青藏高原东北部甘加盆地古梯田地层与年代初探     

张陈彬  吴铎  陈雪梅  袁子杰  陈发虎 《地理学报》2022,77(1):66-78

梯田是人类几千年来利用和改造自然能力的象征,在人类社会发展中发挥了重要的作用。甘加盆地位于青藏高原东北部甘肃省夏河县,盆地内的丘陵、山麓地带分布大面积的层状梯形景观,疑似弃耕的古代梯田。本文在实地考察的基础上,基于卫星遥感资料,通过GIS手段分析发现古梯田面积为42.2 km²（约63000亩）,主要分布在盆地内央曲河及其支流两侧海拔2936~3326 m间的山坡上。通过对3个古梯田剖面样品的磁化率、总有机碳/氮（TOC、TN）含量、孢粉、粒度等环境代用指标分析,同时对比具有准确年代控制的自然剖面磁化率与粒度。研究结果显示：梯田开垦于晚全新世（距今3000 a）古土壤,梯田剖面顶部25~35 cm不同于自然剖面而呈均一化的指标证实了耕作层的存在（距今约1000 a以下层位）;但耕作层之上TOC、TN含量的增多,以及梯田剖面与自然剖面整体一致的指标变化趋势说明了梯田被短期利用后长期废弃;结合历史文献资料推断夏河古梯田是在北宋“弓箭手屯田”制度（1074—1125年）下开垦的;气候重建资料显示该时段温度较高、降水增加,整体有益于农业生产。本文提供了过去人类社会适应气候变化的典型案例。  相似文献   

基于ArcGIS镶嵌数据集的正射影像数据库构建方法初探     

杨眉  刘建军  李雪梅  张元杰 《测绘软科学研究》2014,(1):33-36

数字正射影像数据具有直观、信息量大、覆盖面广和经济、方便、获取快速等优点,是我国基础地理信息数据库的重要内容。本文讨论了基于ArcGIS镶嵌数据集栅格模型构建数字正射影像数据库的一些基本问题。首先对近年来的影像空间数据库技术进行了梳理,然后基于ArcGIS镶嵌数据集模型提出了数字正射影像数据库构建方法,其中对影像入库涉及的栅格数据存储模型、建库步骤、相关参数等问题进行了分析与探讨。最后,开展了海南省某测区小型正射影像数据库构建试验,通过试验证明了文中方法的可用性与可靠性。  相似文献   

Interactions of aquaculture and waste disposal in the coastal zone     

Zhai Xuemei  S. J. Hawkins 《中国海洋大学学报(英文版)》2002,1(1):8-12

Throughout the world, the coastal zones of many countries are used increasingly for aquaculture in addition to other activities such as waste disposal. These activities can cause environmental problems and health problems where they overlap. The interaction between aquaculture and waste disposal, and their relationship with eutrophication are the subjects of this paper. Sewage discharge without adequate dispersion can lead to nutrient elevation and hence eutrophication which has clearly negative effects on aquaculture with the potential for toxic blooms. Blooms may be either toxic or anoxia-causing through the decay process or simply clog the gills of filter-feeding animals in some cases. With the development of aquaculture, especially intensive aquaculture, many environmental problems appeared, and have resulted in eutrophication in some areas. Eutrophication may destroy the health of whole ecosystem which is important for sustainable aquaculture. Sewage discharge may also cause serious public health problems. Filter-feeding shellfish growing in sewage-polluted waters accumulate micro-organims, including human pathogenic bacteria and viruses, and heavy metal ion, presenting a significant health risk. Some farmed animals may also accumulate heavy metals from sewage. Bivalves growing in areas affected by toxic algae blooms may accumulate toxins (such as PSP, DSP) which can be harmful to human beings.  相似文献   

上天梯膨润土在钻井泥浆中的应用研究     

陈廷臻  涂焕生  郭辉  张军营 《河南国土资源》1996,(1)

信阳上天梯矿区钙基膨润土可分为四个自然类型。根据矿石理化性能和蒙脱石晶体结构特征，选用第Ⅲ类矿石，运用对辊挤压钠化法和最佳工艺进行实验研究，获得钻井泥浆用Ａ．Ｐ．Ｉ级膨润土。  相似文献   

校园人群应急疏散行为及其影响因素研究     

钟光淳  翟国方  毕雪梅  葛懿夫 《地震研究》2022,45(1):150-159

校园作为城市高密度地区的典型区域,建筑密度高、道路错综曲折、灾后疏散难度大。以南京中心城区某高校为实证研究案例,展开问卷调查;采用皮尔逊卡方检验法,对校园人群安全意识及疏散行为和性别、年龄、受教育程度及参加疏散演练次数等人员特性信息进行交叉分析,得到存在相关性的变量组;基于Logistic回归模型,建立了人群特征、安全意识评价指标对校园人群疏散行为及心理影响的评价模型,识别疏散行为影响因素,以及各因素的影响程度大小。结果表明:年龄、性别以及参加过疏散演练的次数是影响人群安全意识及疏散行为的显著相关因素,学历是相关因素;地震灾害下受访人群对避难场所的选择偏好为:场地型避难场所>建筑型避难场所>地下空间;参加疏散演练的次数,安全意识、风险认知对灾害发生时的人群疏散行为有显著影响。  相似文献   

海上高—特高含水期稠油油藏提高采收率实验研究     

张伟  戴建文  王亚会  涂乙 《地质科技情报》2022,41(3):193-199

  相似文献   

Damage assessment for tropical cyclones landing in Guangdong Province of China by using a projection pursuit dynamic cluster model     

Tu  Chaoyong  Chen  Shumin  Zhao  Zhongkuo  Li  Weibiao  Ni  Changjian 《Natural Hazards》2022,113(1):475-505

Natural Hazards - Tsunamis occur not only in marine settings but also in lacustrine environments. Most of the lacustrine tsunamis are caused by seismically- or aseismically-triggered mass...  相似文献   

Ensemble standardization constraints on the influence of the tree growth trends in dendroclimatology     

Shi  Feng  Yang  Bao  Linderholm  Hans W.  Seftigen  Kristina  Yang  Fengmei  Yin  Qiuzhen  Shao  Xuemei  Guo  Zhengtang 《Climate Dynamics》2020,54(7):3387-3404

Climate Dynamics - Tree growth trends can affect the interpretation of the response of tree-ring proxies (especially tree-ring width) to climate in the low-frequency band, which in turn may limit...  相似文献   

Reconstruction of hydrometeorological time series and its uncertainties for the Kaidu River Basin using multiple data sources     

Xuemei Li  Lanhai Li  Xixi Wang  Fengqing Jiang 《Theoretical and Applied Climatology》2013,113(1-2):45-62

This paper tried to reconstruct the time series (TS) of monthly average temperature (MAT), monthly accumulated precipitation (MAP), and monthly accumulated runoff (MAR) during 1901–1960 in the Kaidu River Basin using the Delta method and the three-layered feed forward neural network with backpropagation algorithm (TLBP-FFNN) model. Uncertainties in the reconstruction of hydrometeorological parameters were also discussed. Available monthly observed hydrometeorological data covering the period 1961–2000 from the Kaidu River Basin, the monthly observed meteorological data from three stations in Central Asia, monthly grid climatic data from the Climatic Research Unit (CRU), and Coupled Model Intercomparison Project Phase 3 (CMIP3) dataset covering the period 1901–2000 were used for the reconstruction. It was found that the Delta method performed very well for calibrated and verified MAT in the Kaidu River Basin based on the monthly observed meteorological data from Central Asia, the monthly grid climatic data from CRU, and the CMIP3 dataset from 1961 to 2000. Although calibration and verification of MAP did not perform as well as MAT, MAP at Bayinbuluke station, an alpine meteorological station, showed a satisfactory result based on the data from CRU and CMIP3, indicating that the Delta method can be applied to reconstruct MAT in the Kaidu River Basin on the basis of the selected three data sources and MAP in the mountain area based on CRU and CMIP3. MAR at Dashankou station, a hydrological gauge station on the verge of the Tianshan Mountains, from 1961 to 2000 was well calibrated and verified using the TLBP-FFNN model with structure (8,1,1) by taking MAT and MAP of four meteorological stations from observation; CRU and CMIP3 data, respectively, as inputs; and the model was expanded to reconstruct TS during 1901–1960. While the characteristics of annual periodicity were depicted well by the TS of MAT, MAP, and MAR reconstructed over the target stations during the period 1901–1960, different high frequency signals were captured also. The annual average temperature (AAT) show a significant increasing trend during the 20th century, but annual accumulated precipitation (AAP) and annual accumulated runoff (AAR) do not. Although some uncertainties exist in the hydrometeorological reconstruction, this work should provide a viable reference for studying long-term change of climate and water resources as well as risk assessment of flood and drought in the Kaidu River Basin, a region of fast economic development.  相似文献   

山东张夏-崮山地区华北寒武系标准剖面上寒武统研究新进展   总被引：3，自引：0，他引：3  

杜圣贤  张瑞华  张贵丽  张俊波  陈雪梅 《山东国土资源》2007,23(10):1-6,14

华北寒武系标准剖面分布在济南市长清区张夏镇和崮山镇,该剖面寒武纪地层发育,出露良好,三叶虫等古生物化石保存完好,笔者根据微体古生物牙形石的种属及其在地层中的分布序列,建立了上寒武统6个牙形石生物带,并根据牙形石"Cordylodus lindstromi"的首现,准确地确定了寒武系与奥陶系的界线;对寒武系长山阶的碳氧同位素曲线特征进行了分析,并把长山阶底部的碳同位素曲线与我国华南及哈萨克斯坦等国寒武系芙蓉统底部的碳同位素进行了对比,建立了华北寒武系与国内以及国外寒武系的对比关系。  相似文献