2022冬奥会背景下北京区域居民参与冰雪运动消费调查

运用文献资料、问卷调查和数理统计、应用因子分析方法,结合北京区域滑雪场空间分布情况,对比居民冰雪运动参与倾向和频率,发现北京区域居民参与冰雪运动及消费的主要影响因素为性别、年龄、距离、收入水平和政策红利;分析得出雪场密度和区域经济水平、性别等对参与冰雪运动消费特征的影响。归纳4个主要影响北京区域居民参与冰雪运动的公共因子,分别是冰雪运动基础因子、冰雪运动信息因子、冰雪运动距离因子以及冰雪运动友谊因子。提出不断提升冰雪运动产品服务质量,出台鼓励性冰雪运动消费政策,完善冰雪运动消费环境,创新冰雪运动消费内容,逐步扩大冰雪消费规模等建议。     

Damming China’s rivers to expand its cities: the urban livelihoods of rural people displaced by the Three Gorges Dam

Over the next two decades, China, the country with the world’s largest urban population, is orchestrating the urbanization of some 300 million rural people. In its National New-Type Urbanization Plan (2014) the State Council has outlined a range of strategies to grow its cities not least of which is rural-to-urban migration. This plan will have significant effects on other types of displacement, particularly, the forced displacement and resettlement of those living in the path of large dams. This paper reviews what is known about New-Type Urbanization Approach to Reservoir Resettlement. Then, based on a longitudinal study of 145 resettled households at the Three Gorges Dam, the livelihood effects of rural-to-urban resettlement are unpacked to provide lessons for its use in advancing urbanization. It finds that rural-to-urban resettlers have lower incomes than their urban-to-urban and rural-to-rural counterparts, and higher rates of food and income insecurity.     

Spatial and temporal patterns of stable water isotopes along the Yangtze River during two drought years

Changes in the level of the Yangtze River caused by anthropogenic water regulation have major effects on the hydrological processes and water cycle in surrounding lakes and rivers. In this study, we obtained isotopic evidence of changes in the water cycle of Yangtze River during the two drought years of 2006 and 2013. Isotopic evidence demonstrated that the δ¹⁸O and δD levels in Yangtze River exhibited high spatial heterogeneity from the upper to lower reaches, which were controlled by atmospheric precipitation, tributary/lake water mixing, damming regulation, and water temperature. Both the slope and intercept of Yangtze River evaporative line (δD = 7.88 δ¹⁸O + 7.96) were slightly higher than those of local meteoric water line of Yangtze River catchment (δD = 7.41 δ¹⁸O + 6.01). Most of the river isotopic values were located below the local meteoric water line, thereby implying that the Yangtze River water experienced a certain degree of evaporative enrichment on isotopic compositions of river water. The high fluctuations in the isotopic composition (e.g., deuterium excess [d‐excess]) in the middle to lower reaches during the initial stage of operation for the Three Gorges Dams (2003–2006) were due to heterogeneous isotopic signatures from the upstream water. In contrast to the normal stage (after 2010) characterized by the maximum water level and largest water storage, a relatively small variability in the deuterium excess was found along the middle to lower reaches because of the homogenization of reservoir water with a longer residence time and complete mixing. The effects of water from lakes and tributaries on the isotopic compositions in mainstream water were highlighted because of the high contributions of lakes water (e.g., Dongting Lake and Poyang Lake) efflux to the Yangtze River mainstream, which ranged from 21% to 85% during 2006 and 2013. These findings suggest that the retention and regulation of the Three Gorges Dams has greatly buffered the isotopic variability of the water cycle in the Yangtze catchment, thereby improving our understanding of the complex lake–river interactions along the middle to lower reaches in the future.     

大坝变形监测数据的小波分析处理方法

引入小波分析方法对大坝变形监测数据的处理,实现了对离散型的变形数据的尺度分解,对变形趋势的分析。并且对变形数据在滤波、消噪等方面,对分解层次中的偶然误差特性分析,以及阀值的选取方法进行了比较,表明利用小波变换的方法对变形数据的分析处理是有效、可行的。     

中国冰雪旅游研究：内涵辨析、脉络梳理与体系构建

推动冰雪旅游高质量发展践行了“冰天雪地也是金山银山”发展理念,助推着体育强国、健康中国建设,满足了人民日益增长的美好生活需要。中国冰雪旅游历经三十多年的发展,已形成规模化、整体化发展格局;北京冬奥会的筹办更是给冰雪旅游带来重大发展契机,利好政策陆续出台,消费热情不断高涨。与此同时,冰雪旅游相关研究也持续涌现,取得了丰厚研究成果。文章以“内涵辨析-脉络梳理-体系构建”为逻辑主线,从冰雪旅游基础概念、发展脉络演进、研究内容、研究方法及区域等方面对中国冰雪旅游展开分析和评述。研究表明：冰雪旅游内涵丰富,学者们从资源、动机以及季候等视角展开了概念界定;冰雪旅游研究历经4个阶段,研究与实践联系日益紧密,产业发展受资源、政策、市场等因素驱动;研究内容已形成一定体系,与国家、产业发展战略的结合有待加强;以定性研究为主,缺乏定量、纵深研究;研究区域高度集中在东北、华北地区,且视角较为宏观。最后提出从理论构建及研究视角、研究内容、研究方法、区域等方面进行未来研究的创新。以期推动中国冰雪旅游研究的理论化和体系构建,引领和指导未来冰雪旅游领域研究,推进中国后冬奥时代冰雪旅游高质量发展。     

Interacting effects of multiple factors on the morphological evolution of the meandering reaches downstream the Three Gorges Dam

Elucidating the influence of dams on fluvial processes can inform river protection and basin management. However, relatively few studies have focused on how multiple factors interact to affect the morphological evolution of meandering reaches. Using hydrological and topographical data, we analyzed the factors that influence and regulate the meandering reaches downstream the Three Gorges Dam (TGD). Our conclusions are as follows. (1) The meandering reaches can be classified into two types based on their evolution during the pre-dam period: G1 reaches, characterized by convex point bar erosion and concave channel deposition (CECD), and G2 reaches, characterized by convex point bar deposition and concave channel erosion (CDCE). Both reach types exhibited CECD features during the post-dam period. (2) Flow processes and sediment transport are the factors that caused serious erosion of the low beaches located in the convex point bars. However, changes in the river regime, river boundaries and jacking of Dongting Lake do not act as primary controls on the morphological evolution of the meandering reaches. (3) Flood discharges ranging from 20,000 to 25,000 m³/s result in greater erosion of convex point bars. The point bars become scoured if the durations of these flows, which are close to bankfull discharge, exceed 20 days. In addition, the reduction in bedload causes the decreasing of point bar siltation in the water-falling period. (4) During the post-dam period, flood abatement, the increased duration of discharges ranging from 20,000 to 25,000 m³/s, and a significant reduction in sediment transport are the main factors that caused meandering reaches to show CECD features. Our results are relevant to other meandering reaches, where they can inform estimates of riverbed change, river management strategies and river protection.     

Full-scale experimental modal analysis of an arch dam: The first experience in Iran

Forced vibration field tests and finite-element studies were conducted on the Shahid Rajaee concrete arch dam in Northern Iran to determine the dynamic properties of the dam–reservoir–foundation system. The first forced vibration tests on the dam were performed with two different types of exciter units, with a limited maximum force, bolted on the dam crest for alternative in-phase and out-of-phase sequencing. Because of an insufficient number of recording sensors, two arrangements of sensors were used to cover sufficient points on the dam crest and one gallery during tests. Two kinds of vibration tests, on–off and frequency sweeping, were carried out on the dam. The primary natural frequencies of the coupled system for both symmetric and anti-symmetric vibration modes were approximated during on–off tests in two types of sequencing of exciters, in phase and out-of-phase, with a maximum frequency of 14 Hz. The principal forced vibration tests were performed at precise resonant frequencies based on the results of the on–off tests in which sweeping around the approximated frequencies at 0.1 Hz increments was performed. Baseline correction and suitable bandpass filtering were applied to the test records and then signal processing was carried out to compute the auto power, cross power and coherence spectra. Nine middle modes of vibration of the coupled system and corresponding damping ratios were estimated. The empirical results are compared against the results from calibrated finite-element modeling of the system using former ambient vibration tests, considering the dam–reservoir–foundation interaction effects. Good agreement is obtained between experimental and numerical results for eight middle modes of the dam–reservoir–foundation system.     

Application of perfectly matched layers in the transient analysis of dam–reservoir systems

The transient analysis of dam–reservoir systems by employing perfectly matched layers has been investigated. In previous studies, boundary conditions of the PML region in the reservoir have been neglected. In this paper, they are incorporated completely in the formulation. Moreover, a technique is introduced to involve the effect of incident waves caused by vertical ground motions at the reservoir bottom in the analysis. Performing several numerical experiments indicates that applying boundary conditions of the PML domain and utilizing the proposed method for vertical excitation cases reduce the computational cost significantly and make the PML method a very efficient approach for the transient analysis of dam–reservoir systems.     

A semi-analytical method for predicting the outflow hydrograph due to dam-break in natural valleys

The paper presents a semi-analytical method for predicting the flow rate hydrograph due to a hypothetical sudden and total dam failure in a natural valley. The method generalizes the approach proposed by Hunt for the dam-break problem in a rectangular frictionless sloping channel to a valley with a cross-section area expressed by a power-law function of water depth, in order to take into account the most common shapes of natural valleys. The parameters of the deriving model can be set by exploiting data usually available concerning the dam section geometry and the reservoir storage-depth curve. The application of the technique to three different reservoirs is discussed. The results show that the flow rate hydrographs obtained at the dam site agree with the ones calculated by means of a finite volume numerical code based on two-dimensional shallow water equations. The method requires moderate computational and data collecting effort, so it can be regarded as a useful alternative to other procedures commonly adopted in the practice.     

瀑布沟水库区域地震的重新定位

利用双差定位方法对瀑布沟水库区域内2006-10-13~2013-07-31之间发生的3 784个地震进行了重新定位,获得了3 601个地震的重新定位结果,到时残差平均为0.12 s,E-W、N-S和U-D三个方向上平均定位误差分别为0.15 km、0.17 km和1.10 km。重新定位结果显示,在研究区域内的西南方向和水库流域,地震分布密集,这个区域处于鲜水河断裂中南段、安宁河断裂北段和大凉山断裂北段的位置,此区域内地震震源深度主要分布在5~30km间,表明该区域的地震主要是构造活动引起的,而水库库区内地震震源深度主要分布在0~5 km区间,分布比较集中,该地区的地震为水库诱发和人工爆破引起的地震。