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.

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.

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.

Effectiveness of Drought Risk Reduction Policies: Case Study of Hay Production in Kajiado County, Kenya

Kenya has integrated several international, continental, and regional strategies and policies into its national and county programs to address climate-related disasters in livestock systems in pastoralism. This study reviews how these policy instruments have been integrated into local laws and the viability of hay production, a drought risk reduction strategy. The methodology used was a desktop review of policies, a KAP survey using a quantitative and qualitative questionnaire on 354 pastoralists and key informants selected using stratified random sampling, and a cost-benefit analysis of 23 hay farms in Kajiado-Central sub-county. The findings established that Kenya had adopted adequate legal instruments to support disasters in general and droughts specifically. However, the strategies are not elaborated into practical guidance resulting in poor implementation. For instance, the flagship hay production project in Kajiado focuses on building infrastructure on the government farms, with little support going to the actual hay farmers. In addition, staffing levels of technical officers are too low to adequately translate the strategies into activities that address the hay farmer’s pain points, namely the lack of a stable hay market, expensive capital assets and machinery, lack of quality forage seeds, and extension education. This paper recommends reviewing the implementation of the ongoing hay flagship projects to address the hay enterprise’s profitability and elaborating the strategies down to guidance that can be easily rolled out cognizant of the low staffing levels. Public-private partnerships can also address some challenges by stabilizing the hay markets, providing storage, and maintaining good-quality hay. In addition, the strategic feed reserve should include hay for pastoral livestock systems under drought risk reduction programs. Thus, targeted, relevant projects are critical if private hay enterprises are a sustainable drought risk reduction strategy.

Assessment of Agricultural Drought Risk in the Sichuan Basin Based on Information Diffusion Theory

Based on data of agricultural drought situation and sown area of main crops in each county or district of the Sichuan Basin, the spatial distribution and probability of agricultural drought risk at different risk levels were studied using normal information diffusion method, and the risk zoning was carried out. The results showed that normal information diffusion method could fit the distribution of agricultural drought risk in the Sichuan Basin. By comparison with the end of the 20^th century, agricultural drought risk in Meishan, Chongqing City and so on increased at the beginning of the 21^st century when x1≥ 10% or x1≥40%. Agricultural drought risk was low in the west of the Sichuan Basin, which was related to rich precipitation here, but it was high in Bazhong, Zhongjiang, Luxian and so forth. The risk zoning results can provide scientific references for disaster prevention and emergency management of government.

Assessment of drought risk for winter wheat on the Huanghuaihai Plain under climate change using an EPIC model-based approach

Climate change-induced drought poses a serious negative impact on global crop production and food security.The Huang Huai Hai(HHH)Plain,one of the most important grain production areas in China,is heavenly stricken by drought.Motivated by formulating drought risk prevention strategies that adapt to climate change on the HHH Plain,therefore,the present study aims to quantitatively evaluate the winter wheat drought risk under multiple climate scenarios using the Environmental Policy Impact Climate(EPIC)model.Based on the well-validated EPIC model,the drought hazard intensity(dHI),physical vulnerability(pV),and drought risk(dR)of the HHH Plain from 2010 to 2099 are assessed.Temporally,the dR showed an increasing trend in the long term,the high dR areas increased by 0.63%and 1.18%under the RCP4.5 and RCP8.5 scenarios,respectively.Spatially,dR showed a pattern of high in the south and low in the north whether under RCP4.5 or RCP8.5 scenario.Comparatively,the dR was 0.211 under the RCP4.5 scenario which was slightly higher than that under the RCP8.5 scenario,i.e.0.207.The Huanghuai Plain agricultural subregion will be a high dHI-pV-dR region.The temperature increase might be the main factor affecting the wheat drought risk.

Mapping the Global-Scale Maize Drought Risk Under Climate Change Based on the GEPIC-Vulnerability-Risk Model

Drought is projected to become more frequent and increasingly severe under climate change in many agriculturally important areas.However,few studies have assessed and mapped the future global crop drought risk—defined as the occurrence probability and likelihood of yield losses from drought—at high resolution.With support of the GEPIC-Vulnerability-Risk model,we propose an analytical framework to quantify and map the future global-scale maize drought risk at a 0.5°resolution.In this framework,the model can be calibrated and validated using datasets from in situ observations(for example,yield statistics,losses caused by drought)and the literature.Water stress and drought risk under climate change can then be simulated.To evaluate the applicability of the framework,a global-scale assessment of maize drought risk under 1.5℃warming was conducted.At 1.5℃warming,the maize drought risk is projected to be regionally variable(high in the midlatitudes and low in the tropics and subtropics),with only a minor negative(-0.93%)impact on global maize yield.The results are consistent with previous studies of drought impacts on maize yield of major agricultural countries around the world.Therefore,the framework can act as a practical tool for global-scale,future-oriented crop drought risk assessment,and the results provide theoretical support for adaptive planning strategies for drought.

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.

Risk Regionalization of Drought for Flue-cured Tobacco Planting in Qujing City Based on GIS

The risk regionalization of drought for flue-cured tobacco planting in Qujing City was studied to provide reference for drawing on advantages and avoiding disadvantages in flue-cured tobacco planting,disaster reduction,and disaster relief services.According to the production practice of flue-cured tobacco and local climate analysis,the risk of disaster-causing factors,sensitivity of disaster-breeding environment,vulnerability of carriers,and disaster prevention and reduction capability were analyzed and evaluated quantitatively.Secondly,starting from the formation mechanism of drought,a risk assessment model of the meteorological disaster was established by GIS technology.Finally,the risk assessment and regionalization of drought in the critical periods for drought-stricken flue-cured tobacco (transplanting period,root extending stage and vigorous growth period) in Qujing City were carried out.The results showed that in Qujing City,the risk areas of drought for flue-cured tobacco planting were divided into five grades in the transplanting period and six grades in the root extending stage and vigorous growth period.

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.

Study on the Features and Risk Assessment of Drought in Guilin

Based on the precipitation data of all counties in Guilin from 1957 to 2010, the analysis has been made on the features of spatial and temporal distribution, the probability of occurrence and the periodic change of drought in Guilin. Afterwards, by using the method of disaster risk assessment, the disaster-causing factors, breed disasters environment and fragility of hazard-bearing body of Guilin drought have been analyzed, and the comprehensive evaluation on drought disaster has been made. The results show that above medium drought in Guilin mainly appeared in au- tumn, followed by winter, while Guilin only suffered from slight drought in spring; the principal period of drought occurrence in Guilin was six years, while its secondary period was two years; on the whole, drought risk was high in the southeast and low in the northwest.

基于SPI-RRV指数中国气象干旱及其风险时空演变特征研究

为全面揭示变化环境下我国多维气象干旱特征,耦合气象干旱指数(SPI)和可靠性-回弹性-脆弱性(RRV)指数,提出了一种基于SPI-RRV指数的干旱风险评价方法,定量评价了中国气象干旱及其风险的时空演变特征。结果表明:SPI-RRV指数具有特征稳定和时空可比性强的特点,能够较为准确地评估气象干旱风险时空演变特征;南方平均干旱栅格比、干旱月占比和频次大于北方,湿润区和半湿润区干旱历时短、烈度大,半干旱区和干旱区干旱历时长、烈度相对较小;干旱高风险区转移具有显著年代际变化规律,空间上从西北向西南地区转移。

Risk assessment of water security in Haihe River Basin during drought periods based on D-S evidence theory

The weights of the drought risk index （DRI）, which linearly combines the reliability, resiliency, and vulnerability, are difficult to obtain due to complexities in water security during drought periods. Therefore, drought entropy was used to determine the weights of the three critical indices. Conventional simulation results regarding the risk load of water security during drought periods were often regarded as precise. However, neither the simulation process nor the DRI gives any consideration to uncertainties in drought events. Therefore, the Dempster-Shafer （D-S） evidence theory and the evidential reasoning algorithm were introduced, and the DRI values were calculated with consideration of uncertainties of the three indices. The drought entropy and evidential reasoning algorithm were used in a case study of the Haihe River Basin to assess water security risks during drought periods. The results of the new DRI values in two scenarios were compared and analyzed. It is shown that the values of the DRI in the D-S evidence algorithm increase slightly from the original results of Zhang et al. （2005）, and the results of risk assessment of water security during drought periods are reasonable according to the situation in the study area. This study can serve as a reference for further practical application and planning in the Haihe River Basin, and other relevant or similar studies.

干旱形成机制与预测理论方法及其灾害风险特征研究进展与展望

在全球变暖背景下,干旱事件发生的频率和强度不断增大、影响不断加重,干旱发生规律的异常性和机制的复杂性也更为突出,对干旱形成机制、预测理论方法及灾害风险变化规律等方面都提出了新的挑战,也制约了当前干旱预测、预警及其灾害防控能力的提高。近年来,在国家重点基础研究发展计划(973计划)课题等多个国家级项目支持下,已在干旱灾害形成机制与预测理论方法及其风险特征方面取得了一系列新成果。通过动力诊断、数值模拟和田间试验等方法,开展了干旱形成的多因子协同作用和多尺度叠加机制、干旱致灾过程的逐阶递进特征,以及干旱灾害风险分布演化的主控因素等方面的研究。对如下几方面的新进展进行了系统总结归纳:(1)厘清了全球变暖背景下青藏高原热力、海温、夏季风、遥相关等多因子对干旱形成的作用机制。(2)发现了降水亏缺时间尺度和农作物不同生长阶段的干旱敏感性规律。(3)揭示了变暖背景下典型区域干旱灾害风险分布及其变异的新特征;构建了干旱灾害风险新概念模型。(4)研发了东亚季风区的季节和次季节干旱集成预测系统。在总结归纳已取得研究成果的基础上,对未来干旱形成机制及其灾害风险科学研究进行了展望,提出了5个重点研究方向:(1)多因子联动及其多尺度叠加效应对干旱形成的影响;(2)系统整合人类活动和决策以及相关反馈的气候模式研究;(3)揭示陆-气耦合和大气环流协同作用对干旱的影响;(4)认识干旱灾害对粮食安全和生态安全影响的关键过程;(5)提高不同气候情景下干旱预估的准确度。

基于本体和图数据库的流域干旱灾害风险知识图谱构建及应用

针对干旱灾害领域内数据多源异构、难以统一管理与分析的问题,从知识图谱理论出发,首先根据领域知识要素,自顶向下构建干旱灾害风险本体;其次基于全球离散格网系统设计了一种知识抽取方法,并以汉江流域丹江口上游为例,采用该方法从流域时空数据中提取出知识三元组后,利用图数据库进行存储,形成流域干旱灾害风险知识图谱;最后以所建图谱作为空间分析框架,结合游程理论、聚类等方法实现了对流域干旱灾害风险的综合评估。

北方农牧交错区农户干旱风险感知及其适应策略研究:以陕西省榆阳区为例

为增强农户适应气候变化的能力,提升农业生态系统的气候韧性,本研究以陕西省榆阳区为例,基于农户调研数据运用二元Logistic回归模型对北方农牧交错区农户干旱风险感知及其适应策略进行分析。结果表明:农户的干旱风险感知与适应意向之间存在复杂的非线性相关关系。农户对干旱风险严重性的感知由高到低依次为农兼户、兼农户、非农户、纯农户,适应感知由高到低依次为非农户、纯农户、兼农户、农兼户。农兼户对干旱风险严重性的感知最为强烈而适应感知最弱,纯农户对干旱风险严重性的感知程度最低而适应感知较强;接近半数(47.5%)的受访农户愿意积极应对干旱风险,非农化水平较高的农兼户和兼农户适应意向更强烈,分别有72.34%和58.33%的农户产生积极的适应意向,有36.19%的纯农户产生积极适应意向,非农户的比例仅占23.08%;农户适应感知、适应激励、自然资本、物质资本、社会资本与适应意向存在显著相关关系,且均为正相关。基于以上结果,本研究提出了旨在提升北方农牧交错区农户干旱风险适应能力的政策建议。

基于ERA5再分析数据的伊犁河流域干旱灾害风险评估与区划

依据ERA5再分析数据的分布特点,以0.25°×0.25°的网格为旱灾风险评估的基本单元,从危险性、脆弱性、易损性和防灾减灾能力4个方面选取12个指标,采用AHP-熵值法确定指标权重,对基础数据资料匮乏的伊犁河流域构建干旱灾害风险指数模型,进行干旱灾害风险评估与区划。结果表明,分时段校正后的ERA5再分析降水数据精度显著提高,可用于干旱灾害风险评估;次高、高危险性区域主要分布在研究区西北部和东北部,次高、高脆弱性区域主要分布在海拔较高的山区,次高、高易损性区域主要分布在伊宁市及周边地区,次高、高防灾减灾能力主要分布在研究区西北部,分别占研究区总面积的33.45%、31.04%、16.13%、15.09%;旱灾风险区划图显示,低、次低风险区主要分布在研究区西南部,次高、高风险区主要分布在研究区西北部,分别占研究区总面积的44.69%、22.53%。

东北地区未来春玉米干旱风险时空分布及对气候变化的响应

【目的】干旱是影响中国农业生产的主要自然灾害之一。东北地区作为中国最大的玉米生产基地,气候变化背景下干旱频发重发严重影响玉米的高产稳产。评估未来气候情景下东北地区春玉米干旱发生风险及其空间格局变化,为该地区春玉米防旱避灾以及保障其高产稳产提供科学依据。【方法】选取东北地区春玉米潜在种植区为研究区域,基于ISIMIP输出的SSP1-2.6、SSP3-7.0和SSP5-8.53种气候情景的1981—2060年逐日气象资料以及53个农业气象观测站1981—2014年春玉米生育期资料,选取作物水分亏缺指数(crop water deficit index,CWDI)为农业干旱指标,分析东北地区春玉米不同生育时期不同等级干旱时空分布特征,选择最优概率理论分布函数进行干旱指数序列的概率估算,基于信息扩散理论估算得到各点春玉米不同等级干旱风险,构建干旱风险指数,评估未来不同气候情景下东北地区春玉米干旱发生风险及未来各等级风险区的空间格局变化。【结果】(1)1981—2014年东北地区春玉米全生育期干旱指数总体呈西南高东北低的特征,表现为内蒙古东四盟(57.3%)>黑龙江省(40.6%)>辽宁省(39.5%)>吉林省(38.9%)。(2)研究区域春玉米生育中期干旱指数整体高于生育前期和生育后期。其中,2030s和2050s研究区域春玉米生育前期干旱风险概率为轻旱>中旱≈重旱>特旱,生育中期干旱风险概率为特旱>重旱>轻旱≈中旱,生育后期干旱风险概率轻旱>中旱>重旱>特旱。(3)1981—2060年,SSP1-2.6低排放情景下,东北地区春玉米较高等级干旱风险发生概率将减少,极高和较高干旱风险区明显向西南收缩,2030s和2050s面积占比分别减少5.4%和9.6%、0.8%和2.5%;而SSP3-7.0和SSP5-8.5两个高排放情景下,较高等级干旱风险发生概率增加,且较高干旱风险区向东北扩张,2050s面积占比分别增加8.5%和9.7%。【结论】基于干旱风险指数的未来干旱风险时空分布格局中,东北春玉米干旱风险呈现由西南向东北减少的特征,且未来SSP3-7.0和SSP5-8.5情景下,较高干旱风险区向东北方向扩张,需关注作物关键生育时期提出针对性的防御措施。