Land subsidence caused by groundwater exploitation in Suzhou City,China

Suzhou City, located at the lower reaches of the Yangtze River in southeastern Jiangsu Province, is one of the few cities in China which suffer from severe ground settlement. A research project was carried out to investigate this problem. Geological and hydrogeological studies show that there is a multi-layered aquifer system with three distinct, soft mud layers of marine and lagoonal origins. An examination of historical records of groundwater extraction, water levels, and ground settlement shows that the ground subsidence is associated with the continuously increasing groundwater extraction in the deep, confined aquifer. It is believed that the consolidation of the soft mud layers, especially the third layer which is thick and close to the main pumped aquifer, contributes to the ground settlement. A three-dimensional finite difference numerical model representing the multi-layered aquifer system was developed to study the ground settlement in response to groundwater extraction. By calibrating the model with both the measured groundwater level and ground settlement, the aquifer parameters were estimated. The model outputs fit reasonably well with the observed results, which indicates that the numerical model can reproduce the dynamic processes of both groundwater flow and soil consolidation. The hydraulic conductivity of the third mud layer near the center of the ground settlement has been reduced by over 30% in the last 14 years. The gradual deterioration in the hydraulic conductivity of the mud may have significant adverse effect on the sustainable groundwater resource of the deep confined aquifer, since the recharge from the shallow aquifers through the mud layer is the only source of water to the deep aquifer. An analysis of the spatial distributions of groundwater drawdown and ground settlement shows that the area with maximum drawdown is not necessarily the area with maximum ground settlement due to the occurrence of the soft mud layer. A simple reallocation in pumping rates on the basis of the spatial distribution of the thick mud layer could significantly reduce the ground settlement. Electronic Publication     

鄂尔多斯西南缘前陆盆地沉降和沉积过程模拟

本文将东祁东逆冲带与鄂尔多斯西南缘晚三叠世前陆盆地相结合，研究了逆冲带内部变形特征，前陆盆地中层序地层格架特征及其反映的盆缘构造性质和幕式逆作作用。     

变差函数参数的计算

为了求出地质统计学中变差函数理论模型的参数，首先把相应模型化成线性函数的形式，多面手应用线性方程组非负解的理论计算出它的参数。     

2003年淮河流域大洪水的雨情、水情特征分析

利用地面加密资料，分析了2003年淮河流域6~7月降水的时空分布和气候统计特征以及降水雨情、水情特征，并与历史同期进行了比较。结果表明:2003年淮河流域梅雨期经历了7次强降水过程，降水总量和洪水流量都超过1991年同期，但低于1954年梅雨期；2003年淮河流域降水的突出特点是:雨带稳定、暴雨集中和突发性强；水情特点是:洪峰逐次递减；造成淮河流域全线超警戒水位的重要原因是:2003年春季降水偏多、7月份副热带高压位置偏南以及淮河中游下段河床剖面倒比降。     

日本国内旅游业的发展及其地域特征

日本旅游业已成为国民经济的重要部门，据2002年日本交通省的统计表明，观光产业GDP已占国内生产总值的2．2％，这一数字与美国相近。但与西方国家显著不同的是，在美、英、法、意等旅游业发达国家中，国际旅游业占据举足轻重地位，而日本的旅游业却以国内旅游为主体。据日本最大旅行社JTB的统计，2002年日本旅游出行人数为34013万人次(其中出国旅游1664万人次)，而同年日本接待的外国入境游客刚刚超过500万人次。本文旨在介绍和分析日本国内旅游业的发生、发展的变化特征，以及国民不同的旅游方式和旅游地域差异。     

A two‐dimensional coupled hydromechanical discontinuum model for simulating rock hydraulic fracturing

Within the framework of our discontinuous deformation analysis for rock failure algorithm, this paper presents a two‐dimensional coupled hydromechanical discontinuum model for simulating the rock hydraulic fracturing process. In the proposed approach, based on the generated joint network, the calculation of fluid mechanics is performed first to obtain the seepage pressure near the tips of existing cracks, and then the fluid pressure is treated as linearly distributed loads on corresponding block boundaries. The contribution of the hydraulic pressure to the initiation/propagation of the cracks is considered by adding the components of these blocks into the force matrix of the global equilibrium equation. Finally, failure criteria are applied at the crack tips to determine the occurrence of cracking events. Several verification examples are simulated, and the results show that this newly proposed numerical model can simulate the hydraulic fracturing process correctly and effectively. Although the numerical and experimental verifications focus on one unique preexisting crack, because of the capability of discontinuous deformation analysis in simulating block‐like structures, the proposed approach is capable of modeling rock hydraulic fracturing processes. Copyright © 2014 John Wiley & Sons, Ltd.     

渝东南下古生界页岩构造裂缝形成及分布控制因素

天然裂缝对页岩气储集和渗流有重要影响,但目前对页岩构造裂缝研究不够深入。本文通过露头、岩心裂缝观察和分析,探讨了渝东南下古生界页岩构造裂缝类型、形成机理及分布控制因素。基于裂缝特征及力学成因,将剪切裂缝分为高角度剪切裂缝、倾斜滑脱裂缝和水平滑脱裂缝。倾斜滑脱裂缝是在上覆岩层重力和水平构造应力共同作用下沿应力集中的软弱面发生剪切滑动形成,水平滑脱裂缝是在构造挤压应力作用条件下主要沿页理面方向的剪切或层间滑动形成;页理发育程度及岩层曲率是控制水平滑脱裂缝形成的关键因素,岩石矿物组成、构造作用及岩层厚度是控制其它类型构造裂缝形成和分布的主要因素,页岩岩石力学层的划分需要根据裂缝特征、岩性变化特征、岩石力学参数及沉积界面等综合确定,岩层厚度与层间构造裂缝密度呈负相关关系。     

Simulation of quasi-linear mesoscale convective systems in northern China: Lightning activities and storm structure

Two intense quasi-linear mesoscale convective systems(QLMCSs) in northern China were simulated using the WRF(Weather Research and Forecasting) model and the 3D-Var(three-dimensional variational) analysis system of the ARPS(Advanced Regional Prediction System) model.A new method in which the lightning density is calculated using both the precipitation and non-precipitation ice mass was developed to reveal the relationship between the lightning activities and QLMCS structures.Results indicate that,compared with calculating the results using two previous methods,the lightning density calculated using the new method presented in this study is in better accordance with observations.Based on the calculated lightning densities using the new method,it was found that most lightning activity was initiated on the right side and at the front of the QLMCSs,where the surface wind field converged intensely.The CAPE was much stronger ahead of the southeastward progressing QLMCS than to the back it,and their lightning events mainly occurred in regions with a large gradient of CAPE.Comparisons between lightning and non-lightning regions indicated that lightning regions featured more intense ascending motion than non-lightning regions;the vertical ranges of maximum reflectivity between lightning and non-lightning regions were very different;and the ice mixing ratio featured no significant differences between the lightning and non-lightning regions.     

利用尺度空间及多角度地形断面提取山谷山脊线

从数字高程模型中自动提取山脊线和山谷线,在测绘领域有着重要的意义。地形断面高程极值法是其中一种常用的方法,但此方法在提取过程中容易产生遗漏。针对此缺点,本文提出了基于尺度空间及多角度判断的地形断面高程极值法,主要步骤是构建影像金字塔,然后从上到下逐级提取并加密。试验验证了该方法的有效性,提取得到的山谷线或山脊线较为完整,并与实际地形相符合。