【作者】 任明磊；

【导师】 王本德； 程晓陶；

【作者基本信息】 大连理工大学 ， 水文学及水资源， 2009， 博士

【摘要】 洪水灾害是全球影响范围最广、对人类的生存与发展危害最为显著的自然灾害之一,尤其近年来伴随气候变化和社会经济的发展,其出现频率及洪灾损失均呈现不断增加的趋势。日益增长的洪水风险逐渐引起了各国政府部门的关注。英国环境署于2002年采用国家尺度洪水风险量化分析方法(NQFRAM)开发了“策略计划风险评估系统”,该系统可进行全国范围的现状及未来洪水风险评估,利用预估的未来洪水风险结果,可为决策部门提供可有效降低未来洪水风险的科学、合理的措施。本文借鉴英国的NQFRAM方法,并考虑到国情差异、流域降雨特征、防洪设施特点等,对英国的NQFRAM方法进行了改进研究,建立了基于ArcGIS的流域尺度洪水风险量化分析系统。同时,考虑到城市化发展进程中社会经济增长、土地利用变化对洪水灾害发生、洪灾损失的影响,分别定性、定量分析了城市化发展对洪水风险的影响。主要研究内容与成果如下:(1)以为面临洪水灾害威胁城市的洪水风险评价提供度量指标为研究的出发点,在综合分析影响洪水风险的城市特征,考虑指标的可量化性及农村和城市地区的可区分性的基础上,选取人口城市化率、建成区面积率、人均年收入可支配率三项指标,同时利用二元比较互补性决策思维理论确定各指标的权重,提出了基于洪水风险城市化水平综合测度方法。利用该方法对太湖流域八个大中城市现状年及未来三个代表年的城市化水平进行了综合测度,结果表明:上海、无锡、苏州的综合城市化水平位居前三位,由于同等洪水强度下,洪水风险大小取决于城市化水平,这说明在同等洪水淹没深度条件下,该三城市面临的洪水风险最高;八个城市现状年及未来三个代表年的综合城市化水平排序人口城市化率的排序是一致的,这说明各城市人口城市化与城市空间规模、经济发展水平是相互协调的。(2)从变化幅度、变化速度及变化的区域差异性等方面分析了研究时段内研究区太湖流域各城市主要土地利用类型的变化;采用降尺度方法预测了流域内各县级行政单位在未来三个代表年主要土地利用类型的数量,并利用ArcToolbox工具箱进行了空间展布。分析及预测结果表明:上海市建成区用地、耕地总变化幅度、年变化幅度最大;苏州、湖州两地建成区用地相对变化率、建成区用地单一土地利用动态度最大;上海、常州两市耕地相对变化率、耕地单一土地利用动态度最大;流域内各市建成区用地面积增加,耕地面积减少,建成区用地的总变化幅度最大,转化为建成区用地的土地利用类型除包括耕地外,还有一部分林地、草地、水域、未利用土地;各市三个代表年建成区面积的空间分布图亦表明流域内各市未来建成区面积排序与2008年相同,说明太湖流域各城市城市空间规模的大小排序将与现状年保持基本一致。(3)考虑到我国水系复杂、流域间降雨条件、社会经济发展水平的明显差异性,在借鉴国家尺度洪水风险量化分析方法NQFRAM的基础上,进行了流域尺度的洪水风险量化分析方法研究。结合研究区太湖流域自然地理条件、降雨特征、防洪设施特点等将NQFRAM方法应用在太湖流域:一是不采用NQFRAM方法中根据降雨的概率密度分布函数随机选取降雨事件进而计算全国或地区范围综合洪水风险的方法,而是针对太湖流域降雨空间分布差异较大、降雨随机性强、难以确定具体服从何种概率密度分布函数的特征,根据典型洪水事件的降雨及入流信息,选取相应的水力学模型及洪灾损失评估模型计算各典型洪水事件的洪灾损失,然后通过计算有限的典型的场次洪水的风险来度量流域综合洪水风险;二是针对研究流域内各地筑有大量圩区的现象,研究了圩区建设对洪水淹没方式、洪水淹没深度的影响,并以1999年特大洪水为例对考虑圩区影响的洪水淹没深度进行了模拟计算。(4)利用ArcGIS Desktop桌面应用环境及以ArcMap为载体的VBA二次开发环境,建立了基于ArcGIS的流域洪水风险量化分析系统。该系统以典型洪水事件的风险量化为研究的出发点,通过对流域内各县级行政单位社会经济值的空间展布、主要土地利用类型平均损失率的计算,及第四章求得的考虑圩区影响的洪水淹没深度计算结果,以棚格为基本计算单位得出了1999年特大洪水流域内各栅格、各县的洪水灾害损失分布图。通过有、无圩区工程时同一典型洪水事件流域洪灾损失的对比,得出在遭遇200年一遇洪水时圩区建设可给研究区太湖流域减少46.8636亿元的洪灾损失的结论;但是从洪灾损失空间分布可发现:各地区在本区域内建设圩区工程、以期减少洪灾损失的同时,也将洪水风险转移给了邻近区域防洪标准相对较低的地区。(5)首先从定性角度分析了城市化发展对洪水灾害发生、洪水灾害损失大小的影响及城市圩区建设与洪水风险的关系,然后利用已建立的洪水风险量化分析系统及未来代表年研究流域内各城市社会经济发展、土地利用类型变化的预测值,研究了同等洪水淹没深度条件下城市化发展带来的各县级、地级行政单位及全流域洪水灾害损失的变化。太湖流域的研究实例表明:若现有防洪保护设施不变(即同等洪水淹没深度条件),城市土地利用类型以现在的城市化发展速度变化,并且各县级行政单位、地级行政单位的洪灾损失均呈增大的趋势。对此,提出了减少随着城市化及社会经济的发展而不断增加的洪灾损失的若干建议。最后对全文做出总结,并对有待于进一步研究的问题进行了展望。更多还原

【Abstract】 With climate change and socio-economic development in recent years, flood damage, as one of the widest natural disasters, has a significant effect on human survival and development in the world, and its occurrence frequency and the losses caused by floods keep a growing trend. Gradually growing flood risks have generated some the government departments concerns. Environmental Agency of England and Wales(EA) in 2002, using the British national-scale quantitative flood risk quantitative analysis method(NQFRAM), has developed a "strategic plan for risk assessment system", which can be carried out present and future flood risk assessment throughout the country. At last, using above assessment results, we can make some scientific and reasonable measures to reduce flood risk of the future. In this article, taking into account differences among national conditions, rainfall characteristics, characteristics of flood control facilities and so on, improved NQFRAM method is studied and watershed-scale quantitative flood risk analysis system is set up based on ArcGIS. At the same time, considering the impact on flood and its losses since the urbanization process development led to socio-economic growth and land-use change, the impact on flood risk were analyzed qualitatively and quantitatively. So the main research contents and results are as follows:(1) After analyzing urban characteristics impacting on flood risk and considering indexes quantification and rural and urban areas division, the three indexes that the population urbanization rate, urban area rate and income per capita income are selected, the weight of above indexes are determined using decision-making thinking theory of binary comparison complementary and a comprehensive urbanization level measure method is shown to solve flood risk assessment. Using the above method, the urbanization level of present eight years and the future status of three years in large and medium-sized cities of the Taihu Lake Basin are measured comprehensively, and results shows that (a)comprehensive urbanization level of Shanghai, Wuxi and Suzhou is among the top three, moreover it also illustrates on condition that the same flood depth, flood risk is biggest in above three cities; (b)ordering of urbanization level and population urbanization rate is consistent in the status quo year and the future status of three years, so it also shows population urbanization, urban spatial scale and economic development are coordinated mutually.(2) The main land-use types change are analyzed from range of variation, speed of variation and regional differences of variation in different cities of Taihu Lake Basin. By method of down scaling, the amounts of main land-use types are predicted in county-level administrative department of the basin in the future status of three years and spatial distribution is described by mean of ArcToolbox toolbox. The analysis and prediction results show that (a)urban land, overall range of variation of cultivated land and year range of variation are the largest in shanghai;(b)the relatively rate of change and dynamical degree of single land utilization are largest in urban land of Suzhou and Huzhou;(c) the relatively rate of change of cultivated land and single dynamical degree of single cultivated land utilization are largest in Shanghai and Changzhou;(d)due to increasing urban land area and decreasing cultivated land area, total range of variation of urban land is largest; furthermore, some forest land, grass land, water area and unused land besides cultivated land are transformed into urban land;(e) according to spatial distribution map of urban land area in the future status of three years, we can know range of future urban land area is consistent with that of 2008 in cities of Taihu Lake Basin, that is to say the size range of the urban space will be consistent with that of the status quo year in Taihu Lake Basins.(3) Due to complex water system and remark difference of rainfall conditions among basins and socio-economic development level in China, a basin-scale flood risk quantitative analysis method is studied in papers based on British national quantitative flood risk analysis method (NQFRAM). Two aspects of NQFRAM method are improved according to natural and geographical conditions, rainfall characteristics and characteristics of flood control facilities of Taihu Lake Basin. At first, in Taihu Lake Basin, difference of rainfall spatial distribution and rainfall random are quite obvious, in addition it is difficult to determine the specific probability density distribution function. So based on rainfall and inflow information of the typical flood events, we can select appropriate hydraulic model and flood damage assessment model to calculate flood losses of the typical flood events and then measure integrated basin flood risk by calculating risk of limited the typical flood events. The second aspect is as following. In papers due to existing many flood dike in research area, the impact of flood way and depth must be studied, and taking extraordinary flood of 1999 as a example and considering impact of flood dike, flood depth is simulated.(4) Using ArcGIS Desktop application environment and VBA secondary development environment with ArcMap as carrier, basin quantitative flood risk analysis system based on ArcGIS is built and in system quantized risk of typical flood events will be regarded as a research point of departure. Through calculating the spatial distribution of socio-economic value and the average loss rate of the main land-use types in the county level administrative department of basin, and referring flood depth result in chapter 4, we can get every grid and flood losses distribution map as the basic unit of 1999 extraordinary flood in country of Basin. Through comparing basin loss of the same typical flood events with dike work and without that, we can draw the conclusion that flood losses will reduce 46.8636 billion in view of dike construction in the Taihu Lake Basin when encountering flood with period of recurrence of 200 years. However according to floods loss spatial distribution, the flood risk will also be transferred to the neighboring areas with relatively low flood control standard owing to constructing dike project in research basin to decrease flood losses.(5) First, from a qualitative point of view we analyze influence on flood disaster and flood losses because of urbanization development and relationship between the city dike construction and flood risk. Then using quantitative flood risk analysis system established and the predictive values that characterize urban socio-economic development and land-use changes in the future status of years, flood losses changes of country, prefecture-level administrative department and all watershed are studied due to urbanization development under the same flood depth the condition. In Taihu Lake Basin research results show that if the existing flood protection facilities are maintained, urban land-use changes will keep the same pace with current urbanization development, in addition flood losses of country and prefecture-level administrative department demonstrate growth tendency generally. In view of above situation, many suggestions to decrease flood losses are put forward to improve it. Finally, the conclusions are drawn and the problems to be further studied are discussed.更多还原