Assessment on Agricultural Drought Risk Based on Variable Fuzzy Sets Model

Drought is one of the major natural disasters causing huge agricultural losses annually. Regional agricultural drought risk assessment has great significance for reducing regional disaster and agricultural drought losses. Based on the fuzzy characteristics of agricultural drought risk, variable fuzzy sets model was used for comprehensively assessing agricultural drought risk of Liaoning Province in China. A multi-layers and multi-indices assessment model was estab-lished according to variable fuzzy sets theory, and agricultural drought risk of all 14 prefecture-level cities was respec-tively estimated in terms of dangerousness, vulnerability, exposure and drought-resistibility. By calculating the combi-nation weights of four drought risk factors, agricultural drought risk grade of each city was obtained. Based on the as-sessment results, the spatial distribution maps of agricultural drought risk were drawn. The results shows that eastern cities have lower drought dangerousness than western cities in Liaoning Province totally. Most cities are located in low drought vulnerability region and high drought exposure region. Because of frequent and severe drought since 2000, most cities are located in lower drought-resistibility region. Comprehensive agricultural drought risk presents apparent spatial characteristics, escalating from the east to the west. Drought dangerousness is the most important factor influencing comprehensive agricultural drought risk. Through the spatial distribution maps of drought risk, decision makers could find out drought situation and make decisions on drought resistance conveniently.

Impacts of climate change on drought risk of winter wheat in the North China Plain

Drought is a major natural disaster causing crop yield losses,while its occurrence mechanism and spatiotemporal variations in a changing climate are still not clear.Based on a long-term climatic dataset(during 1958–2015)from weather stations in the North China Plain(NCP),the influencing mechanism of various climatic factors on drought risk of winter wheat was quantified by using sensitivity analysis,Mann-Kendall trend test and slope estimation.The results indicated that climatic factors have changed considerably over the past six decades in the growth season of winter wheat.As a result,winter wheat suffered from severe droughts(with 350 mm of water deficit during its growth season),particularly at the jointing–heading and heading–mature stages,which were critical to crop yield formation.There were large spatial and temporal variations in drought risk and climatic change factors at different growth stages of winter wheat.Despite precipitation playing a vital role in determining the spatiotemporal patterns of drought risk,high temperature and low humidity along with other climatic factors at key growth stages of winter wheat aggravated drought risk.Particularly,temperature at nearly 90%weather stations showed a notablely upward trend,which exacerbated water deficit and drought risk of winter wheat.Given the complexity and high uncertainty of climate change,these findings provide important information for adapting crop production to future climate change and accompanied droughts while ensuring food security and agricultural sustainability.

Drought risk assessment in China:Evaluation framework and influencing factors

Global warming and rapid economic development have led to increased levels of disaster risk in China.Previous attempts at assessing drought risk were highly subjective in terms of assessment methods and selection of the assessment indicators and which resulted in appreciable uncertainty in the results of these risk assessments.Based on the assumption that areas with historically high drought losses are more likely to suffer future high drought losses,we develop a new drought risk assessment model that includes historical drought loss data.With this model,we map the regional differentiation of Chinese drought risk.Regions with high(extreme high)drought risk account for 4.3%of China’s area.Five significant high-risk areas have been identified:Northeast China,North China,the east part of Northwest China,the east part of Southwest China and a small part in the west of Northwest China.Areas with high and extreme high drought risk are dominant in the Heilongjiang Province,accounting for 32%of the total area,followed by the Ningxia Hui Autonomous Region,with 26%of total area.The contribution of each influencing factor has been quantified,which indicates that high-exposure and high-vulnerability account for the high-risk of drought.We recommend that measures like strengthening the protection of cultivated land and reducing dependence on the primary industry should be taken to mitigate to drought-induced losses.

Risk assessment of maize drought disaster in southwest China using the Environmental Policy Integrated Climate model

The East Asian monsoon has a tremendous impact on agricultural production in China. An assessment of the risk of drought disaster in maize-producing regions is therefore important in ensuring a reduction in such disasters and an increase in food security. A risk assessment model, EPIC（Environmental Policy Integrated Climate） model, for maize drought disasters based on the Erosion Productivity Impact Calculator crop model is proposed for areas with the topographic characteristics of the mountainous karst region in southwest China. This region has one of the highest levels of environmental degradation in China. The results showed that the hazard risk level for the maize zone of southwest China is generally high. Most hazard index values were between 0.4 and 0.5,accounting for 47.32% of total study area. However,the risk level for drought loss was low. Most of the loss rate was ＆lt;0.1, accounting for 96.24% of the total study area. The three high-risk areas were mainlydistributed in the parallel ridge–valley areas in the east of Sichuan Province, the West Mountain area of Guizhou Province, and the south of Yunnan Province.These results provide a scientific basis and support for the reduction of agricultural drought disasters and an increase in food security in the southwest China maize zone.

GIS-Based Risk Assessment and Regionalization of Drought Hazards in China

Based on the monthly precipitation (1960-2009) of China and associated regional socio-economic data, the spatial and temporal pattern of drought in China was assessed by applying a conceptual framework of disaster system theory, which used the hazard and vulnerability as two variables to define the risk of drought. Sichuan province suffered from the severe risk of drought, while Guangxi, Yunnan, Guizhou provinces, and Chongqing city could be classified as the moderate drought risk area of China. Additionally, Tibet plateau in the Northwest of China had the lowest risk of drought. The integrated data from this result provided the valuable information to cope with the drought in respect of optimization utilization of land resources at the regional scale.

Application of long-range correlation and multi-fractal analysis for the depiction of drought risk

By using the multi-fractal detrended fluctuation analysis method, we analyze the nonlinear property of drought in southwestern China. The results indicate that the occurrence of drought in southwestern China is multi-fractal and long- range correlated, and these properties are indifferent to timescales. A power-law decay distribution well describes the return interval of drought events and the auto-correlation. Furthermore, a drought risk exponent based on the multi-fractal property and the long-range correlation is presented. This risk exponent can give useful information about whether the drought may or may not occur in future, and provide a guidance function for preventing disasters and reducing damage.

Risk Assessment and Zoning of Winter Wheat Drought in Anhui Province

[Objective]The study aimed to assess and zone the drought risk of winter wheat in Anhui Province. [Method] The zoning factors were chosen from three aspects of disaster-causing factors,disaster-bearing bodies and environment conducive to drought,and then their data were standardized,rasterized and graded. Using analytic hierarchy process（ AHP）,we determined the weight of each index at various levels and then established the assessment models of drought intensity,sensitivity,vulnerability and resistance of winter wheat in the whole growth period and at heading and filling stage. Finally,the zoning map of drought risk for winter wheat in Anhui Province was obtained using the farmland data mask of Anhui Province. [Result]The drought risk of winter wheat in Anhui Province in the whole growth period and at heading and filling stage was divided into six grades,which reflected the distribution characteristics and regional difference of drought risk for winter wheat in Anhui Province. Drought risk was the maximum in the main producing areas of winter wheat in the north of Huaihe River,followed by the area along Huaihe River and the area between Yangtze River and Huaihe River,while the drought risk of winter wheat was very low in the south of Anhui Province. The drought risk of winter wheat was markedly affected by the sensitivity to drought,vulnerability and the drought resistance of winter wheat. [Conclusion] The research could provide scientific references for rational distribution of winter wheat and establishment of strategies for disaster prevention and mitigation.

变暖环境下华北地区农业气象灾害风险评估Ⅰ:基于综合指标体系法农业干旱风险评估及适应对策建议

随着全球气候变化,干旱发生频率及强度持续增加,农业干旱灾害风险评估是当前防灾减灾的重要方法之一。基于自然灾害风险形成机理,构建华北农业干旱风险评估指标体系模型,利用内部检验法对模型进行稳健性检验,根据华北34个市农业干旱风险形成特点聚类分类,并提出相应的风险防范建议。结果表明:调整风险评估模型中的指标和方法时,华北地区34个市农业干旱风险排名变化幅度多为1~2.5位,模型稳健性较好;除防灾减灾能力较高的北京、天津外,华北中部和北部农业干旱风险最高,与危险性和脆弱性指标较高有关,河南北部以及山东南部农业干旱风险较低,主要得益于该地区各市危险性较低;华北34个市可分为6个农业干旱风险集群,集群分布在空间上无分散、跨市分布,城市聚集性较好,其中北部山区集群4干旱风险最高,与其极高的环境脆弱性和低防灾减灾能力有关,应在农业种植结构上适当降低农业种植面积并加大农业投入;位于中部和南部的集群2、5和6具有较高的粮食种植面积且粮食因干旱减产率较高,可通过增加农业投入、提高灌溉保证率等进一步降低农业干旱风险。

鄱阳湖流域干旱灾害风险防控体系构建研究

针对鄱阳湖流域旱情发生发展的机理及传递机制不明,旱情监测、预测预警能力及旱灾风险评估与防控措施不足等难题,开展了流域干旱监测、预测和风险评估技术体系构建研究,成功创建了多源数据-多过程要素-多空间维度的监测技术体系、全要素-全过程的旱情动态预测预警技术体系、旱灾风险综合评估与应对技术体系,并研发了融合三种技术体系的鄱阳湖流域防旱抗旱决策指挥系统,有效提升了鄱阳湖流域防旱抗旱能力,为科学应对鄱阳湖流域干旱灾害提供了有力技术支撑。

区域旱灾风险评估若干问题探讨

区域旱灾风险评估是连接旱灾风险科学认识与防范实践的核心环节,一直是旱灾风险防御理论和实践研究领域的前沿热点和难点,是支撑区域水利高质量发展亟需解决的关键科技问题。针对实际旱灾风险评估中存在的概念不清晰、方法适用条件有约束、风险定量计算与物理解析相分离等问题,从评价对象符合风险评价目标关系程度的角度,研究指出了旱灾风险综合评价和旱灾风险定量评估是目前旱灾风险评估研究的主要途径,辨析了其中旱灾风险系统、旱灾风险综合评价、旱灾风险定量评估等若干概念问题,探讨了单指标评价函数构建、指标权重确定、综合指标评价函数构建等若干方法问题,以进一步推动旱灾风险评估理论和实践的深入发展。

Analysis of Hay Demand from Pastoralism Systems on Viability of Hay Production as a Climate Adaptation Strategy in Kajiado County, Kenya

Hay production is a flagship project under drought risk reduction and climate change adaptation programs in pastoralism livestock systems in Kenya. For decision-makers to plan and evaluate their projects, they need localized data on hay production and supply and to understand what attitudes influence demand for hay by pastoralists. A cost-benefit analysis on 23 hay farms and a questionnaire knowledge, attitude and practice survey on 340 pastoralists in Kajiado Central were undertaken. This study provides the hay production versus hay deficit figures in Kajiado Central County. The study also measures the financial losses livestock keepers incur during drought migration and correlates these losses against livestock keeper’s decision to buy hay for their animals. The study established that the drought in 2017, Kajiado Central County had a 48% hay deficit (2,580,000 hay bales) worth about KES 902 million needed to cover three months of the severest period of the drought. At the same time, hay production and supply were 49,138 grown hay and 3292 purchased hay bales and 6177 bags of commercial feeds and forage. The study also found that 86% of livestock keepers buy hay only when their animals started dying at the severest period of the drought. Hay buying mainly occurs in drought years, and averagely for three months only. From 2005 to 2020, there have been five years of severe drought. Because hay production is a critical climate change adaptation and mitigation strategy for droughts, Kajiado needs to reduce the hay deficit by 67% (average of 2015 & 2017), disaster management planners need to align the hay supply to hay purchasing practices. In addition, decision-makers need to address the low hay supply by tackling the challenges of hay production. Furthermore, disaster management planners could use the study to determine the trigger points to start disaster response for livestock feed.

基于链式传递结构的旱灾实际风险定量评估方法与应用模式

面向防灾减灾能力、孕灾环境孕险性实际条件下区域旱灾风险定量评估与区划等自然灾害风险防灾减灾关键问题,应用计算思维、系统科学多学科交叉的研究途径,从风险传导角度探讨了区域旱灾风险物理成因机制,阐述了面向致灾机理的区域旱灾五要素系统结构、基于链式传导的旱灾风险六要素系统结构,探讨了区域旱灾实际风险的概念、由旱灾脆弱性连接干旱与损失变量间关系的因旱致灾机理、连接干旱危险性关系与损失风险关系的旱灾风险传导机理、定量评估方法及其主要应用模式,在自然灾害风险评估中具有推广应用前景。

水旱灾害风险普查技术体系探索与应用

结合第一次全国自然灾害综合风险普查要求,基于水旱灾害风险管理理论,从水旱灾害致灾调查与评估、洪水隐患调查与评估、风险评估与区划、数据库建设等方面探索构建了水旱灾害风险普查技术体系。该体系在普查实践中得到验证和完善,支撑各地圆满完成水旱灾害风险普查任务,形成系列普查成果,实现预期普查目标,为水利高质量发展提供了技术支撑。

江苏省水旱灾害风险普查成果管理系统建设

为推广、应用江苏省水旱灾害风险普查成果,江苏省水旱灾害风险普查工作领导小组办公室组织构建了江苏省水旱灾害风险普查数据库、开发了江苏省水旱灾害风险普查成果管理系统。本系统建设为完善区域防洪减灾工程体系和水旱灾害防御工作提供了数据支撑,也为类似水旱灾害风险普查成果管理提供参考。

旱灾风险评估的初步理论框架

旱灾风险评估是定量认识旱灾风险机理、科学防控旱灾风险的重要基础性研究,在旱灾风险管理理论与实践中具有重要意义。根据旱灾风险的形成机制,在旱灾风险评估基本概念分析的基础上,提出并系统地阐述了由旱灾致灾因子危险性、承灾体的灾损敏感性、暴露和抗旱能力组成的旱灾风险系统。在此系统结构基础上提出了旱灾风险评估方法论和旱灾风险评估理论模式,进而建立了由致灾因子危险性分析、承灾体脆弱性分析、旱灾损失风险分析、旱灾风险评价、旱灾风险决策分析方法组成的旱灾风险评估方法体系,以及由干旱频率与旱灾损失关系曲线图、干旱频率空间分布图、旱灾损失空间分布图、与旱灾风险有关的致灾因子危险性分布图等各种专题图、旱灾风险区划图组成的旱灾风险评估应用模式体系。由上述旱灾风险系统结构、旱灾风险评估方法论和理论模式、旱灾风险评估方法体系和应用模式体系组成旱灾风险评估的初步理论框架,该理论框架在其它自然灾害风险评估中具有参考应用价值。

基于三元链式传递结构的区域旱灾实际风险综合防范机制分析

区域旱灾风险防范对保障粮食安全、推动经济社会和生态环境可持续发展具有重要意义。针对旱灾风险防范的复杂性,为分析区域旱灾风险综合防范机制,采用自然灾害系统理论和结构水资源学方法相结合的研究途径,分析了区域旱灾风险形成的物理过程,提出了由六要素组成的区域旱灾风险系统,揭示了以致灾因子危险性、承灾体脆弱性和损失风险这三种关系(简称三元)链式传递为灾害风险系统基本结构特征的区域旱灾实际风险三元链式传递机理,以及相应的旱灾风险调控三元链式传递机理,进而从功能调控、准则调控、要素调控、空间调控、过程调控、综合调控等方面探讨了这些动态优化防范实施策略的区域旱灾风险防范机制及其可行性,认为区域旱灾风险综合防范迫切需要深入开展水科学、自然灾害学、系统科学和智能科学等多学科交叉融合的相应研究。

基于自然灾害系统理论的辽宁省玉米干旱风险分析

为了减轻旱灾对辽宁地区玉米生产的影响,该文通过对辽宁省23个气象站点46 a气象数据和气象站点所在县玉米产量、种植面积的分析,用实际干旱发生频率、农业气象干旱发生频率、玉米生产相对暴露率和单产水平等4个因素构建了辽宁地区玉米干旱风险指数,用社会科学统计程序(statistical program for social sciences)和地理信息系统(geographic information system)对辽宁地区玉米干旱进行了风险分析和风险区划。结果表明,辽宁省有30%的站点处于玉米干旱较高或高风险区,主要分布于辽西山地丘陵和辽南沿海地区;玉米干旱中等风险区主要分布在辽西走廊和辽中平原及渤海湾附近地区;玉米干旱低风险区主要分布在辽东山地丘陵地带。经检验50%以上站点的干旱风险指数与玉米相对气象产量显著相关。所构建的辽宁地区玉米干旱风险指数能客观地反应干旱对玉米生产的影响。该研究为玉米避灾和减灾管理提供科学依据。

陕西省冬小麦干旱风险分析及区划

根据自然灾害分析原理 ,以县为单元 ,从干旱对冬小麦造成的减产出发 ,分别就各县灾损率、易灾性、抗灾能力三方面进行了讨论。以风险指数为区划指标 ,在GIS系统 (CityStar)中 ,按等级划分标准对各县属性值进行分级、赋色 ,获得GIS系统支持下的陕西省冬小麦干旱风险区划图 ,并分区予以评述。

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。

基于GIS的区域干旱灾害风险区划研究

根据自然灾害风险理论,从致灾因子危险性、孕灾环境暴露性、承灾体易损性、防灾减灾能力等4个子系统选取指标,建立干旱灾害风险指数模型,结合GIS中自然断点分类法进行聚类分析,全面综合地分析各地区相关性和差异性。以淮河流域为研究实例,根据拟定的区划原则,采用"自下而上"和"自上而下"相结合的区划方法,将淮河流域分为6个旱灾风险分区,并对区划结果进行分析,为因地制宜地采取工程和非工程的防灾减灾措施,提供参考依据。