Fiji's worst natural disaster: the 1931 hurricane and flood

At least 225 people in the Fiji Islands died as a result of the 1931 hurricane and flood, representing the largest loss of life from a natural disaster in Fiji's recent history. This paper explores the causes of disaster and the potential for recurrence. The disaster occurred because a rare event surprised hundreds of people—especially recently settled Indian farmers—occupying highly exposed floodplains in north‐west Viti Levu island. The likelihood of a flood disaster of such proportions occurring today has been diminished by changed settlement patterns and building materials; however, a trend towards re‐occupancy of floodplains, sometimes in fragile dwellings, is exposing new generations to flood risks. The contribution of this paper to the global hazards literature is set out in three sections: the ethnicity, gender and age of flood fatalities; the naturalness of disasters; and the merit of choice and constraint as explanations for patterns of vulnerability.     

加强国土规划建设与城市防灾的协同性分析

我国经济持续发展主要体现之一就是大规模的基础工程、道路交通和城市建设。近年来,各种灾害频繁发生,造成了巨大的人身和财产损失,也给"国土规划建设"和"城市防灾规划"工作提出了更迫切更严峻的挑战。我国拥有广大面积的洪泛区[2],洪灾是制约我国社会和经济可持续发展的重要因素;我国又是淡水资源极度缺乏的国家,雨水是淡水,应变灾害为资源。调整区域土地的使用性质和格局,国土规划建设是今后一个时期内科学发展、可持续发展的基础,做好国土规划建设刻不容缓。把国土规划建设结合其它城市灾害提出具体的措施,整体提高我国城市防灾规划水平,以达到节约投入,节省时间,根治水患、长期受益的目的。     

基于DEM的SAR图像洪水水体的提取

星载雷达遥感已广泛应用于洪水灾害的监测和评估中。但是由于其阴影与水体严重混淆 ,使得从雷达图像中提取洪水水体较为困难。为此 ,本文探讨了在地形数据的支持下 ,实现星载SAR图像洪水水体半自动提取的方法。主要包括以下几步 :首先 ,对雷达图像进行滤波处理 ,并将其与地形数据匹配 ,从雷达图像中提取出初步的洪水水体范围 ;其次 ,利用地形数据生成DEM ,并根据雷达图像的成像参数和DEM生成相应的模拟雷达图像 ;最后 ,利用模拟雷达图像上的阴影 ,剔除被误提为洪水水体的阴影 ,从而实现洪水水体的准确提取。研究表明 ,该方法能有效地、半自动地将星载雷达图像上的洪水水体提取出来 ;同时 ,该方法可以用于多种星载多模式的雷达图像的洪水水体的识别提取 ,尤其对含山区的大范围洪水水体的半自动提取 ,更为适用。     

局部洪水灾害下集疏运路网韧性分析

针对运输网络的韧性标准尚未统一的问题,在集疏运路网特征分析基础上,从结构韧性和功能韧性2个角度构建韧性评价指标框架,通过吸收时间、吸收速率、恢复时间、恢复速率和功能韧性说明路网的某一部分在受到灾害扰动后路网服务能力的保留程度,通过节点保存率和网络结构指标量化路网的结构韧性,依托上海市历年降水数据进行集疏运路网韧性分析。研究结果表明：抵抗能力与功能韧性呈正比,网络属性分布与结构韧性呈正比;网络属性应均匀地分布在功能区域,保证集疏运主要路线的功能性和结构完整性。研究结果可为集疏运路网性能分析和集疏运路网韧性评价指标体系构建提供思路。     

洪水风险分析的研究进展与展望

我国洪涝灾害频繁,损失极大,引人注目。洪水的风险分析工作是实施非工程措施,从而科学有效地防洪减灾的前提和基础。在概括系统风险定义和来源的基础上,对洪水风险分析的研究现状作了评述。洪水风险分析的研究方法已从直接积分法、蒙特卡罗法、均值一次两阶矩法,发展到改进一次两阶矩法、二次矩法和JC法等。综述了洪水风险分析的研究成果,同时建议：（1）明确并统一风险分析的内涵;（2）开展“风险分析的风险”的研究;（3）将熵理论引入到风险分析之中;（4）拓展风险分析的基本理论和研究方法,如应用模糊信息优化处理技术、灰色系统、未确知数学等。     

Effects of Flooding on Lead and Cadmium Speciation in Sediments from a Drinking Water Reservoir

Římov water reservoir on the river Malše is the main source of drinking water for the town of České Budějovice and for the majority of inhabitants in the South Bohemian region, Czech Republic. Changes in cadmium and lead contents in bottom sediments before and after an extensive flood on the river Malše in August, 2002 were therefore determined. A five-step sequential extraction procedure was used in order to obtain more detailed information about the influence of the flood on heavy metal retention. In order to determine the mobility of lead and cadmium, the mobility factor (MF) for these heavy metals was calculated. The mobility factor of cadmium showed a significant decrease in the upper parts of the sediment profiles after the flood (e.g., from 59.4% to 49.1%) caused by a release of cadmium especially from the exchangeable fraction. There were no significant changes in the lead mobility factor after the flood, but a decrease of lead concentration in the exchangeable fraction was observed. Presented results show that the flood led to a leaching of the heavy metals present in bottom sediments into the environment.     

区域洪水灾害易损性评价

基于洪水灾害系统特征,提出了区域洪水灾害易损性概念,认为洪水灾害易损性是指在一定社会经济条件下,特定区域各类承灾体在遭受不同强度洪水后可能造成的损失程度;建立了包括致灾因子、孕灾环境、承灾体属性和社会救灾能力在内的洪水灾害易损性评价指标体系;基于层次分析法,构建了目标层为区域洪水易损性,准则层为致灾因子、孕灾环境、承灾体和社会救灾能力,指标层为降水、地形、植被、生命、环境与经济等要素的区域洪水灾害易损性评价模型与评价方法。为便于决策,将易损性分为1～10共10个等级,等级越大,表明区域洪水易损性越高。      

Impact of 20 Years of Land-Cover Change on the Hydrology of Streams in the Southeastern United States1

Cruise, James F., Charles A. Laymon, and Osama Z. Al-Hamdan, 2010. Impact of 20 Years of Land-Cover Change on the Hydrology of Streams in the Southeastern United States. Journal of the American Water Resources Association (JAWRA) 46(6):1159–1170. DOI: 10.1111/j.1752-1688.2010.00483.x Abstract: Land-cover changes for portions of Alabama, Georgia, and Tennessee were estimated for the years 1980, 1990, and 2000 using classified Landsat images, and associated with hydrologic indices for 12 watersheds in the region. Rainfall-adjusted mean annual streamflow, an ET proxy (precipitation minus runoff), frequency of inundation above thresholds, and duration of inundation were used to characterize the hydrologic response of the test basins over the two-decade study period. Results indicate that several of the watersheds had undergone significant (>20%) reductions in agricultural land cover with a coincident increase in forested land. Attempts to correlate the hydrologic results with the land-cover changes were only partially successful. Watersheds with the largest land conversion from agriculture to forest (20% or more) did show significant trends in hydrologic indices indicating decreasing streamflow; however, other basins evidenced ambiguous results. The net conclusions of the study are that land-cover effects on hydrologic variables may be nuanced and can sometimes be only indirectly evident, and that a rigorous and detailed land-cover classification effort along with a battery of statistical tests with the same objective may be necessary to uncover these effects.     

湖北省双季稻生长季降水及洪涝变化特征

利用1961～2008年湖北省双季稻区常规气象站资料,统计计算了双季稻产区在早晚稻生长季的降水量、暴雨量、暴雨日数以及洪涝发生次数,揭示了近50 a来双季稻区降水及洪涝的变化特征。结果显示：湖北省双季稻区在早晚稻生长季的降水量都有弱的增加趋势,尤其是鄂东北局部和江汉平原南部;在水稻抽穗扬花至成熟期间,早稻暴雨量大部有不显著的增加趋势,而晚稻则大部为弱减少趋势。早稻生长季内洪涝的发生次数总体呈增加趋势,局部地区严重洪涝发生次数加大;晚稻生长季洪涝总次数有略减少趋势,重度以上洪涝发生很少,但呈略增加趋势     

基于“3S”技术的村镇住宅洪灾脆弱性曲线研究

脆弱性曲线常用来表示各类承灾体的洪灾损失率与洪水特征之间的关系,是洪灾风险评价方法中的关键部分。为了构建村镇住宅洪灾脆弱性曲线,以2010年永吉县口前镇洪灾为案例,根据抽样理论运用GPS技术开展了村镇住宅洪灾损失的实地调查;运用RS技术和GIS技术提取出洪水淹没水深用以补充未调查房屋的淹没水深数据;采用回归分析方法建立了各类平房住宅水深-损失率之间的关系,用以表征脆弱性曲线。结果表明:居民住宅的洪灾损失率与水深高度相关,且在同一淹没水深下,平房住宅的使用时间越长损失率越大。脆弱性曲线的建立为计算洪灾潜在损失和区域防灾减灾提供了依据。