Local level rainfall and temperature variability in drought-prone districts of rural Sidama,central rift valley region of Ethiopia     

Tafesse Matewos  Tewodros Tefera 《自然地理学》2020,41(1):36-53

ABSTRACT

The purpose of this study is to examine local level spatiotemporal rainfall and temperature variability in drought-prone districts of rural Sidama, Central Rift Valley region of Ethiopia. The study used 129 gridded monthly rainfall and temperature data of 32 years (1983–2014). The gridded rainfall and temperature records were encoded into GIS software and evaluated through different statistical and geospatial techniques. Mann-Kendal rank test and F distribution tests were used to test temporal and spatial statistical significance, respectively, of the data. The analysis revealed that Belg and Kiremt are the main rainfall seasons, constituting 81% of the annual rainfall. Although annual, Kiremt, and Belg rainfall amounts appear to have decreased over time, the decreasing trend is statistically significant only for Belg rainfall records. On the other hand, rainfall standard anomaly results indicated seven droughts of different magnitudes: one extreme, two severe, and four moderate. The study also revealed increasing temperature trends over the years under consideration that are statistically significant. The findings of this study on rainfall contradict other findings obtained around the study area. Thus, climate change adaptations need to focus on location-specific climate data analysis so that the intended adaptive interventions can be successful.  相似文献   

Analytical study of ground motion caused by seismic wave propagation across faulted rock masses          下载免费PDF全文

J.C. Li  N.N. Li  S.B. Chai  H.B. Li 《国际地质力学数值与分析法杂志》2018,42(1):95-109

Studying seismic wave propagation across rock masses and the induced ground motion is an important topic, which receives considerable attention in design and construction of underground cavern/tunnel constructions and mining activities. The current study investigates wave propagation across a rock mass with one fault and the induced ground motion using a recursive approach. The rocks beside the fault are assumed as viscoelastic media with seismic quality factors, Q_p and Q_s. Two kinds of interactions between stress waves and a discontinuity and between stress waves and a free surface are analyzed, respectively. As the result of the wave superposition, the mathematical expressions for induced ground vibration are deduced. The proposed approach is then compared with the existing analysis for special cases. Finally, parametric studies are carried out, which includes the influences of fault stiffness, incident angle, and frequency of incident waves on the peak particle velocities of the ground motions.  相似文献   

THE POSITION AND ROLES OF PORTS AND RAILWAYS IN THE EURASIA LAND BRIDGE TRANSPORTATION IN NORTHEAST CHINA     

叶宝明  李文杰 《中国地理科学(英文版)》1992,2(3):235-244

This paper systematically analyzes and proves the favorable factors of utilizing the ports and the railways in Northeast China for the Asia-Europe land bridge transportation. It will be more beneficial to Dalian Port and HaDa (Harbin-Dalian) and Binzhou (Harbin-Manzhouli) railways in Northeast China to the Siberia railway in Russia than 1) to other ports and the corresponding railways in China, 2) to the Nakhodka Port in Russia and the corresponding railways and 3) to the Chongjin Port in North Korea and the corresponding railways. This paper also puts forward the reform measures to adopt the ports and the railways in the northeast region in China for the land bridge transportation and the problems in transportation policies and management systems.  相似文献   

南山站对陆地—5号资源卫星的可观测范围及以该站为中心的覆盖区域     

桑思武 《天文研究与技术》1996,(4)

本文简要介绍了陆地系列地球资源卫星的轨道特征，并以陆地—５号资源卫星为例，根据南山站的座标计算出该站对陆地—５号资源卫星的可观测范围及以该站为中心的卫星的覆盖区域。  相似文献   

Geochemical survey of thermal system in Northeast China and their geothermometric characters     

MohammedHazaea HUKe MohammedMattash CHENBing M.O.AI-JabaliAref MohammedAbdussalam 《东北亚地学研究》2004,7(2):181-184

The chemical composition of several thermal springs around Changbaishan area has been investigated. Cenozoic basaltic rocks are widely distributed in Northeast China and geothermal characteristics have been described. About one hundred hot springs exist around Changhaishan Volcano at the border between China and D.P.R.Korea with high temperature about 82~C. The pH values of the spring water range from 6.9 to 7.1 and the total flow rate is about 4.8 L/sec. The chemical composition of the thermal springs is sodium carbonate; the high-mineral contents of thermal water are believed to have medicinal properties. Bathhouses are already built along the hot springs to take the advantage of the supposed healing properties. The high quality of those hot springs is believed to be utilitized for mineral water. The chemical equilibrium temperatures were estimated at about 160℃ based on the Na-K-Ca geochemical thermometer.  相似文献   

昆仑山口大地震与地形变异常的讨论   总被引：7，自引：5，他引：2  

薄万举  张祖胜  郭良迁 《大地测量与地球动力学》2003,23(1):22-28

针对昆仑山口大地震，总结了多种地形变（大地测量）手段所显示的异常变化及其时空分布，结果显示：8．1级大震前存在空间尺度大，时间尺度的地形变前兆异常，简要介绍了相关的异常图像，给出了初步解释，并对未来震情的发展进行了探讨，认为近期内强震活动向华北迁移的可能性不大。  相似文献   

SORPTION AND DESORPTION CHARACTERISTICS OF CADMIUM BY FOUR DIFFERENT SOILS IN NORTHEAST CHINA   总被引：3，自引：0，他引：3  

ZHANG Lei SONG Feng-bin 《中国地理科学(英文版)》2005,15(4):343-347

1IN TR O D U C TIO NA s a persistentand toxic pollutant, cadm ium (C d) canresultin m any adverse health effects in a variety oftis-suesand organssuch asthe lung,kidney,urinary,blad-der,pancreas,breast and prostate (SA TA R U G etal.,2003).C adm ium in so…  相似文献   

电离氢区S140,S141和S142的红外发射研究     

李金增  陈培生 《中国天文和天体物理学报》1996,(3)

本文使用红外天文卫星（IRAS）巡天数据的最新版本IRAS天空巡天图（ISSA），经过进一步处理，得到了S140S141和S142SharplessHII区－分子云复合体的红外发射强度、温度及其光深的分布．在此基础上对各HII区的一些物理参量进行了统计分析，得到了分子云复合体的红外发射总光度以及复合体中尘埃的分布情况，对小尺度尘埃（VSG）的丰度进行了分析．并对各恒星形成区中的致密团块进行了研究，揭示出其中一些可能的恒星形成区域．同时，对S140区中的有关红外点源作出了能谱分析，并对S141区的激发星进行了讨论．  相似文献   

Synthetic SH seismograms in a laterally varying medium by the discrete wavenumber method   总被引：1，自引：0，他引：1  

Michel Campillo  Michel Bouchon 《Geophysical Journal International》1985,83(1):307-317

Summary. We present a new method to calculate the SH wavefield produced by a seismic source in a half-space with an irregular buried interface. The diffracting interface is represented by a distribution of body forces. The Green's functions needed to solve the boundary conditions are evaluated using the discrete wavenumber method. Our approach relies on the introduction of a periodicity in the source-medium configuration and on the discretization of the interface at regular spacing. The technique developed is applicable to boundaries of arbitrary shapes and is valid at all frequencies. Some examples of calculation in simple configurations are presented showing the capabilities of the method.  相似文献   

中国大陆科学钻探先导孔零偏VSP资料解释   总被引：3，自引：3，他引：0  

姜修道  朱光明  朱龙生  张文波  李桂花 《地球科学与环境学报》2004,26(1):55-60

用六级三分量检波器在中国大陆科学钻探先导孔中实施了零偏VSP测量.数据处理结果表明,中国大陆科学钻探孔区超高压变质岩石的地震波速度主要介于4500～7000m/s之间,显著高于一般的沉积岩地区,而且随深度变化不明显.声波测井速度系统地稍低于VSP层速度,可能是由于井壁处岩石的完整性受到破坏而造成的.地震波速度与岩石密度和岩性存在明确的对应关系,榴辉岩的密度和地震波速度均显著高于片麻岩类岩石;由榴辉岩退变生成的斜长角闪岩类岩石,其密度和地震波速度均呈现出较大的变化,主要与其退变质程度有关;超基性岩中的裂隙系统导致其密度和地震波速度大幅度下降.由于榴辉岩与其他岩石类型之间存在较大的波阻抗差异,因此用零偏VSP资料标定该区地震波的地质层位是有效的.关于地震波反射的原因,通过综合研究地震波(包括反射纵波、上行转换横波、井筒波)的特征、岩石速度和密度分布以及井径变化,认为主要是岩性分界面、韧性剪切带和断裂(带),但还有一些因素尚待进一步研究.  相似文献