变化环境下广东旱涝时空变化规律与风险概率研究

The standardized precipitation evapotranspiration index and its modified one，joint drought deficit index，the standardized precipitation index and some representative extreme climate indicators will be used to study the temporal-spatial evolvement rule of drought and flood events in Guangdong under the changing environment, and their responses to global climate change will also be analyzed in this application project. A fixed point experimental approach will be adopted to monitor the evapotranspiration processes, so as to explore the occurrence and development mechanism of drought in humid Guangdong. The extreme value distribution theory, copula theory and methods will be applied to calculate the waterlogging risk probabilities among heavy rains, floods and corresponding tide levels with different combinations in the urban group of pearl river delta, and to optimally construct the multivariate joint probability distribution models for calculating the return level values and risk probabilities among the flood peak discharge, flood volume and flood duration and among the drought intensity, drought severity and drought duration of main rivers in Guangdong，respectively. Optimally constructing the region frequency distribution models for flood, storm rainfall or low water of different basin at regional scale is another research content of application project, from which the more accurate return level values of the extreme hydro-climatic events will be get.To construct several integrated models to forecast the medium and long term trends of precipitation and stream diacharge will also be explored. The application project will deepen the research in the variation laws and mechanism of extreme hydro-climatic events, the risk probability and the medium and long term trend forecast that are the some hot science issues of frontier research field in climate changes, which can provide the important scientific and technological support for tackling regional climate change and adaptive decision, disaster prevention and mitigation.

采用标准化降水蒸散发指数与改进的标准化降水蒸散发指数、联合干旱指数、标准化降水指数和代表性的极端气候指标等，分析变化环境下广东旱涝事件的时空演变规律及其对全球气候变化的响应；采用定点监测蒸散发过程，探索位于湿润区域广东的干旱的发生发展机理；应用极值分布理论、Copula理论和方法，推断珠江三角洲城市群暴雨与洪水和潮位的不同组合遭遇情况下的内涝风险概率；分别择优构建广东主要河流的洪峰流量-洪水总量-洪水历时、水文干旱强度-干旱重度-干旱历时等多变量联合概率分布模型，推算极端事件的重现水平和风险概率；从区域尺度择优构建广东不同流域的区域洪水、暴雨和枯水极值频率分布模式，推算区域重现水平值；构建多个集成的模式预测降水、径流中长期变化趋势。 申请项目将深化旱涝变化规律、风险概率和中长期预测等气候变化前沿领域热点科学问题的研究，为广东有效应对与适应区域气候变化、防灾减灾决策提供重要科技支撑。

全球气候变暖背景下极端水文气象事件出现频率增大，亟需深入研究变化环境下广东旱涝的时空变化规律及其对全球气候变化的响应特征，加强极端水文气象事件的风险分析。. 项目应用融合了气温蒸散作用与降水之间水量平衡关系的标准化降水蒸散发指数——SPEI，探讨了极端气温和降水事件变化与大尺度气候振荡的潜在联系；构建了新的干旱监测和评价的多尺度联合干旱指数——JDI，验证了JDI的有效性，对比分析了多种干旱指数在珠江流域的适用性；通过北江流域气象干旱烈度和干旱峰值的联合概率分布模式，对区内干旱变量进行了空间分析，对比研究了韩江流域3个子流域的水文干旱历时和干旱程度的遭遇风险概率差异；采用超阈值在内的多种概率分布推算了珠江三角洲城市短时强降水不同重现期的设计暴雨，计算了珠江三角洲城市珠海和广州排水排涝两级标准衔接的风险与联合设计暴雨，为不同排涝标准的风险概率决策提供技术支撑。分析了西江和北江流量之间的时空关联与变异，分别计算了西江北江枯水流量联合分布的“或”重现期、“且”重现期和二次重现期及其最可能的设计分位数。由二次重现期计算的马口站枯水流量最大可能设计值Q7d,T=20a和Q7d,T=10a设计值更适合分别作为西江三角洲供水规划和生态需水设计参考值。分别以广东西江、东江和珠江三角洲增江三个水文站历年洪水和粤东海洋站极端风浪为研究示例，采用新的划分安全与危险的临界域的多变量重现期风险理论，对比研究了Kendall重现期和“或”重现期、生存Kendall重现期和“且”重现期的差异，并以最大可能概率推算了多变量联合设计值，为防洪与防浪工程设计标准提供新的参考依据。探讨了珠江口磨刀门咸潮上溯的机理及其对水文气象要素的频率响应特征，研究结果加深了对河-海相互作用下的珠江河口咸潮入侵机理、入侵时空过程的认识。. 项目研究成果深化了对研究区域内的旱涝变化规律与风险概率等气候变化前沿领域热点科学问题的认识，为广东在有效应对与适应区域气候变化、防灾减灾决策等方面提供了重要的科技支撑。