基于信息扩散和频率曲线适线的农业旱灾风险评估方法

为克服农业旱灾风险计算中小样本导致的信息不足,以农业因旱受灾率为损失指标,采用信息扩散理论和频率曲线适线方法相结合的方法,构建损失与概率之间的函数关系,建立了旱灾风险评估方法。据此方法定量计算不同旱灾水平年下的农业因旱受灾率,绘制旱灾风险空间分布图。该方法通过优化利用样本模糊信息来弥补小样本导致的信息不足,对小容量样本的概率分布估计有较高的精确度。将该方法用于安徽省农业旱灾风险评估,绘制了安徽省农业旱灾风险图,以便为安徽省抗旱减灾提供参考。     

基于信息扩散技术的黑龙江省农业旱灾风险分析

基于优化利用不完备信息进行风险评估的信息扩散技术,根据黑龙江省2001～2011年旱灾灾情数据,建立灾害样本与相应论域的模糊关系,根据扩散后的样本信息估计了黑龙江省因旱受灾率、因旱成灾率、因旱绝收率的概率分布,定量分析旱灾风险。分析结果表明,黑龙江省因旱受灾率在10%左右的几率最大,因旱成灾率在6%左右的几率最大;黑龙江省平均每1.2年发生一次受灾面积超过10%的旱灾,平均每2年发生一次受灾面积超过25%的旱灾,平均每5年发生一次受灾面积超过45%的旱灾,平均每10.3年发生一次受灾面积超过55%的旱灾,平均每54年发生一次受灾面积超过70%的旱灾;平均每1.7年发生一次成灾面积超过10%的旱灾,平均每6.5年发生一次成灾面积超过25%的旱灾,平均每13.6年发生一次成灾面积超过30%的旱灾,平均每40.2年发生一次成灾面积超过35%的旱灾。     

基于信息扩散理论的贵州省农业旱灾风险评估

农业旱灾风险评估对农业旱灾防护有重要作用。以贵州省1951—2010年统计资料为基础,基于信息扩散理论,对贵州省农业旱灾进行风险评估。结果表明:随着贵州省各地市旱灾成灾损失标准的提高,成灾风险概率值总体上呈下降趋势,成灾面积指数为5%~10%时,研究区发生旱灾的频率基本为1.0~2.0 a一遇;成灾面积指数为15%~20%时,风险概率下降较为明显,表现出明显的空间差异,旱灾发生频率总体为西高东低,东北、东南偏高;成灾面积指数为10%以下时全省多为高风险区,旱灾发生的频率很高。     

阜新市农业旱灾风险决策方案研究

农业旱灾风险评估是风险管理和减灾管理的基础,可为农业生产和防灾减灾提供科学依据。针对研究区域现有的灾情数据资料时间序列短、数量少的特点,建立了基于信息扩散理论的灾害风险估计模型,对辽宁省阜新市进行了概率风险分析,避免了分析结果的不稳定性。同时,对所得的农业损失经验频率点进行P-Ⅲ拟合,并提出了阜新市的抗旱风险决策方案。     

基于干旱事件过程的农业旱灾风险评估研究-以辽西北为例

科学地评估旱灾风险是实施旱灾风险管理的核心内容和关键环节。本文从旱灾风险的定义和物理形成过程出发,提出了基于干旱事件过程的旱灾风险评估原理、概念模型,形成了一整套旱灾风险评估技术流程,并以位于我国东北旱灾频发、重发中心的辽西北地区为例开展了应用研究。研究表明,基于干旱事件过程的旱灾风险评估方法具有较强的物理意义,可用于快速预估一定抗旱能力条件干旱可能造成的损失,可为抗旱指挥决策提供技术支撑,具有进一步推广应用的价值。     

基于深度学习的旱灾风险评估方法

针对当前旱灾风险评估中将影响干旱的因素与历史旱灾记录直接进行关联研究的成果相对较少的问题,从历史旱情文本数据和气象数据出发,提出了一种新的基于深度学习的旱灾风险等级评估方法。利用长短期记忆神经网络与支持向量机构建了旱灾风险等级评估模型,将其用于对未来可能发生的旱灾风险等级进行评估。在此基础上,以郑州市为研究实例,并用1951～2020年的气象数据以及灾情文本描述记录对所构建的模型进行有效性检验。结果表明：研究区2019年和2020年春季干旱状况比较严重,与实际情况相比,预测准确率为75%。这也验证了所提出的融合多源数据旱灾风险评估方法在风险等级预测方面具有一定的有效性。     

甘肃省旱灾基本特征及发展趋势分析

分析了甘肃省1950—2007年58 a长系列旱灾资料。结果表明:甘肃旱灾特征明显,一是春旱、夏旱、春夏旱、冬春旱和冬春夏三季连旱是旱灾的基本季节特征;二是旱灾具有明显的空间分布特征,表现为黄河流域干旱发生的频次最高、范围最大、灾情最重,长江流域次之,内陆河流域相对较轻;三是旱灾具有持续性和连续性等。旱灾还具有一定的变化规律:一是因旱粮食损失量随年代呈现逐步增长的变化过程;二是因旱受灾面积和成灾面积呈现大幅度增加趋势;三是虽然旱灾损失在不断增长,但是全省粮食产量保持持续稳定增长;四是旱灾随降水也有明显的变化规律。     

广西旱灾易发等级划分研究

介绍了1990年以来广西各地发生的旱情及其损失,分析了旱灾的成因。论述了旱灾易发等级的划分标准和方法,采用因旱粮食损失率、因旱人饮困难等指标划分广西各地旱灾易发等级,为全区各级政府部门抗旱工作提供依据。     

基于农业旱灾损失风险曲线的区域旱灾风险率空间分布研究

以辽宁西部18个典型县区为实例,对各县区干旱频率和因旱损失率进行关联度分析,得到区域农业旱灾损失风险曲线,并得到不同干旱频率(5％、10％、20％、30％、50％、60％)的旱灾风险率空间分布图.结果 表明:各县区频率与因旱损失率相关系数介于0.5～0.8,呈现较好的相关度,满足对数函数变化特征,潜在因旱损失随着干旱频...     

基于EPIC 模型的云南元谋水稻春季旱灾风险评估方法

旱灾风险评估对于揭示旱灾发生规律,减少旱灾损失具有重要意义。以云南元谋县水稻1961—2010年的春季干旱为例,利用copula 函数计算干旱发生频率,根据EPIC 模型计算干旱在不同灌溉水平下的旱灾损失率,拟合干旱频率-旱灾损失率的分布曲线。云南元谋县实例研究表明,水稻春季干旱发生频率与其旱灾损失率之间基本符合对数函数的趋势关系,决定系数R2 在0.7以上,灌溉水量对于减少旱灾损失的作用显著。建立的干旱频率-灌溉水平-旱灾损失率分布曲线,可作为研究区水稻春季旱灾风险的定量评估方法。     

A Novel Method for Agricultural Drought Risk Assessment

Climate change, increased temperatures and imbalanced precipitation distributions will potentially increase the local drought risk in certain areas. Drought assessment can identify the hidden dangers of drought and provide a theoretical basis for disaster prevention and mitigation. In this paper, a new agricultural drought risk assessment method proposed from the perspective of grain yield. The first principal components of precipitation, temperature, humidity and soil moisture represent hazard factors. The sensitive yield, which represents the sensitivity, was separated from the grain yield using a regression method. Additionally, the trend component of the grain yield represents the adaptive capacity, and the crop planting area represents exposure. Based on these definitions, the concepts of unit drought risk and regional drought risk are proposed. Four cities in Heilongjiang Province, which has the highest grain yield of any province in China, were used as application examples, and the spatial and temporal variation in the agricultural drought risk were analyzed. Application example show that the method for evaluating agricultural drought presented in this paper is reasonable in a statistical sense. The process for calculating sensitivity and adaptability shows that this method is suitable for arid and semi-arid areas, where grain yield is sensitive to hazard factors, and areas where grain yield has a certain trend.

     

水旱灾害风险评估方法体系及其实证研究

针对水旱灾害系统的不确定性,从系统论角度提出了水旱灾害致灾因子的危险性、承灾体的暴露、灾损敏感性和防灾减灾能力这4个子系统组成的水旱灾害风险系统及其定量表征。从方法论角度,提出了由水旱灾害危险性分析评估、脆弱性分析评估、损失风险分析评估、风险评价、风险决策分析这5类方法组成的水旱灾害风险评估方法体系,并归纳分析本文作者以往的实证研究。结果表明该方法体系具有通用性和有效性,在自然灾害风险评估中具有参考应用价值;今后亟须进一步解析该方法体系的物理成因机制,进一步丰富、发展、完善这些水旱灾害风险评估方法,特别是基于水旱灾害损失风险形成过程的损失风险曲线评估方法。     

Assessment of Probabilistic Multi-Index Drought Using a Dynamic Naive Bayesian Classifier

The proper consideration of all plausible feature spaces of the hydrological cycle and inherent uncertainty in preceding developed drought indices is inevitable for comprehensive drought assessment. Therefore, this study employed the Dynamic Naive Bayesian Classifier (DNBC) for multi-index probabilistic drought assessment by integrating various drought indices (i.e., Standardized Precipitation Index (SPI), Streamflow Drought Index (SDI), and Normalized Vegetation Supply Water Index (NVSWI)) as indicators of different feature spaces (i.e., meteorological, hydrological, and agricultural) contributing to drought occurrence. The overall results showed that the proposed model was able to account for various physical forms of drought in probabilistic drought assessment, to accurately detect a drought event better than (or occasionally equal to) any single drought index, to provide useful information for assessing potential drought risk, and to precisely capture drought persistence in terms of drought state transition probability in drought monitoring. This easily produced an alternative method for comprehensive drought assessment with combined use of different drought indices.     

Risk-Based Assessment of Drought Mitigation Options: the Case of Syros Island,Greece

Drought-related risk estimation is widely acknowledged as a tool towards enhancing drought preparedness and minimizing impacts on people, the economy and the environment. In this paper a method is proposed for the risk-based assessment and prioritisation of long-term drought mitigation options in order to support decision making for drought planning. The assessment combines water balance modelling, hazard analysis, and risk and cost effectiveness analysis. The proposed approach allows an improved understanding of drought-related risks by following a probabilistic analysis of drought impacts under different mitigation options. The method is applied in a drought-prone area with water scarcity problems, the Greek island of Syros. The assessment focuses on agriculture and domestic water use, the two main water using sectors in the island. Six mitigation options are cross-compared in terms of contribution to future drought risk reduction using three criteria: risk, vulnerability and benefit-cost ratio. The results validate the use of risk-based assessment of mitigation options as a valuable tool for improved drought management.     

基于模糊集对分析的灌区水库旱限水位及供水策略优化研究

随着经济社会发展和气候条件改变,我国区域干旱问题日益突出,水库在抗旱减灾过程中的作用越来越凸显,旱限水位的提出与应用对有效发挥大中型水库在抗旱中的调控作用、缓解流域旱情具有重要意义。针对旱限水位研究现状,本文以史河灌区梅山水库为例,首先考虑城乡供水、农业灌溉、水力发电和生态环境等诸多因素,构建基于模糊集对分析法的水库灌区水资源系统运行效果综合评价模型,并以水资源系统综合运行等级最优为目标,以分期分级旱限水位、灌溉限供措施(基于水库来水特征和作物生长特性)为优化变量,运用免疫遗传算法进行系统优化求解,最后对比有无旱限水位下水库水资源系统综合运行效果,并分析了不同控制方式下水库供水变化和灌区作物因旱减产风险。结果显示：该优化方法相较于以水库供水经济效益为目标旱限水位确定方法,多项年均指标都有较大改善,其中梅山水库经济效益提高了46万元,充反调节水库水量增加了555万m³,而水库弃水量减少了566万m³;史河灌区塘坝供水量增加了253万m³,而作物减产率下降了3.32%,同时作物因旱减产风险降低了3.15%。可见,运用系统综合...     

Fuzzy Risk Assessment of Flash Floods Using a Cloud-Based Information Diffusion Approach

The assessment of flash flood risks is the basis on which flash flood prevention measures and early-warning systems can be proposed and reasonably implemented. However, inadequate monitoring of flash flood data which mainly occurs in remote areas restricts quantitative risk assessment. This study aimed to address the problems of limited data availability. A new model that integrating the Cloud-based Information Diffusion (CID) model and Analytic Hierarchy Process (AHP) approach is developed to assess flash flood risks. The proposed method improves the information diffusion function by introducing cloud model, while converting single-valued observations with incomplete information into fuzzy set-valued samples. The new approach can perform comprehensive risk assessment tasks with various indexes that are composed of incomplete information. Another advantage of this approach is that it can illustrate fuzzy uncertainty, fuzziness, and randomness of risk indexes by coupling with the cloud model, the risk magnitude is quantified with membership degree. A mountainous watershed in Southern China named Yangshan County was selected as the study area. Compared with information diffusion (ID) and entropy-based information diffusion (EID), the assessment results of the three models are, in general, consistent with one another, and agree with the reported values. According to the principle of maximum membership degree, Yangshan County is determined as a high-risk region when confronting with flash flood hazards. This model provides a feasible and effective method on fuzzy risk assessment of flash flooding, and is expected to be applied in other multi-criteria decision with limited available information or small sample problems.

     

南水北调受水区干旱灾害风险评估方法探讨

南水北调工程的受水区为黄淮海流域,干旱问题已经成为该区域经济和社会发展的瓶颈,因此有必要对受水区内的干旱风险做出准确评估.区域干旱风险可以理解为区域内暴露于干旱下的承灾体,在外部致灾因子扰动下,由于自身的脆弱性,所遭受损失的可能性及可能的损失程度的大小.区域干旱风险评估的任务是明晰发生干旱时暴露于干旱下各个部门和社会生活的各个方面,确定引发干旱的自然致灾因子,分析承灾体的脆弱性,预测干旱造成的影响和损失,并通过数学方法合理量化风险的大小,同时确定造成各部门、地区和人口风险的主要原因,即干旱风险的主要影响因素,从而寻求降低风险的有效途径.现以南水北调某一特定受水区域为研究对象,分析了干旱灾害的成灾机理,对干旱致灾因子的危险性及承灾体的脆弱性进行了讨论,提出相应的计算公式,建立了针对特定区域的干旱灾害风险评估模式,对干旱灾害风险提出了量化的方法.并结合南水北调受水区济南市的实际情况对本文提出的方法进行了应用和验证,实践证明该风险评估模式有一定的科学性和应用价值.     

基于GIS的南盘江流域区域农业旱灾风险区划应用研究

根据农业干旱发生发展规律和风险理论,从旱灾造成农作物减产的角度出发,分别对致灾因子危险性、孕灾环境脆弱性和承灾体易损性进行分析,建立农业旱灾风险评估模型,结合GIS中自然断点分类法进行聚类分析,开展区域农业旱灾风险区划。以云南省南盘江流域为研究区域,根据干旱等级划分标准,将研究区域按4个等级进行农业旱灾风险区划,并对分区结果进行分析,为该区域政府部门制定防灾减灾规划提供技术支撑。