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大河流域的水系统是支撑社会-生态系统的基础,理解水系统的结构变化是深入揭示区域系统演化的关键。基于自然-社会水系统视角,从黄河全流域和二级水资源分区尺度,利用1998—2018年降水、蒸发、径流、社会经济耗水等水系统变量,通过Mann-Kendall趋势检验和线性回归分析方法,分析了水系统要素的变化趋势及结构演变特征。结果表明：在全流域尺度,降水、蒸发分别以4.25 mm·a-1、4.09 mm·a-1的速率上升,但蒸发在空间上的变化更显著;径流量呈现先减少再上升后急剧下降的趋势,且与降水量显著正相关。社会系统耗水量呈现增速减缓的特征,农业灌溉占耗水结构的比例以0.50%的速率逐年下降;城镇公共、居民生活和生态环境耗水比例分别以0.07%、0.29%、0.11%的速率上升。在二级水资源分区尺度,各水系统分异特征明显,兰州至头道拐段及花园口以下区域水系统所支撑社会经济发展的功能已经出现了超载。各水系统要素间具有不同程度的协同演变趋势,在湿润区域,蒸发相较于降水具有明显的滞后现象,但在干旱区域两者变化趋势基本一致。黄河流域水系统要素在时空上均存在明显的异质性,未来人口和经济的进一步发展可能会使区域的水资源压力加剧。 相似文献
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新疆乌什6.2级地震的中期预测 总被引：2，自引：0，他引：2
介绍了利用地倾斜资料和中国地壳运动网络工程GPS复测资料对新疆地区震情进行跟踪研究的基本依据、方法和过程,对2005年2月15日发生的乌什Ms6.2地震给出了较好的年度预测意见。 相似文献
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ZHANG Jing LYU Zhipeng SHAO Siya LI Fangfang YANG Shengtian SONG Wenlong LI Wei LI Shun-jiang 《中国地理科学(英文版)》2016,26(4):495-507
The effects of acid deposition on pine forest ecosystems in Longli of Guizhou Province, southwestern China are studied using indoor experiments and model simulations. Indoor experiments are designed to explore the aluminum toxicity on pine seedlings, and the long-term soil acidification model（LTSAM） and a terrestrial biogeochemistry model（CENTURY） are used to simulate the influences of acid deposition on pine forest ecosystems. The indoor experiment results of aluminum toxicity show that aluminum ions in solution limit plant growth and acid deposition enhances this effect by facilitating the release of aluminum ions from the soil. Pine seedling biomass and root elongation decrease as the aluminum concentration increases. The results of model simulations show that the soil chemistry varies significantly with different changes in acid deposition. When the acid deposition increases, the pH value in the soil solution decreases and the soil Al3+ concentration increases. The increased acid deposition also has negative impacts on the forest ecosystem, i.e., decreases plant biomass, net primary productivity（NPP） and net CO2 uptake. As a result, the soil organic carbon（SOC） decreases because of the limited supply of decomposition material. Thus acid deposition need be reduced to help protect the forest ecosystems. 相似文献
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研究晚全新世季风气候演变有助于进一步认识与预测未来季风区气候变化。太平洋东西两岸是全球季风集中分布的地区,已经有大量的古气候记录发表,但是缺乏对各个季风区气候突变事件以及整体变化趋势的对比研究。针对这一问题,选取亚洲季风区、印澳季风区、北美季风区、南美季风区11个洞穴石笋δ18O和1个湖泊Ti含量,对比研究各个记录在3.5~0.5 ka B.P.期间指示的夏季风变化特征。通过对比发现四大季风区的石笋δ18O在晚全新世整体上呈现偏正趋势,指示夏季风减弱;2次重要的气候突变事件1.5 ka B.P.和2.7 ka B.P.弱夏季风事件在各个季风区内均有表现;同时也记录了一系列十年际-百年际尺度的弱夏季风事件,表明太平洋东西两岸和南北半球的夏季风都有减弱的趋势,这与先前研究认为的南北半球呈现"see-saw"模式表现出不一样的特征。晚全新世以来ENSO(El Nino-Southern Oscillation)活动的增强对太平洋东西两岸南北半球夏季风减弱具有重要影响。在El Nino事件发生时,Walker环流减弱,而且它的上升支向东移动远离西太平洋暖池,西太平洋副热带高压增强并向西移动,导致亚洲夏季风减弱。Walker环流的东移也会使得印度尼西亚-太平洋暖池(Indo-Pacific Warm Pool,简称IPWP)海温下降,热带季节内震荡减弱致使印澳夏季风减弱;此外,El Nino事件发生时,赤道东太平洋海水温度上升导致东西太平洋海水温度梯度减弱,在此状态下南美季风区低空急流(Low Level Jet,简称LLJ)减弱,导致南美夏季风减弱;同时,北美洲加勒比海低空急流增强,使得该季风区下沉气流增强,导致北美夏季风减弱。我们的研究表明,在晚全新世ENSO活动增强的状态下,太平洋东西两岸南北半球夏季风变化可能都呈现减弱趋势。 相似文献
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Chen Chaojun Yuan Daoxian Cheng Hai Yu Tsailuen Shen Chuanchou Edwards R. Lawrence Wu Yao Xiao Siya Zhang Jian Wang Tao Huang Ran Liu Ziqi Li Tingyong Li Junyun 《中国科学:地球科学(英文版)》2021,64(10):1761-1773
It is conducive to the sustainable development of human beings in karst regions to research the mechanism of karst rocky desertification(KRD) expansion. Whether the large-scale KRD in southwestern China is caused by climate change or human activities is still controversial. In this study, the evolution of the KRD in southwestern China over the past 2000 years was reconstructed through the high-precision δ~(13) C record of stalagmites from Shijiangjun(SJJ) Cave, Guizhou Province, China. Theδ~(13) C of the stalagmites from SJJ Cave exhibited heavy values from the Medieval Warm Period(MWP) to the Little Ice Age(LIA). Furthermore, the δ~(13) C records of other stalagmites and tufa from southwestern China also showed the same significant heavy trend. Because the stalagmite δ~(13) C could record the change of ecological environment, it indicated that the consistent change of the stalagmites δ~(13) C may record the process of KRD expansion in the karst regions of southwestern China. During the MWP, the stronger Asian summer monsoon and the northward movement of the rain belt led to a dry period in southwestern China and a wet period in northern China. In contrast, it was wet in southwestern China and dry in northern China during the LIA.In addition, after the Jing-Kang event(JK event, AD1127) occurred at the end of the Northern Song dynasty, the political and economic center of China migrated to southern China for the first time, which changed the population distribution pattern of larger population in the north and smaller population in the south. Therefore, the expansion of KRD in southwestern China was exacerbated in the MWP due to the change of climate in southwestern China, the migration of a large number of people, wars, the large-scale reclamation of arable land, and the cultivation of large areas of crops. 相似文献
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