Risk analysis and influencing factors of drought and flood disasters in China

The risk analysis of flood and drought disasters and the study of their influencing factors enhance our understanding of the temporal and spatial variation law of disasters and help identify the main factors affecting disasters. This paper uses the provincial administrative region of China as the research area. The proportion of the disaster area represents the degree of the disaster. The statistical distribution of the proportions was optimized from 10 alternative distributions based on a KS test, and the disaster risk was analyzed. Thirty-five indicators were selected from nature, agriculture and the social economy as alternative factors. The main factors affecting flood and drought disasters were selected by Pearson, Spearman and Kendall correlation coefficient test. The results demonstrated that the distribution of floods and drought is right-skewed, and the gamma distribution is the best statistical distribution for fitting disasters. In terms of time, the risk of flood and drought disasters in all regions showed a downward trend. Economic development and the enhancement of the ability to resist disasters were the main reasons for the change in disasters. Spatially, the areas with high drought risk were mainly distributed in Northeast and North China, and the areas with high flood risk were mainly distributed in the south, especially in Hubei, Hunan, Jiangxi and Anhui. The distribution of floods and drought disasters was consistent with the distribution characteristics of precipitation and water resources in China. Among the natural factors, precipitation was the main factor causing changes in floods and drought disasters. Among the agricultural and socioeconomic factors, the indicators reflecting the disaster resistance ability and regional economic development level were closely related to flood and drought disasters. The research results have reference significance for disaster classification, disaster formation mechanisms and flood and drought resistance.

     

Flood events, fatalities and damages in India from 1978 to 2006

High temporal and spatial variability of rainfall qualifies India to be highly vulnerable to floods. Recurring floods of various magnitudes play havoc with the lives and property of the people, leading to unplanned development and unchecked environmental degradation, thwarting and retarding the overall development of the country. Therefore, the purpose of the present study is to analyze the types and trends in terms of flood events, frequency, number of people killed, injured, missing and economic damage both in space and time on the basis of a nationwide database published by India Meteorological Department, Pune, from 1978 to 2006. Analysis of these long-term data has revealed that 2,443 flood events claimed about 44,991 lives with the average of 1,551 lives each year. In terms of population size, these figures translate into a loss of 1.5 human lives per million of the population. A majority (56 %) of flood fatalities were caused during severe flood events. However, the frequency of these events was just 19 % in comparison with heavy rainfall events (65 %). In spatial context, flood-related fatalities are distributed all over the country with highest fatalities in Uttar Pradesh (17 %), Maharashtra (13 %), and Bihar and Gujarat (10 % each). Most fatalities occurred during the summer season monsoon months of August (30 %) followed by July (29 %) and September (20 %). The country suffered a cumulative flood-related economic loss of about 16 billion US$ between 1978 and 2006 and a maximum economic loss of 1.6 billion US$ in the year 2000 alone. The study further suggests that both flood events and fatalities have increased in India over a period of time.     

浅析甘肃小流域分布特性及山洪灾害成灾特点

暴雨洪水是自然界的主要灾害之一,它是水文现象的极端事件。山洪给国民经济和人民的生命财产造成很大损失,它是甘肃经济社会发展的重要制约因素之一。随着经济发展,人口增加,山洪给国民经济和社会发展带来的损失将越来越大,因此,防洪减灾任务仍十分艰巨。本文对甘肃省小流域分布特性及山洪成灾特点进行了分析,并提出了山洪灾害防治的建议。     

Global Perspectives on Loss of Human Life Caused by Floods

Every year floods cause enormous damage all over the world. This study investigates loss of human life statistics for different types of floods and different regions on a global scale. The OFDA/CRED Database contains data on international disasters and is maintained by the Centre for Research on the Epidemiology of Disasters in Brussels (CRED) in cooperation with United States Office for Foreign Disaster Assistance (OFDA). Information from this source on a large number of flood events, which occurred between January 1975 and June 2002, is evaluated with respect to flood location and flood type. Due to the limited availability of information on coastal flood events, the scope of this study is limited to three types of freshwater flooding: river floods, flash floods and drainage problems. First, the development of loss of life statistics over time is discussed. Second, the dataset is analysed by region, by flood type and by the combination of type and region. The study shows that flash floods result in the highest average mortality per event (the number of fatalities divided by the number of affected persons). A cross analysis by flood type and location shows that average mortality is relatively constant for the different types over various continents, while the magnitude of the impacts (numbers of killed) and affected for a certain type varies between the different continents. On a worldwide scale Asian river floods are most significant in terms of number of persons killed and affected. Finally, a comparison with figures for other types of natural disasters shows that floods are the most significant disaster type in terms of the number of persons affected.     

Flood damage assessment of an urban area in Chennai, India, part I: methodology

Floods are random phenomena that not only cause damage to the lives, natural resources and the environment, but also affect the health of people. The severity of flooding tends to increase with urbanization. Socio-economic impacts of floods depend on the area, duration and depth of inundation, population density, housing typology, construction materials of dwellings, etc. This article examines the different available methods to trace the flood damage and illustrates the methodology to explore the economic loss through social investigation in Velachery, a part of urban Chennai in India. This paper is Part I of a two-part series in which the objectives and methodology are discussed. Based on the objectives and methodology developed for the study, a comprehensive flood management strategy can be proposed for the efficient management of future flood disasters. The results of the study are discussed in Part II.     

Flood, drought and typhoon disasters during the last half-century in the Guangdong province, China

In this paper, we present the changing properties of losses due to occurrences of droughts, floods and typhoon disasters in the Guangdong province, a comparatively economically prosperous province in the south China. Influences of typhoon activities on droughts and floods are also analysed. Results based on extensive and thorough investigations indicate that (1) generally, Guangdong province is both humid and warm; however, in recent decades, the negative impacts of droughts seem to be enhancing, which is proved by increasing drought-induced economic loss. In this sense, considerable importance should be attached to droughts, but not solely to floods, in the Guangdong province; (2) low-lying terrain of the Guangdong province makes this region easy to be influenced by flood inundation. Moreover, highly urbanized areas are mostly located in the low-lying areas. Flood-induced loss was increasing before 1990s and is decreasing after 1990s, and this should be attributed mainly to seasonal shifts of precipitation changes and enhancing human mitigation to flood disasters; (3) typhoon activities often inflict considerable loss on the economy of the Guangdong province. Moreover, flood events in the study region are mostly the results of typhoon activities. Flash floods, strong wind and storm surge accompanying typhoon activities are the major factors intensifying the negative impacts of the typhoon disasters.     

Global snowmelt flood disasters and their impact from 1900 to 2020北大核心CSCD

Under the background of climate warming, the occurrence time, frequency, intensity, and impact of snowmelt flood disasters have changed significantly. Thus, establishing a global snowmelt flood disaster database is particularly important for disaster risk management. With the help of a web crawler, and based on multiple data sources such as natural disaster databases, documents, books, government agency websites, and news media, this study collected relevant information of snowmelt floods and mixed floods and established standards for identifying snowmelt flood events and their disaster impacts based on data from the different sources. Following the screening, sorting, fusion, and integration of snowmelt flood events, a global snowmelt flood disaster dataset containing 579 pieces of data with strong pertinence and reliability was constructed. The temporal and spatial distribution characteristics of global snowmelt flood disasters from 1900 to 2020 were preliminarily analyzed. The results showed that the snowmelt floods were mainly distributed between 30° N and 60° N, with more mixed floods south of 50° N and more snowmelt floods north of 50° N. Spring was the period of highest incidence of snowmelt flood disasters, followed by winter, summer, and autumn, respectively. The snowmelt floods that occurred in spring, autumn, and winter were mainly at 40°~50° N, and the snowmelt floods that occurred in summer were mainly at 30°~40° N. Compared with the snowmelt floods, the mixed floods were more frequent and more destructive, and their frequency increased with climate warming. The results provide a scientific basis for risk prevention and loss assessment of global snowmelt flood disasters. © 2022 Science Press (China).     

Hydroclimatological Perspective of the Kerala Flood of 2018

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 95^th 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.     

Analysis of flash flood disaster characteristics in China from 2011 to 2015

Flash floods are one of the most disastrous natural hazards and cause serious loss of life and economic damage every year. Flooding frequently affects many regions in China, including periodically catastrophic events. An extensive compilation of the available data has been conducted across various hydroclimatological regions to analyze the spatiotemporal characteristics of flash floods in China. This inventory includes over 782 documented events and is the first step toward establishing an atlas of extreme flash flood occurrences in China. This paper first presents the data compilation strategy, details of the database contents, and the typical examples of first-hand analysis results. The subsequent analysis indicates that the most extreme flash floods originate mainly from small catchments over complex terrains and results in dominantly small- and medium-sized flooding events in terms of scales; however, these events, abrupt and seasonally recurrent in nature, account for a large proportion of the overall flooding-related disasters, especially disproportionately affecting elderly and youth populations. Finally, this study also recommends several immediate measures could be implemented to mitigate high impacts of deadly flash floods, although it still requires long-term significant efforts to protect human life and property in a country like China.     

Spatial dimension of impact,relief, and rescue of the 2014 flood in Kashmir Valley

Flood relief and rescue form an important basis of disaster management, and the assessment of flood damage is a critical component of flood risk management. In its recent history, Kashmir Valley witnessed the floods in 2014, 2015, 2017, 2019, 2020, and 2021, but the worst flood in the living memory of the people was witnessed in the year 2014, which created widespread loss in economic and societal aspects. The present study discusses the spatial dimension of impact, relief, and rescue of the flood of 2014 in the Kashmir Valley. It analyses the distribution of relief and politics of relief and rescue and highlights the role of the communitarianism and the heroics of the community members in dealing with floods. The study provides the data of relief distribution under different government schemes and reveals that the relief was not distributed equally in various districts of the valley. The study relies on primary and secondary sources of data. Ethnographic approach was used for acquiring primary data because it provides the complex narratives of disasters and the political and social rupture experienced during the disasters. The data have been analysed with the help of Geographic Information System.

     

Impact of Flood Disasters on Taiwan in the Last Quarter Century

The increasing natural disasters, especially floods during the last quarter century, are raising the economic losses in Taiwan. The most severe hazard in Taiwan is flooding induced by typhoons and storms in summer and autumn. By comparing the rivers around the world, the ones in Taiwan have the steepest slopes, the largest discharge per unit drainage area, and the shortest time of concentrations. Rapid urbanization without proper land uses managements usually worsen the flood problems. Consequently, flood hazards mitigation has become the most essential task for Taiwan to deal with. Although the government keeps improving flood defense structures, the flood damage grows continuously. In this article, possible flood mitigation strategies are identified for coping with complex environmental and social decisions with flood risk involved.     

洪水影响的综述

洪水影响涉及到自然和社会系统的诸多方面.本文将洪水影响纳入洪水环境系统进行统一考虑,综述了洪水对自然生态、社会经济及国家政策的可能影响,提出了对特定洪水事件应通过多学科的合作,探求技术、经济和环境综合效应,为洪水灾害的防治提供科学依据.     

洪泽湖流域洪涝灾害的成灾机理分析与探讨

本文从洪泽湖历史洪涝灾情入手,分析了洪涝灾害的孕灾机理,认为自然因素叠加了人类不合理的活动共同导致了洪泽湖洪涝发生。典型洪涝孕灾区的过渡性地理位置是导致洪涝发生的大环境背景原因；流域暴雨降水高度集中的特征是洪涝的触发器；黄河夺淮历史和泥沙淤积而成的“悬湖”和“倒比降”的脆弱性地形地貌是洪涝发生的历史根本原因；下游排洪通道标准低、行洪能力不足以及人类过度围垦造成库容和湖面减小的影响都加重加大了洪涝灾害的程度和频次。     

A macro-scale flood risk model for Jamaica with impact of climate variability

Floods account for more than half of the global hydrometeorological risks. Severe floods cause significant economic shocks and loss of lives, particularly for developing countries such as Jamaica. There is need for more information on the present and projected flood risks to justify macro-scale planning for climate change adaptation and facilitate the decision-making processes. In this study, a catalogue of 198 flood events occurring between 1678 and 2010 is compiled for Jamaica and used to examine the climatology, occurrence, trends, causes and duration of the island’s severe events. The annual flood risk is estimated to be a loss of life rate of 4 persons and estimated annual damage of USD96.3 million per annum in 2010 values and approximately 0.84 % of GDP per annum. Macro-scale models for flood risks (deaths and damages) are also developed using data from the flood catalogue and maximum precipitation at the town and parish level. The models examine the relationship between flood risks (death and damages) and extreme rainfall depths and intensities. Future climate risks of loss of lives and damages are predicted to increase 11 and 9 %, respectively, to 4.4 persons and USD105.2 million per annum.     

Major flood disasters in Europe: 1950–2005

There is a need for comprehensive, standardised and georeferenced information on floods for political and economic decision-making. Relevant, accurate and up-to-date data is an important aspect for resource distribution, mitigation programmes, disaster monitoring and assessment. Despite this, there is a lack of spatial and thematic accurate global data for floods. In Europe, historic data on flood losses and casualties are neither comprehensive nor standardised, thus making long-term analyses at continental level difficult. In this article, we present a map and catalogue of the major flood events of the last 56 years in the European Union (EU), Bulgaria and Romania. This study is an effort to alleviate the lack of homogeneous and georeferenced information on flood disasters for large periods in Europe. The objectives of this paper are to identify and classify the major flood disasters of the last 56 years in the EU; to map the major flood disasters at pan-European scale with the support of a potential flood hazard map and ancillary GIS datasets; and to give a picture of the current situation for major floods in the EU on the basis of past events and current trends. The Emergency Events Database (EM-DAT) of the Centre of Research on Epidemiology of Disasters in Brussels (CRED) and United States Office for Foreign Disaster Assistance (OFDA) and NATHAN of Munich Re are two of the main public global databases for natural disasters. Information from EM-DAT and NATHAN on flood disasters producing more than 70 casualties and/or more than 0.005% of EU GDP in damage has been assessed for the production of the map and catalogue of major flood disasters in Europe.

Meteorological Office, Pune-411 005

Natural disasters like floods, tornadoes, tropicalcyclones, heat and cold wavewreak havoc and cause tremendous loss ofproperty all over the world. Most ofthe natural disasters are either dueto weather or are triggered due toweather related processes.Extreme weather events claimed thousands oflives and caused damage on vastscale. Recent super cyclone which affectedOrissa in 1999, Bangladesh cyclone of1970 and Hurricane Andrew in 1992 areexamples of some of the more damagingtropical cyclones which affected developingas well as the developed world. Heatand cold waves are also extreme events,which cause enormous losses in terms oflives lost and human discomfort and ailmentsarising out of them. The heat waveof 1995 and 1998 are still fresh in the mindof the Indian public. The estimated lossof human lives due to heat wave in 1998 was morethan 15,000. Economic losses asa result of these disasters and in particular inassociation with tropical cyclones haveincreased enormously over the last three decades.During 1961–1991, total loss oflives from drought alone was 1,333,728 overthe whole world. In terms of economiclosses, there is 8–10 fold increase from thebase figure of 1960. The socio-economicimpact of natural disaster is complex dependingupon the vulnerability of the placeand mitigation strategies that are put in place.Meteorology plays a crucial role in forewarningpeople about the severe/extremeweather systems and a constant endeavour by themeteorological services worldover has gone a long way towards minimizing thelosses caused by natural disasters.The paper summarises the natural disasterstatistics over south Asia and the possibleprediction strategies for combating theirsocio-economic impacts.     

Integrating the geographic information system and predictive data mining techniques to model effects of compound disasters in Taipei

Located in the circum-Pacific seismic zone, Taiwan is continually threatened by such natural disasters as typhoons, floods, landslides, and earthquakes, which increase risk of property loss and severely endanger public safety. Taipei City, the political and economic capital of Taiwan, must address disaster prevention and relief operations for compound disasters and extreme climatic events in addition to existing metropolitan disaster prevention operations. This study formulates 48 compound-disaster scenarios based on threats to Taipei City due to heavy rainfall and surrounding faults. Hydrology and flood analysis results and the Taiwan earthquake loss estimation system are utilized to assess the potential for compound disasters and the number of people they would displace in Taipei’s administrative districts. Analytical results can be used to create a pre-disaster static potential diagram and a refuge or shelter capacity assessment table. The disaster potential diagram is adopted to conduct geographic information system spatial and data analysis, and temporary refuges or shelters planned by the city government are integrated for shelter capacity comparison. Furthermore, a dynamic assessment curve for the number of displaced people during a disaster is plotted using data mining and attribute filtering. Subsequently, a cross table is obtained and employed to predict the number of refugees in the various administrative districts. Finally, conclusions and recommendations are provided for making disaster prevention and relief decisions simultaneously concerning earthquakes and flooding.     

Does a Kuznets curve apply to flood fatality? A holistic study for China and Japan

A Kuznets curve is the graphical representation of Simon Kuznets’ hypothesis that as a country develops, there is a natural cycle of economic inequality driven by market forces, which at first increase inequality and then decrease it after a certain average income is attained. The concept has been applied to environmental studies hypothesizing that the relationship between per capita income and the use of natural resources and/or the emission of wastes has an inverted-U shape. This paper presents a holistic study aimed at validating the applicability of the Kuznets curve to flood disaster. The focus is China and Japan. Both countries are prone to flooding and have experienced great economic growth. Data analysis detected the turning points of annual flood fatality in both countries, and the change in annual flood fatality with economic growth in both countries was found to match the Kuznets curve. However, the variation pattern of annual flood-caused economic loss was different between China and Japan. The difference may be partially attributed to the difference in residential characteristics between the two countries. Besides, it was found that climate change affected the flood-caused economic loss in Japan over recent decades. Furthermore, the variations in annual flood fatality and economic loss in the largest city of China were also analyzed.     

从2020年长江上游洪水看流域防洪对策

2020年长江上游和中下游先后发生特大洪水,其中干流编号洪水全部发生在上游,构成了长江流域洪水的主要部分。首先回顾2020年洪水及洪灾情况,然后根据历史上几次特大洪水过程和历年实测资料,分析长江上游洪水特征、洪灾类型及特点,最后提出新时代长江流域洪水整体防御战略及山洪灾害防治战术。研究表明:金沙江洪水是长江上游洪水基础部分,岷江、嘉陵江和干流区间是洪峰的主要来源,三者洪水遭遇是产生上游特大洪水的主因,上游洪水又是全流域特大洪水的基础和重要组成部分。目前造成洪灾死亡人数最多的是山洪以及山洪引起的地质灾害,财产损失最大的是中下游及湖泊地区。未来堤防仍然是防洪的基础,提高沿江城市防洪标准主要手段是控制性水库的联合优化调度,而减少洪涝灾害损失最有效的途径是给洪水以空间的自然解决方案等非工程措施。