活动显著影响,洪涝威胁日趋增大,研究结果可为城市化地区防洪减灾提供一定参考。     

Quantitative multi-hazard risk assessment with vulnerability surface and hazard joint return period

Risk assessment plays an important role in disaster risk management. Existing multi-hazard risk assessment models are often qualitative or semi-quantitative in nature and used for comparative study of regional risk levels. They cannot estimate directly probability of disaster losses from the joint impact of several hazards. In this paper, a quantitative approach of multi-hazard risk assessment based on vulnerability surface and joint return period of hazards is put forward to assess the risk of crop losses in the Yangtze River Delta region of China. The impact of strong wind and flood, the two most prominent agricultural hazards in the area, is analyzed. The multi-hazard risk assessment process consists of three steps. First, a vulnerability surface, which denotes the functional relationship between the intensity of the hazards and disaster losses, was built using the crop losses data for losses caused by strong wind and flood in the recent 30 years. Second, the joint probability distribution of strong wind and flood was established using the copula functions. Finally, risk curves that show the probability of crop losses in this multi-hazard context at four case study sites were calculated according to the joint return period of hazards and the vulnerability surface. The risk assessment result of crop losses provides a useful reference for governments and insurance companies to formulate agricultural development plans and analyze the market of agricultural insurance. The multi-hazard risk assessment method developed in this paper can also be used to quantitatively assess multi-hazard risk in other regions.     

Changing of flood risk due to climate and development in Huaihe River basin,China

Assessing the response of flood risk caused by climate change and social development is very important in terms of determining high risk areas in different periods as well as making disaster mitigating plans. We establish a flood risk assessment model based on geographic information system and natural disaster risk assessment theory. In order to compare the index value in different periods and spaces, we utilize the spatial and temporal standardization method to standardized index. To avoid one-sidedness caused by using one weight calibration method only, we employ the least square method to synthesize weights determine by the Analytic Hierarchy Process (AHP) method and the Entropy weight method. We adopt the observed data of the Huaihe River basin from 1960 to 2010 to assess the changing of flood risk between period I (1960–1980) and period II (1980–2010). After pre-processing the atmosphere–ocean coupled global circulation models (AOGCM) data, including bias correction and downscaling, we use the corrected data to predict the flood risk during future period III (2010–2040). The results show that high risk areas and moderate to high risk areas during period I take up 17.68 and 33.88 % of the total area of the Huaihe River basin, respectively. During period II, the high risk areas show an increasing percent change of 1.93 % and a decreasing trend in moderate to high risk areas of 3.8 %. Compared with period II, the high risk areas and the moderate to high risk areas during period III show an increasing trend of 8.02 and 0.77 %, which is the result of the combined effects of climate change and social development. The results presented here can provide useful information for decision-makers.     

Flood-hazard assessment and risk-based zoning of a tropical flood plain: case study of the Yom River,Thailand

Abstract

This study contributes to the comprehensive assessment of flood hazard and risk for the Phrae flood plain of the Yom River basin in northern Thailand. The study was carried out using a hydrologic–hydrodynamic model in conjunction with a geographic information system (GIS). The model was calibrated and verified using the observed rainfall and river flood data during flood seasons in 1994 and 2001, respectively. Flooding scenarios were evaluated in terms of flooding depth for events of 25-, 50-, 100- and 200-year return periods. An impact-based hazard estimation technique was applied to assess the degree of hazard across the flood plain. The results showed that 78% of the Phrae flood-plain area of 476 km² in the upper Yom River basin lies in the hazard zone of the 100-year return-period flood. Risk analyses were performed by incorporating flood hazard and the vulnerability of elements at risk. Based on relative magnitude of risk, flood-prone areas were divided into low-, moderate-, high- and severe-risk zones. For the 100-year return-period flood, the risk-free area was found to be 22% of the total flood plain, while areas under low, medium, high and severe risk were 33, 11, 28 and 6%, respectively. The outcomes are consistent with overall property damage recorded in the past. The study identifies risk areas for priority-based flood management, which is crucial when there is a limited budget to protect the entire risk zone simultaneously.

Citation Tingsanchali, T. & Karim, F. (2010) Flood-hazard assessment and risk-based zoning of a tropical flood plain: case study of the Yom River, Thailand. Hydrol. Sci. J. 55(2), 145–161.     

长江三角洲地区全新世以来海面变化与古洪水发生关系探讨

通过对长江三角洲地区埋藏古树、泥炭、以及海相贝壳测年资料以及地方志、历史文献当中关于研究区洪灾事件记录的搜集、整理,研究结果表明,由于长江三角洲地区地势低平这一地貌特点,使得海面变化对于研究区洪灾的发生有着重要的影响.在长江中下游地区,海面的上升是导致冰后期长江河谷泥沙加积的主要原因,随着海面的上升和河床的抬高,长江中下游的水位也随之上升,从而导致长江洪水期排泄不畅,加重了洪灾的影响,加上长江三角洲地势低平,使海面变化成为长江三角洲地区洪灾发生的一个重要影响因子.同时,海面上升对长江水流的顶托作用也是加剧洪灾危害的一个重要原因.本文对于未来研究区洪水发生的预测,加强海岸带地区自然灾害的预防工作,减少生命财产的损失,具有一定的理论与实践意义.     

浅谈长三角地区典型地市防震减灾工作成效、困难与解决对策

以长三角地区典型城市嘉兴市作为研究对象,重点介绍近几年来嘉兴市开展防震减灾工作取得的一些成效、面临的困难及相关解决对策,旨在为全国既是少震弱震区,又是经济发达地区的城市开展防震减灾工作提供参考与借鉴。      

基于空间分析技术的海岛地震灾害风险分析研究

我国约有1.1万个海岛,多处于地震活跃带,地震灾害特征明显,目前地震领域研究主要针对城市展开,海岛地震灾害风险的研究较少。此背景下,该研究收集了海岛地震相关的地质和地震数据,形成海岛地震灾害空间数据库;从地震危险性、承灾体易损性和防震减灾能力3个方面构建海岛地震灾害风险评价指标体系;利用ArcGIS空间分析技术,采用熵权法与AHP法相结合建立海岛地震灾害风险综合评价模型,以长岛县、洞头区和东山县为例进行分析,并将海岛地震灾害风险等级划分为4个等级。结果显示:东山县为地震灾害高风险区,洞头区和长岛县为地震灾害较低风险区。该研究对海岛工程抗震规划与设计有重要意义。     

A new era of flood control strategies from the perspective of managing the 2020 Yangtze River flood

Flood control of the Yangtze River is an important part of China’s national water security.In July 2020,due to continuous heavy rainfall,the water levels along the middle-lower reaches of the Yangtze River and major lakes constantly exceeded the warning levels,in which Taihu Lake exceeded its highest safety water level and some stations of Poyang Lake reached their highest water levels in its history.In August 2020,another huge flood occurred in the Minjiang River and the Jialing River in the upper Yangtze River,and some areas of Chongqing Municipality and other cities along the rivers were inundated,resulting in great pressure on flood control and high disaster losses.The 2020 Yangtze River flood has received extensive media coverage and raised concerns on the roles of the Three Gorges Dam and other large reservoirs in flood control.Here we analyze the changes in the pattern of the Yangtze River flood control by comparing the strategies to tackle the three heavy floods occurring in 1954,1998,and 2020.We propose that the overall strategy of the Yangtze River flood control in the new era should adhere to the principle of"Integration of storage and drainage over the entire Yangtze River Basin,with draining floods downstream as the first priority"by using both engineering and non-engineering measures.On the basis of embankments,the engineering measures should use the Three Gorges Dam and other large reservoirs as the major regulatory means,promote the construction of key flood detention areas,keep the floodways clear,and maintain the ecosystem services of wetlands and shoals.In terms of non-engineering measures,we should strengthen adaptive flood risk management under climate change,standardize the use of lands in flood detention areas,give space to floods,and promote the implementation of flood risk maps and flood insurance policies.The ultimate goal of this new flood control system is to enhance the adaptability to frequent floods and increase the resilience to extreme flood disasters.     

全球变暖导致洪水风险增加——长江洪水前景分析

近期在很多地方洪水越来越频繁且破坏性更大.20世纪90年代以来全球大洪水造成社会经济财产巨大损失,30次大洪水每次总损失额均超过10×10⁸美元.1990-1998年的9a时间的大洪水爆发的次数比1950-1985年期间Ma大洪水次数还要多.近年来中国大陆也遭受了若干重大洪水灾害(包括1996和1998年两次大的财产损失).与气候变率和变化相关的洪水灾害和易爆发程度的显著增加,这是当前最紧迫的问题.随着气温升高大气中持水量也增加,因此大规模强度的降水的可能性也增大.己观测到高而集中的大降水事件而且这种趋势在未来气候变暖条件下可能增加,大降水事件的增加是洪灾增加的必然条件.当然也有一些其它的非气象因素加剧洪灾的发生,比如土地利用变化(森林砍伐、城市化)导致土壤持水能力下降,径流系数增加;此外,人类占据了洪泛区,可能导致洪水损失增大.另外物质财富在洪泛区的积聚也导致了洪灾损失增加.毫无疑问,由于人类活动和气候的共同作用,未来洪水风险在很多地方可能增加.洪水易爆发程度被认为是暴露系数和调节能力的函数,而且在许多地方所有这些变量都可能增加.而随着暴露系数比人类调节能力增加快,因此洪水易爆发程度增大.然而,要完全从径流变化中区分气候因素导致的强烈自然变率还是直接的人为环境变化是很困难的.由于使用不同的假定情景和不同的气候模型,得到的未来环境的预测结果差异也很大.IPCC第三次评估报告中广泛讨论了气候变化与洪水之间的关系.IPCC第三次评估报告警告说,在东亚季风区非常湿润的季风季节出现的可能性非常大,进而会导致相应地区洪水风险增加.本文总结了迄今为此可收集到的有关长江洪水的资料.利用一些案例来分析研究未来假定情景下气候对水文的影响,并对东亚地区的模拟结果进行了讨论.     

Comprehensive flood risk assessment based on set pair analysis-variable fuzzy sets model and fuzzy AHP

On the basis of the disaster system theory and comprehensive analysis of flood risk factors, including the hazard of the disaster-inducing factors and disaster-breeding environment, as well as the vulnerability of the hazards-bearing bodies, the primary risk assessment index system of flood diversion district as well as its assessment standards were established. Then, a new model for comprehensive flood risk assessment was put forward in this paper based on set pair analysis (SPA) and variable fuzzy sets (VFS) theory, named set pair analysis-variable fuzzy sets model (SPA-VFS), which determines the relative membership degree function of VFS by using SPA method and has the advantages of intuitionist course, simple calculation and good generality application. Moreover, the analytic hierarchy process (AHP) was combined with trapezoidal fuzzy numbers to calculate the weights of assessment indices, thus the weights for flood hazard and flood vulnerability were determined by the fuzzy AHP procedure, respectively. Then SPA-VFS were applied to calculate the flood hazard grades and flood vulnerability grades with rank feature value equation and the confidence criterion, respectively. Under the natural disasters risk expression recommended by the Humanitarian Affairs Department of United Nations, flood risk grades were achieved from the flood hazard grades and flood vulnerability grades with risk grade classification matrix, where flood hazard, flood vulnerability and flood risk were all classified into five grades as very low, low, medium, high and very high. Consequently, integrated flood risk maps could be carried out for flood risk management and decision-making. Finally, SPA-VFS and fuzzy AHP were employed for comprehensive flood risk assessment of Jingjiang flood diversion district in China, and the computational results demonstrate that SPA-VFS is reasonable, reliable and applicable, thus has bright prospects of application for comprehensive flood risk assessment, and moreover has potential to be applicable to comprehensive risk assessment of other natural disasters with no much modification.     

River networks system changes and its impact on storage and flood control capacity under rapid urbanization

Urbanization significantly affects both the drainage network structure and the storage capacity of river channels in lowland plain river networks. The Yangtze River Delta region has experienced a rapid and profound urbanization of any region worldwide in the past 30 years. The southeast Yinfeng plain in the Yangtze River Delta region was used as the study area to assess changes in the river network structure from 1990 to 2010, using river feature parameter analyses and GIS spatial analysis. The elastic method was adopted to analyse river network pattern response to both urbanization and climate change, and the rates at which these factors contributed to changes in the river network pattern were investigated. Changes in the storage capacity and flood control capacity of the channel network over the past 21 years were then analysed. The results indicated that: (1) the number of river networks, and the complexity of the river network spatial structures were reduced, the drainage density decreased by 20%, the water surface ratio by 36%, the river area–length ratio by nearly 18% and the fractal dimension of the river networks by 4.5%; (2) the river network changes were due more to human activities than to climate change in this study period. Limited changes occurred in the structure of the river system, as indicated by an urbanization variability rate of less than 20% and precipitation variability range of ?5% to ?15%, although the stream structure gradually decreased with increasing urbanization variability; and (3) the storage capacity of the main river network decreased earlier (1990–2003) and was restored later (2003–2010) because of dredging and widening activities. In addition, the number of lower‐order rivers decreased, which resulted in significant decreases in the storage and flood control capacities of the river networks. Copyright © 2016 John Wiley & Sons, Ltd.     

Research on meteorological thresholds of drought and flood disaster: a case study in the Huai River Basin,China

Together with affected areas of crops from 1978 to 2008, the daily precipitation of 110 stations located in the Huai River Basin during 1959–2008 was used to study the critical conditions when drought and flood occur, based on which the quantitative relationship between the critical condition and the affected area of crops was further studied. Based on the research on the hazard-formative factor of precipitation and the damage degree of crops, the spatial-temporal characteristics of disasters were analyzed, the drought and flood disaster-causing threshold was determined, and the quantitative relationship between the disaster-causing threshold and affected area of crops was established. The results are as the follows: (1) During 1959–2008, extreme precipitation levels were high in the eastern and western part of the Huai River Basin and were low in its central part; the spatial distribution of the coefficient of variation (CV) differed greatly from average extreme precipitation: the series of most stations were located in the central basin, and especially there was a positive trend in Anhui and Henan Provinces. (2) The cumulative precipitation during the disaster period of each station was divided by its mean cumulative precipitation during the same period in 1959–2008 to obtain the disaster-causing threshold, which has shown a good effect on reflecting the actual grade and affected areas in disasters. (3) The relationship among disaster grade, disaster-causing threshold and damage area of crops was established; this threshold can be used as a tool for agricultural disaster assessment and early warning, and can effectively improve the ability to prevent and mitigate disaster in the Huai River Basin. (4) The disaster-causing threshold can be an important input parameter for hazard assessment; other underlying surface indicators can be good supplements for determining the threshold in hazard assessment.     

Dynamic risk assessment model for flood disaster on a projection pursuit cluster and its application

Aiming at reducing the losses from flood disaster, a dynamic risk assessment model for flood disaster is studied in this article. This model is built upon the projection pursuit cluster principle and risk indexes in the system, proceeding from the whole structure to its component parts. In this study, a fuzzy analytic hierarchy approach is employed to screen out the index system and determine the index weight, while the future value of each index is simulated by an improved back-propagation neural network algorithm. The proposed model adopts a dynamic evaluation method to analyze temporal data and assesses risk development by comprehensive analysis. The projection pursuit theory is used for clustering spatial data. The optimal projection vector is applied to calculate the risk cluster type. Therefore, the flood disaster risk level is confirmed and then the local conditions for presenting the control strategy. This study takes the Tunxi area, Huangshan city, as an example. After dynamic risk assessment model establishment, verification and application for flood disasters between the actual and simulated data from 2001 to 2013, the comprehensive risk assessment results show that the development trend for flood disaster risk is still in a decline on the whole, despite the rise in a few years. This is in accordance with the actual conditions. The proposed model is shown to be feasible for theory and application, providing a new way to assess flood disaster risk.     

Flood disasters and social resilience during the decline of the Qing Dynasty: Case studies of 1823 and 1849

Based on historical records and crop harvest scores extracted from historical documents, this study reconstructed the spatial–temporal distribution and severities of floods in the Yangtze-Huai River valley (YHRV) in 1823 and 1849. We also summarized the effects of the floods on society and identified government measures taken to cope with the floods in the context of the economic recession in the period of 1801–1850. The 1823 flood, which was caused by the heavy precipitation of the Meiyu period and typhoons, severely affected areas in the lower reaches of the Yangtze River. Meanwhile, the 1849 flood, triggered by long-term, high-intensity Meiyu precipitation in the middle and lower reaches of the Yangtze River, mainly affected areas along the Yangtze River. The 1849 disaster was more serious than the one in 1823. In the lower reaches of the Yangtze River, the 1849 flood caused the worst agricultural failure of the period 1730–1852. To deal with the disasters, the Qing government took relief measures, such as exempting taxes in the affected areas, distributing grain stored in warehouses, and transferring grain to severely afflicted areas. These relief measures were supplemented by auxiliary measures, such as exempting commodity taxes on grain shipped to disaster areas and punishing officials who failed to provide adequate disaster relief. The flood disasters disrupted the water system of the Grand Canal and forced the Qing government to transport Cao rice by sea beginning in 1826. This laid the groundwork for the rise of coastal shipping in modern China. With the economic recession of the 19th century, Chinese society was not as resilient to floods as it was in the 18th century. Compared to droughts, floods are more difficult to deal with and pose greater threats to infrastructure and normal life and work in the cities.     

珠江三角洲城市群地震灾害应急管理的问题分析及对策

以珠江三角洲城市群发展趋势与地震灾害形势为背景,分析其地震应急管理体系存在的突出问题,借鉴国外大城市灾害应急管理的经验,提出构建珠江三角洲城市群地震灾害应急管理新体系的对策。     

Prediction and prevention of the impacts of sea level rise on the Yangtze River Delta and its adjacent areas

The Yangtze River Delta region is characterized by high density of population and rapidly developing economy. There are low lying coastal plain and deltaic plain in this region. Thus, the study area could be highly vulnerable to accelerated sea level rise caused by global warming. This paper deals with the scenarios of the relative sea level rise in the early half period of the 21st century in the study area. The authors suggested that relative sea level would rise 25 50 cm by the year 2050 in the study area, of which the magnitude of relative sea level rise in the Yangtze River Delta would double the perspective worldwide average. The impacts of sea level rise include: (i) exacerbation of coastline recession in several sections and vertical erosion of tidal flat, and increase in length of eroding coastline; (ii) decrease in area of tidal flat and coastal wetland due to erosion and inundation; (iii) increase in frequency and intensity of storm surge, which would threaten the coastal protection works; (iv) reduction of drainage capacity due to backwater effect in the Lixiahe lowland and the eastern lowland of Taihu Lake region, and exacerbation of flood and waterlogging disasters; and (v) increase in salt water intrusion into the Yangtze Estuary. Comprehensive evaluation of sea level rise impacts shows that the Yangtze River Delta and eastern lowland of Taihu Lake region, especially Shanghai Municipality, belong in the district in the extreme risk category and the next is the northern bank of Hangzhou Bay, the third is the abandoned Yellow River delta, and the district at low risk includes the central part of north Jiangsu coastal plain and Lixiahe lowland.     

Assessment of social vulnerability to natural hazards in the Yangtze River Delta, China

China is exposed to a wide range of natural hazards, and disaster losses have escalated over the past decade. Owing to the pressure from natural disasters, along with changes in climate, social conditions, and regional environment, assessment of social vulnerability (SV) to natural hazards has become increasingly urgent for risk management and sustainable development in China. This paper presents a new method for quantifying SV based on the projection pursuit cluster (PPC) model. A reference social vulnerability index (SVI) at the county level was created for the Yangtze River Delta area in China for 1995, 2000, 2005, and 2009. The result of social vulnerability assessment was validated using data of actual losses from natural disasters. The primary findings are as follows: (i) In the study area, the major factors that impact SVI are regional per capita GDP and per capita income. (ii) The study area was more vulnerable in 1995 than in later years. SV of the whole region had decreased over the study period. (iii) Most part of Shanghai and the southeast part of Jiangsu Province had been the least vulnerable within the region. From this least vulnerable zone to the periphery of the region, the situation deteriorated. The highest SVI values in all evaluated years were found in the northern, western, or southern tips of the Yangtze River Delta.     

Nonstationarity-based evaluation of flood risk in the Pearl River basin: changing patterns,causes and implications

Nonstationary GEV-CDN models considering time as a covariate are built for evaluating the flood risk and failure risk of the major flood-control infrastructure in the Pearl River basin, China. The results indicate: (1) increasing peak flood flow is observed in the mainstream of the West River and North River basins and decreasing peak flood flow is observed in the East River basin; in particular, increasing peak flood flow is detected in the mainstream of the lower Pearl River basin and also in the Pearl River Delta region, the most densely populated region of the Pearl River basin; (2) differences in return periods analysed under stationarity and nonstationarity assumptions are found mainly for floods with return periods longer than 50 years; and (3) the failure risks of flood-control infrastructure based on failure risk analysis are higher under the nonstationarity assumption than under the stationarity assumption. The flood-control infrastructure is at higher risk of flood and failure under the influence of climate change and human activities in the middle and lower parts of Pearl River basin.

EDITOR D. Koutsoyiannis

ASSOCIATE EDITOR G. Thirel     

A paleo‐hydro‐geomorphological perspective on urban flood risk assessment

Comprehensive flood risk assessment requires enhanced understanding of the coevolution of the river and its floodplain occupation. Paleoflood analysis to determine flood prone areas in combination with numerical simulations to estimate flood hazard and a historical analysis of urban development to consider the evolution of exposure to floods is a possible way forward. The well‐documented 2006 extreme flood in the Biobío River system and the impacted metropolitan area of Concepción, Chile (~1 million inhabitants) was used as a complex scenario to test the reliability of the proposed method. Results showed that flood prone areas determined with hydro‐geomorphological methods are consistent with those computed with numerical models based on detailed digital elevation models. The flood generation via superficial flow pathways resulting in inundated areas could explain that rivers tend to reactivate paleochannels in extreme conditions. Urban development progressively increased the city's exposure to floods from 0 ha in 1,751 to 1,363 ha in 2006 evidencing a lack of appropriate flood risk management. The 100‐year peak discharge resulted in a high flood risk for about 5% of the total urbanized area of Concepción, and higher discharges are likely to reactivate a paleochannel that crosses the current city centre. We conclude that the proposed paleo hydro‐geomorphology, hydraulic, and urban planning multimethod approach is a necessary tool to enhance understanding of flood risk in complex scenarios to improve flood risk management.