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291.
More than 240 items of historical records containing climatic information were retrieved from official historical books, local
chronicles, annals and regional meteorological disaster yearbooks. By using moisture index and flood/drought (F/D) index obtained
from the above information, the historical climate change, namely wet-dry conditions in borderland of Shaanxi Province, Gansu
Province and Ningxia Hui Autonomous Region (BSGN, mainly included Ningxialu, Hezhoulu, Gongchanglu, Fengyuanlu and Yan’anlu
in the Yuan Dynasty) was studied. The results showed that the climate of the region was generally dry and the ratio between
drought and flood disasters was 85/38 during the period of 1208–1369. According to the frequencies of drought-flood disasters,
the whole period could be divided into three phases. (1) 1208–1240: drought dominated the phase with occasional flood disasters.
(2) 1240–1320: long-time drought disasters and extreme drought events happened frequently. (3) 1320–1369: drought disasters
were less severe when flood and drought disasters happened alternately. Besides, the reconstructed wet-dry change curve revealed
obvious transition and periodicity in the Mongol-Yuan Period. The transitions occurred in 1230 and 1325. The wet-dry change
revealed 10- and 23-year quasi-periods which were consistent with solar cycles, indicating that solar activity had affected
the wet-dry conditions of the study region in the Mongol-Yuan Period. The reconstructed results were consistent with two other
study results reconstructed from natural evidences, and were similar to another study results from historical documents. All
the above results showed that the climate in BSGN was characterized by long-time dry condition with frequent severe drought
disasters during 1258 to 1308. Thus, these aspects of climatic changes might have profound impacts on local vegetation and
socio-economic system. 相似文献
292.
历史将永远铭记他们——记在叠溪大地震的考察、研究和救灾工作中作出贡献的几位前辈 总被引:4,自引:0,他引:4
考证并记叙了在1933年叠溪地震的考察、研究和救灾工作中作出过重要贡献的若干前辈的事迹,包括常隆庆、李善邦、周郁如、徐近之、庄学本、张雪岩等先生和四川大学的师生们。他们是中国地震科学和防震减灾事业的先行者,永远值得我们怀念。 相似文献
293.
Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks(MS≥5.4) have been observed at Tangshan well.We analyze the correlation between coseismic parameters(maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earth-quake parameters(magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from ... 相似文献
294.
295.
Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS8.0 earthquake and its larger aftershocks 下载免费PDF全文
Baojun Yin Li Ma Huizhong Chen Jianping Huang Chaojun Zhang Wuxing Wang 《地震科学(英文版)》2009,22(2):149-157
Coseismic water level changes which may have been induced by the Wenchuan MS8.0 earthquake and its 15 larger aftershocks (MS≥?5.4) have been observed at Tangshan well. We analyze the correlation between coseismic parameters (maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earthquake parameters (magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well. The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence. MS magnitude has the strongest correlation with the coseismic water level changes comparing to MW and ML magnitudes. There exists strong correlation between the maximum amplitude, step size and the oscillation duration. The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves. Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves. The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments. 相似文献
296.
巢湖凌家滩遗址古人类活动的地理环境特征 总被引:3,自引:0,他引:3
通过对巢湖凌家滩文化遗址的野外勘查、采样和室内磁化率、烧失量、化学元素及光释光年代分析,结合巢湖湖泊岩芯记录的中全新世环境特征、研究区较高分辨率遥感影像和文物考古成果,综合研究表明:古凌家滩人生活于中全新世气候适宜期,其文化的发展和繁荣处在气候由温暖湿润向温和略干转换的过渡阶段;晚更新世末期堆积形成的地面(OSL年代11.6 ±1.0 ka B.P.)是古凌家滩人生活的地貌面,本区古地貌面海拔以及拔河高度与现今不同,这与该区新构造运动沉降和气候-水文因素作用有关;中全新世温暖湿润的气候条件下,太湖山南麓台地被进一步切割为山前长条形岗地与河流相间的地貌形态,遗址所在的长岗岗地是东、西、南三面临水的"半岛"环境,河川相连,便于水运交通、渔猎和水稻种植。 相似文献
297.
298.
对采自重庆金佛山梁天湾洞穴的一根长达295mm的石笋进行了高精度的TIM S-U系定年和碳氧稳定同位素测试分析,初步建立了末次冰期晚期( 31. 90~15. 21 ka B. P. )以来长江中游地区较高分辨率的古气候变化序列。石笋大约从31.90kaB. P.开始沉积,至15. 21kaB. P.沉积结束,属于末次冰期晚期的产物,其平均沉积速率为1. 77mm /100a。从石笋的氧同位素曲线中明显地检出了Heinrich事件,并且氧同位素曲线与周边地区的石笋记录有着良好的对比关系。 相似文献
299.
One new species and two new records of free-living marine nematodes from the Huanghai Sea 总被引:4,自引:3,他引:1
1 IntroductionIn January 2003, undisturbed sediments were tak-en from a grid of 22 sampling stations (from 32.5° to37°N, 122° to 125°E) during the cruise of an ecologi-cal survey of the over-winter ground for anchovy inthe Huanghai Sea. Meiofaunal abundance varied from55.3 to 152.0 ind/cm2 [(95.4 ±27.0) ind/cm2], with81% to 93% [(83.1 ±22.7) ind/cm2] of the specimensbeing nematodes. Up to now, twenty-nine species ofmarine nematodes have been recorded from theHuanghai Sea (Zhang and P… 相似文献
300.
针对地磁观测工作流程,提出了一种简单易行、可自动观测的配套仪器设计方案。叙述了其工作原理和设计要点,得出该仪器自动化程度高,性价比高,使用简单方便,适用性广的结论。 相似文献