多源遥感技术在地质灾害早期识别应用中的问题探讨——以西南山区为例

在对滑坡、崩塌等地质灾害的早期识别工作中,基于InSAR、光学遥感、机载LiDAR等多源遥感技术发挥了重要作用。针对应用中出现的一些问题,基于多个项目实践,总结了多源遥感技术在西南山区地质灾害早期识别领域的适用条件,提出了相应的应用建议。主要认识如下: ①InSAR对地质灾害隐患的识别效果受植被覆盖程度、地形条件和数据源类型的制约; 广域InSAR应用中,需注意数据处理关键参数的取舍问题,尽快建立InSAR识别效果的野外判定方法,统一地表形变区“变形程度”和地质灾害InSAR识别效果的评价标准; ②地质灾害光学遥感早期识别适用于“斜坡区域具有明显变形特征”、“历史斜坡灾害”、“泥石流灾害和潜在泥石流沟”这3种类型,在具体应用中应根据不同工作任务要求,选取适合的数据源,注意对地质环境背景条件的分析,不挑战“微变形”探测短板; ③相比较InSAR和光学遥感,机载LiDAR在高密度植被覆盖区地质灾害早期识别方面优势明显,在具体应用中,建议激光点云密度不少于30~50处/m²; ④贴近摄影测量技术适用于高位崩塌(危岩体)早期识别,该技术属于光学遥感范畴,识别效果同样受植被覆盖程度影响,在具体应用中应设置合理探测距离,其具体数值需根据危岩壁分布情况进行调整,建议不小于30 m; ⑤提出了“多源遥感技术手段综合应用,优势互补”“工作部署多层次布置”“注重交叉学科应用及解译人员综合培养”“尽快开展地质灾害信息化获取能力建设”等应用建议。     

地震勘探中的时间-暴光声学

本文提出用于地下成像无源地震方法的分析,在该方法中应用环境地震噪声作为地下散射体的照明源。该成像算法能够以递归方式将新的数据融入到成像中,这使成像背景噪声随时间减少。在空间域不相干环境背景噪声的假设前提下推导出成像算法的点-扩展函数。点-扩展函数表征成像的分辨率,即接收排列长度和环境带宽的函数。     

数字摄像能见度仪器系统控制电路的设计

数字摄像能见度仪器系统(DPVS)是完全仿照人工目测能见度的方法测量能见度的,比传统的透射式、散射式能见度仪更具客观性。为了说明DPVS在硬件方面的工作原理,从该仪器系统的控制电路原理、电路详细构成、元器件的选配、电路设计思路以及系统在实际运行中出现的一些问题和解决方法等方面做了详细介绍。同时还对控制电路中应用的单片机的部分软件做了简要介绍。     

Effects of wet meadow riparian vegetation on streambank erosion. 1. Remote sensing measurements of streambank migration and erodibility

We quantified how rates of stream channel migration in a montane meadow vary as a function of the riparian vegetation community. The South Fork of the Kern River at Monache Meadow, located in California's southern Sierra Nevada range, supports two distinct types of vegetation: a dry meadow community dominated by sagebrush and non‐native grasses (xeric scrub and meadow), and a wet meadow community dominated by rushes and sedges (hydric graminoids). We measured rates of lateral stream migration for dry versus wet meadow reaches from aerial photographs spanning a 40‐year period (1955–1995). While stream migration rates averaged only 0·24 ± 0·02 m a^?1 in the wet meadow, the dry meadow channel migrated an average of 1·4 ± 0·3 m a^?1. We used a linear model of meander migration to calculate coefficients that characterize bank migration potential, or bank erodibility, independent of channel curvature. These calculations demonstrate that, at Monache Meadow, banks without wet meadow vegetation are roughly ten times more susceptible to erosion than banks with wet meadow vegetation. Where stream bank heights consistently exceed 1 m, low water availability creates riparian habitats dominated by dry meadow vegetation. Thus, channel incision may reduce bank stability not only by increasing bank height, but also by converting banks from wet meadow to dry meadow vegetation. Copyright © 2002 John Wiley & Sons, Ltd.     

Remote sensing documentation of historic rangeland remediation treatments in southern New Mexico

The Jornada Experimental Range and the New Mexico State University Chihuahuan Desert Rangeland Research Center are fruitful areas to study the long-term effects of rangeland remediation treatments which started in the 1930s. A number of diverse manipulations were completed under the direction of federal agency and university scientists, and abundant remote sensing imagery is available to assist in relocating the treatments and evaluating their success. This is particularly important because few of the treatments were maintained following the loss of scientific personnel coinciding with the start of World War II, and most records of Civilian Conservation Corps scientific work were lost with the disbanding of the agency in 1942. Aerial photography, which was systematically used to image the United States beginning in the 1930s, can be used to identify types of treatments, measure areal coverage, estimate longevity, and help plan locations for new experiments. No long-lasting vegetation response could be determined for contour terraces, brush water spreaders, strips grubbed free of shrubs (despite the fact that these strips have remained visible for 65 years), and mechanical rootplowing and seeding. Distinct positive, long-term vegetation responses could be seen in aerial photos for water retention dikes, certain fenced exclosures, and some boundaries where different land management practices meet. It appears from both aerial photos and existing conventional records that experimental manipulation of rangelands has often been ineffective on the landscape scale because treatments are not performed over large enough contiguous areas and hydrological and ecological processes overwhelm the treatments. In addition, treatments are not maintained over time, treatment evaluation periods are sometimes too short, multi-purpose treatments are not used to maximize effects, and treatments are often not located in appropriate sites.     

航测技术在高速公路勘测中的应用与实施——以二广高速为例

以二连浩特至广州高速公路(粤境段)为例,着重介绍了航测技术在高速公路勘测中的工作流程与相关技术的运用,对其在高速公路勘测中的应用现状与发展前景进行了总结与展望.     

地震映像法及其应用

简述了地震映像法的特点,并列举了在各种浅部不均体探测中的应用实例,指出了提高其应用效果,拓宽其应用领域应研究的问题。     

无人机倾斜摄影在城市规划中的应用

无人机倾斜摄影技术,是一种全新的地理信息获取手段,本文通过该技术制作出了深汕合作区实景三维模型及数字线画图,平面点位中误差和高程中误差均符合国家1:500地形图相关规范,可作为深汕合作区城市规划及建设的基本资料,为城市规划部门的决策提供了便利.通过清晰的纹理将城市及农村地物逼真地进行展示,对监管城市违法建筑物及新农村建...     

开放型摄影测量实验基地的设计与建立

摄影测量技术的学习和掌握离不开实验。文中提出建立开放型摄影测量实验基地模式,该基地应该具有如下功能:航空摄影,航测控制测量与调绘,数码相机检校,航测内业处理与测图。在该基地上,学生可以根据摄影测量的学习内容,选择相关实验项目,理论联系实际地学习掌握摄影测量基本理论和方法;学生也可以在基地上自主设计、模拟摄影测量生产过程,训练摄影测量技能,并进行摄影测量试验研究。该实验基地的设计理念和建立模式,将为高校现有摄影测量课程的教学和实验提供一种创新形式。