1983-2013年西藏自治区气象灾害时空分布特征与变化趋势

西藏自治区地处青藏高原这一独特的孕灾环境中,气象灾害的频发对当地农牧业、生态环境等敏感领域的影响尤为显著。通过收集西藏自治区1983-2013年气象灾害事件,分析了干旱、雪灾、霜冻、冰雹和洪涝五种灾害的年际、月际、空间分布特征。结果表明：在时间分布上,研究区五种气象灾害在1983-1995年发生总频次呈增涨趋势,1995年后趋于稳定,其中干旱多发生在3-6月,雪灾全年均有发生,霜冻多发生在4月、5月和8月,冰雹和暴雨洪涝灾害季节性强,主要发生在6-9月;在空间分布上,气象灾害高发区分布于西藏自治区南部,其中,干旱多发区分布于日喀则市中东部和山南市北部,雪灾多发区分布于那曲、阿里以及西藏自治区南部边缘地区,霜冻多发区分布于西藏自治区东、南部少数地区,冰雹频发区多呈带状且分布于雅鲁藏布江流域,暴雨洪涝多发区分布于西藏自治区中、东部河谷地带。基于历史气象灾害事件,开展西藏自治区气象灾害的时空分布特征及趋势研究,其结果对农业气象灾害预测预报,区域农业防灾减灾等具有重要的意义。     

Risk analysis and influencing factors of drought and flood disasters in China

The risk analysis of flood and drought disasters and the study of their influencing factors enhance our understanding of the temporal and spatial variation law of disasters and help identify the main factors affecting disasters. This paper uses the provincial administrative region of China as the research area. The proportion of the disaster area represents the degree of the disaster. The statistical distribution of the proportions was optimized from 10 alternative distributions based on a KS test, and the disaster risk was analyzed. Thirty-five indicators were selected from nature, agriculture and the social economy as alternative factors. The main factors affecting flood and drought disasters were selected by Pearson, Spearman and Kendall correlation coefficient test. The results demonstrated that the distribution of floods and drought is right-skewed, and the gamma distribution is the best statistical distribution for fitting disasters. In terms of time, the risk of flood and drought disasters in all regions showed a downward trend. Economic development and the enhancement of the ability to resist disasters were the main reasons for the change in disasters. Spatially, the areas with high drought risk were mainly distributed in Northeast and North China, and the areas with high flood risk were mainly distributed in the south, especially in Hubei, Hunan, Jiangxi and Anhui. The distribution of floods and drought disasters was consistent with the distribution characteristics of precipitation and water resources in China. Among the natural factors, precipitation was the main factor causing changes in floods and drought disasters. Among the agricultural and socioeconomic factors, the indicators reflecting the disaster resistance ability and regional economic development level were closely related to flood and drought disasters. The research results have reference significance for disaster classification, disaster formation mechanisms and flood and drought resistance.

     

中国北方地区几种农业气象灾害指标研究综述

针对我国北方地区常见的几种农业气象灾害:干旱、低温冷害、霜冻和干热风,对其各类指标进行了归纳和描述。干旱指标是从监测、防御、经济损失评估、社会经济发展水平和科技进步5个方面来分别描述;冷害指标就目前常见的几类进行了简要介绍;霜冻指标多针对不同作物给出具体判别标准;干热风指标从气象、判别、危害和防御4个方面进行了描述。总结了不同指标的优缺点,同时也对这些灾害指标目前存在的问题和今后改进的方向提出了看法,为形成北方地区农业气象灾害指标体系奠定基础,同时为今后该地区各类农业气象灾害的监测、评估及防灾减灾工作提供参考与支撑。     

Spatial and temporal changes of agro-meteorological disasters affecting maize production in China since 1990

Agro-meteorological (AM) disasters have been reported to be more frequent with climate change. In this study, the spatial and temporal changes in the frequency of major AM disasters affecting maize production are investigated by analyzing observed records at 224 national AM stations in China from 1991 to 2009. To investigate the temporal changes of the disasters with climate warming, the whole study period was separated into a cool period (1991–2000) and a warmer one (2000–2009). We found drought was the most common disaster with a frequency of 49 %, followed by chilling injures (19.46 %). The frequency of disasters affecting maize increased significantly during the reproductive growth period than the vegetative growth period. Spatial patterns of major disaster frequency were characterized by region-specific, with more cold stress in northeastern China, drought in northern and western China, and rainstorms in southwestern China. Our study highlighted that the frequency and scope both increased significantly, implying a potential increasing risk for maize production. It is critical and important for local farmers and governors to take reasonable and timely adaptation measures based on the latest disasters’ features to mitigate the potential yield loss from AM disasters in order to ensure food security in China.     

Assessment on agricultural drought vulnerability in the Yellow River basin based on a fuzzy clustering iterative model

Drought is one of the major natural disasters occurring in China and causes severe impacts on agricultural production and food security. Therefore, agricultural drought vulnerability assessment has an important significance for reducing regional agricultural drought losses and drought disaster risks. In view of agricultural drought vulnerability assessment with the characteristics of multiple factors and uncertainty, we applied the fuzzy comprehensive evaluation framework to agricultural drought vulnerability model. The agricultural drought vulnerability assessment model was constructed based on the multi-layer and multi-index fuzzy clustering iterative method, which can better reveal the drought vulnerability (including sensitivity and adaptation capacity). Furthermore, the cycle iterative algorithm was used to obtain the optimal index weight vector of a given accuracy by setting the objective function. It provides a new approach to weight determination of agricultural drought vulnerability assessment. In this study, agricultural drought vulnerability of 65 cities (as well as leagues and states) in the Yellow River basin was investigated using a fuzzy clustering iterative model and visualized by using GIS technique. The results showed clear differences and regularities among the spatial distribution of agricultural drought vulnerability of different regions. A large number of the regions in the basin consisted of those exhibiting high to very high vulnerability and were mainly distributed throughout Qinghai, Gansu, northern Shaanxi, and southern Shanxi, accounting for 46 % of the total assessment units. However, the regions exhibiting very high vulnerability were not significantly affected by droughts. Most of the regions exhibiting moderate vulnerability (21.5 % of the assessment units) were mainly concentrated among agricultural irrigation areas, where agriculture is highly sensitive to droughts, and drought occurrence in these regions will likely cause heavy losses in the future. The regions exhibiting slight to low vulnerability were relatively concentrated, accounting for 32.3 % of the assessment units, and were mainly distributed in the plains of the lower reaches of the Yellow River, where the economy was rather well developed and the agricultural production conditions were relatively stronger.     

Assessment of tectonic-controlled rock fall processes threatening the ancient Appia route at the Aurunci Mountain pass (central Italy)

The Ningxia Hui Autonomous Region of China (Ningxia), one of main agriculture areas in northwest China, has been severely affected by drought. Based on observed meteorological data, outputs of 20 global climate models and drought disaster data, future climate change and relevant drought hazard in the twenty-first century were projected in Ningxia, with the scenarios of RCP2.6 and RCP4.5; the risks of people, crop, and agriculture economy to drought disasters are quantitatively assessed, with the application of physical vulnerability curve models, probability distribution functions and Monte Carlo simulation method. It is found that the climate in Ningxia is likely to have a warming and wetting tendency in the twenty-first century. The extent of drought hazard is likely to increase. The increase rate is greater under RCP4.5 than that under RCP2.6. In general, the risks of population, crop, and agriculture to drought disasters are likely to increase in Ningxia in the twenty-first century. The magnitude of increase is likely to reach the greatest in the immediate term (2016–2035), followed by the increase in the medium term (2046–2065), and the long term (2081–2100). In comparison with RCP2.6, the drought disaster risks under the scenario of RCP4.5 are likely to increase further in three periods of the twenty-first century. The findings of this work have potential to provide data support for drought disaster risk management and support risk-based decision-making.

     

淮河流域旱涝灾害致灾气候阈值

采用淮河流域内1959—2008年110个气象站的逐日降水资料,结合流域1978—2008年农作物旱涝灾害受灾面积数据,基于降水致灾因子与农作物承灾体受损程度等研究,提出旱、涝致灾气候阈值概念,在此基础上分析旱涝灾害发生的时空特征,确定淮河流域合理的旱涝致灾气候阈值区间并建立致灾气候阈值与农作物受灾面积之间的定量关系。结果表明:① 致灾气候阈值可通过计算发生旱涝事件时间段累积降水量除以1959—2008年相应时段累积降水量的平均值来定义,得到的旱、涝致灾气候阈值在不同尺度下对旱、涝灾害事件均有较好地稳定反映,可满足研究区旱、涝事件分析需求;② 洪涝致灾气候阈值与农作物受灾面积存在一致的变化趋势,而干旱致灾气候阈值与农作物受灾面积相关系数高达0.96,构建了基于干旱致灾气候阈值的农作物受灾面积预测模型。     

中国西北地区干旱气象灾害监测预警与减灾技术研究进展及其展望

干旱灾害是制约中国西北地区社会经济发展、农业生产和生态文明建设的重要自然灾害,而且随着气候变暖西北地区极端干旱事件发生频率和强度均呈增加趋势,影响不断加重。"中国西北干旱气象灾害监测预警及减灾技术研究"成果是在数十个国家级科研项目的支持下,经过过去20年的理论研究和应用技术开发所取得的一系列创新性成果。该成果对西北干旱形成机理及重大干旱事件发生、发展的规律取得了新认识,尤其是发现了形成西北干旱环流模态的4种主要物理途径;研制了西北干旱预测的新指标、干旱监测的新指数及监测农田蒸散的新设备,明显提高了干旱监测准确性和针对性;提出了山地云物理气象学新理论,研发了水源涵养型国家重点生态功能区——祁连山空中云水资源开发利用技术;发现了干旱半干旱区陆面水分输送和循环的新规律,揭示了绿洲自我维持的物理机制;认识了干旱气候变化对农业生态系统影响的新特征,建立了旱作农业对干旱灾害的响应关系;开发了旱区覆膜保墒、集雨补灌、垄沟栽培、适宜播期等应对气候变化的减灾技术,为西北实施种植制度、农业布局及结构调整和农业气候资源高效利用提供了科学方案。该成果的完成提升了中国干旱防灾减灾技术水平,培养了中国干旱气象科技队伍,推进了西北地区干旱气象业务服务能力,对西北地区社会经济发展、农业现代化和生态文明建设等方面起到了重要的促进作用。在此基础上,展望了西北地区干旱气象科学研究中迫切需要、有可能突破的主要领域。     

Risk assessment to China’s agricultural drought disaster in county unit

China faces drought disaster risk under the changing climate. Risk analysis is a suitable approach in order to design ex-ante measure able to anticipate effects of drought on agricultural production. In this article, with the support of historic drought disaster data from 583 agro-meteorological observations (1991–2009), a risk analysis method based on information diffusion theory was applied to create a new drought risk analysis model, and the risk of China’s agriculture drought disaster was evaluated on higher spatial resolution of county unit. The results show that in more than three hundred counties of China, risk probability was biyearly or annually when Drought Affected Index (DAI) was over 5%. When DAI was up to 40%, more than one hundred counties were prone to drought disaster annually or once every 5 years. This showed that the impact of drought disaster on China’s agriculture, whether in frequency or intensity, was large. With the different level of DAI, China’s agricultural drought risk pattern showed variable pattern characteristics. When DAI was low, the distribution of county agricultural drought risk in China presented the East–West pattern of differentiation, and high risk mainly lied in the eastern, low risk mainly in the western. On the other hand, when DAI was high, the distribution of county risk appeared a pattern of high in center, and the north areas higher than the south, increased gradually from southwest to northeast. Drought risk presents a clear zonal differentiation that may be result from stepped topography, different precipitation and hazard-affected bodies. Spread of high value area of drought risk in northern may be related to the southeast monsoon and ecological degradation in northern Ecotone.     

Risk assessment of rainstorm and flood disasters in China between 2004 and 2009 based on gray fixed weight cluster analysis

Rainstorm and flood disasters frequently occur in China, causing heavy losses for people’s lives and property and reducing the capability of sustainable development of the national and local economy. In this study, the risks of the rainstorm and flood disasters are assessed for the Chinese mainland, excluding Hong Kong, Macao, and Taiwan and also employ the historical data of seven indicators, including the affected area of crops, the affected population, the direct economic loss, and etc., from 2004 to 2009. Based on the large 1,302 historical sample data, the impact of rainstorm and flood disasters were analyzed using the methodology of gray fixed weight cluster analysis according to disaster losses, which were divided into the three gray classes of high, medium, and low. The regional differences of the risk assessment of the rainstorm and flood disasters are discussed, and the dynamical risk zoning map is conducted. The results show a consistent conclusion with the actual losses of rainstorm and flood disasters over each administrative district, which can provide more scientific evidence for the relevant departments of disaster prevention and mitigation.     

Global snowmelt flood disasters and their impact from 1900 to 2020北大核心CSCD

Under the background of climate warming, the occurrence time, frequency, intensity, and impact of snowmelt flood disasters have changed significantly. Thus, establishing a global snowmelt flood disaster database is particularly important for disaster risk management. With the help of a web crawler, and based on multiple data sources such as natural disaster databases, documents, books, government agency websites, and news media, this study collected relevant information of snowmelt floods and mixed floods and established standards for identifying snowmelt flood events and their disaster impacts based on data from the different sources. Following the screening, sorting, fusion, and integration of snowmelt flood events, a global snowmelt flood disaster dataset containing 579 pieces of data with strong pertinence and reliability was constructed. The temporal and spatial distribution characteristics of global snowmelt flood disasters from 1900 to 2020 were preliminarily analyzed. The results showed that the snowmelt floods were mainly distributed between 30° N and 60° N, with more mixed floods south of 50° N and more snowmelt floods north of 50° N. Spring was the period of highest incidence of snowmelt flood disasters, followed by winter, summer, and autumn, respectively. The snowmelt floods that occurred in spring, autumn, and winter were mainly at 40°~50° N, and the snowmelt floods that occurred in summer were mainly at 30°~40° N. Compared with the snowmelt floods, the mixed floods were more frequent and more destructive, and their frequency increased with climate warming. The results provide a scientific basis for risk prevention and loss assessment of global snowmelt flood disasters. © 2022 Science Press (China).     

基于文献记录的黑河流域历史时期旱涝特征分析

流域的旱涝灾害特征及其变化规律是流域水资源演变研究的重要内容。利用历史文献资料重建了西北内陆河黑河流域公元0-1949年的旱涝灾害等级序列,结合滑动平均、小波变换处理等方法,探讨了流域历史时期旱涝等级的频数特征、旱涝变化的周期特征及其与气候冷暖和人类活动之间的关系。对公元1000年以后的旱涝灾害规律进行分析,结果表明：流域存在5个旱灾高发阶段（1230-1270年、1430-1530年、1640-1760年、1860-1890年、1900-1940年）,3个涝灾高发期（1650-1690年、1730-1790年、1830-1910年）,并呈现出旱涝灾害频发的态势;1000-1949年期间,流域旱涝灾害存在4个准周期变化,对比发现这与太阳黑子活动等环境变化周期有紧密的联系;1580年以前,气候冷暖是影响旱涝灾害发生的主要因子,但16世纪以后,旱涝灾害交替频发,很可能是人类活动加剧了该现象。所以,定量辨析自然因素和人类活动对流域旱涝灾害的影响将是未来研究的重点方向。     

洪涝灾害风险评估与分区研究进展

在全球气候变化和城市化进程不断加快的背景下,城市洪涝灾害频发,造成严重的经济损失和人员伤亡问题。对近年来中国典型城市洪涝灾害进行系统整理介绍,说明洪涝灾害带来的人员伤亡和经济损失巨大。风险评估作为一种非工程性防洪措施,是城市洪涝风险管理的首要工作,精确、高效的把握洪灾过程等特征可以为防灾减灾工作提供科学依据。对城市洪涝风险评估与分区的概念和内容进行系统梳理,常用的风险评估方法有数理统计法、不确定性分析法、遥感影像评估法、指标体系评估法、情景模拟评估法；风险分区常用方法有阈值法、经验公式法和物理机制法。论述了城市洪涝风险评估与分区常用方法的应用范围、优缺点及其发展前景。     

Basinwide disaster loss assessments under extreme climate scenarios: a case study of the Kaoping River basin

This study examined the Kaoping River basin, Taiwan, an area severely destroyed by Typhoon Morakot in 2009. Dynamically downscaled data were applied to simulate extreme typhoon precipitation events for facilitating future preparation efforts (2075–2099) under climate change conditions. Models were used to simulate possible impacts in upstream and downstream areas for basinwide disaster loss assessment purposes. The Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability and FLO-2D models were applied to simulate slope-land disaster impacts and sediment volume in the upstream area. The sediment delivery ratio was used to calculate the valid sediment amount delivered downstream and the riverbed uplift altitude. SOBEK was used to build a flood impact model for the Kaoping River basin, and the model was used to simulate potential flooding caused by future extreme typhoon events. The Taiwan Typhoon Loss Assessment System established by the National Science and Technology Center for Disaster Reduction was used to evaluate the potential loss associated with extreme events. The property loss calculation included 32 land-use categories, including agriculture, forestry, fishery, and animal husbandry losses; industrial and commercial service losses; public building losses; and traffic and hydraulic facility losses. One of the Kaoping River basin townships, Daliao District, had the highest flood depth increase ratio (12.6%), and the losses were 1.5 times the original situation. This was much worse than were the losses suffered during Typhoon Morakot. These results also show that sediment delivered from the upstream areas had a significant influence on the downstream areas. This is a critical issue for future flood mitigation under climate change conditions.     

Exploring the characteristics of major natural disasters in China and their impacts during the past decades

The exploration of the characteristics of natural disasters (NDs) and their impacts have important implications for guiding disaster prevention and mitigation. This paper discussed the characteristics of the major NDs that occurred in mainland China between 1980 and 2011 based on the number of disasters and fatalities, the affected population, and the resulting economic damages. We further examined the relationships between the level of social/economic development and the disaster losses. At last, we also explored the trend variations in disaster losses and losses expressed as a percentage of gross domestic product (losses/GDP) for 31 provinces in China over the period from 1990 to 2011. The results show that over the past three decades, the number of major NDs and the number of affected population appear to exhibit a detectable increasing trend, while the direct economic losses and the deaths show a slight increase trend. The correlations between the number of disasters and the economic losses as well as deaths and between the economic losses and socioeconomic status were not significant (p > 0.05), which indicates that the growth in the number of disasters do not result in a significant increase in the disaster losses. Further investigations demonstrate that as economies develop, there are fewer losses/GDP in China over the past two decades. The per capita accumulative losses and losses/GDP in the western and central regions were higher than that in the eastern parts of China. There are significant regional differences in the trends in disaster losses and losses/GDP in China. Statistics also indicate that more than 70 % provinces in underdeveloped regions show an increasing trend in disaster losses, whereas exceeding 90 % provinces exhibit a decreasing trend in their losses/GDP. These results suggest that the economic development may have played an important role in improving the capacity of disaster prevention and reduction.     

Geospatial analysis of Maize yield vulnerability to climate change in Nigeria

The fifth assessment report (AR5) predicted that land temperatures would rise faster over Africa than other global averages while changes in rainfall are uncertain across Sub-Saharan Africa. These portend water availability challenges with direct impacts on agricultural production. Existing studies on yield vulnerability in Nigeria are mostly at a national scale, which is not adequate for local decision making. This study provides a spatially explicit model of Maize yield vulnerabilities across the growing areas (GA). Thereby, turning available data into actionable information to support development actions. Yield vulnerability index was constructed as a relationship among exposure, yield sensitivity and adaptive capacity. Exposure was computed as the ratio between long and short-term climatic factors. Yield sensitivities were expressed as the ratio between expected and actual yield. Adaptive capacity was captured using a combination of socio-economic proxies. The result shows that Maize yields were vulnerable to climate variability across most of the GAs. Exposure values indicate a very high level of climate variability with the northern region more exposed. Yield sensitivity ranges between ranges 0.47 and 0.95, and highest along the northern extremes, moderate sensitivities were observed across large tracts of the north-west, northeast, south-east and south–south geopolitical regions. Adaptive capacity is highly variable ranging between 0.27 and 1. Yield vulnerability ranges between 0.46 and 1.51. The general assumption of a north–south divide for yield vulnerability was invalidated. Vulnerability is more disparate beyond latitudinal differences. The model presented, creates a framework to support targeted response, and opportunity for building resilience to climate change impact for crop yield.

     

Agricultural drought risk analysis based on three main crops in prefecture-level cities in the monsoon region of east China

Drought, a frequent environmental disaster in the monsoon region of east China, significantly affects the agricultural economy. In recent years, researchers have emphasised drought risk management. This paper presents a preliminary method to analyse the risk of agricultural drought with regard to the loss of three main crops in individual prefecture-level cities in the monsoon region of east China. In this study, the agricultural drought risk is assessed by developing the index of consecutive rainless days and establishing loss rate curves based on the historical drought data from 1995 to 2008. The results show that the North China is seriously affected by drought hazard. Northeast China is the most sensitive to drought due to its large sown crop areas and weak irrigation. Approximately 11 % of the cities are in the extreme risk category; this category includes 26 % of the cultivated land area and 11 % of the total crop yields in the region. Twenty-three per cent of the cities, accounting for 28.5 % of the total cultivated land area and 26.4 % of the crop yields of the study area, are in high-risk areas, and 77 % of the cities with high and extreme risk levels are distributed in North and Northeast China. Moreover, 64 % of the cities in the monsoon region of East China are in moderate- and low-risk levels. These cities are primarily located south of the Yangtze River. In conclusion, minimising the risk of agricultural drought must be emphasised in northern China because of the high level of risk.     

植被状况指数的改进及在西北干旱监测中的应用

干旱是全球分布最广、发生频率最高、持续时间最长、影响范围最大、造成的经济损失最为严重的一种自然灾害，干旱也是所有自然灾害中影响因子最为复杂、人类了解最少、监测最为困难的一种自然灾害，干旱监测是世界性的难题。干旱可以发生在任何气候带上，但干旱、半干旱地区是全球干旱灾害发生最频繁的地区。干旱发生特征和规律因地区的不同会有很大的差异，不同地区对干旱监测方法不同。目前，世界各国干旱监测主要利用基于气象、水文、农业和卫星遥感等观测资料建立的各种干旱指数开展，已经有150多种干旱指数。植被状况指数VCI是应用最为广泛的一种卫星监测干旱的指数，研究和业务应用结果表明，VCI对全球各地的干旱均有较好的反映，已经应用在美国国家大气海洋局（NOAA）日常干旱监测业务中，中国国家卫星气象中心干旱卫星遥感监测服务产品也是以VCI为基础。 我国干旱半干旱地区主要分布在新疆、甘肃、青海、陕西、宁夏以及内蒙古自治区的中西部，这里降水少且不稳定，降水变率大，是中国干旱发生频率最高的地区。干旱严重制约着当地经济发展和人类生活质量的提高，使本身非常脆弱的生态环境趋于恶化。为了了解条件植被指数VCI对西北地区不同气候区干旱的监测能力，以上述6省（区）为研究区，利用1982—2003年22年NDVI数据，计算了研究区域22年来逐月的VCI，对比分析了不同气候区VCI与降水距平的关系。结果表明，VCI在空间和时间上较好地反映了西北大部分气候干旱发生、发展和空间分布，是干旱监测的较好指标，但在干旱和极端干旱地区，VCI经常出现异常偏高现象，不能反映干旱气候区常年干旱的基本特点。通过对西北不同生态系统之间NDVI特点和各生态系统间NDVI年变化及其年际变化规律的研究，设计了VCI改进方案，提出了改进的条件植被指数RVCI。通过对22年来逐月RVCI与VCI的对比，RVCI客观地反映了干旱气候区常年干旱特点，较VCI有显著改进。      

The impact of climate change on coastal geological disasters in southeastern China

Climate change is presently a major global challenge. As the world??s largest developing country, China is particularly vulnerable to global warming, especially in the rapidly developing coastal regions in the southeast of the country. This paper provides an overview of the impacts of climate change on the nature of geological disasters in the coastal regions of southeastern China. In the context of climate change, processes with the potential for causing geological disasters in this region, including sea-level rise, land subsidence, storm surges, and slope failures, which already have a substantial occurrence history, are all aggravated. All these processes have their own characteristics and relevance to climate change. Sea-level rise together with land subsidence reduces the function of dikes and flood prevention infrastructure in the study areas and makes the region more vulnerable to typhoons, storm surges, floods, and astronomical tidal effects. Storm surges have caused great losses in the study areas and also have contributed to increases in rainstorms. As a result, numerous rainfall-induced slope failures, characterized by focused time concentration, high frequencies, strong ??burstiness,?? and substantial damage, occur in the study areas. To prevent and mitigate such disasters that are accelerated by climate change, and to reduce losses, a series of measures is proposed that may help to achieve sustainable development in coastal southeastern China.     

清代华北蝗灾时空分布及其与水旱灾害的关系*

利用《清史·灾赈志》中的历史灾害信息,重建清代(公元1644—1911年)华北蝗灾、水灾和旱灾的逐年频次序列,并以核密度估计法刻画3种灾害的空间分布,在此基础上展开时空对比分析。结果表明,蝗灾频次体现出一定的阶段性,1640s—1690s与1800s—1850s为2个多发时段,空间上主要分布于冀鲁豫三省的平原地区及山西的汾河谷地。年际尺度上蝗灾与旱灾呈显著正相关,干旱对于蝗灾的触发作用较为明显,但极端干旱会在一定程度上抑制蝗灾的规模;水灾对于当年灾区的蝗情有显著抑制,但灾后由涝转旱的气候背景可能诱发大面积蝗灾。在空间上,蝗灾与水旱灾害多发区有良好的对应,但水旱灾害的不同影响机制以及蝗虫的迁飞特性,使得3种灾害的极端多发区并不重合。蝗灾最集中的区域呈新月状分布于河北省西部,可能是蝗虫从孳生地(海河水系下游近水荒滩)迁飞于此,在太行山脉的阻隔之下形成。上述结论有助于推进对历史时期蝗灾发生机制的科学认识,以及指导气候变化背景之下的蝗灾防治工作。