The influences of the tectonic subsidence and the siltation on the situation of preventing flood disasters in the Dongting Lake area

With the long-term data of the geodetic sea level measurements undertaken in the Dongting Basin and the recent sediment data of Dongting Lake, we analyze the tectonic subsidence rate of the Dongting Basin and the sedimentary rate of Dongting Lake. From the point of view of geomorphology and hydrogeology, we distinguish the two different spatial concepts between 'the basin of Dongting Lake' and 'the Dongting Basin'. Then, we discuss the influences of the tectonic subsidence and the siltation on the levees and the space of storing flood. The better quality of levees is required due to the tectonic subsidence and the siltation, and the difficulties of preventing flood disasters are increasing. The space of storing flood is not affected by the tectonic subsidence, but by the siltation. At present, the sedimentary rate of Dongting Lake is higher than the tectonic subsidence rate of the Dongting Basin. The tectonic subsidence capacity of the Dongting Basin counteracts a part of sedimentary capacity, and the shrinking tendency of Dongting Lake is restrained to a certain extent, but the tectonic subsidence is harmful to the situation of preventing flood disasters in the Dongting Lake area.

Constrction of watershed flood disastermanagement information system and its application to the catastrophic flood of theYangtze River in 1998

This paper introduces a general method of establishing Watershed Flooding Disaster Management Information System (WFDMIS). The functions, database, models, user interface, software and hardware are considered. An application example in Poyang Lake Basin was given.

Flood disaster monitoring based on Sentinel-1 data:A case study of Sihu Basin and Huaibei Plain,China

Summer floods occur frequently in many regions of China,affecting economic development and social stability.Remote sensing is a new technique in disaster monitoring.In this study,the Sihu Basin in Hubei Province of China and the Huaibei Plain in Anhui Province of China were selected as the study areas.Thresholds of backscattering coefficients in the decision tree method were calculated with the histogram analysis method,and flood disaster monitoring in the two study areas was conducted with the threshold method using Sentinel-1 satellite images.Through satellite-based flood disaster monitoring,the flooded maps and the areas of expanded water bodies and flooded crops were derived.The satellite-based monitoring maps were derived by comparing the expanded area of images during a flood disaster with that before the disaster.The difference in spatiotemporal distribution of flood disasters in these two regions was analyzed.The results showed that flood disasters in the Sihu Basin occurred frequently in June and July,and flood disasters in the Huaibei Plain mostly occurred in August,with a high interannual vari-ability.Flood disasters in the Sihu Basin were usually widespread,and the affected area was between Changhu and Honghu lakes.The Huaibei Plain was affected by scattered disasters.The annual mean percentages of flooded crop area were 14.91%and 3.74% in the Sihu Basin and Huaibei Plain,respectively.The accuracies of the extracted flooded area in the Sihu Basin in 2016 and 2017 were 96.20% and 95.19%,respectively.

Risk Identification for the Ecological Environment of Flood Disasters Based on the Life Cycle

Aiming at the complexity of ecological environment risk of flood disaster, the life cycle of flood disaster is defined based on the relevant literatures, which is divided into incubation period, development period, outbreak period, recession period and extinction period. The characteristics of each period are analyzed. Further, the main risks for ecological environment faced at each stage under the life cycle of flood disaster are studied systematically to form the systematic ecological environment risk system for flood disaster.

Urban Flood Disaster Risk Assessment and Planning Response: A Case Study of Handan, Hebei Province

Flood disaster is a serious threat to urban security,and flood control and drainage planning is an important measure to ensure urban security.This paper takes planning guidance to empirical research as the main axis.On the basis of meteorological data and spatial data,through the analysis on the risk of disaster-causing factors of flood disasters,the sensitivity of disaster-pregnant environment,the vulnerability of disaster-bearing bodies and the ability of disaster prevention and mitigation,12 indicators are selected to construct a comprehensive evaluation index system for flood disaster risk.Handan City is taken as an example to study the spatial distribution characteristics of flood disaster risk.Based on AHP,weights are assigned to the evaluation indicators of flood disasters in the system,and the risk visualization is carried out in GIS.According to comprehensive risk assessment results,it could put forward corresponding disaster prevention planning strategy for defending flood disaster in Handan City.

Characteristics of Rainstorm and Flood Disaster in Shaoyang City and Flood Protection Countermeasures

Based on ground meteorological observation data at 10 representative stations of Shaoyang City during 1951-2017 and rainfall data at over 220 automatic weather stations during 2005-2017,statistical analysis on rainstorm and flood disaster in Shaoyang was conducted. Occurrence characteristics and rule of rainstorm and flood disaster were found,and disaster situation was evaluated and analyzed. The results showed that（ 1）there was almost local rainstorm and flood in Shaoyang City every year,with strong seasonal characteristic.（ 2） The loss caused by rainstorm and flood disaster was the most serious in various meteorological disasters.（ 3） Rainstorm and flood disaster generally had the sudden and devastating characteristics. Via the analysis and research on rainstorm and flood disaster,defense measure and countermeasure of rainstorm and flood were proposed,which could provide scientific decision basis for party and government leading flood relief,and had important guidance significance for preventing and mitigating disasters by government agencies.

Analysis and Zoning of Rainstorm Flood Disaster Risk in Huaihe River Basin

Taking the rainstorm flood disaster of Huaihe River basin as the research object,according to the principles of risk assessment for natural disasters,starting from the fatalness of inducing factors and the vulnerability of hazard bearing body,the weight of each impact factor was calculated by using AHP. By using spatial analysis and statistical function of GIS,the integrated risk chart of rainstorm flood disaster in Huaihe River basin was obtained. The results showed that the high risk areas of rainstorm flood disaster in Huaihe River basin mainly distributed in the southern part of Henan,the central northern part of Anhui and eastern part of Jiangsu Province. Due to higher fatalness of inducing factors in southern Henan,there was high risk in the region. Central Anhui and east Jiangsu were not only high-fatalness zones but also high vulnerability zones of population and economy.

Risk assessment of coastal flooding disaster by storm surge based on Elevation-Area method and hydrodynamic models:Taking Bohai Bay as an example

The future inundation by storm surge on coastal areas are currently ill-defined.With increasing global sealevel due to climate change,the coastal flooding by storm surge is more and more frequently,especially in coastal lowland with land subsidence.Therefore,the risk assessment of such inundation for these areas is of great significance for the sustainable socio-economic development.In this paper,the authors use Elevation-Area method and Regional Ocean Model System(ROMS)model to assess the risk of the inundation of Bohai Bay by storm surge.The simulation results of Elevation-Area method show that either a 50-year or 100-year storm surge can inundate coastal areas exceeding 8000 km^(2);the numerical simulation results based on hydrodynamics,considering ground friction and duration of the storm surge high water,show that a 50-year or 100-year storm surge can only inundate an area of over 2000 km^(2),which is far less than 8000 km^(2);while,when taking into account the land subsidence and sea level rise,the very inundation range will rapidly increase by 2050 and 2100.The storm surge will greatly impact the coastal area within about 10-30 km of the Bohai Bay,in where almost all major coastal projects are located.The prompt response to flood disaster due to storm surge is urgently needed,for which five suggestions have been proposed based on the geological background of Bohai Bay.This study may offer insight into the development of the response and adaptive plans for flooding disasters caused by storm surge.

The Dynamics of Interorganizational Collaboration in Disaster Management:A Network Study Based on Flood Disasters in China

Interorganizational collaboration networks have become an important tool for disaster management.However,research on how different organizations can effectively collaborate throughout the entire disaster management process in centralized states such as China is scarce.This study begins to fill this lacuna by investigating interorganizational collaboration in different phases of disaster management and analyzing changes in the structure of the networks constructed during the preparedness and response phases of the 2020 flood disaster in Hubei Province,China.Building on the complex adaptive systems(CAS)theory,we argue that interorganizational collaboration changes dynamically according to its tasks and requirements.In the preparedness phase,interorganizational collaborations primarily follow established plans and choose horizontal selforganized collaboration mechanisms.However,when the urgent information and resource requirements increase in the response phase,many organizations choose vertical mandatory collaboration mechanisms.We found that organizations at the central and provincial levels in China were well positioned to coordinate information and resources and strengthen the interorganizational collaboration and communication that is crucial in disaster management.These findings contribute to the study of interorganizational collaboration networks in disaster management.

Application of Fengyun-4 Satellite to Flood Disaster Monitoring through a Rapid Multi-Temporal Synthesis Approach

Fengyun-4 A(FY-4 A) belongs to the second generation of geostationary meteorological satellite series in China. Its observations with high frequency and resolution provide a better data basis for monitoring of extreme weather such as sudden flood disasters. In this study, the flood disasters occurred in Bangladesh, India, and some other areas of South Asia in August 2018 were investigated by using a rapid multi-temporal synthesis approach for the first time for removal of thick clouds in FY-4 A images. The maximum between-class variance algorithm(OTSU;developed by Otsu in 2007) and linear spectral unmixing methods are used to extract the water area of flood disasters. The accuracy verification shows that the water area of flood disasters extracted from FY-4 A is highly correlated with that from the high-resolution satellite datasets Gaofen-1(GF-1) and Sentinel-1 A, with the square correlation coefficient R2 reaching 0.9966. The average extraction accuracy of FY-4 A is over 90%. With the rapid multi-temporal synthesis approach used in flood disaster monitoring with FY-4 A satellite data, advantages of the wide coverage, fast acquisition,and strong timeliness with geostationary meteorological satellites are effectively combined. Through the synthesis of multi-temporal images of the flood water body, the influence of clouds is effectively eliminated, which is of great significance for the real-time flood monitoring. This also provides an important service guarantee for the disaster prevention and reduction as well as economic and social development in China and the Asia-Pacific region.

Glacial Lake Outburst Flood Disasters and Integrated Risk Management in China

High-risk areas for glacial lake outburst flood(GLOF) disasters in China are mainly concentrated in the middle-eastern Himalayas and Nyainqe?ntanglha(Nyenchen Tanglha Mountains), Tibetan Plateau. In the past 20 years, glaciers in these regions have retreated and thinned rapidly as a response to regional climate warming,leading to the formation of new glacial lakes and the expansion of existing glacial lakes. These areas are located in the border belt between the Indian and the Eurasian plates, where tectonic seismic activity is also frequent and intense. Earthquakes have often compromised the stability of mountain slopes, glaciers, and moraine dams, resulting in an imbalance in the state of glacial lakes and an increase of loose materials in valleys. It is foreseeable that the possibility of GLOFs and disaster occurrence will be great in the context of frequent earthquakes and continued climate warming. This article presents the temporal and spatial characteristics of GLOF disasters, as well as the conditions and mechanisms of GLOF disaster formation,and proposes an integrated risk management strategy to cope with GLOF disasters. It aims to facilitate the mitigation of the impacts of GLOF disasters on mountain economic and social systems, and improve disaster risk analysis, as well as the capability of risk management and disaster prevention and reduction.

Evolution of Collaborative Governance in the 2015,2016,and 2018 Myanmar Flood Disaster Responses:A Longitudinal Approach to a Network Analysis

In disaster response,collaboration facilitates interactions among actors,such as the government,the military,nongovernmental organizations,and civil society organizations.This study examined the longitudinal changes in collaborative governance in Myanmar’s disaster responses based on cases of flooding in 2015,2016,and 2018.To examine the mechanisms underlying this dynamic network formation,the collaborative ties of the actors involved in search and rescue activities were converted into longitudinal relational data sets,and the evolution of collaborative governance was analyzed by relying on the assumptions of social capital,transaction cost,homophily,and resource dependency theories and using a longitudinal social network analysis method.The findings show that the collaborative networks of search and rescue processes in disaster response evolved and changed over time according to the hypothesized patterns of strong,weak,and preferential tie formations.The study also revealed that the collaborative governance system assumes the form of a hierarchy rather than a generalized exchange,and the actors’reliance on military organizations is not obvious due to the emerging alternative non-military actors and diverse local actors observed in the cases.

Dryness-wetness change and regional differentiation of flood-drought disasters in Guangdong during 1480-1940AD

Based on the historical records of the drought and flood disasters during 1480-1940AD, this paper reconstructs the sequences of wetness index （WI） and drought and flood disasters. We find a good identical relationship between the fluctuation of WI sequence and the δ^18O record of the GISP2 ice core in Greenland, which shows an apparent monsoonal disposal pattern of moisture and temperature. By applying the Morlet Wavelet Transform Method to deal with the data, several apparent periodicities, such as 7-8a, 11-15a, 20-23a and ca 50a, are revealed, among which some can be attributed to the solar forcing. Based on results of Cluster Analysis of dry-wet changes, we resume the regional differentiation pattern of flood-drought disasters all over Guangdong during different climatic intervals in the LIA and, find the western and northern parts of Guangdong have undergone drastic changes in drought-flood regional differentiation, but the eastern part is relatively stable, and the area of the Pearl River Delta shows stable condition of more flood disasters.

Spatiotemporal Characteristics of Droughts and Floods in Shandong Province,China and Their Relationship with Food Loss

Mastering the pattern of food loss caused by droughts and floods aids in planning the layout of agricultural production,determining the scale of drought and flood control projects,and reducing food loss.The Standardized Precipitation Evapotranspiration Index is calculated using monthly meteorological data from 1984 to 2020 in Shandong Province of China and is used to identify the province’s drought and flood characteristics.Then,food losses due to droughts and floods are estimated separately from disaster loss data.Finally,the relationship between drought/flood-related factors and food losses is quantified using methods such as the Pearson correlation coefficient and linear regression.The results show that:1)there is a trend of aridity in Shandong Province,and the drought characteristic variables are increasing yearly while flood duration and severity are decreasing.2)The food losses caused by droughts in Shandong Province are more than those caused by floods,and the area where droughts and floods occur frequently is located in Linyi City.3)The impact of precipitation on food loss due to drought/flood is significant,followed by potential evapotranspiration and temperature.4)The relationship between drought and flood conditions and food losses can be precisely quantified.The accumulated drought duration of one month led to 1.939×10^(4)t of grain loss,and an increase in cumulative flood duration of one month resulted in1.134×10^(4)t of grain loss.If the cumulative drought severity and average drought peak increased by one unit,food loss due to drought will increase by 1.562×10^(4)t and 1.511×10^(6)t,respectively.If the cumulative flood severity and average flood peak increase by one unit,food loss will increase by 8.470×103t and 1.034×10^(6)t,respectively.

Analysis of Forecast and Early Warning of Flood in Medium and Small Rivers

Flooding of small and medium rivers is caused by environmental factors like rainfall and soil loosening.With the development and application of technologies such as the Internet of Things and big data,the disaster supervision and management of large river basins in China has improved over the years.However,due to the frequent floods in small and medium-sized rivers in our country,the current prediction and early warning of small and medium-sized rivers is not accurate enough;it is difficult to realize real-time monitoring of small and medium-sized rivers,and it is also impossible to obtain corresponding data and information in time.Therefore,the construction and application of small and medium-sized river prediction and early warning systems should be further improved.This paper presents an analysis and discussion on flood forecasting and early warning systems for small and medium-sized rivers in detail,and corresponding strategies to improve the effect of forecasting and early warning systems are proposed.

Yellow River Valley flood and drought disaster：spatial－temporal distribution prediction and early－warning

By means of analysing the historical data of flood-drought grade series in the past 2000 years(A.D.0-1900),especially in the last 5000 years (1470-1900) , this paper revealed the spatial-temporaldistribution features of severe flood and drought in Yellow River Valley. Statistical methods of varianceanalysis, probability transition and the principles of scale correspondence were employed tocomprehensively predicate 90's tendency of severe flood and drought in the Yellow River Valley. In addi-tion, this paper pointed out the possible breaching dikes, sectors and the flooding ranges by future's se-vere flood, meanwhile estimating the associated economic losses and impact to environment.

Comprehensive Evaluation of Flood and Flood in the Yellow River Basin Based on Gray Correlation Analysis

Due to the concentrated rainfall and serious soil erosion in July and August in the Yellow River Basin, the flood discharge is not timely leading to serious floods. Therefore, a reasonable assessment of the flood-affected areas, advance arrangements for the deployment of the Yellow River basin flood disaster prevention and control plays a decisive role. For this purpose, this paper proposes a level assessment method based on the flood which analyzes three factors related to flooding disaster (disaster impact range, social index, and property index) through the gray correlation analysis method, to evaluate the level of flood disaster. Different from the traditional assessment method, which evaluates the nature of flood from the perspective of indicators such as frequency, duration, and magnitude, or indirect factors such as rainfall and soil loss, this paper conducts qualitative calculation of macro-scale indicators from the perspective of post-disaster losses in previous years. This study provides a new way of thinking and method for the classification of the flood disaster, which has certain practical application value under the condition of conforming to its own use.

Engineering Strategies on Flood Control in Middle Reach of Yangtze River, China

Flood disaster has been a serious hidden danger since the ancient time. The essential cause for the fact that floods have not been eliminated for hundreds of years is that time honored strategies do not suit the cases of flood prevention. In the view of geological environmental analyses of flood formation and from the synthesis of experiences gained in flood control in the past hundreds of years, sluggish draining of flood, silt sedimentation in channel and building levee blindly constitute the main cause of intractable flood for a long time in the middle reach of the Yangtze River. Draining away silt and water is the only way to stamping out flood disaster. Opening up artificial waterways for flood diversion, draining away the silt of channel into the polders, and storing the flood water are important engineering measures for the flood control and damage reduction.

GIS-based Risk Zone of Flood Hazard in Anhui Province

[Objective] The aim was to study the flood disaster risks in Anhui Province based on GIS. [Method] Taking country as basic unit, the 1∶ 250 000 basic geographic data in Anhui Province as basis, from the angle of flood disaster hazard and economic vulnerability, and by dint of the calculation of the weight of each impact factor with entropy-based fuzzy AHP method, flood risk assessment model was established to study the flood disaster risks zoning in Anhui Province. Using nearly 10 years of disaster information in Anhui Province, the flood risk zoning of Anhui Province was studied. And the risks evaluation results of flood disaster risks in Anhui Province in recent 10 years were checked. [Result] The regional difference of flood disaster in Anhui Province was large. The most serious area of flood disaster was in Lingquan in Fuyang and Lingbi in Huaibei. The risks degree degraded from south mountainous area in north Anhui Plain to the mountainous area of west Anhui Province, from Huaibei Plain to the hilly area of Jianghuai and mountainous area of south Anhui Province. The disaster situation in Anhui Province in recent 10 years suggested that the areas suffering from serious economic losses were in Lingbi, Guzheng and Huainan in the south part of Huaibei Plain. The places having serious agricultural crops damages were in Tangshan and Xiao County in Huaibei Plain. Besides, the Jingzhai area in the Dabieshan in west Anhui Province also had serious agricultural crops in Jinzhai. Other places had limited disaster-stricken impacts; the distribution of disaster-stricken population and impacted area of agricultural crops were basically consistent. Therefore, the risk evaluation of flood disaster of Anhui Province based on GIS was basically consistent with reality. [Conclusion] This GIS-based flood risk zoning method had good practicability.