Stream channel erosion in a rapidly urbanizing region of the US–Mexico border: documenting the importance of channel hardpoints with Structure‐from‐Motion photogrammetry          下载免费PDF全文

Kristine T. Taniguchi  Trent W. Biggs  Eddy J. Langendoen  Carlos Castillo  Napoleon Gudino‐Elizondo  Yongping Yuan  Douglas Liden 《地球表面变化过程与地形》2018,43(7):1465-1477

Urbanization can lead to accelerated stream channel erosion, especially in areas experiencing rapid population growth, unregulated urban development on erodible soils, and variable enforcement of environmental regulations. A combination of field surveys and Structure‐from‐Motion (SfM) photogrammetry techniques was used to document spatial patterns in stream channel geometry in a rapidly urbanizing watershed, Los Laureles Canyon (LLCW), in Tijuana, Mexico. Ground‐based SfM photogrammetry was used to map channel dimensions with 1 to 2 cm vertical mean error for four stream reaches (100–300 m long) that were highly variable and difficult to survey with a differential GPS. Regional channel geometry curves for LLCW had statistically larger slopes and intercepts compared with regional curves developed for comparable, undisturbed reference channels. Cross‐sectional areas of channels downstream of hardpoints, such as concrete reaches or culverts, were up to 64 times greater than reference channels, with enlargement persisting, in some cases, up to 230 m downstream. Percentage impervious cover was not a good predictor of channel enlargement. Proximity to upstream hardpoint, and lack of riparian and bank vegetation paired with highly erodible bed and bank materials may account for the instability of the highly enlarged and unstable cross‐sections. Channel erosion due to urbanization accounts for approximately 25–40% of the total sediment budget for the watershed, and channel erosion downstream of hardpoints accounts for one‐third of all channel erosion. Channels downstream of hardpoints should be stabilized to prevent increased inputs of sediment to the Tijuana Estuary and local hazards near the structures, especially in areas with urban settlements near the stream channel. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

山东地磁台网受宁东高压直流输电干扰预处理质量分析   总被引：2，自引：0，他引：2  

林秀娜  曲保安  贾立国  陈传华  范晓勇  邢伟伟  袁倩  池国民 《中国地震》2018,34(1):141-149

为进一步提高山东地磁台网受高压直流输电干扰的预处理质量,通过中国地震前兆数据处理系统中相对差值检测和预处理检测功能,对山东地磁台网多年来受宁东高压直流输电干扰预处理情况进行了总结分析。结果表明,经过数据预处理,宁东高压直流输电干扰基本被去除,但仍然存在高压直流输电干扰误判、起止时间错判、干扰幅度计量不精确等问题。针对上述问题,对数据进行复核和校对,应用"缓变台阶"功能重新处理,并加强对H、D分量干扰特征的研究。  相似文献   

大鹏湾海区营养盐年际变化及富营养化研究   总被引：5，自引：0，他引：5  

黎广媚  林洪瑛  陈凯彪  董燕红 《海洋通报》2004,23(3):61-65

根据1993—2003年7月、8月和9月在大鹏湾海区3个站位的表、底层水样现场监测资料,分析了大鹏湾海区氮、磷营养盐的年际变化趋辨。分别运用水质质量标准指数法、综合指数WQI法评价了大鹏湾海区水质质量。运用营养状况综合指数法进行了营养状况评价。结果表明,大鹏湾海区夏季的氮、磷营养盐水平较低,N／P比值介于7～30之间。  相似文献   

近岸海水质量量化方法及分类评价   总被引：2，自引：1，他引：1  

曾江宁  黄韦艮  曾淦宁  郑平  周青松  吕海燕  王正方 《海洋学报》2004,26(4):139-146

近岸海域是陆地、海洋和大气之间各种过程相互作用最活跃的界面[1],沿海100km以内区域聚积着约60%的世界人口[2],其环境质量强烈受人类活动影响.对近岸海域进行水质环境管理,应依据海水物理、化学和生物学性质对海水进行分类评价[3,4].  相似文献   

Geochemistry of the Springfield Plateau aquifer of the Ozark Plateaus Province in Arkansas,Kansas, Missouri and Oklahoma,USA     

James C. Adamski 《水文研究》2000,14(5):849-866

Geochemical data indicate that the Springfield Plateau aquifer, a carbonate aquifer of the Ozark Plateaus Province in central USA, has two distinct hydrochemical zones. Within each hydrochemical zone, water from springs is geochemically and isotopically different than water from wells. Geochemical data indicate that spring water generally interacts less with the surrounding rock and has a shorter residence time, probably as a result of flowing along discrete fractures and solution openings, than water from wells. Water type throughout most of the aquifer was calcium bicarbonate, indicating that carbonate‐rock dissolution is the primary geochemical process occurring in the aquifer. Concentrations of calcium, bicarbonate, dissolved oxygen and tritium indicate that most ground water in the aquifer recharged rapidly and is relatively young (less than 40 years). In general, field‐measured properties, concentrations of many chemical constituents, and calcite saturation indices were greater in samples from the northern part of the aquifer (hydrochemical zone A) than in samples from the southern part of the aquifer (hydrochemical zone B). Factors affecting differences in the geochemical composition of ground water between the two zones are difficult to identify, but could be related to differences in chert content and possibly primary porosity, solubility of the limestone, and amount and type of cementation between zone A than in zone B. In addition, specific conductance, pH, alkalinity, concentrations of many chemical constituents and calcite saturation indices were greater in samples from wells than in samples from springs in each hydrochemical zone. In contrast, concentrations of dissolved oxygen, nitrite plus nitrate, and chloride generally were greater in samples from springs than in samples from wells. Water from springs generally flows rapidly through large conduits with minimum water–rock interactions. Water from wells flow through small fractures, which restrict flow and increase water–rock interactions. As a result, springs tend to be more susceptible to surface contamination than wells. The results of this study have important implications for the geochemical and hydrogeological processes of similar carbonate aquifers in other geographical locations. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Accuracy improvement of ASTER stereo satellite generated DEM using texture filter     

Mandla V.Ravibabu  Kamal Jain  Surendra Pal Singh  Naga Jyothi Meeniga 《地球空间信息科学学报》2010,13(4):257-262

The grid DEM(digital elevation model) generation can be from any of a number of sources:for instance,analogue to digital conversion of contour maps followed by application of the TIN model,or direct elevation point modelling via digital photogrammetry applied to airborne images or satellite images.Currently,apart from the deployment of point-clouds from LiDAR data acquisition,the generally favoured approach refers to applications of digital photogrammetry.One of the most important steps in such deployment i...  相似文献   

通过技术规定提高软件质量     

王聿贤 《国土资源信息化》2010,(1):72-75

本文主要介绍了《上海局应用软件产品技术规定》的缘起、编制过程、主要内容和如何落地实施等方面的内容,以及规定本身和落实过程中遇到的问题,分析了问题的成因并就如何解决提了一些建议。  相似文献   

GPS网中基准点的数量及位置分布对精度的影响分析     

李金生  杨学锋  马驰 《全球定位系统》2010,35(2):30-32

GPS网中,基准点的数量、组合方式及其分布位置都将影响到GPS网的定位精度,不合理的组合和分布方式也会影响GPS网固有的高精度。为了获取高质量的GPS定位成果,布设高等级控制网时必须要科学地选择基准点的数量及其分布,以便找到最佳组合方案。通过工程实例,分析了GPS网中基准点组合及分布方法,得出了相关结论。  相似文献   

GIS中属性数据质量控制的研究     

张明  周世健  曾绍炳 《测绘科学》2010,35(3):71-73

随着土地信息系统应用的扩大和分析功能的扩充,对数据的要求也越来越高,尤其是对属性数据的要求越来越高,因而对属性数据进行质量检验和分析就显得格外重要。目前对GIS数据质量控制的大多数研究主要是针对表示拓扑关系的图形数据,对属性数据的研究则相对较少。本文在前人对GIS中数据精度的度量和质量控制作了初步的描述的基础上,对其中属性数据的质量控制与评价方法进行了研究。  相似文献   

基于图像匹配的机载遥感影像质量自动检查方法研究   总被引：1，自引：0，他引：1  

段福洲  赵文吉 《测绘科学》2010,35(6):57-58,102

航空遥感平台和技术的发展,促进了航空遥感影像在基础地理信息获取、国土监测、环境监测、应急救灾等各个领域中的应用。同时,航空遥感系统对飞行环境、气候气象反应较为灵敏,遥感影像质量的检查十分重要。本文系统地阐述了航空遥感影像质量中旋转角、航向重叠率、旁向重叠率、航带生成等参数的计算理论与方法,该方法是适应数字遥感影像的现状上提出的,并且通过自行开发的系统对算法的可行性和有效性进行验证。本文利用2009年6月机载遥感系统拍摄的1400多张影像进行实验。实验结果表明技术方法、软件系统都较为有效,达到机载遥感影像质量自动检查要求。  相似文献