Assessing Maize Drought Hazard for Agricultural Areas Based on the Fuzzy Gamma Model

Drought is one of the severe meteorological disasters and causes of serious losses for agricultural productions, and early assessment of drought hazard degree is critical in management of maize farming. This study proposes a novel method for assessment of maize drought hazard in different growth stages. First, the study divided the maize growth period into four critical growth stages, including seeding, elongation, tasseling, and filling. Second, maize drought causal factors were selected and the fuzzy membership function was established. Finally, the study built a fuzzy gamma model to assess maize drought hazards, and the gamma 0.93 was finally established using Monte Carlo Analysis. Performing fuzzy gamma operation with 0.93 for gamma and classifying the area yielded a map of maize drought hazards with four zones of light, moderate, severe, and extreme droughts. Using actual field collected data, seven selected samples for drought hazard degree were examined, the model output proved to be a valid tool in the assessment maize drought hazard. This model will be very useful in analyzing the spatial change of maize drought hazard and influence on yield, which is significant for drought management in major agricultural areas.

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.

Evaluation of Drought Hazard Area of GharehAghaj Basin in Iran, Using GIS

In GharehAghaj basin drought has the most profound effect on the way of living and regional economy. Drought Hazard by nature is a result of interrelated parameters concerned. The objective of this paper presents a model to assess hazard of drought using the Geographical Information System (GIS). The data analyzed have been gathered from the records, reports and maps published by the governmental offices of Iran. Various drought hazard indicators have different severity classification in different models. The drought hazard indicator maps take into account the meteorological, hydrological, physical and socioeconomic characteristics that related to drought hazard. Each of the hazard indicator maps and also final hazard map are classified into 4 hazard classes of drought: mild, moderate, severe and very severe. The final hazard classes were defined on the basis of hazard scores arrived at by assigning the appropriate attributes to the indicators and the final hazard map was prepared by overlaying different hazard indicator maps in the GIS, deploying the new model. The final Hazard Map shows that moderate hazard areas (89.87% of the basin) are much widespread than areas under severe hazard (10.13% of the basin) which are observed in the Southeast of the region.

Drought hazard assessment and spatial characteristics analysis in China

Based on the monthly precipitation data for the period 1960-2008 from 616 rainfall stations and the phenology data of main grain crops, the spatial characteristics of drought hazard in China were investigated at a 10 km×10 km grid-cell scale using a GIS-based drought hazard assessment model, which was constructed by using 3-month Standard Precipitation Index （SPI）. Drought-prone areas and heavy drought centers were also identified in this study. The spatial distribution of drought hazard in China shows apparent east-west difference, with the eastern part of China being far more hazardous than the western part. High hazard areas are common in the eastern and central parts of Inner Mongolian Plateau, the central part of Northeast China Plain, the northern part of Heilongjiang, the southeastern part of Qinghai-Tibet Plateau, the central and southern parts of Loess Plateau, the southern part of North China Plain, the northern and southern parts of Yangtze River Plain, and Yun- nan-Guizhou Plateau. Furthermore, obvious differences in drought hazard were found both within and between different agricultural zonings.

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.

Combined Impacts of Antecedent Earthquakes and Droughts on Disastrous Debris Flows

This paper describes a study on the combined impacts of antecedent earthquakes and droughts on disastrous debris flows.This is a novel attempt in quantifying such impacts using the effective peak acceleration(EPA)(to represent earthquakes) and standardized precipitation index(SPI)(to represent droughts).The study is based on the analysis of 116 disastrous debris flow events occurred in China's Mainland in the last 100 years covering a wide spectrum of climate types and landforms.It has been found that the combined impacts from earthquakes and droughts on disastrous debris flows do exist and vary from low to very high according to different climate conditions and terrains.The impacts from earthquakes increase with the increased terrain relief,and the impacts from droughts are strongest in semi-humid climate condition(with reduced impacts in humid and semi-arid /arid climate conditions).Hypothetical explanations on the study discoveries have been proposed.This study reveals the possible reasons for the disastrous debris flow distributions around the world and has significant implications in paleo-climate-seismicanalysis and disastrous debris flow risk management.

THE PRELIMINARY STUDY ON POSSIBLE SCENARIOS OF FLOOD AND DROUGHT IN CHINA IN THE CASE OF GLOBAL WARMING

ＴＨＥ ＰＲＥＬＩＭＩＮＡＲＹ ＳＴＵＤＹ ＯＮ ＰＯＳＳＩＢＬＥ ＳＣＥＮＡＲＩＯＳ ＯＦ ＦＬＯＯＤ ＡＮＤ ＤＲＯＵＧＨＴ ＩＮ ＣＨＩＮＡ ＩＮ ＴＨＥ ＣＡＳＥ ＯＦ ＧＬＯＢＡＬ ＷＡＲＭＩＮＧ ＣｈｅｎＪｉａｑｉ（陈家其）（Ｎａｎｊｉｎ...

2004—2019年中国干旱多承灾体灾损风险特征评估

基于2004—2019年中国省级年干旱灾情和社会经济资料,对干旱农作物受灾面积、受灾人口和直接经济损失三个指标及其灾损率的时空变化规律进行分析,采用信息扩散方法开展不同承灾体的干旱灾损率风险评估,为摸清近十几年的干旱风险格局,提高灾害风险管理能力提供参考。结果表明:三个指标的年干旱灾损率均呈现下降趋势,其中年农作物受灾面积和人口受灾率减少趋势显著,年降水量增加、年干旱累积强度和干旱日数减少以及防灾抗旱能力增强为主要原因。农作物、人口和经济不同承灾体的干旱风险格局存在差异。出现农作物面积受灾率≥20%时的旱灾可能性不高,仅宁夏、山西、内蒙古、甘肃超越概率达较高等级,出现人口受灾率≥30%和直接经济损失率≥1%时的旱灾可能性更低,超越概率小,无省份达高、较高可能性等级。年农作物面积受灾率20年一遇水平下,干旱重灾区分布在西北地区、西南地区东部及湖北、湖南、浙江、海南。年人口受灾率20年一遇水平下,干旱重灾区位于西北地区中东部、西南地区东部以及安徽、山西、内蒙古。年直接经济损失率20年一遇水平下,干旱重灾区集中在东北、西北地区中部、西南地区东部及内蒙古、海南。

Influence of droughts on remote villages in the karst region of Guizhou Province, China: Causes and control

Even though the precipitation is abundant in the Karst region of Guizhou Province, remote villages in this area frequently suffer severe droughts. This paper studied the causes of droughts in this region through field investigation and references collection. Based on the cause analysis, some suggestions were provided for hazard prevention and control from an engineering perspective. Besides occasional extreme weathers, the drought in this area is primarily caused by its unique geological structures of Karst plateau and underdeveloped agricultural techniques. Meanwhile, the vicious cycle between drought and poverty, which causes the deficiency of water conservancy facilities and hazard prevention awareness, is an important reason for the frequent occurrence of agricultural and socioeconomic drought. Considering the social and economic conditions of remote villages, the long-term control of drought can only be realized if current measures are capable of bring immediate effects and benefits. Therefore, the construction of well-planned and designed water conservancy system based on each village's natural and social conditions are the priority for current hazard prevention. Generally, the exploitation of subterranean river should be considered as the first choice to stabilize the water supply for remote villages. Meanwhile, the construction and improvement of micro water conservancy facilities, such as small water tank, small pond and so on, can effectively support the water providence during droughts as well.

西藏青稞主要种植区干旱时空分布及致灾危险性评估

西藏青稞主要种植区是西藏地区主要粮食作物的产区,在气候变化和人类活动加剧的背景下,该区的农业深受干旱影响。根据《气象干旱等级》(GB/T 20481-2017)国家标准,计算西藏青稞主要种植区25个气象站点全生育期的逐日气象干旱综合指数(MCI),统计1981—2020年各站点的气象干旱过程,并进一步分析了西藏青稞主要种植区各生育期气象干旱的时空变化特征及致灾危险性等级分布。结果表明:(1)近40 a来西藏青稞主要种植区呈现气温显著上升(P<0.01),降水不显著增多的特点;季节性的气温和降水变化趋势差异明显。(2)干旱覆盖范围和持续日数总体呈现不同程度的下降趋势,干旱强度(除播种-分蘖期外)均有所增强;分蘖-抽穗期干旱最严重,1981—1990年干旱最重,2001—2010年干旱最轻。(3)各生育期干旱发生频率的高值区主要集中在日喀则市东部、拉萨市南部、昌都市西南部和山南市中部地区,低值区位于林芝市中部。(4)经验正交函数法(EOF)分析的各生育期主要模态有中部与中西部相反、全区一致、西南与东北相反。(5)各生育期干旱致灾危险性等级总体呈现西高东低的分布特征,其中,分蘖-抽穗期致灾危险性总体较高,抽穗-成熟期次之,播种-分蘖期最低。

保定市干旱灾害危险性评估

历年来保定市旱灾发生频率高、灾情重、范围广,在对保定市近年来干旱灾害分析的基础上,结合1980—2020年降水量数据,分析确定保定市的旱情等级,并利用1980—2020年保定市各行政区水资源总量数据,获得干旱灾害综合危险性指数。根据干旱灾害危险性等级划分标准,将保定市干旱灾害危险性进行等级划分,并从时空尺度上对保定市干旱灾害危险性进行分析。结果表明:保定市干旱灾害危险性区域分布规律较明显,高及中高风险区主要分布在水资源短缺的平原区,中低及低风险区主要分布在水资源充沛的山区;保定市干旱灾害危险性与干旱指数的空间分布规律基本一致。本次分析结果可为保定市干旱灾害的风险评估、风险管理及防灾减灾预案编制等提供重要依据。

利用MCI指数和Gumbel-Copula函数评估新疆干旱灾害危险性

干旱是新疆地区的主要气象灾害之一,其危险性评估对该地区防旱抗旱工作具有重要的指导意义。该研究基于新疆106个气象站1961—2019年逐日观测数据计算气象干旱综合指数(meteorological drought composite index,MCI),根据游程理论识别干旱过程,采用Gumbel-Copula函数建立干旱历时和烈度的联合分布并计算干旱重现期;选取干旱频次、历时和烈度作为危险性评估因子,采用随机森林算法计算权重并得到新疆干旱灾害危险性结果。结果表明:1961—2019年间新疆共出现了47次干旱过程,其中短历时、低烈度(干旱烈度≤50且干旱历时≤60 d)干旱过程多发,长历时、高烈度(干旱烈度≥200且干旱历时≥180 d)重现期较长。长历时和高烈度倾向于同时发生,但随着干旱历时和烈度的增加,长历时和高烈度干旱过程发生概率较低。新疆地区干旱灾害危险性空间分布上呈现“中间低,南北高”的特点,天山山脉地区干旱重现期长于其他地区,危险性低,天山北坡的干旱过程发生频率低、持续时间短、强度小,危险性较低;南疆大部分地区的干旱过程发生频率较低,但持续时间长、强度大、危险性较高。而北疆大部分地区干旱发生频率高,但持续时间不长,强度不高,但塔城地区西北部和阿勒泰地区危险性较高。因此南北地区对干旱灾害应对应有所不同。在全球变暖背景下,新疆各地区用水矛盾进一步加剧,各地应结合实际,统筹提高水资源高效配置合理利用水平,合理开发水资源,降低干旱灾害的风险。

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。

1956～2000年中国地表水资源状况:变化特征、成因及影响

系统搜集了中国590个雨量站和383个水文站1956～2000年长序列月降水量与月径流量资料，及1978～2000年全国各省、自治区的旱涝受灾与成灾面积、灌区面积、已建水库库容等数据资料，全面分析了地表径流时空演变特征以及农业旱涝灾害的时空分布特征，并分析了其原因及可能影响，研究结果表明，中国北方降水减少，其中山东和黄河中游地区的降水量减小最显著。另外，冬季降水增加明显，而春秋季降水减少明显，极易导致春秋旱灾；北方地区降水减少是造成地表径流量减小的主要原因，农业灌溉进一步加剧地表径流量减小，南方径流量的增加主要是由降水量增加引起的；降水时空分布不均匀造成水资源分布不均，进而造成大部分地区农业受旱涝灾害面积呈增加趋势，其中旱灾受灾面积远大于水灾的受灾面积；农村水利基础设施（灌区、水库等）能提高地区的抗旱能力，但是对洪涝灾害的影响没有旱灾那么明显。节水灌溉技术的推广应用是北方地区在水资源短缺的前提下保证农业生产稳定的重要措施。

1961～2010年中国农业洪旱灾害时空特征、成因及影响

搜集并分析了全国29个省份（不包括港、澳、台地区）1961-2010年农业洪旱灾害数据，深入探讨了中国洪旱灾害时空变异规律及其对粮食产量的影响。研究结果表明：中国大部分省份农业洪涝、干旱灾害具有明显的突变和趋势特征。中国中部、中西部及西北部洪涝灾害呈显著上升趋势；西北、东北地区及云南等地区干旱灾害呈显著上升趋势。除华北和东北地区外，洪涝灾害对农业的威胁日益严峻，而干旱灾害则无显著变化。这对中国粮食安全形成了重大挑战，尤其是西部以及北部地区粮食灾损率和灾损量显著上升。降水时空分布发生变化以及人类活动共同影响了中国农业洪涝、干旱时空变化特征。

中国东北春玉米区干旱时空分布特征及其对产量的影响

为了研究东北地区春玉米不同生育阶段干旱时空分布规律及其对产量的影响,基于研究区域1961—2012年69个气象站点逐日气象资料和春玉米生育时期及产量资料,采用Penman-Monteit法计算潜在蒸散量,在此基础上利用农业干旱指标标准化降水蒸散指数(SPEIPM)划分干旱等级-最后利用干旱等级权重及发生概率评分等级计算每个站点的干旱危险指数(DHI);利用Mann-Kendall检验法计算5个生育阶段的SPEI变化趋势,利用回归分析进行SPEI与玉米气候产量的关系分析。结果表明,吉林省西部和辽宁省西部在玉米生长季内始终为干旱高风险区,吉林省东部和辽宁省东部则为干旱低风险区,黑龙江省东部干旱风险随生育进程增大;近52 a玉米苗期干旱强度和范围有减小趋势,而生育后期在增加;1991—2012年辽宁省西部玉米气候产量与SPEIPM3-7(5—7月份的SPEIPM)以及吉林省西部、吉林省东部和松嫩平原气候产量与SPEIPM3-8(6—8月份的SPEIPM)的关系达极显著(P<0.01),吉林省中部气候产量与SPEIPM3-8(6—8月份的SPEIPM)关系达显著水平(P<0.05)。春旱严重地区如松嫩平原、吉林省西部、辽宁省西部和南部的干旱强度和范围正在减小,而东北干旱程度在玉米生育后期整体呈增强趋势,其中东部最明显。在降水充沛的吉林省东部,气候产量与干旱指数的回归方程对称轴在0附近,表明正常降水情况下即能保证高产和稳产。降水较少的地区如辽宁省西部和吉林省西部等地,回归方程对称轴在1附近,提高玉米产量需增加灌溉和提高水分利用效率。

SRES B2情景下西南地区干旱致灾危险性时空格局预估

气候变化和自然灾害已经、正在、未来也将继续深刻地影响人类社会。预估未来极端天气事件致灾危险性对于评估气候变化对人类社会和自然系统的潜在风险具有极其重要的意义。本研究采用PRECIS模式模拟的气候情景数据,综合考虑降水和蒸发两个因素,选取地表湿润指数为指标,对SRES B2情景下未来(2011-2100)西南地区县域尺度干旱致灾危险性时空格局进行预估。结果表明:相对于现阶段(1981-2010),未来西南地区年均潜在蒸散量呈现逐渐增加的趋势,而地表湿润指数则总体上呈减小之势;未来各时段西南地区旱灾危险性明显增大,其中近期(2011-2040)是最严重的时段;在近期时段,西南地区干旱致灾危险性处于5级的县域个数和面积百分比分别为236个和50.3%,是现阶段的4.82倍和6.24倍。

基于EPIC模型的中国典型小麦干旱致灾风险评价

运用EPIC(Environmental Policy Integrated Climate)农作物生长模型模拟了1966—2005年中国典型小麦生长过程,构建了基于水分胁迫的小麦干旱致灾强度指数,对中国小麦干旱致灾强度和风险的时空分布规律进行了定量评价分析。结果表明:小麦干旱致灾强度呈现出从西北干旱区向东南湿润区递减的趋势,且春小麦分布区旱灾致灾强度高于冬小麦分布区;中国农牧交错带是小麦干旱致灾强度较强且波动较大的区域,也是小麦干旱致灾风险较高的区域;1966-2005年春小麦区干旱致灾强度呈现下降趋势,而冬小麦区呈现普遍上升趋势,其中北部和黄淮冬麦上升趋势最为明显。

农业干旱风险评估研究综述

对农业干旱风险致险性、脆弱性及损失模型等方面进行了深入系统的回顾与评述,阐述了农业干旱风险研究的前沿领域和学术问题,展望了农业干旱风险未来的发展趋势:农业干旱致险性评估的关键是构建合适的干旱指标,目前干旱评估指标很多,大致可分为水分变异程度指标、干旱发展过程指标和干旱空间差异指标三类,但多数指标对农业干旱成灾过程反映不足,在评估方法上对农业干旱灾害机理认识不深入,成为了农业致险性评估的瓶颈;农业干旱脆弱性通常决定着农业干旱风险的高低,其中,灌溉能力、技术、资金等是影响农业脆弱性高低的重要因子,而定量刻画农业干旱脆弱性对政策、技术、保险等人文因素的响应是当前研究的薄弱环节;农业干旱风险损失评估模型较多,但由于受区域、人为等因素影响,多数模型普适性较差。因此,未来农业干旱风险评估需要深入认识农业干旱影响的机理和过程,突出研究农业干旱脆弱性对人文因素变化的响应,并通过区间合作来进一步改进风险损失模型。

“4·20”芦山地震后的四川地质灾害形势预测与防治对策

"4·20"芦山地震诱发了大量次生地质灾害。针对此次地震引发的次生地质灾害,通过分析地形地貌、地质条件、地震活动和极端干湿气候对泥石流发育的影响,建立地质灾害易发性评价指标,利用GIS空间分析技术对四川震后地质灾害易发性进行了快速定量评价。结果显示,2013年四川省地质灾害高、中、低易发区面积分别为9.97×104 km2、6.67×104 km2、1.41×104 km2。其中高易发区主要集中于芦山地震影响区、汶川地震影响区、川东南和川南干旱区。在此基础上提出了防控建议。