Bound and mobile soil water isotope ratios are affected by soil texture and mineralogy,whereas extraction method influences their measurement     

Rachel E. Adams  Ayumi Hyodo  Toby SantaMaria  Cynthia L. Wright  Thomas W. Boutton  Jason B. West 《水文研究》2020,34(4):991-1003

Questions persist about interpreting isotope ratios of bound and mobile soil water pools, particularly relative to clay content and extraction conditions. Interactions between pools and resulting extracted water isotope composition are presumably related to soil texture, yet few studies have manipulated the bound pool to understand its influence on soil water processes. Using a series of drying and spiking experiments, we effectively labelled bound and mobile water pools in soils with varying clay content. Soils were first vacuum dried to remove residual water, which was then replaced with heavy isotope-enriched water prior to oven drying and spiking with heavy isotope-depleted water. Water was extracted via centrifugation or cryogenic vacuum distillation (at four temperatures) and analysed for oxygen and hydrogen isotope ratios via isotope ratio mass spectrometry. Water from centrifuged samples fell along a mixing line between the two added waters but was more enriched in heavy isotopes than the depleted label, demonstrating that despite oven drying, a residual pool remains and mixes with the mobile water. Soils with higher clay + silt content appeared to have a larger bound pool. Water from vacuum distillation samples have a significant temperature effect, with high temperature extractions yielding progressively more heavy isotope-enriched values, suggesting that Rayleigh fractionation occurred at low temperatures in the vacuum line. By distinctly labelling bound and mobile soil water pools, we detected interactions between the two that were dependent on soil texture. Although neither extraction method appeared to completely extract the combined bound and mobile (total water) pool, centrifugation and high temperature cryogenic vacuum distillations were comparable for both δ²H and δ¹⁸O of soil water isotope ratios.  相似文献   

A literature synthesis of LiDAR applications in transportation: feature extraction and geometric assessments of highways     

Suliman A. Gargoum  Karim El Basyouny 《地理信息系统科学与遥感》2019,56(6):864-893

Interest in using Light Detection and Ranging (LiDAR) technology in Transportation Engineering has grown over the past decade. The high accuracy of LiDAR datasets and the efficiency by which they can be collected has led many transportation agencies to consider mobile LiDAR as an alternative to conventional tools when surveying roadway infrastructure. Nonetheless, extracting semantic information from LiDAR datasets can be extremely challenging. Although extracting roadway features from LiDAR has been considered in previous research, the extraction of some features has received more attention than others. In fact, for some roadway design elements, attempts to extract those elements from LiDAR have been extremely scarce. To document the research that has been done in this area, this paper conducts a thorough review of existing studies while also highlighting areas where more research is required. Unlike previous research, this paper includes a thorough review of the previous attempts at data extraction from LiDAR while summarizing the detailed steps of the extraction procedure proposed in each study. Moreover, the paper also identifies common tools and techniques used to extract information from LiDAR for transportation applications. The paper also highlights common limitations in existing algorithms that could be improved in future research. This paper represents a valuable resource for researchers and practitioners interested in knowing the current state of research on the applications of LiDAR in the field of Transportation Engineering while also understanding the opportunities and challenges that lie ahead.  相似文献   

Landsat长时间序列的阳澄湖湖面围网时空变化     

计璐艳  尹丹艳  宫鹏 《遥感学报》2019,23(4):717-729

准确提取湖泊围网区域的时空分布信息对湖泊的保护和可持续发展具有重要意义。本文以阳澄湖为研究区域,收集该地区1984年—2017年所有的Landsat 5和Landsat 8影像(共计396景),提出了结合光谱和纹理特征的围网提取新算法,同时利用时间序列滤波消除年际间因数据不一致造成的偏差。以高清影像人工解译作为参考,阳澄湖围网提取结果的生产者精度在72.57%—88.53%,用户者精度在79.79%—98.10%,围网面积变化与文献记录吻合。结果表明,阳澄湖围网经历了"无围网期"(1984年—1994年)、"快速增长期"(1994年—1998年)、"巅峰期"(1999年—2002年)、"快速下降期"(2003年—2006年)和"稳定期"(2007年—2017年)5个阶段,最高达到100 km2,目前稳定在30 km2;通过研究围网区植被指数发现,2002年之后围网区浮水植物的种植面积增大;通过对比水质数据发现,2002年至今持续15年的围网拆除并未使阳澄湖恢复到80年代无围网养殖时期的II类水,其水质依然处于Ⅲ—Ⅳ类。因此在湖泊养殖开发过程中,政府应该坚持可持续发展道路,在不破坏湖泊水质的基础上发展湖泊经济。  相似文献   

基于决策树分类的大屯矿区地物信息提取及矿区污染分析     

于海若  燕琴  董春  战丽丽 《测绘与空间地理信息》2016,(4):67-69,72

本文在对国内外遥感图像分类方法充分研究分析的基础上,选择决策树分类法对大屯矿区的Landsat 8遥感图像进行分类研究。选取样本提取并分析研究区典型地类光谱特征曲线,依据光谱曲线特征和归一化植被指数建立了土地利用分类决策树模型,通过反复试验和修正,筛选出适宜大屯矿区地物分类的决策树最优阈值,对研究区进行分类和精度评价,最后通过分类结果对研究区的水体污染状况进行简要分析。  相似文献   

运用ENVI实现SPOT-5卫星影像的RVI提取     

尹芬  丁美青 《测绘与空间地理信息》2016,(1)

运用ENVI软件处理长沙地区的SPOT-5影像,将全色影像和多波段影像进行融合,分析融合后的影像,再选择感兴趣区域进行影像裁剪;采用ENVI的波段运算(Band3/Band2)提取该地区比值植被指数并进行分析。结果表明:比值植被指数对植被覆盖率较高的区域有非常高的敏感度;在植被覆盖率小于50%的时候,其敏感度明显降低,在绿色植被覆盖区域的比值植被指数远大于1,在裸露地表、建筑物、水体等没有植被覆盖区域的比值植被指数则在1附近,而比值植被指数大于2的则出现在高覆盖健康绿色植被上。  相似文献   

基于光谱角匹配算法的水体信息提取研究     

齐庆超  张小磊  金江峰  金玉玲 《测绘与空间地理信息》2016,(2):93-96

针对水体信息提取时,传统算法不能较好地解决山体阴影被误提为水体的问题,引入多用于高光谱数据处理的光谱角匹配算法,以Land-sat8 OLI(band1-band7)为数据源,以黄河小浪底水库周边区域为实验区,开展水体信息提取研究,结果显示:水体指数法和波段关系提取的结果中有大量的山体阴影信息,提取精度不超过30%,而光谱角匹配法提取结果受阴影的影响较小,提取精度在99%以上。  相似文献   

地理国情普查时点核准作业方法探讨     

赵永亮  高明  张佳彬 《测绘与空间地理信息》2016,(2)

通过核实从数据采集到标准时点阶段发生变化的内容,补充新增内容,消除普查前阶段由于资料时效性和外业局限性等导致的现势性不统一现象,对变化的地理国情信息进行核准,使地理国情普查数据成果在时间上达到统一,是开展地理国情监测的基础。  相似文献   

基于CIPS软件探讨高山地DOM数据的生产方式     

刘涛  王明宇  于洪雨 《测绘与空间地理信息》2016,(4):186-188

在DOM数据生产中,山地、高山地数据一直以来都是重点和难点。本文分析了高山地影像数据的特点,提出一种与山地、高山地数据相适应的处理方式。最后基于CIPS软件,按需求设计对应的软件处理流程,并使用满足实验要求的高山地影像数据,对这种方式加以实现和验证。  相似文献   

基于OSTU算法利用新型水体指数进行Landsat数据自适应阈值水体自动提取研究     

赵紫薇 《测绘与空间地理信息》2016,(9):57-60

利用Landsat数据,结合NDWI与MNDWI提取水体信息的特点提出了一种新的水体指数NMWI,并结合OSTU算法自适应地确定最佳分割阈值,完成了对海洋、河流、湖泊和水库4种主要的典型水体信息的自动提取,均取得了较好的效果。  相似文献   

Pleiades高分辨率卫星影像道路提取技术     

张心红 《测绘与空间地理信息》2016,(11):115-117

遥感影像上的道路提取是摄影测量与计算机视觉研究的一项重要内容,本文设计了一种高分辨率卫星影像道路提取方法,首先,利用Canny边缘提取算子提取左影像上的边缘,并利用霍夫变换对线特征进行检测,根据道路的几何特性检测平行直线,再基于影像匹配方法匹配立体像对上的道路;然后,利用卫星影像RPC参数前方交会原理实现道路的几何定位。利用Pleiades卫星影像开展试验,自动提取的道路与人工采集的道路几何定位误差在1个像素以内,试验结果验证了本文方法的有效性。  相似文献