淮北平原旱灾风险驱动机制与定量评估研究

Quantitative assessment of drought disaster risk is the core task as well as an important advanced topic in drought disaster risk management. In this proposal, a comprehensive research method combined theoretical analysis data statistic analysis is adopted to analyze the temporal-spatial distribution and evolution law of drought and drought disaster, and to reveal the main driving factors of them on different temporal and spatial scales. Then the drought index is constructed based on the driving mechanism of drought and drought disaster, and the hazard risk represented by recurrence period of drought event is estimated with Copula function based on the drought index. On the extraction of channel networks with artificial intervention method in the plain region, the distributed hydrological model of four water phases transformation will be established by combining experiment analysis, theoretical derivation and diving unsteady flow calculation. To reflect the hysteresis impacts of drought disasters to crop yields, this proposal aims at designing the experimental schemes of drought disasters stress level and establishing statistical models to describe the relationships of disasters stress level and crop yields (such as via artificial neural networks and set pair analysis methods) by analyzing the characteristics and mechanism of drought disasters in Huaibei Plain. Then, disaster vulnerability is analyzed on the four water phases transformation model and the relationships of disasters stress level and crop yields. Coupling hazard risk and disaster vulnerability, the quantitative risk of drought disaster will be obtained. Based on the quantitative assessment of drought disaster risk model, the water resources regulating strategy of Huaibei Plain be proposed to obtain suitable drought-resistant ability and acceptable risk. The propsed research will have a wide application prospect in reducing drought disasters losses and ensuring food security in Huaibei Plain. Also, this study will promote the cross and integration of hydrology, disaster science, system science, statistical science and intelligence science, also enrich and perfect the theroy and method of disaster risk management.

旱灾风险定量评估是灾害风险管理的核心任务和前沿课题。本项目拟采用理论分析和数据统计分析相结合的方法，分析淮北平原干旱和旱灾的时空分布和演变规律，揭示不同时空尺度上干旱和旱灾的主导取到因素，构建基于驱动机制的干旱指标，分析旱灾危险性。采用实验数据分析、理论推导和潜水非稳定流演算相结合的途径，在人工干预方式提取平原区沟网的基础上，构建淮北平原四水转化分布式水文模型；根据淮北平原干旱时空特征，设置干旱胁迫试验方案，通过试验研究作物生长和产量对干旱胁迫下的响应，构建反映干旱胁迫对作物产量影响滞后效应的作物生长模型，定量分析旱灾脆弱性。合成旱灾危险性和脆弱性，构建旱灾风险定量评估模型，并基于该模型分析淮北平原防灾减灾措施。项目成果在减轻淮北平原干旱灾害、保障粮食安全中具有重要应用前景，有利于促进水文学与灾害学、系统科学、数理统计科学的交叉和融合，也有利于完善和发展平原地区灾害风险管理理论与方法。

项目在分析淮北平原水分需求主要供给源的基础上，以表层土壤含水量和一定埋深内的地下水储量作为作物蒸散的水分供给源，构建了基于标准化土壤含水量指数和标准化地下水储量指数的综合水文干旱指数，识别了干旱过程，分析了旱灾危险性。设置干旱胁迫试验方案，通过试验研究了作物产量对干旱胁迫的响应，构建了作物生长模型，定量分析了旱灾脆弱性。合成旱灾危险性和脆弱性，构建了旱灾风险定量评估方法体系。.研究过程中发现：多特征变量极值事件的重现期概念易被误解和误用。一般而言，重现期为T的单特征变量事件在N年中平均发生N/T次。与单特征变量事件不同，即使在无特大值事件条件下，重现期长于T年的多特征变量事件在分析的N年中发生的次数与N/T时有较大差别，鲜有对此现象的系统解释。在特征变量表征的灾害系统负荷越大，对应的系统响应(灾害损失)越大时，单特征变量负荷的频率P与灾害损失L具有“一一对应”关系，可以用损失大于L的灾害事件发生频率为P表达灾害风险，而直接将该“L—P”关系移用到多特征变量负荷环境下表达灾害风险会导致对灾害损失的低估或高估。项目在分析copula函数主要特性和常用的“or”、“and”事件的第1重现期和第2重现期的基础上，给出了“or”、“and”事件第1重现期和其第2重现期的定量关系，解释了所关注的长重现期严重事件在研究时段内的发生次数不同于传统的相同重现期单特征变量事件发生次数的原因。基于copula双（多）特征变量联合分布表征灾害系统负荷发生概率的风险评估不能直接采用单特征变量环境下的“L—P”关系，应基于灾害系统响应过程，构建“灾害负荷—灾害损失响应”的灾害脆弱性函数，合成脆弱性函数和copula表达的灾害系统负荷的发生概率，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22篇，其中SCI检索4篇，EI检索2篇；获大禹水利科学技术奖二等奖1项，授权发明专利2项；培养硕士毕业生6人。