Evaluating land subsidence by field survey and D-In SAR technique in Damaneh City,Iran

Based on the data from piezometers, well logs, geophysical surveys and the interferometric synthetic aperture radar(In SAR) technique, this study investigates the main causes of land subsidence in Damaneh City, Iran. The size, openings and direction of fissures were measured by micrometer and compass. The locations of fissures and wall cracks were determined by GPS. The geoelectrical data were used to determine the composition, thickness, depth and shape of lower parts of the aquifer. Groundwater fluctuations were evaluated by available piezometers. The In SAR technique was used to measure land deformation from space and to map the dense changes of surface displacements. The results indicate that the main cause of ground subsidence is the decline of groundwater heads and changes in composition and thickness of compressible lacustrine sediments. The subsidence map obtained from the radar data of ASAR sensor of ENVISAT satellite shows that the subsidence zone is mainly in northern city that is underlain by very thick fine sediments. The subsidence rates from March to December 2005 and from July 2011 to January 2012 are 6.7 and 7.0 cm/a, respectively. The results also show good correlations among the formation of earth features, decline in groundwater head and thickness of fine-grained sediments. We recommend that the groundwater withdrawal for agricultural and industrial sectors should be restricted and urban expansion in the northern part of the city should be constrained.     

探地雷达用于树木单根成像的模拟技术研究

利用超宽带探地雷达技术,以及衍射层析成像算法实现对根系的探测与成像。通过时域有限差分法,对树木根系进行建模仿真,生成探地雷达扫描数据,然后利用衍射层析成像算法对仿真数据进行目标重建,得到根系横截面反演图像。并讨论了根的直径、介电特性及其分布情况对探地雷达探测根系的影响。仿真结果表明,在近似为无损的均匀土壤中,超宽带探地雷达能快速无损地实现地下根系目标探测,衍射层技术通过重建根系图像,初步实现树根的介电属性、形状特征估计和位置标定等,因而可用于探地雷达根系探测中,对树木根系的研究具有重要意义。     

物探方法在地下异常体勘探的应用

通过对地质雷达探测数据的分析,找出地下异常体的范围,为设计部门提供能够选择合理的桥址的资料。     

基于探地雷达的田块尺度下不同深度土壤含水量监测

为确定田块尺度下探地雷达对不同深度及相邻反射层间土壤含水量的反演精度、有效反演深度、最佳反演深度及最优反演模型,本研究采用1000 MHz中心频率探地雷达设备,分别在无降雨偏干旱土壤和降雨后湿润土壤两种条件下,在选定农田区域基于共中心点法采集雷达波数据,提取有效地表波与反射波数据,通过双曲线拟合法分别获取不同深度反射层...     

星载高分辨率合成孔径雷达影像纠正技术

TERRASAR、COSMO SkyMed、RADARSAT-2等星载高分辨率合成孔径雷达影像为土地利用调查监测提供了重要数据源,但尚未形成业务化应用技术流程。该文根据高分辨率星载合成孔径雷达影像成像机理,在对典型特征地物点定位精度分析的基础上,提出几何纠正控制点选取方法;通过类比法分析了不同纠正模型应用效果。试验表明高分辨率星载合成孔径雷达影像几何纠正需要10～15个控制点,1?m聚束模式纠正中误差约3～5 m,3 m条带模式纠正中误差约5～8 m,分别满足1∶1万和1∶2.5万土地调查监测几何精度要求。     

利用多普勒雷达产品识别重庆冰雹云指标分析

利用重庆、万州、恩施三部多普勒天气雷达产品,分析了重庆2008-2010年的9次冰雹过程,总结了一些冰雹天气的多普勒雷达回波特征指标.发现当回波强度大于等于50dBZ,回波顶高大于等于11km,垂直累积液态含水量大于等于44kg/m2,冰雹指数出现连续几个实心三角标志,中层具有强的风速辐合或者中气旋时容易降雹;出现三体散射回波等冰雹典型特征时肯定降雹.垂直累积液态含水量越大,大于60kg/m2的强VIL持续时间越长,冰雹直径越大.在冰雹云发展阶段VIL存在≥15kg/m2的明显跃增且跃增后VIL≥50kg/m2,这是冰雹独特的特征,对判别冰雹云有较高应用价值.     

Nocturnal Migration of Coleoptera: Carabidae in North China

Vertical-looking radar （VLR） has allowed long-term automatic monitoring of the altitudinal and temporal dynamics of high- flying insect populations. To investigate whether ground beetle, insect of Coleoptera, was capable of migrating and its migration pattern by taking advantages of capability of the VLR for long-term real-time automatic monitoring, the migration of Coleoptera ground beetle was investigated by setting up radar observation points, making long-term observation using the VLR and related supplementary equipment, and analyzing low altitude air current and large area circulating current in combination with the meteorological data. Information obtained in 2005 and 2006 showed that the seasonal activities of ground beetles traps of trap lamps were mainly from late June to late August, peak period was mainly in August, seasonal traps of high-altitude lamps and ground lamps were featured by sudden increase and sudden decrease; in peak period, the height of radar echo point could be as high as 600 m, while it was mainly below the height of 450 m; night activities mainly occurred from 20：00 to 22：00, in very few nights, radar echo could last until about 04：00, changes in numbers of ground beetles within the searchlights were consistent with radar echo intensity; ground beetle images were successfully trapped in the sweep nets carried by captive balloons at the height of 200 m. Some species of Carabidaes had some degrees of migration, thus providing the foundation for investigating the migration of Coleoptera insects.     

利用时序合成孔径雷达数据监测水稻叶面积指数

为了确定全极化雷达数据监测水稻叶面积指数动态变化的精度,该文对水稻叶面积指数与后向散射系数进行了各生长阶段建模比较。采用广东雷州地区多时相多入射角精细全极化Radarsat-2数据,结合水稻全生育期地面样方实测数据,首先分析多入射角归一化后四极化(vertical-horizontal polarization,VH;vertical-vertical polarization,VV;horizontal-horizontal polarization,HH;horizontal-vertical polarization,HV)、比值极化HH/VV后向散射系数与水稻叶面积指数(leaf area index,LAI)随时间变化特征以及在营养生长阶段、生殖生长阶段和全生育期的相关关系,提取相关系数高于0.8的极化与生长阶段进行水云模型建模,最终生成多期水稻LAI反演分布图,并验证该数据反演水稻各生长阶段LAI的精度,探索SAR数据追踪区域尺度水稻长势的可行性。结果表明,在地形较为平坦的水稻集中连片种植区,VV、HH/VV后向散射系数与LAI在营养生长期、全生育期极显著相关(P0.01),相关系数均高于0.83。营养生长阶段VV、HH/VV水云模型拟合决定系数分别为0.77、0.87,全生育期VV、HH/VV水云模型拟合决定系数分别为0.73、0.8,营养生长阶段模型优于全生育期模型。精细四极化SAR数据监测区域尺度水稻LAI动态变化具有应用潜力,优选的极化模型为进一步的水稻长势监测提供依据。     

探地雷达树木根系定位与直径估算

针对树木根系的探地雷达(Ground Penetrating Radar,GPR)检测图像复杂、解译困难、自动化程度低且精度不高等问题,该研究提出了一种基于YOLOv3的树根自动识别和参数估计的方法.通过不同的根预埋试验分析了根直径、掩埋深度和朝向对根系识别和预测的影响,对比评估了在复杂现场环境下该方法与商业软件常用的...     

濮阳市一次短历时强降水诊断分析

利用常规天气图、NCEP全球分析资料(FNL)、自动站观测资料、新一代多普勒雷达资料,对2013年7月18日05:00 ～09:00濮阳市出现的一次短历时强降水天气过程进行了诊断分析.结果表明,这次强降水过程是由高空三层的暖切变、584 dagpm线边缘的暖湿气流、地面西南倒槽北上及华北冷空气向南扩散共同影响造成的.高空三层东西向暖切变在濮阳市上空的重合,既提供了动力抬升,又有利于暖湿气流的辐合及上升;高空三层西南暖湿气流的叠加,提供了深厚的水汽通道;西南倒槽顶部冷暖空气交汇处具有较大的斜压性,有利于强降水的产生.强降水发生时高空有充足的水汽输送及其在濮阳上空的辐合,该地又有近于饱和的湿层配合,为强降水的产生提供了充足的水汽条件.在湿度层结深厚且具有热力不稳定、对流不稳定的气层中,有垂直风切变的触发,很容易产生短时强天气.濮阳位于等θse线密集带南部边缘大值区内,斜压性大,有利于气旋性涡度发展,致使上升运动增强,可使降水强度增大.