Geostatistical features of streambed vertical hydraulic conductivities in Frenchman Creek Watershed in Western Nebraska     

Olufemi P. Abimbola  Aaron R. Mittelstet  Troy E. Gilmore 《水文研究》2020,34(16):3481-3491

This study evaluated the spatial variability of streambed vertical hydraulic conductivity (K_v) in different stream morphologies in the Frenchman Creek Watershed, Western Nebraska, using different variogram models. Streambed K_v values were determined in situ using permeameter tests at 10 sites in Frenchman, Stinking Water and Spring Creeks during the dry season at baseflow conditions. Measurements were taken both in straight and meandering stream channels during a 5 day period at similar flow conditions. Each test site comprised of at least three transects and each transect comprised of at least three K_v measurements. Linear, Gaussian, exponential and spherical variogram models were used with Kriging gridding method for the 10 sites. As a goodness-of-fit statistic for the variogram models, cross-validation results showed differences in the median absolute deviation and the standard deviation of the cross-validation residuals. Results show that using the geometric means of the 10 sites for gridding performs better than using either all the K_v values from the 93 permeameter tests or 10 K_v values from the middle transects and centre permeameters. Incorporating both the spatial variability and the uncertainty involved in the measurement at a reach segment can yield more accurate grid results that can be useful in calibrating K_v at watershed or sub-watershed scales in distributed hydrological models.  相似文献   

Effect of spatial variation characteristics on contouring of design storm depth     

Ke‐Sheng Cheng  Chiang Wei  Yen‐Ben Cheng  Hui‐Chung Yeh 《水文研究》2003,17(9):1755-1769

The ordinary kriging method, a geostatistical interpolation technique, was applied for developing contour maps of design storm depth in northern Taiwan using intensity–duration–frequency (IDF) data. Results of variogram modelling on design storm depths indicate that the design storms can be categorized into two distinct storm types: (i) storms of short duration and high spatial variation and (ii) storms of long duration and less spatial variation. For storms of the first category, the influence range of rainfall depth decreases when the recurrence interval increases, owing to the increasing degree of their spatial independence. However, for storms of the second category, the influence range of rainfall depth does not change significantly and has an average of approximately 72 km. For very extreme events, such as events of short duration and long recurrence interval, we do not recommend usage of the established design storm contours, because most of the interstation distances exceed the influence ranges. Our study concludes that the influence range of the design storm depth is dependent on the design duration and recurrence interval and is a key factor in developing design storm contours. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Influence of Structural Non-Stationarity of Surface Roughness on Morphological Characterization and Mechanical Deformation of Rock Joints   总被引：2，自引：2，他引：0  

N. Fardin 《Rock Mechanics and Rock Engineering》2008,41(2):267-297

Summary Structural non-stationarity of surface roughness affects accurate morphological characterization as well as mechanical behaviour of rock joints at the laboratory scale using samples with a size below the stationarity threshold. In this paper, the effect of structural non-stationarity of surface roughness is investigated by studying the scale dependence of surface roughness and mechanical behaviour of rock joints. The results show that the structural non-stationarity mainly affects the accurate characterization of the surface roughness of the fracture samples. It also controls the amount and location of the contact areas during shear tests, which in turn affects the mechanical properties and asperity degradation of the samples. It is concluded that for accurate determination of the morphological and mechanical properties of rock joints at laboratory and field scales, samples with size equal to or larger than the stationarity threshold are required. Author’s address: Nader Fardin, Rock Mechanics Group, Department of Mining Engineering, Faculty of Engineering, University of Tehran, P.O. Box: 11365/4563, Tehran, Iran  相似文献   

Change of multifractal thermal characteristics in the western Philippine sea upper layer during internal wave-soliton propagation     

Peter C. Chu  Chung-Ping Hsieh 《Journal of Oceanography》2007,63(6):927-939

The upper layer (above 140 m depth) temperature in the western Philippine Sea near Taiwan was sampled using a coastal monitoring buoy (CMB) with 15 attached thermistors during July 28–August 7, 2005. The data were collected every 10 min at 1, 3, 5, 10, 15, and 20 m using the CMB sensors, and every 15 sec at 15 different depths between 25 m and 140 m. Internal waves and solitons were identified from the time-depth plot of the temperature field. Without the internal waves and solitons, the power spectra, structure functions, and singular measures (representing the intermittency) of temperature field satisfy the power law with multi-scale characteristics at all depths. The internal waves do not change the basic characteristics of the multifractal structure. However, the internal solitons change the power exponent of the power spectra drastically, especially in the low wave number domain; they also break down the power law of the structure function and increase the intermittency parameter. The physical mechanisms causing these different effects need to be explored further.  相似文献   

实验变差函数计算方法的研究与运用   总被引：1，自引：0，他引：1  

李章林  王平  李冬梅 《国土资源信息化》2008,(2):10-14

本文系统、详尽地分析讨论了不同样品数据条件下实验变差函数的计算方法。在实验变差函数计算流程的设计和有效样品搜索域的确定方面提出了自己独特的见解。最后用一个矿山的控矿工程教据对文中介绍的方法进行了测试。结果表明,利用本文的方法,容易得到稳健、准确、信息量高的实验变差函数。  相似文献   

Kriging with imprecise (fuzzy) variograms. I: Theory   总被引：2，自引：0，他引：2  

A. Bardossy  I. Bogardi  W. E. Kelly 《Mathematical Geology》1990,22(1):63-79

Imprecise variogram parameters are modeled with fuzzy set theory. The fit of a variogram model to experimental variograms is often subjective. The accuracy of the fit is modeled with imprecise variogram parameters. Measurement data often are insufficient to create good experimental variograms. In this case, prior knowledge and experience can contribute to determination of the variogram model parameters. A methodology for kriging with imprecise variogram parameters is developed. Both kriged values and estimation variances are calculated as fuzzy numbers and characterized by their membership functions. Besides estimation variance, the membership functions are used to create another uncertainty measure. This measure depends on both homogeneity and configuration of the data.  相似文献   

灌淤土壤可溶性盐分空间变异性与棉花生长关系研究   总被引：8，自引：3，他引：8  

杨玉玲  田长彦  盛建东  文启凯 《干旱区地理》2002,25(4):329-335

运用地统计学方法，在灌淤土壤上进行了棉田土壤可溶性盐分的空间变异规律与棉花生长关系系统研究。传统统计学分析表明土壤盐分测试数据基本符合正态分布；在一定取样间距下，土壤可溶性盐分的田间合理取样数目为27。半方差分析显示：土壤可溶性盐分具中等的水平变异性，但随着聚样深度的增加未表现出明显的垂直变异特性；随着棉花的生长发育，土壤可溶性盐分呈现出逐渐减弱的时间变异规律，采用直线或曲线拟合方程估计了可溶性盐分的半方差图及其参数，并绘制了其相应的等值线图。土壤可溶性盐分与棉花产量之间的相关分析表明：可溶性盐分含量与棉花产量之间呈显著负相关关系，且花铃期的相关性较播前显著。研究结果为提高田间试验有效性以及盐渍化土壤改良提供了科学依据与基础资料。  相似文献   

三种地统计学图像纹理用于遥感图像分类的比较   总被引：5，自引：0，他引：5  

李培军  李争晓 《地理与地理信息科学》2003,19(4):89-92

该文运用LANDSAT TM数据对三种地统计学纹理量测方法用于图像分类的性能进行了比较和分析。研究发现，基于绝对值变差函数的纹理具有更好的性能。经典的变差函数和基于方根的变差函数的性能依赖于提取纹理时所用的窗口大小。  相似文献   

两种方法在地下水位估值中的应用   总被引：2，自引：0，他引：2  

李金荣  杨振放  李云峰  李金玲 《水文地质工程地质》2003,30(3):42-46

对于许多区域水资源问题,用数值方法进行潜水水流模拟时,需要给出每个节点上地下水位值。本文首先简单介绍了趋势面方法,然后着重阐述了泛克里格方法的基本原理及它们在地下水位估值中的应用,通过比较两种方法的计算结果可以得出泛克里格方法是进行地下水位估值的空间最优估计方法。  相似文献   

Statistical tests for regional seismic phase characterizations   总被引：1，自引：0，他引：1  

L. Persson 《Journal of Seismology》2003,7(1):19-33

In seismic analysis some assumptions are often made aboutthe data, e.g. stationarity and Gaussianity. This is not obvious for all realseismic data. Here, we use statistical tests for characterization of regionalseismic data. We apply tests for stationarity, symmetry, linearity, andtime-reversibility. In the analysis we use twelve regional seismic events inFennoscandia recorded with the seismic small-aperture arrays NORESS,ARCESS and FINESA at hypocentral distances in the range from 160 to1580 km. For the tests we use the regional phases Pn, secondary P, Sn and Lg-phases and the preceding noise. Two of the eventsare explosions, two are rockbursts and eight are earthquakes. Theperformance and possibilities of using statistical tests based on bispectra, asa complementary tool for conventional analysis of seismic phases isdemonstrated. The preceding noise recorded before the first onset of theP-wave for the twelve events is tested to be spatially stationarybetween each channel within each array and temporal stationary in 21consecutive time windows of 3.2 sec each. Also, the preceding noise issymmetric and linear. The seismic phases defined by the symmetry test asnon-Gaussian (not symmetric) are all linear. This means a linear model canbe used to characterize both the noise and the phases. The first P-phase for the two explosions is characterized as non-Gaussian at thethree arrays. For all 36 possibly first P-phase arrivals at the three arraystations, 23 are non-Gaussian. The second P-phase is non-Gaussian at13 of 36 data records, the S-phase at eleven of 36 and the Lg-phase at nine of 36. For all the four phases more than 32 of possible36 are time-reversible.  相似文献