Rainfall occurrence and its relation to flood damage in China from 2000 to 2015

China is highly susceptible to flood disasters and subjected to great damage every year.Furthermore, the flood frequency has exhibited an increasing trend in recent years. Most flood events,including flash floods and river flood, are induced by rainfall. This study investigates annual variations of rainfall occurrence over China during the period from 2000 to 2015 at the national and regional scale using daily rainfall data from the Tropical Rainfall Measuring Mission. The Mann-Kendall test is performed for trend detection, and statistical data of flood damage published by China's government,including destroyed crop area, damaged buildings,direct economic loss, percentage of GDP(gross domestic product), and death toll are correlatively analysed with rainfall occurrences. The results show that storm rain events show the greatest variation among three rainfall types(moderate rain, heavy rain and storm rain). The variation coefficients of rainfall over Northeast China, North China, and Northwest China are the highest, whereas that for Southwest China is the smallest. Moderate rain, heavy rain over Central China, and moderate rain over Southwest China exhibits decreasing trends, whereas the remaining exhibit increasing trends. The correlation between the rainfall occurrences and these flood damage indices at the national scale shows that only direct economic loss has a strong positive correlation with rainfall occurrences, and the other indices have weaker correlations. The correlation is strong in three north regions, except for death toll in Northwest China. In contrast, the correlation between flood damage and rainfall is weak in East China, Central China, Southwest China, and South China. Overall,death toll is strongly correlated with the number of damaged buildings, implying that flood fatalities in China are likely associated with building collapse, and are dominated by specific extreme events. This study can provide a scientific reference for flood management in China.

A GIS-based method for flooded area calculation and damage evaluation

Using geographic information system to study flooded area and damage evaluation has been a hotspot in environmental disaster research for years. In this paper, a model for flooded area calculation and damage evaluation is presented. Flooding is divided into two types: ‘soruce flood’ and ‘non-source flood’. The source-flood area calculation is based on seed spread algorithm. The flood damage evaluation is calculated by overlaying the flooded ara range with thematic maps and relating the results to other social and economic data. To raise the operational efficiency of the model, a skipping approach is used to speed seed spread algorithm and all thematic maps are converted to raster format before overlay analysis. The accuracy of flooded area calculation and damage evaluation is mainly dependent upon the resolution and precision of the digital elevation model (DEM) data, upon the accuracy of registering all raster layers, and upon the quality of economic information. This model has been successfully used in the Zhejiang Province Comprehensive Water Management Information System developed by the authors. The applications show that this model is especially useful for most counties of China and other developing countries.

Mapping of Flood Risk Zones Using Multi-Criteria Approach and Radar a Case Study of Ala and Akure-Ofosu Communities, Ondo State, Nigeria

Floods are among the worst natural catastrophes, devastating homes, businesses, public buildings, farms, and crops. Studies show that it’s not the flood itself that’s deadly but people’s vulnerability. This study investigates the Ala and Akure-Ofosu flood-prone zones;identifies elements that cause flooding in the study area;classifies each criterion by its effect;develops a flood risk map;estimates flood damage using Sentinel-1A SAR data;compares AHP results. Literature study and GIS-computer database georeferenced fieldwork data. Photos from the 2020 Sentinel 2A satellite have been organized. Built-up area, cropland, rock, the body of water, and forest Land use and cover, slope, rainfall, soil, Euclidean River Distance, and flow accumulation were mapped. These variables were integrated into a Multi-Criteria Analysis (MCA) using GIS tools, resulting in the creation of a flood risk map that categorizes the region into five risk zones: 5% of the area is identified as high-risk, 21% as low-risk, and 74% as moderate-risk. Copernicus SAR data from before and after the flood were processed on Google Earth Engine to map flood extent and ensured that the MCA map accurately reflected flood-prone areas. Periodic review, real-time flood susceptibility monitoring, early warning, and quick damage assessment are suggested to avoid flood danger and other environmental problems.

Research and application of flood damage evaluation information system

The fast evaluation method of flood damages was explored with the combination of high technologies, such as remote sensing (RS) and geographic information system (GIS), namely the land classification and extraction of flood areas were accomplished in RS image processing software, ENVI, the flood damages information system, digital terrain model and flood damages evaluation information system were developed on GIS platform GeoMedia. The problem of the combination of multi-source data was addressed, furthermore, the problems of how to build the flood damages evaluation model and the inundating elevation model were deeply probed, the calculating formulas were also given. Case study result shows that the evaluation models are correct and data are reliable, we can use it to evaluate real-time flood damages and provide evidences for decision-making of leaders, moreover, it is of great instructive significance to the research of flood damages evaluation theories.

Flood and Waterlogging Disaster Damage Evaluation in Middle-Lower Yangtze River by 3S technology

The evaluation method, model and process for the flood and waterlogging disaster condition by GIS,RS and GPS technology and the method for setting up disaster condition database, dyke database and historical disaster damage database are presented. An index of flood damage degree(FDD) used to evaluate the relative degree of disaster loss and divide flood and waterlogging area is suggested. The value of flood damage degree can be calculated as follows :taking the various disaster losses of sample area in a base year as standard value and computing the ratios of various disaster loss values in different areas and years to the standard flood disaster loss values, then summing up the weighted ratios. The computed results are the value of flood damage degree in the every year. The macroscopic flood disaster distribution can be evaluated by the values of flood loss degree.

Progress in recent study of drought,flood and waterlogging damages in China

The Drought, Flood and Waterlogging Damage (DFWD) study is related to many subjects such as meteorology and climatology, hydrology, geography, and agricultural science In the aforementioned subjects, substantial work has been done on DFWD study by a lot of researchers from the views of their specialities This paper tries to introduce the recent progress on the field Four main problems are referred to the DFWD study, they are as following: (1) The change sequence in historical period The historical data must be quantatitively processed For this purpose, many schemes were suggested in the past years Studies of the historical DFWD have been emphasized in the last fivehundred years as well as the other time scales (2) The mechanism and trigger event Natural disasters are related to factors disastrous to human activities in the evolution of physical environment, and they can reflect natural features of constitution of the physical environment The factors include the monsoon circulation, the sea tempereature effects, the ENSO, and the others (3) The loss estimation The DFWD is not a pure meteorological damage, and it is also a complex ecological damage The ecological effects, crop influences and other socialenvironment features will be considered on the estimation of DFWD loss (4) The measures of prevention and control Many forecast models are developed, and the measures of prevention and control are suggested, ie, the adoption of measures combining engineering techniques with biological measurres In the past years, advances have been made in those four aspects

Overview of flooding damages and its destructions: a case study of Zonguldak-Bartin basin in Turkey

A number of devastating flood events have oc-curred in the various river basins of Turkey in the last decade. Because floods caused deaths, suffering and extensive damages to both public and private properties in the flood areas, the government had to most of the damage in addi-tion to losing significant revenues due to the consequences of costly social and economic disruption. On the other hand, some social structures such as socioeconomic activities, land-use patterns and hydro-morphological processes are destroyed. Whereas flood control structures are considered as one of the basic strategies that can reduce flood damages and in this context flood protection planning should consider the full range of the hazard mitigation activities. In Turkey, between 1945 and 1990, 737 flooding events were occurred and at least 830 people were killed. In 1998, there was a major flooding in Zonguldak-Bartin region located on north of Turkey. Due to this devastated flooding, people lost their life and numbers of engineer-ing structures built on the river and surrounding area were totally destroyed or heavily damaged. Both side of the canal were covered with muddy soil having 0.10-0.15 m thickness. Cleaning up process took sometimes in the region. In this paper, all these subjects have been investigated in the basin and some engineering proposals have been presented.

Riverine Flood Damage Assessment of Cultivated Lands along Chenab River Using GIS and Remotely Sensed Data: A Case Study of District Hafizabad, Punjab, Pakistan

Flood is one of a kind of disasters which harms human and animal life around the globe. Pakistan has been observing massive floods for many years because of daily and seasonal variation in the temperature levels. Wheat, rice, sugarcane and cotton are major crops cultivated in Punjab region of Pakistan in which rice and sugarcane are mostly effected by floods. In this research paper, damage assessment of cultivated land in district Hafizabad along Chenab River has been calculated. Supervised Classification and Soil Adjusted Vegetation Index (SAVI) methods are applied. Pre-flood 2014, post-flood 2014, and pre-flood 2015 Landsat 8 images have been used to calculate the extent of damages to cultivated lands. Water, sand, silt, bare soil and vegetation are classified to identify damage. Results show that vegetation cover has plummeted to 50% after the arrival of flood 2014 in the Chenab. Similarly, 6.7047% of sand and 15.7339% of bare soil deposits have surfaced which have not yet been removed from fertile lands in 2015. 18.4376% standing crop damage has been analyzed under this study. 14.0245% silt deposits have been calculated as post-flood effects. 46.4260% land has been cultivated in 2015 which is 15.5024% lower than 2014 cultivated land. Furthermore, field verification survey has given promising results and has a great correlation with satellite based recovery results.

Visualization and Damage Assessment for Flooded Area

A practical method for visualizing flood area and evaluating damage is presented, which consists of two technical approaches: self\|programming and adapting commercial GIS platforms. The low\|cost and easy\|to\|use GIS\|Based model developed by self\|programming can meet current requirements of most local authorities, especially in developing countries. In this model, two cases, non\|source flood and source flood, are distinguished and the Seed\|spread algorithm suitable for source\|flood is discussed; The flood damage is assessed by overlaying the flood area range with thematic maps and other related social and economic data. and all thematic maps are converted to raster format before overlay analysis. Two measures are taken to improve the operation efficiency of speed seed\|spread algorithm. The accuracy of the model mainly depends on the resolution and precision of the DEM data, and the accuracy of registering all raster layers and the quality of attribute data.

Stabilizing silica nanoparticles in high saline water by using polyvinylpyrrolidone for reduction of asphaltene precipitation damage under dynamic condition

In this study, the performance of stable nanofluid containing SiO2 nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this work, the stability of silica nanoparticles in different range of water salinity(0–100000 mg·L-1) is investigated. Next, stable nanofluid containing highest salinity is selected as asphaltene inhibitor agent to inject into the damaged core sample. The estimated values of oil recovery for base case, after damage process and after inhibition of asphaltene precipitation using nanofluid are 51.6%, 36.1% and 46.7%, respectively. The results showed the reduction in core damage after using nanofluid. In addition, the relative permeability curves are plotted for the base case, after damage process and also after inhibition of asphaltene precipitation using nanofluid. Comparison of relative permeability curves shows, relative permeability of oil phase decreased after damage process as compared with the base case. But after using nanofluid the oil relative permeability curve has shifted to the right and effective permeability of oil phase has been improved.

Climate Change and Heavy Rainfall-Related Water Damage Insurance Claims and Losses in Ontario, Canada

The objective of this paper was to project possible impacts of climate change on heavy rainfall-related water damage insurance claims and incurred losses for four selected cites (Kitchener-Waterloo, London, Ottawa, and Toronto) located at Ontario, Canada. To achieve this goal, the future climate change scenarios and rainfall simulations, at local scale, were needed. A statistical downscaling method was used to downscale five global climate model (GCM) scenarios to selected weather stations. The downscaled meteorological variables included surface and upper-air hourly temperature, dew point, west-east and south-north winds, air pressure, and total cloud cover. These variables are necessary to project future daily rainfall quantities using within-weather-type rainfall simulation models. A model result verification process has been built into the whole exercise, including rainfall simulation modeling and the development of downscaling transfer functions. The results of the verification, based on historical observations of the outcome variables simulated by the models, showed a very good agreement. To effectively evaluate heavy rainfall-related water damage insurance claims and incurred losses, a rainfall index was developed considering rainfall intensity and duration. The index was evaluated to link with insurance data as to determination of a critical threshold of the rainfall index for triggering high numbers of rainfall-related water damage insurance claims and incurred losses. The relationship between rainfall index and insurance data was used with future rainfall simulations to project changes in future heavy rainfall-related sewer flood risks in terms of water damage insurance claims and incurred losses. The modeled results showed that, averaged over the five GCM scenarios and across the study area, both the monthly total number of rainfall-related water damage claims and incurred losses could increase by about 13%, 20% and 30% for the periods 2016-2035, 2046-2065, and 2081-2100, respectively (from the four-city seasonal average of 12 ± 1.7 thousand claims and $88 ± $21 million during April-September 1992-2002). Within the context of this study, increases in the future number of insurance claims and incurred losses in the study area are driven by only increases in future heavy rainfall events.

Capsizing Probability of Dead Ship Stability in Beam Wind and Wave for Damaged Ship

The International Maritime Organization has developed the second-generation intact stability criteria. Thus, damage stability criteria can be established in the future. In order to identity the capsizing probability of damaged ship under dead ship condition, this paper investigates two methods that can be used to research the capsizing probability in time domain, which mainly focus on the nonlinear righting lever GZ curve solution. One method subjects the influence of damaged tanks on the hull shape down to the wind and wave, and the other method is consistent with the real-time calculation of the GZ curve. On the basis of one degree of freedom rolling equation, the solution is Monte Carlo method, and a damaged fishery bureau vessel is taken as a sample ship. In addition, the results of the time-domain capsizing probability under different loading conditions are compared and analyzed. The relation of GM and heeling angle with the capsizing probability is investigated, and its possible reason is analyzed. On the basis of combining the time-domain flooding process with the capsizing probability calculation, this research aims to lay the foundation for the study of capsizing probability in time domain under dead ship condition, as well as provide technical support for capsizing mechanism of dead ship stability and damage stability criteria establishment in waves.

Study on the damage of the “91．7” rainstorm in Sihu drainage area with remote sensing application technique

In this paper, the water equilibrium and ground truth are analyzed for '91.7' rainstormin Sihu drainage area, Hubei Province, China. The flood and waterlogging situation of ' 91.7'rainstorm in this area are investigated using remote sensing, especially the estimation of inundatedarea, the analysis of temporal and spatial characters of this flood and waterlogging damage. Andthe way of flood-trace using remote sensing is explored. At last, the disastroiis conditions are evalu-ated.

Water-sensitive damage mechanism and the injection water source optimization of low permeability sandy conglomerate reservoirs

The global mobility theory was used to evaluate the experimental results of oil displacement with water of different salinities.The results of scanning electron microscopy,X diffraction of clay minerals,nonlinear seepage and nuclear magnetic resonance experiments and particle migration inhibition experiments before and after water flooding were compared to determine the mechanisms of water sensitive damage and enhanced water flooding mechanism of low permeability sandy conglomerate reservoirs in Wushi region of Beibuwan Basin,China.A production equation of the oil-water two phase flow well considering low-speed non-Darcy seepage and reservoir stress sensitivity was established to evaluate the effect of changes in reservoir properties and oil-water two-phase seepage capacity on reservoir productivity quantitatively,and injection water source suitable for the low permeability sandy conglomerate reservoirs in Wushi region was selected according to dynamic compatibility experimental results of different types of injected water.The seepage capacity of reservoir is the strongest when the injected water is formation water of 2 times salinity.The water-sensitive damage mechanisms of the reservoirs in Wushi region include hydration of clay minerals and particle migration.By increasing the content of cations(especially K+and Mg2+)in the injected water,the water-sensitive damage of the reservoir can be effectively inhibited.The formation water of Weizhou Formation can be used as the injection water source of low permeability sandy conglomerate reservoirs in the Wushi region.

基于VOF方法的规则波下破舱进水数值模拟

文中以某理想客滚船舱段模型为研究对象,基于VOF方法建立两相流体积模型,采用重叠网格和交界面网格技术,分析规则波下不同破口形状舱室模型破舱进水下的运动响应.结果表明:不同破口形状对破舱进水过程的影响主要表现为横摇时域的高频成分,且不同破口形状导致的流量不同.

两层泄洪孔口对特高拱坝抗震性能影响研究

我国强震区200 m以上的特高拱坝,在动力响应较为显著的中上部坝体通常布置多层泄洪孔口,有必要就孔口及闸墩结构对拱坝抗震性能的影响进行研究。以金沙江上游旭龙特高拱坝为研究对象,对坝体布置泄洪孔口与不设泄洪孔口两种方案,考虑混凝土的动力损伤效应,从拱坝整体应力及变形、坝体损伤、拱坝极限承载力等方面进行对比分析。研究结果表明,坝身泄洪孔口结构对大坝整体的刚度、强度影响较小,合理的泄洪孔口布置对于拱坝主坝体的抗震安全性能影响有限;但由于闸墩的悬挑、截面变化以及孔口对坝身的削弱作用,闸墩根部与坝体交界处、上游闸墩大梁连接处等位置在强震过程中更容易出现损伤,需开展抗震设计;对于表、中两层泄洪孔口布置拱坝而言,两层孔口之间的坝体部位也是抗震安全的薄弱环节,需采取针对性抗震措施以增强抵御地震破坏的能力。

洪水灾害损失信息系统—FLOODIS系统设计

本文借助遥感技术，设计出一个专题地理信息系统一洪灾损失信息系统ＦＬＯＯＤＩＳ，为损失评估模型提供评估区域洪水灾害损失的各种自然地理和社会经济信息以及经系统内专家模块处理后的专题信息，同时对其计算结果进行多种方式输出。

鄱阳湖防洪圩堤坝潜在破坏风险及治理方案研究

本文围绕鄱阳湖经济区防洪圩堤的安全保障问题展开研究,详细分析了防洪圩堤坝的潜在破坏风险,包括流土破坏、管涌破坏和脱坡破坏等,并提出了判别这些潜在破坏风险的方法,深入探讨了除险加固方案。研究结果表明,采用复合土工膜、斜墙、透水戗台和心墙等加固措施,结合适当的防渗措施,可以有效提高防洪圩堤的安全性和稳定性。本文的研究对于指导鄱阳湖经济区防洪圩堤的加固工作,保障湖区百姓生命财产安全具有重要的理论和实践价值。

基于组合权重-TOPSIS法的矿井突水风险评价

矿井突水是威胁煤矿开采的重大隐患,通过定量化评价煤矿矿井底板突水危险性,能够及时预测煤矿水害严重程度,提高煤矿水害防治水平。本文以山东省济宁市某煤矿为例,根据影响矿井突水的各类主要指标,采用AHP法和熵权法组合赋权确定各指标权重,并基于TOPSIS逼近理想解排序法计算了山东省济宁市某矿井工作面的突水风险等级,评价结果与矿井实际情况也基本一致。该方法较为全面地考虑了影响煤层底板突水的各类风险因素,同时指标权重的确定综合考虑了专家主观经验和钻孔数据的客观规律,为矿井开采前的突水风险评价提供了参考依据。

川西特大暴雨后公路山洪泥石流灾损分析

为分析山洪泥石流对公路的灾损特征,基于2019年8月雅安特大暴雨后国道351调查,结合区域工程地质条件,针对63处公路损毁段,从泥石流堆积物、支挡结构损毁、路基损毁和总损失4个方面研究灾损特征,并提出应急措施。结果表明:泥石流堆积物超2×10^(4)m^(3)的工点占81.28%,堆积多呈扇形,且泥石流冲出物粒径差异较大,其成分因物源形成而存在差异;支挡结构损毁超1500 m3的工点占56.82%,损毁主要为河道侧蚀、块石撞击等导致;路基损毁超300 m的工点占26.67%,主要为河流冲刷侧蚀掏空路基、靠山侧崩塌、滑坡掩埋路基等导致;总损失超700万元的工点占26.55%。山区公路勘察设计应充分评估公路沿线易损区段和承灾脆弱区段,分阶段实施不同粒径填料搭建临时保通道路。