2015—2019年辽宁省暴雨红色预警信号分布及其特征     

刘静  陈传雷  严俊  王瀛  才奎志  任川  韩梅  董巍 《气象与环境学报》2021,37(1):100-105

利用2015—2019年辽宁省发布的暴雨红色预警信号和1605个自动站的分钟级降水资料,统计暴雨红色预警信号和短时大暴雨年际变化和时空分布,分析暴雨红色预警信号的高分布区、易发时段。结果表明：2015—2017年辽宁省暴雨红色预警信号发布站数逐年递增,最大值出现在2017年,发布站数为147个;2015—2018年预警信号准确率提升,提前时间略减少,最低值为2018年,提前时间为19 min;2019年比2018年暴雨红色预警信号发布站数减少59个,提前时间增加29 min;暴雨红色预警信号的空间分布为东南部地区多、中部地区少;暴雨红色预警信号多在夜间发布;在辽宁省发布的50%以上的暴雨红色预警信号中,降水量达到预警发布标准的时间滞后于最大雨强出现时间90 min,最大雨强出现时间为暴雨红色预警信号发布的重要指标。为了达到防灾减灾的服务效果,发布暴雨红色预警信号时,应充分考虑最大雨强出现时间、发布时机、短时大暴雨高发区及地形的影响。  相似文献   

Basin modeling of the Late Miocene Zeit source rock in the Sudanese portion of Red Sea Basin: Implication for hydrocarbon generation and expulsion history     

《Marine and Petroleum Geology》2017

The Late Miocene Zeit Formation is exposed in the Red Sea Basin of Sudan and represents an important oil-source rock. In this study, five (5) exploratory wells along Red Sea Basin of Sudan are used to model the petroleum generation and expulsion history of the Zeit Formation. Burial/thermal models illustrate that the Red Sea is an extensional rift basin and initially developed during the Late Eocene to Oligocene. Heat flow models show that the present-day heat flow values in the area are between 60 and 109 mW/m². The variation in values of the heat flow can be linked to the raise in the geothermal gradient from margins of the basin towards offshore basin. The offshore basin is an axial area with thick burial depth, which is the principal heat flow source.The paleo-heat flow values of the basin are approximately from 95 to 260 mW/m², increased from Oligocene to Early Pliocene and then decreased exponentially prior to Late Pliocene. This high paleo-heat flow had a considerable effect on the source rock maturation and cooking of the organic matter. The maturity history models indicate that the Zeit Formation source rock passed the late oil-window and converted the oil generated to gas during the Late Miocene.The basin models also indicate that the petroleum was expelled from the Zeit source rock during the Late Miocene (>7 Ma) and it continues to present-day, with transformation ratio of more than 50%. Therefore, the Zeit Formation acts as an effective source rock where significant amounts of petroleum are expected to be generated in the Red Sea Basin.  相似文献   

Possible change in distribution of seaweed, Sargassum horneri, in northeast Asia under A2 scenario of global warming and consequent effect on some fish     

Teruhisa Komatsu  Masahiro Fukuda  Atsuko Mikami  Shizuha Mizuno  Attachai Kantachumpoo  Hideaki Tanoue  Michio Kawamiya 《Marine pollution bulletin》2014

Global warming effects on seaweed beds are already perceptible. Their geographical distributions greatly depend on water temperatures. To predict future geographical distributions of brown alga, Sargassum horneri, forming large beds in the northwestern Pacific, we referred to future monthly surface water temperatures at about 1.1° of longitude and 0.6° of latitude in February and August in 2050 and 2100 simulated by 12 organizations under an A2 scenario of global warming. The southern limit of S. horneri distribution is expected to keep moving northward such that it may broadly disappear from Honshu Island, the Chinese coast, and Korean Peninsula in 2100, when tropical Sargassum species such as Sargassum tenuifolium may not completely replace S. horneri. Thus, their forests in 2100 do not substitute those of S. horneri in 2000. Fishes using the beds and seaweed rafts consisting of S. horneri in East China Sea suffer these disappearances.  相似文献   

振荡流作用下波状底床上流场特性的实验研究   总被引：2，自引：0，他引：2       下载免费PDF全文

林缅  袁志达 《地球物理学报》2005,48(6):1466-1474

本文利用U型振荡水槽和粒子图像测速仪(PIV)对三种固定波状底床上的流场进行了测量,得到一系列不同振幅条件下的瞬时速度场和涡量场.通过分析不同时段涡强度以及涡轨迹,讨论了底床形状对其附近流场的影响.实验结果分析表明,底床形状决定着整个涡量场特征及涡轨迹,从而决定着泥沙的净输移.这些结果对于探讨浅海区沙波、沙纹和沙垄等波状底床上泥沙输移的力学机制是很有意义的.  相似文献   

溪洛渡电站软弱夹层剪切强度分析研究   总被引：2，自引：0，他引：2  

黄志全  陈尚星  李华晔  姜彤 《地质与勘探》2005,41(4):98-101

岩体的力学强度参数,特别是软弱夹层剪切强度参数c、f的优化选取进行分析对比,对大型和特大型水电工程来说是非常必要的.本文采用多种力学参数选取方法讨论了溪洛渡水电站软弱夹层剪切强度参数c、f的取值问题,使剪切强度的选取有了更大的可比性,提高了c、f值的选取精度和可靠性.  相似文献   

三种红层岩石常规三轴压缩下的强度与变形特性研究   总被引：7，自引：2，他引：5  

周应华  周德培  封志军 《工程地质学报》2005,13(4):477-480

利用MTS815Teststar程控伺服岩石力学试验系统研究了川东地区一红层边坡中的砂岩、粉砂岩和泥岩围压为03MPa的应力-应变全过程曲线,建立了峰值强度、峰值强度前弹性模量以及峰值强度后的弹性模量和围压的关系。将低围压下红层的全应力-应变曲线概化成5个阶段,分别为压密段、弹性段、屈服段、应变软化段和塑性流动阶段。试验结果得出,红层弹性模量随围压的增加而提高且变化明显,砂岩和粉砂岩在此围压内为脆性破坏,泥岩为塑性破坏的规律。  相似文献   

楔形体破坏模式下红层边坡岩体质量SMR法评价   总被引：4，自引：2，他引：2  

周应华  周德培  张辉  冯君 《工程地质学报》2005,13(1):89-93

简要介绍了边坡岩体质量分类的SMR法,将之应用于2个典型楔形体破坏模式下红层岩体高边坡稳定性宏观评价。 指出在评价过程中要注意对边坡起控制作用的优势结构面,并将其作为SMR法中结构面项评分的主要依据,这样得出的评分 值与边坡的实际情况才会比较相符。对地应力的影响进行了定性的分析,指出高地应力地区边坡SMR法应该慎用。  相似文献   

阿尔卑斯-喀尔巴阡上白垩统大洋红层特征与对比   总被引：2，自引：0，他引：2  

陈曦  王成善  李祥辉  胡修棉 《地学前缘》2005,12(2):61-68

在前人研究的基础上,从时代、岩性、古生物、沉积速率、沉积环境等方面对阿尔卑斯—喀尔巴阡地区的上白垩统大洋红层进行了详细对比,发现研究区内上白垩统大洋红层最早出露于Cenomanian期,最晚可延续至古近纪,且在Campanian期出露最为广泛,其岩性以灰岩、泥灰岩和含泥灰岩为主,生物化石以浮游有孔虫为主,沉积速率较低且在各地不尽相似,在CCD面上、下均可以出现,沉积环境一般是大陆边缘盆地、斜坡和大洋盆地等远洋、半远洋环境。通过比较分析,为进一步深入研究上白垩统大洋红层提供较为全面的基础资料。  相似文献   

白垩纪中期异常地质事件与全球变化   总被引：12，自引：1，他引：11  

胡修棉 《地学前缘》2005,12(2):222-230

白垩纪中期(125~90 Ma)是地质历史中一个极端温室时期,集中出现一系列异常事件。异常事件是地球系统内各圈层相互耦合的产物,事件相互之间不是孤立的,单个事件引起的全球变化对其他事件起着明显的正/负反馈机制作用。文中基于对白垩纪中期异常事件的深入解剖和分析,包括大规模海底火山事件、大洋缺氧事件、生物异常更替与绝灭、白垩纪超静磁带、大洋红层出现等,在探讨白垩纪中期各个事件特征基础上,重点阐述异常事件所引起的全球变化及其对海洋、气候的影响;提出异常事件之间的相互关联与反馈机制。研究发现,大规模海底火山作用是引起白垩纪中期异常海洋和气候的最根本原因,直接促进大洋缺氧事件、生物绝灭与更替、沉积记录的转变等事件的发生。  相似文献   

Structural improvement of age-hardened gypsum-treated bauxite red mud waste using readily decomposable phyto-organics     

Mark Anglin Harris 《Environmental Geology》2009,56(8):1517-1522

Several years (7) after incidental lithification by added gypsum, the effect of crushing and phyto-organics on some physical properties of red mud wastes (RMW) was examined under laboratory conditions. It was hypothesized that mechanically breaking up the hardened masses would increase their permeability. However, on the contrary, crushing these rock-hard masses into <2-mm particles did not increase permeability. A phyto-organic treatment on the other hand greatly improved permeability of the crushed entities such that infiltration rates increased from 0 to 10 cm/h. After 24 weeks of incubation, the structure of the newly formed phyto-organically treated gypsum-hardened RMW aggregates was also substantially improved over that of the controls, as a >3-fold increase in resistance to disintegration during wet sieving was exhibited by the phyto-organically treated samples. The increase in water infiltration by combining crushing with phyto-organic applications was ascribed to a decrease in particle dispersion, creating more stable clay clusters, which in turn stabilized channels and pores. Conversely, it was concluded that the singular crushing of gypsum-hardened bauxite waste in the waste dumps is potentially wasteful and ineffective.  相似文献