顾及平原区微地貌的地形湿度指数及其地表水环境意义

我国平原区广泛分布的沟渠、水塘等微地貌对地表水环境的空间分布特征具有重要影响,为深入探究平原区微地貌对区域地表水环境的影响,文章利用添加微地貌特征线的方法,构建出顾及微地貌的数字高程模型(digital elevation model,DEM),据此计算出能够顾及微地貌的地形湿度指数(topographic wetness index,TWI),并进一步阐明其所蕴含的地表水环境意义。研究结果表明,顾及微地貌的TWI空间分布能较直观地反映区域地表水系的空间分布规律及其地表径流特征,特别是能够很好地反映地表积水区或易发展为积水区的空间分布规律,可为研究区的水环境保护、防洪与抗旱、农业生产等提供辅助决策依据。     

大兴安岭中段阿尔山地区第四纪火山地貌特征及其构造意义

基于资源三号(ZY-3)的高分辨率卫星影像和数字高程模型(DEM), 运用地理信息系统(GIS)技术, 通过遥感影像解译以及地形起伏度和坡度的定量计算, 分析阿尔山火山区的地质地貌特征。共识别出 19 座第四纪喷发的火山, 并且将其划分为5个类型。该区火山地貌按地形起伏度可分为4个类型, 以低位中山为主(39.61%), 其次为低位低山(36.24%)。80%的椭圆形火山锥长轴走向介于45°~75°之间, 中值为58.5°, 与NE向排列的小东沟火山?十号沟盆地火山?岩山?高山火山链走向平行。火山锥的马蹄形缺口主要朝向为NE向, 也有SW向和NW向。NE向与SW向马蹄形缺口的角度中值相差约180°, NW向的马蹄形缺口与NW向的断裂几乎平行, 推测存在控制火山喷发和展布的NE向断裂。根据研究结果推断, 中生代的基底断裂使该区形成NE走向的脆弱裂隙带, 为岩浆提供良好的上侵通道; 裂隙控制着岩浆的上升, 形成呈NE向线性分布的火山机构, 并最终影响地表火山锥的分布和地貌形态。     

不受DEM空间分辨率影响的地形指数计算

为了减小数字高程模型(DEM)分辨率对地形指数计算的影响,开发了一种不受DEM空间分辨率影响的地形指数计算方法.选取汉江上游褒河流域作为研究区域,通过引入分辨率因子考虑DEM空间分辨率对单宽上坡集水面积的影响,应用分形方法处理DEM空间尺度对地形坡度的影响,将该算法应用到褒河流域DEM数据的计算中.结果表明:此法可以成功地由低分辨率的DEM数据获得与目标高分辨率精度相仿的地形指数分布,能在一定程度上消除DEM空间分辨率对地形指数计算的影响,因而对无资料地区的水文预报有着十分重要的现实意义.     

基于DEM数据的地形分析研究与实现

数字地形分析是在数字高程模型DEM上进行地形属性计算和特征提取的信息处理技术,它主要分成地形因子计算和地性特征提取两大部分,在实际生产应用中具有十分重要的意义。本文主要介绍了数字地形分析产生的背景及原理,最后以某试验区为对象,基于ArcGIS软件平台,实现了对该试验区的地形分析。     

基于LS-SVM的海底微地形预测应用研究

为解决传统机器学习中模型选择、过学习与局部极小值问题,针对自然海底微地形强烈的非线性、不确定性特点,提出海底微地形的LS-SVM预测模型.采用等式约束代替不等式约束,将二次规划问题转化为求解一次线性方程组,提高了收敛速度.实验结果表明,该方法预测结果误差较小,且实时性较好,可满足建立钴结壳最佳切削深度模型的需要.     

基于DEM的澧水流域水系特征及其对新构造运动的响应

水系发育特征是对新构造运动的敏感响应,是研究新构造活动过程的良好载体.澧水地质构造背景独特,其水系展布特征研究可为新构造活动特征及其河流演变是提供有力的证据.本研究利用DEM和Arcgis软件,获取了澧水源头水系和河流地貌参数,定量分析了流域水系分异发育的特征.研究结果表明,在澧水源头北岸的水系参数均较南岸高,呈明显不对称性.水系发育受新构造运动强度和性质的影响,区域自西北向的掀斜隆升和流域南侧的断块抬升是造成澧水南北两侧水系形态差异的主要原因.干流在沿断裂发育的过程中缓慢的逆扭错动,由南西向北东方向流动.     

最近邻河道相对高度及其在中国洪水淹没制图中的应用

基于国际上由数字高程模型（digital elevation model,DEM）衍生的最近邻河道相对高度（height above nearest drainage,HAND）概念,采用STRM DEM数据派生了中国1000和250 m水平分辨率的HAND数据集,并将HAND数据集应用于洪水淹没制图,建立了河道水位相较枯水期上涨1~10 m情景下的中国河道型洪水淹没图库．进一步以淮河一级支流淠河2020年7月大洪水为例,采用遥感提取及HEC-RAS计算的淹没范围,验证了基于HAND绘制的淹没图．结果表明,HAND相对于经典的DEM能够补充提供局地地形信息,基于HAND的淹没制图方法具有可行性和合理性．本文计算的中国HAND数据集可为地理学相关领域的研究提供凸显局地特征的地形数据,建立的基于HAND的淹没图库可为中国的洪水淹没制图工作及洪水风险管理提供参考．      

基于高分7号卫星立体像对的DEM提取及其精度评定

测绘卫星立体像对提取DEM效率高、提取速度快,在无控制点的情况下,利用立体像对提取DEM的方法提取DEM成本低、精度高。高分7号(GF-7)卫星是我国首颗民用亚米级高分辨率的立体测绘卫星,实现我国民用1∶10 000比例尺高精度卫星立体测图。主要目的是利用ENVI软件对高分7号卫星立体像提取DEM,并在有无控制点的情况下对提取的DEM进行精度评定。以福建省龙岩市测区为实验区,论述了基于立体像对提取DEM的基本原理,介绍了采用ENVI软件对高分7号立体像对的相对定向、绝对定向、核线影像生成、提取DEM等一般步骤,基于RPC模型即无控制点和1个地面控制点、5个地面控制点生产的DEM。比较在有无控制点及控制点个数不同的情况下提取DEM的效果,并采用检查点法对不同情况下提取的DEM进行高程精度评定。结果显示,无控制点情况下提取的高程精度为14.6 m,增加控制点的个数可以提升DEM的精度。在1个控制点情况下提取的高程精度达到2.4 m。在有控制点的情况下,DEM高程精度可达到山地地区1∶10 000的精度要求。     

Amery冰架附近区域年际表面高程变化分析

使用基于坡度改正的ICESat(冰云和地面高度卫星)激光测高数据重复轨分析法对2003至2009年2月与10月Amery冰架及其附近区域进行了表面高程变化分析.该区域的ICESat轨道重复轨之间的平均距离为100m,平均坡度为0.3%,使用数字高程模型(DEM)进行重复轨间的坡度改正可以消除坡度对重复轨之间高程点投影时的影响.最终得到了2003～2009年2月和10月的总体平均高程变化,以及不同高程区间内的平均高程变化.结果表明海拔较低即更靠近海洋的区域高程变化剧烈,波动范围在±40cm左右甚至超出,而海拔较高即内陆区域的高程变化较缓和,波动范围在±10cm以内.     

杨山群的构造特征及对北淮阳区构造演化的意义

北淮阳豫皖交界地区发育有一套含有煤线的杨山群 ,研究表明杨山群发育两期构造变形 ,第一期构造变形 (D1 )为北西西向褶皱及伴生的逆冲断层 ,第二期变形 (D2 )为北西西向的脆性断层。研究区佛子岭群发育三期构造变形 ,不同与前人认识 ,杨山群第一期构造变形与佛子岭群第二期构造变形存在着明显的差异 ,它们不是同一期构造变形的产物。这一新的认识可能预示着在晚古生代时本区北部还有一次重要的构造事件     

Early tectonic uplift of the northern Tibetan Plateau

The Hexi Corridor is the northmost foreland basin of the Tibetan Plateau and its formation is controlled by the northern marginal fault of Tibet, Altyn Tagh Fault （ATF）-North Qilian Shan marginal Fault （NQF）, and the southern Kuantan Shan-Longshou Shan Fault （KLF）. So its study is important to understanding the mechanism of Tibet formation and its influence on global climate change. The oldest Cenozoic sediments in the Corridor is the Huoshaogou Formation which consists of terrigenous fine conglomerate, sandstone, sandy mudstone and mudstone, depositing in al- luvial to lacustrine and fan delta sedimentary environments. Detailed paleomagnetic measurements of this sequence at Yumen clearly reveal eleven pairs of normal and reversed polarities. Fossil mammals found around the section support that most of the observed polarities can be well correlated with chrons between 13n and 18r of the standard geomagnetic polarity time scale, yielding ages of 40.2-33.35 Ma. The mean declinations of this sequence and its immediately above stratigraphy indicate an 18.3° rapid clockwise rotation of the Hexi Corridor. Since this sequence has been strongly folded and is capped by an angular unconformity, we think that the presence of the thick alluvial fan conglomeration at the bottom of the foreland basin may indicate the initial deformation and uplift of the northern Qilian Shan. This process could occur at latest at 40.2 Ma, driven by the faults NQF and KLF that thrust onto the Hexi corridor respectively from its southern and northern margins. These faults are in an early response to the collision of India with Asia, while the unconformable termination and rotation of the Huoshaogou Formation at -33.35 Ma indicate other early episode of rapid tectonic deformation and uplift of the northern Tibet.     

青藏高原湖泊湖面变迁及影响因素

 湖泊对气候波动有敏感记录。以地理信息系统（GIS）和遥感（RS）技术为基础,从20世纪70年代、90年代、2000年前后和2010年前后4期Landsat遥感影像中,提取青藏高原所有湖泊边界信息,建立青藏高原湖泊空间数据库,并收集了青藏高原47个气象台站的年平均气温和年降雨量资料（1961-2010）,研究青藏高原湖泊湖面变迁及其影响因素。结果表明,1973-2010年,青藏高原湖泊个数和总面积呈显著增加的趋势;青藏高原湖泊湖面变迁主要受气温升高、降雨量增加和蒸发量减少的影响;此外,影响青藏高原湖泊湖面动态变化的因素还有冰川分布、人类活动、湖盆形状、补给和排泄区等。     

柴达木盆地成盐期与青藏高原第四纪冰期及构造运动阶段的相关性

 柴达木盆地沉积有巨厚的晚新生代沉积物和丰富的矿产资源,是研究晚新生代以来气候与环境变化、构造运动与盆地演化、成盐成矿规律的理想地区。通过对柴达木盆地钻孔和剖面的含盐地层测年数据进行总结,并与青藏高原第四纪冰川活动和构造运动进行对比,认为柴达木盆地成盐期与青藏高原第四纪冰期及构造运动阶段具有一定的对应关系。柴达木盆地西部盐湖和干盐湖中通常发育有倒数第二次冰期及末次冰期的石盐层,某些盐湖中还有希夏邦玛冰期、望昆冰期、中梁赣冰期的石盐层;迄今为止在柴达木盆地东部的察尔汗盐湖区中仅发现末次冰期以来的石盐层。冰期环境下的干冷气候及冰川扩张,造成盐湖补给水源的减少,有利于盐类物质的沉积。     

青藏高原东北部地面风时空分布特征研究

青藏高原东北部地区对全球变化异常敏感,系统研究该区地面风时空分布特征对理解青藏高原乃至北半球的大气环流演变具有重要意义.本文通过分析青藏高原东北部20个气象台站1982~2011年的年、季平均风速和年、季平均最大风速,2004~2011年大风日数、极大风以及最大风的风向、风频发现:(1)青藏高原东北部年平均风速和年平均最大风速总体呈下降趋势,春季的平均风速和平均最大风速在四季中最大.(2)2004~2011各台站累计大风(17m/s)日数总体呈上升趋势,2010年达到一个极大值;托勒、野牛沟、冷湖3台站大风较多,冷湖、茫崖、刚察、兴海次之,海拔较低的西宁最少;台站春季多大风.(3)各个台站极大风速的风向和最大风速的风向较为一致;青藏高原东北部总体上风向可分为四种类型:WNW,W,WNW、NW,总体以偏西风为主.     

青藏高原隆升及其环境效应研究综述

青藏高原及其隆升对全球尤其是我国自然环境影响十分深刻,它也是当前全球地球科学界研究的热点.文章简述了青藏高原研究的历程,介绍了高原隆升机制的几种观点,并对高原隆升的环境效应作了较详细的阐述.最后对高原隆升及其环境效应研究的新近进展作了简要概述.     

Climatic significance of n-alkanes and their compound-specific dD values from lake surface sediments on the Southwestern Tibetan Plateau

The content and hydrogen isotope ratios of n-alkanes extracted from recent lake surface sediments sampled from nine lakes in three different climate zones on the Southwestern Tibetan Plateau were analyzed.Values were compared with n-alkanes in plants from lake drainages,and dD values of meteoric water,lake water,and mean annual precipitation.The results showed that n-C23was predominantly derived from aquatic plants,and n-C27–n-C33from terrestrial higher plants.The average carbon chain length of n-C27–n-C33(ACL27–33)was positively correlated with the mean annual precipitation.dD values of the long-chain n-alkanes n-C29and n-C31of terrestrial origin(varying between-214%and-169%,and-226%and-185%,respectively)were inversely correlated with mean annual precipitation;but in accordance with the average annual variations in dD(OIPC),dD values of n-C31were strongly related to the dD values of growing season meteoric water(R2=0.74).The large difference between dD values of n-C23of aquatic origin and n-C31(an average of about 27%)demonstrates the enrichment of the lake water dD compared to precipitation,caused by strong evaporation in the semiarid–arid areas of the southwestern Tibetan Plateau.Average value of en C25 31=p(-95%)is evidently higher than the value observed in European wet regions(-128%);besides,en C31(about-116%)is constant along the study transect(SD=9),which indicates that n-C31is a useful proxy for the environment.     

青藏高原西部燕山晚期花岗岩地球化学特征及其大地构造意义

对青藏高原西部燕山晚期花岗岩进行了地质、地球化学综合研究。结果表明 ,燕山晚期早白垩世花岗岩为 I型 ,形成于火山弧环境 ,岩石组合为石英二长闪长岩 -花岗闪长岩 -二长花岗岩 ,岩石系列为高钾钙碱性系列 ,A/ CNK<1,稀土元素含量中等 ,并且属轻稀土富集型 ,铕亏损不明显 ,L IL E有选择地得到富集 ,HFSE相对亏损 ;晚白垩世花岗岩为 S型 ,形成于同碰撞环境 ,岩石组合为二云母二长花岗岩 -二云母花岗岩 ,岩石系列为高钾钙碱性系列 ,但 A/CNK>1.1,稀土元素含量较低 ,铕亏损明显 ,微量元素中以 Rb和 F含量高为显著特征。为研究喀喇昆仑山构造演化提供了限定条件     

Seasonal transition and its boundary layer characteristics in Anduo area of Tibetan Plateau

Using the data, especially the GPS rawinsode data, observed in Anduo area of the Tibetan Plateau during the intensive observation period of GAME/Tibet in 1998, the transition from the dry to the rainy season along with their boundary layer characteristics is analyzed comprehensively. The result shows that the formation of the rainy season in Anduo area is related closely to the general atmospheric circulation. The westerly belt moving north and the southeast damp current are basic conditions for development of the rainy season in Anduo area. In the dry season, the air is drier, air temperature higher, and the atmospheric boundary layer is strongly developed to cause its maximum height to reach about 3550 m. Moreover the sensible heat flux is dominant, and the latent heat flux is small in the interaction of land-atmosphere energy exchange, and a reverse humidity phenomenon occurs frequently. In the rainy season, the air is damper, air temperature lower, and the ABL height, with maximum of only about 2300 m, is lower. And the sensible heat flux becomes much smaller, the latent heat flux much larger in the interaction of land-atmosphere energy exchange. The reverse humidity phenomenon disappears.     

Eclogites in the interior of the Tibetan Plateau and their geodynamic implications

Eclogites have been recently reported in the interior of the Tibetan Plateau, including in the central Qiangtang metamorphic belt, in the Basu metamorphic massif of the eastern Bangong-Nujiang suture zone, and at Songdo and Pengco in the eastern Lhasa terrane. Some typical ultrahigh-pressure （UHP） metamorphic phenomena, e.g., garnet exsolution from clinopyroxene, were documented in the Basu and Pengco eclogites. The UHP metamorphism in the interior of the Tibetan Plateau marked by these eclogites generally took place in the Early Mesozoic. Along with exhumation of these eclogites, （post-） collision-related magmatism extensively occurred around the central Qiangtang belt, the eastern Bangong-Nujiang suture zone, and the eastern Lhasa terrane. The occurrence of these Early Mesozoic eclogites manifests an out-of-sequence evolution of the Tethys, and they could be a product of diachronous collision between the eastern Qiangtang terrane and the irregular continental margin of the united western Qiangtang-Lhasa plate, along the linked eastern Bangong-Nujiang-central Qiangtang zone. The collision-related magmatic rocks could have been originated from lithospheric thickening, melting, or detachment due to the collision. The presence of UHP metamorphic rocks in central Qiangtang and Basu implies likely continental deep-subduction, and the denudation of these two metamorphic zones could have served as the source of the Triassic turbidites in the Songpan-Garze complex and the Jurassic turbidites in the western Bangong-Nujiang zone, respectively. However, studies of the eclogites in the interior of the Tibetan Plateau just began, and many principal aspects still remain to be explored, such as their distributions, typical lithologies and minerals, temperature-pressure conditions, timing of formation and exhumation, protoliths and tectonic setting, and relationship with the evolution of the Tethys and large-scale basins in Tibet.