干旱的尺度特征研究及其应用

Currently, there are some issues on research relating to drought, such as obscure definition of drought, arbitrary selection of drought index, mismatch between spatial and temporal scale of drought index, lacking physical meaning of threshold value of drought index, unsatisfied assumption in drought disaster risk assessment based on system engineering theory, etc. In this proposal, the research approach which is based on the combination of geo-hydrology and engineering hydrology will be adopted to analyze the formation of drought from the view of coupling the land processes of hydrological cycle and the atmosphere process in hydrological cycle. Leading influencing factors of drought phenomenon on different spatial and temporal scales will be identified from planetary scale weather system, synoptic weather system, and the geomorphologic and geologic factors controlling runoff formation from precipitation. Based on spatial and temporal scales of precipitation event and the scales of water demand process of hazard-affected body, the intrinsic scales of drought phenomenon will be analyzed. And then, divisions of drought on different level will be completed based on the leading influencing factors of drought phenomenon on corresponding level using the cluster methods. Regular pattern of drought phenomenon in different region will be revealed. On the basis of intrinsic scales of drought phenomenon and the practical water supply and demand processes of hazard-affected body, the drought processes will be identified on run theory. Through precipitation process reflecting drought degree, the disaster loss of hazard-affected body will be calculated on the practical water shortage process. So, various different precipitation processes bring different disaster loss. Through calculation the of the drought disaster losses based on the long-term practical historical precipitation series or simulated precipitation series, the drought risk will be achieved directly. .The results and finding in this research have great theoretical significance for perfecting mechanism of drought formation and intrinsic scales of drought phenomenon relating theory, also have great importance to the establishment of technological setup for drought risk assessment. They also may be expected to promote crossing and penetration of among hydrology, geography, meteorology, pedology, catastrophology, and mathematic statistics.

目前干旱相关研究中存在着干旱定义模糊，干旱指标选择主观任意，干旱指标的时空尺度匹配随意，指标阈值含义不清，以及基于系统论的旱灾风险定量评估中诸多假设难以满足等问题。本申请项目拟采用工程水文学和地理水文学相结合的研究途径，从水循环全过程的角度，分析干旱的形成过程，从行星尺度、天气尺度天气系统和降水形成径流的下垫面因素中识别不同时空尺度上驱动干旱现象的主导因子，识别干旱现象的时空特征尺度，进行干旱分区、揭示干旱的区域分异规律，依据干旱的特征尺度和承灾体的实际水分供需过程，识别干旱过程，计算承灾体在承受以降水过程表示的各种程度干旱时的旱灾损失，实现旱灾风险的直接定量评估。研究成果将丰富和发展干旱形成机理、干旱特征尺度分析的理论方法，完善基于水文过程的旱灾风险定量评估技术体系。项目的开展，有利于推动工程水文与地理水文的融合，促进水文研究与气象学、地理学、土壤学、灾害学以及数理统计科学等的交叉。

项目在分析干旱内涵及其驱动机制的基础上，从行星尺度天气系统和天气尺度天气系统角度识别了降水的阶段性，结合承灾体需水的阶段性特征，提出了干旱指标时间尺度的确定方法。分析并筛选了可较全面准确地反映干旱对承灾体影响的干旱事件特征值的组合。构建了干旱过程三维动态识别方法。分析了干旱多特征变量联合重现期的内涵，以及多变量水文设计事件法推求水利工程设计参数所存在的问题。提出了基于Copula的多特征变量干旱事件发生可能性的计算方法，以及旱灾风险定量评估方法。. 研究过程中发现：可采用最优分割法等统计方法对研究区域（江淮地区）的多年平均日降水量序列进行阶段初步划分，再结合降水阶段的大气环流背景分析，识别研究区域的降水阶段，结果表明受季风气候影响显著的江淮地区各降水阶段对应着相对稳定的天气气候背景。江淮地区梅雨季、黄淮雨季降水以及台风降水的具有明显的时空差异性，可据降水和承灾体需水的阶段性特征，参考水文响应单元的划分方法，确定干旱指标的时间尺度。干旱烈度和干旱峰值强度的组合比干旱烈度和干旱历时的组合更能反映干旱对承灾体的影响。水文多变量设计事件的联合重现期与水利工程设计标准所对应的重现期并不等效，多变量条件下，水利工程设计参数不能通过多变量水文设计事件法进行推求。定量的旱灾风险也不能通过多变量水文设计事件法计算，应合成“以特征值表示的灾害负荷—灾害损失”的灾害脆弱性函数，和以Copula概率密度函数积分表达的多变量致灾因子事件的发生概率，构建描述一定孕灾环境下“灾害损失—损失发生概率”的风险定量评估的方法体系。. 共发表学术论文43篇，其中SCI检索18篇；获安徽省科技进步一等奖1项，大禹水利科学技术奖一等奖1项、二等奖1项；培养硕士毕业生6人。