广东省水旱灾害风险分析与农业可持续发展

水旱灾害历来是威胁严重的自然灾害,它制约着广东省农业生产和社会经济发展.本文分析了广东省水旱灾害的特点及成因,根据1950～2002年的资料,应用信息扩散方法对广东省的水旱灾害进行了风险评估,勾画出广东省水旱灾受灾率概率分布曲线图,提出了广东省农业减灾的措施:合理调整农业布局和作物种植结构,采取趋利避害的农业措施,推行有效的防灾技术,改善农业生态环境,增强防灾减灾意识,提高防灾减灾水平.     

西气东输工程沿线陕西段洪水风险评价

在ARC/INFO的支持下,利用1:5万的DEM,1:25万全国数字化地形图,以及定边、靖边、子长和延川4县1:10万土地利用图与多年水文统计资料,通过叠加分析,对西气东输工程沿线陕西段的洪水风险进行了评估.选取地形、降水、土地利用和社会经济易损性4个因子进行综合分析,分别得到了它们对洪水影响的栅格图,通过对各栅格图的叠加,得到了洪水风险分级图.结果表明,管线西部的定边和靖边,其降水量较低,海拔较高,村镇密度相对较低,洪水风险较低,主要为1级、2级和3级;管线西部的子长和延川县,其地形起伏大,降水量大,植被覆被较低,村镇密度大,洪水风险较大,主要为4级和5级,风险最高的地区集中在秀延河、永坪川、清涧河、东部丘陵沟壑区河谷平原、黄河周围地区及子长县的大部分地区.     

历史洪水在洪水序列隐含周期分析中的应用

历史洪水调查是洪水序列的重要组成部分,对揭示洪水序列的周期,论证周期的稳定性和可靠性具有重要的作用.本文提出具有历史洪水调查的不连序序列三种周期分析模型,理论分析和实例计算结果表明,文中提出的模型是合理和可行的.     

海安地区近1000年来的气候变化与洪灾

对海安地区史志资料作了搜集与整理,利用Mann-Kendall法对该区1951年以来汛期总量与夏季最高温作了突变检测分析,以对该区近1000年来洪旱灾害的发生规律做一探讨.结果表明,小冰期时期湿润与波动剧烈的气候条件是研究区频繁发生水灾的一个重要因素,同时研究区地势低平,极易遭受水灾、热带风暴及海潮涨溢的影响.MK突变检验表明,研究区汛期总量的突变发生时间大致在20世纪60年代中期,而历年夏季最高温序列在20世纪90年代中期发生突变,具体时间大致在1993年左右.汛期总量在20世纪90年代以前呈波动下降趋势,但在其后汛期径流量又呈上升趋势;夏季最高温在20世纪90年代以前呈波动下降趋势,而在其后呈波动上升趋势,夏季最高温与汛期总量变化趋势相一致.夏季极端高温事件发生概率的增大可能导致洪灾事件的增多,因而在未来气候持续变暖的情景下,研究区乃至长江下游防洪抗灾任重而道远.     

中国水灾风险综合管理--平衡大都市区水灾致灾强度与脆弱性

中国大都市区主要分布在大江大河的中下游地区,由于区域土地利用格局的巨大变化,特别是较多的水域和湿地因城市化而被占据,因此,一方面大都市区面临严重的洪水危险,另一方面为了使大都市区尽可能减轻洪水灾害,而加强了防洪能力的建设.然而,近50年的减灾实践证明,洪水灾害却在波动中趋于上升,即大都市区对洪水的脆弱性在增大.在对中国大都市区洪水灾害的区域分析基础上,以广东省为例,构造了综合水灾致灾因子和承灾体为一体的风险评估模型体系,以此提出了平衡大都市区水灾致灾强度与脆弱性的基本土地利用模式,和"政府-企业(社区)-保险公司"相结合的企业风险管理模式.     

洞庭湖区旱涝特征浅析

洞庭湖区是一个旱涝频繁发生的地区；整个洞庭湖区以洪涝年居多，干旱年次之；湖区洪涝发生具有持续性特点，干旱发生具有间歇性特点。     

江苏省里下河腹部地区防洪效益计算

通过建立特定工程条件下洪涝淹没面积与水文特性之间的相关关系，并合理确定单位面积资产值和洪灾综合财产损失率，提出了防洪效益计算的一种简易可行的方法，并在里下河腹部地区进行了实际应用。     

A MODIFIED RATIONAL FORMULA FOR FLOOD DESIGN IN SMALL BASINS1

ABSTRACT: New formulas and procedures under the framework of the Rational Formula are presented that are applicable to flood design problems for a small basin if the geometry of the basin can be approximated as an ellipse or a rhombus. Instead of making the assumption in the traditional rational formula that the rainfall is uniformly distributed in the whole duration (D_w) of a design storm, the new method modifies that assumption as: the rainfall is uniformly distributed only in each time interval CD) of the design storm hyetograph, thus extending the rational formula applicable to the case that the rainfall duration is less than the basin concentration time (T_c). The new method can be applied to estimate the flood design peak discharge, and to generate the flood hydrograph simultaneously. The derivation of the formulas is provided in detail in this paper, and an example is also included to illustrate how to apply the new formulas to the flood design problems in small basins.     

SERENDIPITY: CAPTURING A DESIGN LEVEL PRECIPITATION EVENT1

ABSTRACT: On February 23–24, 1998, a frontal system moved across the U.S. Department of Energy's 3,500 km² Nevada Test Site (NTS) and resulted in significant depths of precipitation at all recording gages on the NTS. A preliminary analysis suggested that this precipitation event was of the magnitude and duration for which many flood mitigation structures have been designed. Given the data and field observations available and the potential implications of the event on the methodologies used to size flood mitigation structures throughout the West, a detailed analysis of this event was undertaken. The goals of this study were to compare this event with the regulatory design precipitation event, compare the estimated peak flow rates from the rainfall/runoff model used to size the flood mitigation structures at a radioactive waste management site with the estimated peak flows from the precipitation event, and examine if modification of the standard source of the design depths of precipitation is warranted.     

DEMAND SIGNALS FOR URBAN DRAINAGE AND FLOOD CONTROL PROJECTS1

ABSTRACT: Planning for urban drainage and flood control requires the use of a rational procedure for setting priorities and allocating funds. An innovative procedure developed by the Los Angeles County Flood Control District is described. It consists of the use of bond election voting results as a surrogate for demand signals representing the public preference for project approval. A regression equation has been developed to relate project characteristics to the likelihood of approval. The procedure is implemented through a “funnel-screen” review procedure which results in a list of reviewed and approved projects.