Duststorms and Mesoscale Cloud Systems over The East Asian Deserts in Spring

Meteorological characteristics and morphology of duststorms and other dust weather phenomena in the arid regions of East Asia were described in order to investigate a possible role of mesoscale cloud disturbances that develop in synoptic-scale mid-latitude cyclones in intensifying dust weather. This study is a statistical examination of conventional surface observational data as well as satellite data obtained during April 2000–2003. In the deserts of Mongolia and northern China (e.g., the Gobi Desert) duststorms and other weaker dust weather (i.e., dust whirls, blowing dust) frequently occur under a strong influence of synoptic-scale cyclones; on the other hand in the Taklamakan Desert (northwestern China), dust weather phenomena occur in a less organized fashion and may be driven mainly by local meteorological and geographical effects. A significant signal was identified, revealing of the intensification of dust weather by the presence of convective cloud disturbances. Meteorological changes such as pressure rise and temperature drop, typically found during the passage of cold fronts, were frequently observed in the cases of duststorms occurring in the analysis region. However, no definite tendency was found for moisture change and wind speed in relation to cloud activity, probably because rainfall amount is generally too low to moisten the boundary-layer air.     

MODELING FLOOD DAMAGE: CASE OF TOKAI FLOOD 20001

ABSTRACT: In conventional flood damage reduction studies, flood damage is usually estimated with a damage function according to the depth of inundation. However, this method may not reflect the conditions of each family residing in the floodplain because it ignores not only the distribution of flood damage but also the effect of building characteristics and residents' preparedness. This paper uses data from a questionnaire based survey (N= 3,036) conducted 17 months after the Tokai Flood of 2000 that caused disastrous losses to household properties. It provides a conceptual “doughnut structure” model of flood damage to houses and house contents and a mathematical basis for models to explore the determinants of flood damage. Besides the inundation depth, house type significantly affects both the house structural and content damage probabilities, while house ownership and house structure affect house damage probability but not house content damage probability at a given depth. Inundation depth, residing period, and household income significantly affect both house and content damage values. In addition, house ownership has a significant impact on the house damage value, while house structure has an impact on content damage value.     

USING GEOLOGY TO IMPROVE FLOOD HAZARD MANAGEMENT ON ALLUVIAL FANS ‐ AN EXAMPLE FROM LAUGHLIN,NEVADA1

A study of the piedmont of the Newberry Mountains near Laughlin, Nevada, demonstrates that geologic information can improve the scientific basis of flood‐hazard management on alluvial fans in desert areas. Comparison of geologic information against flood insurance rate maps (FIRMs) reveals flaws in conventional methods for flood hazard delineation in this setting. Geologic evidence indicates that large parts of the Newberry piedmont have been isolated from significant flooding for at least the past 10,000 years. This contrasts with existing FIRMs that include large tracts of nonflood prone land in the 100‐year and 500‐year flood hazard zones and exclude areas of indisputably flood prone land from the regulatory flood plain. From the basis of the geology, flood hazards on at least one‐third of the piedmont are mischaracterized on the regulatory maps. The formal incorporation of geologic data into flood hazard studies on desert piedmonts could significantly reduce this type of discrepancy and substantially reduce the scope, hence cost, of more elaborate engineering studies and hazard mitigation strategies. The results of this study affirm the value of new Federal Emergency Management Agency (FEMA) recommendations for characterizing alluvial fan flood hazards and support an argument for mandating geological studies in the regulatory process.     

Pollution and Self-Cleansing of an Urban River in a Developing Country: A Case Study in Dar es Salaam, Tanzania

Pollution and self-purification trends of an urban river namely, Msimbazi River, in Dar es Salaam City, Tanzania, were investigated. Site investigations and water quality analyses were done. The river is polluted in terms of high organic and nutrient concentrations, low dissolved oxygen, and high counts of indicator organisms. Biochemical oxygen demand (BOD₅) concentrations were 27– 340 mg/L. Dissolved oxygen was found to be as low as 0.9 mg O₂/L. Bacteriological pollution increased with distance downstream of the river, a trend attributable to an increase in the catchment of pollution sources, which are on-site sanitation systems. Although the river has an appreciable self-purification capacity, the capacity is strained by persistent pollution overloads. The pollution plight of the river is attributable to its being flanked by expanding human habitats and vibrant industrial, institutional, and socio-economic activities. Provision for pretreatment of discharges into the river is put forward as a remedial measure for the observed pollution. Matching nontechnical and techno-social remedial measures are also recommended. These include sensitization of polluters on merits of environmental protection practices such as cleaner production and strict enforcement of environmental protection laws.     

长江南通段江面风的观测分析

通过在长江南通段江面、江岸建立风观测站,并在江岸建设80m高的风梯度观测塔,与邻近气象站开展了较长时间的风同步观测,获得了实地观测数据.利用同步风观测数据进行对比分析,揭示出长江南通段江面风的观测事实,并利用风梯度观测资料,分析给出了风随高度的变化规律.在此基础上,结合邻近气象站长年的风观测资料,推算了该处的设计基本风速及其他工程设计风参数.分析表明,该处江面风况明显有别于邻近气象站,风参数计算结果也明显高于风工程理论推算值.     

中国大都市群地区的水灾风险与应急管理研究

在经典风险评价理论模型的基础上,结合自然灾害系统理论,建立了简明水灾综合风险评价模型,完成了中国九大都市群的水灾风险评价.结果表明:我国都市群水灾风险呈现出以都市区中心市为核心的(近)圈层状分布;水灾风险由高到低依次为长三角、珠三角、长江中游、京津唐、吉黑、中原、成渝、辽中南和山东半岛都市群.基于上述研究,强调应建立包含水灾综合风险评价、水灾风险应急预案编制与情景模拟以及水灾风险区划与规划的水灾风险应急管理体系.     

浙江省洪涝灾害的统计分析

根据浙江省1949－1998年（缺1966－1975年及1978年）共39年的洪涝成灾面积资料及39年（1961－1999年）的36个站点的分季降水资料，对该省洪涝灾害进行了统计分析。分析表明，浙江洪涝灾害面积大，且有随时间而增加的趋势，此外，不同地区表现为不同的受灾特征，浙江省应该对不同地区采取不同的减灾防灾措施，因地制宜，减少水患的经济损失。     

水旱灾害对我国农业及社会经济发展的影响

水旱灾害首先影响到我国农业生产。粮食产量的大幅减产还会波及到整个国民经济及人民生活水平的下降。研究自然灾害不仅要注意因灾损失的自然因素，同时要联系造成灾害的社会、经济、人文因素等诸多方面进行自与非自然因素的综合分析。     

中国洪水灾后恢复重建行动与理论探讨

基于中国洪水灾后恢复重建的实践 ,总结了中国洪灾灾后恢复重建的结构体系 ,并依此讨论了洪水灾后恢复重建的若干理论和实践问题。文章指出 ,应明确洪水灾后恢复重建与备灾和防灾的关系 ,并提出了洪水灾后恢复重建的结构体系与程序。     

塔里木河中下游的整治与基础设施建设

塔里木河中下游地区是南疆社会经济发展较快的地区，人类活动对塔河干流区生境干扰，在该区域表现得也较为突出，严重地影响了整个南疆地区的发展。在西部大开发中，塔河中下游的整治是基础建设的前提和保证，基础设施建设必须与塔河中下游整治结合起来。