Assessment of channel changes due to long-term bedload supply decrease, Roubion River, France   总被引：1，自引：0，他引：1  

F. Libault  H. Pigay 《Geomorphology》2001,36(3-4)

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GPS／BeiDou 组合单点定位的定权与结果分析     

潘林  蔡昌盛  戴吾蛟  高晓 《全球定位系统》2013,(6):12-16

利用Helmert方差分量估计方法为GPS/BeiDou组合单点定位不同系统观测值定权,获得了合理的权值。分析了开阔环境和遮挡环境两种情况下的动态GPS/BeiDou组合单点定位的精度。结果表明：在静态观测和动态观测中,组合单点定位与单独G PS单点定位相比精度有显著提高。  相似文献   

局部曲面正切曲率与流线曲率的水流路径算法   总被引：1，自引：0，他引：1  

张占阳  郑红梅  郭新成  王金良 《测绘科学》2013,38(2)

在局部特殊地形如细窄的沟渠等地带,水流方向可能是惟一的,即当前点的水应全部流入下游惟一的格网点,此时若采用多流向算法不仅会导致水流方向产生较大误差,而且可能影响区域汇水面积的精确计算。为解决此问题,本文提出了一种水流路径算法,该算法通过以各格网点为中心建立3×3窗口范围内的局部趋势面,利用该点在局部趋势面中的正切曲率和流线曲率选取合适的单流向或多流向算法来确定并计算该点的水流流向及流量分配比例。最后通过实例证明了该方法在水流累积量计算中的良好效果,并在一定程度上为格网DEM沟谷段和分水线段的提取奠定了基础。  相似文献   

Similar single-difference model and its algorithm for solving GPS monitoring deformation directly at single epoch     

Yu Xuexiang  Xu Shaoquan  Gao Wei  Lü Weical 《地球空间信息科学学报》2013,16(4):51-56

A new similar single-difference mathematical model (SS-DM) and its corresponding algorithm are advanced to solve the deformation of monitoring point directly in single epoch. The method for building the SSDM is introduced in detail, and the main error sources affecting the accuracy of deformation measurement are analyzed briefly, and the basic algorithm and steps of solving the deformation are discussed.  相似文献   

PUBLICATIONS OF THE IAHS     

《水文科学杂志》2013,58(3):365-370

Abstract

Gauging stations where the stage—discharge relationship is affected by hysteresis due to unsteady flow represent a challenge in hydrometry. In such situations, the standard hydrometric practice of fitting a single-valued rating curve to the available stage—discharge measurements is inappropriate. As a solution to this problem, this study provides a method based on the Jones formula and nonlinear regression, which requires no further data beyond the available stage—discharge measurements, given that either the stages before and after each measurement are known along with the duration of each measurement, or a stage hydrograph is available. The regression model based on the Jones formula rating curve is developed by applying the monoclinal rising wave approximation and the generalized friction law for uniform flow, along with simplifying assumptions about the hydraulic and geometric properties of the river channel in conjunction with the gauging station. Methods for obtaining the nonlinear least-squares rating-curve estimates, while factoring in approximated uncertainty, are discussed. The broad practical applicability and appropriateness of the method are demonstrated by applying the model to: (a) an accurate, comprehensive and detailed database from a hydropower-generated highly dynamic flow in the Chattahoochee River, Georgia, USA; and (b) data from gauging stations in two large rivers in the USA affected by hysteresis. It is also shown that the model is especially suitable for post-modelling hydraulic and statistical validation and assessment.  相似文献   

Assessing the impacts of reservoir operation on downstream water diversions using a simplified flow model     

Zhaohua Sun  Xuefeng Chu 《水文科学杂志》2013,58(12):1488-1503

ABSTRACT

The operation of the Three Gorges Reservoir (TGR) affects the evolution of the interactions between the Yangtze River and Dongting Lake in China and water diversions from the river, which are essential to water resources management in this large river–lake system. Due to the lack of up-to-date and detailed channel topographic/bathymetric data, a simplified flow model based on rating curves was developed to simulate discharges in the river system, and to further quantify and differentiate the contributions of river erosion and flow regulation of the TGR at a seasonal scale. The results indicate that the effect of channel alteration counteracts the effect of reservoir regulation in the high-flow periods. The impacts of TGR regulation on water diversions for both pre- and post-flood seasons were significant, but no obvious changes in the discharge diversion ratios were observed on an annual time scale.  相似文献   

单台全球地震快速分析软件介绍及应用     

李万金 《地震研究》2013,36(2):224-230

阐述了自主研发的单台全球地震快速分析软件的功能、特点及应用效果。通过分析原有地震分析软件存在的不足并加以改进,使该软件具有台站地震快速分析所需的多种功能。应用实践表明,该软件具有功能完备、自动化程度高、界面友好等优点,在保障测震分析质量、减轻测震分析人员的工作量以及提高大震速报能力等方面成效显著。  相似文献   

IPSTAR卫星在高斯信道中传输数据应用与性能分析     

景晟  韩进  宋澄 《地震地磁观测与研究》2013,34(3)

IPSTAR系统由IPSTAR号卫星、地面业务关口站和小口径天线地面终端组成.本文通过建立调制方式模型和高斯信道模型,分析卫星信号信噪比及传输性能,对比信噪比不同的星座图,分析卫星通信系统使用QPSK调制方式调制、传输地震数据对信号的影响,为使用卫星通信系统传输地震数据提供理论依据.  相似文献   

Stream Channel Enlargement Response to Urban Land Cover in Small Coastal Plain Watersheds,North Carolina   总被引：1，自引：1，他引：0  

《自然地理学》2013,34(6):528-555

Stream channel response to urban land use has not been well documented for southeastern Coastal Plain streams. In this study, urban channel response was evaluated in small Inner Coastal Plain watersheds (<5 km²) in eastern North Carolina. Reaches were selected across a range of watershed total impervious area (0-67% TIA). Channel dimensions and sediment grain size data were collected along 20 urban (>10% TIA) and 20 rural reaches (<10% TIA), and at 10 stormwater outfall sites (180 cross-sections). Urban cross-sectional area, channel incision ratio, and channel grain size (gravel%, D₅₀, and D₈₄) were greater, relative to rural channels. Bankfull cross-sectional areas were approximately 1.78 times greater for urban watersheds than for rural watersheds. Channels in urban watersheds were incised and had median full-channel capacities approximately 3.4 times greater than channels draining rural watersheds. Watershed TIA explained 65-72% of channel capacity enlargement. Urban expansion in the region began in the 1960s, with major urbanization occurring over the last 25 years. Channels draining urban watersheds are still responding to this land use change by downcutting and widening. Urban channel incision has frequently cut off streams from their floodplains, reducing floodplain sediment retention and water quality functions.  相似文献   

The Geomorphology of Valley-Floor Troughs Illustrated From Depositional Sequences in the Durance Valley,Southeast France     

《自然地理学》2013,34(6):475-493

Three kinds of valley-floor troughs occur in the Durance catchment of southeast France. Details of widths and spatial variations of 10 different sedimentary forms are presented to show how these relate to the present types of troughs and their margins. Internal controls, such as geology, altitude, and available relief, provide a wide variety of conditions, which have been modified through time by external controls such as past and present climates and their hydrological regimes, as well as by anthropogenic activity over several millennia. The 10 sedimentary forms occupy more than 900 km² or 6.4% of the total catchment area, with the present enlarged floodplain having just over 50% of this area. The present channel occupies less than 10%, which is less than the Würm terrace (17.2%) but somewhat more than the marginal colluvia in the lower valley (8.6%). The other forms include older Pleistocene terraces, moraines from the last three glacial stages, and alluvial fans. It is the type of trough and its relative age that condition what, where, and how much of past and present sedimentary forms can survive.  相似文献