Spatio-temporal Distribution of Three Kinds of Flash Droughts over Agricultural Land in China from 1983 to 2015   总被引：1，自引：0，他引：1  

Xiang Zhang  Nengcheng Chen  Chuli Hu  Xiaoting Peng 《地球科学进展》2018,33(10):1048-1057

At present, flash drought occurs globally and regionally and causes a lot of socio-economic loss in a very short time. Therefore, flash drought has been regarded as one of the hottest issues in drought research. However, flash drought monitoring, prediction and decision-making have encountered a lot of challenges due to its multiple driven factors and complex spatio-temporal process. Aiming at this problem, this paper focused on the agricultural land in China, and analyzed the spatio-temporal distribution of three kinds of flash droughts (i.e., precipitation-deficit, high-temperature, and composite flash droughts) from 1983 to 2015. We studied the occurrences, duration, spatial distribution, temporal distribution, and trend of all three kinds of flash droughts. Our results demonstrated that, the occurrences of flash drought agricultural land in China increased year by year, among which high-temperature flash drought increased dramatically; duration of flash droughts had different trends, but the variations were relatively smooth; Northeast China was identified as a vulnerable area of flash drought, indicating more flash drought events and longer duration; flash droughts in China were found to concentrate in spring (high-temperature drought) and summer seasons (precipitation-deficit drought). This study is helpful for building new flash drought monitoring method and system, and it is also valuable for flash drought preparedness on regional scale.  相似文献   

渤海湾盆地南堡凹陷南部深层沙一段优质碎屑岩储层特征及成因机制     

赵晓东  时阳  文雯  李亮  张博明  陈刚强 《地质论评》2021,67(3):67040015-67040015

利用岩芯、薄片、扫描电镜和分析化验等资料,对南堡凹陷南部深层古近系沙一段（沙河街组一段）优质碎屑岩储层特征进行了分析并揭示其成因机制。研究表明：①南堡凹陷南部沙一段优质碎屑岩储层属于低孔中渗储层,发育原生孔隙、次生孔隙和微裂缝;②沙一段沉积期处于强水动力沉积环境,辫状河三角洲前缘水下分流河道砂体普遍发育,岩性主要为中粗砂岩、含砾砂岩和砂砾岩等粗岩性,岩石类型主要为岩屑长石砂岩,石英、岩浆岩岩屑等刚性组分含量高,储层在强压实作用下仍保留了局部原生残余粒间孔,部分刚性组分强压条件下形成微裂缝;③沙一段与东三段为区域不整合接触,大气水的酸性流体在成岩初期以及烃源岩成熟之后产生的有机酸在成岩后期通过油源断裂和不整合面进入储层,造成长石、易溶碎屑等组分溶蚀形成次生孔隙,溶蚀作用不仅增加孔隙空间,而且扩大喉道宽度。结论认为：粗岩性和高刚性颗粒含量为原生孔隙的保存提供了物质基础;油源断层、不整合面为酸性流体的进入提供路径,促进了次生孔隙发育。  相似文献   

2017年辽宁省春夏季精细化气象干旱监测评估     

李晶  王婉昭  刘东明  黄岩  王莹  李荣平 《气象与环境学报》2019,35(3):100-105

基于辽宁省1114个国家级和区域级地面台站1961年以来的逐日气温和降水观测资料,利用距离平方反比法差值生成了1717个乡镇的气象资料序列,采用气象干旱综合监测指数统计分析了辽宁省2017年4—8月精细化到乡镇的气象干旱特征。结果表明:2017年辽宁省春夏季异常高温,同时降水异常偏少,致使气象干旱不断发展;干旱在4月5日前从中部和北部开始,4月末扩展到西部,5—6月再向东南发展,波及88%的乡镇,7月以来气象干旱程度开始减轻;气象干旱持续时间长的乡镇主要集中在中部和北部,最长持续时间153d;受气温偏高和降水过程的影响,中度以上气象干旱面积呈阶段性变化,且极端干旱的发展伴随高温时段。由于气象干旱不同于农业干旱,在开展为农服务时要因地制宜采取应对措施。  相似文献   

On the linkage between changes in cloud cover and precipitation extremes over Central India     

《Dynamics of Atmospheres and Oceans》2019

In this study, linkage between changing characteristics of precipitation extremes and cloud covers over Central India is explored during summer monsoon period using Satellite data (1998–2015). This is a first attempt to relate the changes in cloud cover to the changes in precipitation extremes. Non-rainy cirrus clouds are excluded from this study. Results show that heavy rainfall (≥ 60 mm/day) is associated with cold cloud tops (Tb≤220 K) while moderate rainfall (<60 mm/day and ≥20 mm) occurs mostly with middle clouds (Tb>220 K and ≤245 K). Low level clouds (Tb> 245 K) are responsible for light rainfall (<20 mm/day). Increases in top 20%, 10%, 5% and 1% heavy precipitation relate well with the increases in very deep convective, deep convective and convective cloud cover. Among these relations, increase in top 5% heavy precipitation relates best with increase in very deep convective cloud cover. Decrease in bottom 30% low precipitation relates with decrease in low level cloud cover. The results reported in this study fit into the framework of how weather extremes respond to climate change.  相似文献   

A comprehensive approach to drought and desertification in Northern Nigeria     

E. O. Oladipo 《Natural Hazards》1993,8(3):235-261

Drought has been a recurring feature of the arid and semi-arid areas of Nigeria. This paper reviews the extent, severity, and consequences of drought and desertification in Nigeria with particular emphasis on the northern part of the country. The haphazard manner in which these environmental hazards have been tackled is examined and a systematic approach for the formulation of a national policy is proposed. It is recommended that a detailed formulation and implementation of the proposed policy plan is imperative to mitigate the often devastating impacts of drought and desertification in the very prone areas of Nigeria. Until such is done, some areas of Nigeria will always be vulnerable to the whims of an inevitable climatic hazard of drought and associated land degradation in the form of desertification.  相似文献   

Some aspects of the spatial characteristics of drought in northern Nigeria     

E. Olukayode Oladipo 《Natural Hazards》1993,8(2):171-188

A long-period instrumental data set (1916–1987) of monthly growing season (April–October) rainfall totals for 34 stations in northern Nigeria is used to quantify drought following the method of H. N. Bhalme and D. A. Mooley. It is established that there are remarkable seasonal changes in the patterns of wetness and dryness over the region with no consistent recurrent spatial patterns in the moisture anomalies. In general, large-scale droughts only rarely cover the region as a whole, and there are distinct spatial differences dominating the wet and dry years. The length and severity of drought varies from sub-area to sub-area with very low interannual persistence. Although discrete areas do catch the brunt of drought on a year-by-year basis, drought occurrence in the region is largely sporadic in its spatial distribution. The rather noisy spatial characteristics of drought in northern Nigeria suggests that the seasonal shift in the Intertropical Discontinuity (ITD) is not likely the most important causal mechanism of drought in the region.  相似文献   

坝上高原近90年以来降水变化趋势   总被引：5，自引：0，他引：5  

哈斯 《中国沙漠》1994,(4)

根据史料和降水量资料，建立了自１９００年以来坝上高原旱涝级别（５级）序列，并对其进行了周期分析和趋势分析。结果表明，坝上高原降水变化具有明显的４２年和９年周期，自６０年代初以来该区进入干旱少雨阶段，并将持续到本世纪末下世纪初。此外，还有一些短周期，如４－５年和２－３年等，因而，在今后１０年内，干旱和少雨仍将持续，土地沙漠化也将继续发展。  相似文献   

Drought forecasting: Methodological topics from a systems perspective     

R. Krzysztofowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(4):267-279

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Drought monitoring     

J. A. Dracup 《Stochastic Hydrology and Hydraulics》1991,5(4):261-266

Drought detection, monitoring and indices are closely related to its definition. The specific definition chosen for a particular drought analysis will affect the procedures one uses in drought detection and monitoring. The traditional Palmer Drought Severity Index (PDSI) has been proven to be ineffective in regions of predominantly irrigated agriculture.The recently developed ALERT (Automated Local Evaluation in Real Time) system is proposed for use in monitoring the spatial and temporal variations of drought in real time. The ALERT system uses standardized instruments, radio frequencies, software and hardware. It was originally developed as a flash flood waming system by local flood control districts and the National Weather Service. However, now it has expanded to over 100 other uses in the areas of natural and man-made disaster detection and warning. The successful ALERT system indicates the need for the continued development of a national drought monitoring index that is applicable to a wide range of climate, hydrologic and water resource environments.  相似文献   

黄河流域旱涝年地面热量收支变化特征   总被引：1，自引：0，他引：1       下载免费PDF全文

朱超群  高国栋 《应用气象学报》1994,5(3):284-289

根据北京、郑州３年热量平衡观测资料，建立波文（Ｂｏｗｅｎ）比计算模式。并用此模式及辐射计算式等估计黄河流域８年５－８月地面月辐射收支、蒸发耗热、湍流热交换量和土壤热交换量，并比较分析旱涝年它们的差异以及随旱涝（用降水距平表示）的变化。   相似文献