The spatial heterogeneity of riverbed saturated permeability coefficient in the lower reaches of the Heihe River Basin,Northwest China

In arid region, direct infiltration from rainfall contributes little to groundwater compared with localized recharge from streams. How to quantify riverbed infiltration to groundwater systems is an important area of research in hydrology. In this study, saturated permeability coefficient of a riverbed in an arid inland river basin located in the northwest of China was obtained by Guelph Permeameter and laboratory analysis methods. The characteristics of riverbed infiltration and its spatial patterns were analysed using geostatistical method and kriging method. The results showed that the saturated permeability coefficient varied from 0.089 to 2.802 m/d, indicating moderate degree of variability. The Guelph Permeameter and laboratory test methods provided consistent estimates of saturated permeability coefficient. There was a strong spatial correlation for K_fs of the riverbed in this study area when Range (A) was less than 0.276°, suggesting that the maximum sampling distance for saturated permeability coefficient of the riverbed was 0.276° under isotropic conditions. The K_fs near the centre of the riverbed was higher than the value near riverbank. The K_fs values decreased in the direction of upstream to downstream in the Heihe River Basin. The riverbed mechanical composition, initial soil water content and bulk density have significant influence up on the riverbed infiltration. Besides, the topographical factors including the width, altitude and distance factors of the riverbed together impacted the riverbed infiltration and the slope of the riverbed and also influenced the riverbed infiltration. Copyright © 2015 John Wiley & Sons, Ltd.     

基于改进的风险矩阵法的生命线网络地震脆弱性分析

生命线网络的脆弱性不单单只表示地震发生后对网络作用而产生的后果,还应该包括网络的连通情况。本文在重新确定生命线网络脆弱性定义的基础上,运用风险评估理论中的风险矩阵方法综合考虑生命线网络的连通性能和失效后果两个方面来评价生命线网络的脆弱性,并以一个供气管网为例说明改进的风险矩阵法评价生命线网络脆弱性的有效性和合理性,找出供气管网中脆弱性等级最高的节点,分析其脆弱性等级最高的原因,以便于重点保护,并降低网络的脆弱性。     

海拉尔地震台重力潮汐扰动分析

基于前兆数据跟踪及分析应用,对海拉尔台重力潮汐滤波观测值在远震前后有向下扰动的现象进行分析,对海拉尔地震台和乌加河地震台的重力潮汐滤波观测值在全球Ms7.0以上地震、中国大陆Ms6.0以上地震的震后效应及同震响应进行统计。得出,海拉尔台重力潮汐滤波值中叠加向下扰动属非地球物理事件。     

Dynamic response of a large-diameter pile with variable section in layered saturated soil considering construction disturbance effect

ABSTRACT

An analytical solution is developed in this paper to investigate the vertical time-harmonic response of a large-diameter variable-section pile, and it considers the radial inhomogeneity of the surrounding soil caused by construction disturbance. First, the saturated soil surrounding the pile is described by Biot’s poroelastic theory and a series of infinitesimally thin independent layers along the shaft of the pile, and the pile is represented by a variable-section Rayleigh–Love rod. Then, the dynamic equilibrium equations of the soil and pile are solved to obtain an analytical solution for the impedance function at the pile top using the complex stiffness transfer method and impedance function transfer method. Finally, the proposed solution is compared with previous solutions to verify its reliability, and a parameter study is conducted to provide insights into the sensitivity of the vertical dynamic impedance of the pile and velocity response in low-strain integrity testing on defective piles.     

Major ion chemistry of groundwater in the extreme arid region northwest China

The Ejina Basin, located in arid northwest China, is one of the most arid areas in the world. In recent years, rapid development has created a greater demand for water which is increasingly fulfilled by groundwater abstraction. Detailed knowledge of geochemical evolution of groundwater and water quality can improve the understanding of a hydrochemical system, and promote sustainable development and effective management of groundwater resources. To this end, a hydrochemical survey was conducted in the Ejina Basin in order to identify the major hydrochemical characteristics. The results of chemical analysis indicate that groundwater in the area is brackish. The major ions, TDS, and hydrochemical types of different areas are highly variable and show an obvious zonation from the recharge area to the discharge area. Saturation index (SI), calculated according to the ionic ration plot, indicates that the gypsum-halite dissolution reactions take place under the condition of the rock weathering to some extent, and evaporation is the dominant factor to determine the major ionic composition in the study area.     

A GIS-based DRASTIC model for assessing shallow groundwater vulnerability in the Zhangye Basin,northwestern China

Groundwater vulnerability is a cornerstone in evaluating the risk of groundwater contamination and developing management options to preserve the quality of groundwater. Based on the professional model (DRASTIC model) and geographical information system (GIS) techniques, this paper carries out the shallow groundwater vulnerability assessment in the Zhangye Basin. The DRASTIC model uses seven environmental parameters (depth to water, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability. According to the results of the shallow groundwater vulnerability assessment, the Zhangye Basin can be divided into three zones: low groundwater vulnerability risk zone (risk index <120); middle groundwater vulnerability risk zone (risk indexes 120–140) and high risk zone (risk index >140). Under the natural conditions, the middle and high groundwater vulnerability risk zones of the Zhangye Basin are mainly located in the groundwater recharge zones and the important cities. The high, middle and low groundwater vulnerability risk zones of the Zhangye Basin cover around 17, 21 and 62% of study area, respectively.     

宜良可保盆地构造特征及煤层赋存规律分析

可保盆地位于小江断裂带西支主干断裂（嵩明-华宁断裂）东侧,盆内断裂及褶皱构造发育,以南北向及北北东向为主。含煤地层为新近系中新统,4个含煤段共含煤30余层,其中可采27层,煤层总厚度110．87m。受西侧盆缘断裂F41及基底控制,厚煤带围绕宋家地背斜倾伏方向呈带状分布,在垂向上煤层明显向东超覆迁移。     

基于姿态测量的深埋小口径地下管道探测技术研究

鉴于非开挖深埋地下管线一直是城市管线探测中的难题,本文针对小口径非开挖深埋地下管线提出了基于姿态测量原理的探测方法,推导了磁三分量及重力加速度三分量姿态定向公式以及曲线构建公式,对误差校正等进行了分析.并对基于此原理研制的仪器进行了探测试验,给出试验结果,评价了该方法的有效性及优缺点.     

Nutrient status of Populus euphratica growing in desert riparian forests of northwestern China

Seasonal and microhabitat variations of chemical constituents of foliar organic carbon (C), total nitrogen (N), total phosphorus (P), and total potassium (K), in Populus euphratica growing in desert riparian forests in northwestern China and their correlations were studied. Results show that ranges of C, N, P and K contents in the leaves of P. euphratica were 39.08%?46.16%, 0.28%?2.81%, 0.05%?0.18% and 0.35%?2.03%, with means of 43.51%, 1.49%, 0.102% and 1.17%, respectively. The ratio of C/N, C/P and N/P changed from 16.26 to 146.61, from 258.08 to 908.67 and from 2.89 to 26.67; the mean was 37.24, 466.27 and 15.14, respectively. The mean N content was significantly lower than of deciduous trees in China, but the mean P content was nearly equivalent. The ratio of C/N was remarkably higher than of global land plants. The ratio of N/P indicated that growth of P. euphratica was jointly limited by N and P nutrient deficiency. During the growth season, total trends of leaf C, N, P and K contents decreased. The maximum appeared in May, and the minimum in September. Among microhabitats, C, N and K contents gradually increased from riparian lowland, flatland, sandpile, Gobi and dune, but C/N ratio was opposite, and P content was not apparent. Foliar C content was extremely, significantly and positively correlated with N and K contents, respectively. The relationships of N-K and P-K were both significantly positive.