Quantifying the temporal dynamics of wood in large rivers: field trials of wood surveying,dating, tracking,and monitoring techniques

Wood plays an important role in stream ecology and geomorphology. Previous studies of wood in rivers have quantified spatial distributions but temporal dynamics remain poorly documented. The lack of such data is related to limitations of existing methods, especially when applied to large rivers. Five techniques are field‐tested to assess their utility for quantifying the temporal dynamics in rivers: repeated high‐resolution aerial surveys, the measurement of wood physical characteristics as proxies for ¹⁴C dating, passive and active radio frequency identification (RFID) tags, radio transmitters, and video. The spatial distribution of wood is surveyed using aerial imagery with a resolution finer than 0·10 m. The estimation of temporal trends by repeated aerial‐based surveys needs to consider vegetation growth and hiding. Wood residence times can be calculated using ¹⁴C analysis, but the assessment of wood physical characteristics including decay status and wood density offers a cheaper, if less accurate, alternative. Wood resistance to penetration is tested but results are not significant. Radio transmitters are reliable for multi‐year (～5 year) surveys and can be detected at 800 m. Passive RFID tags are limited by a read range of 0·30 m but are reliable for longer term (>5 year) studies. Active RFID tags combine a moderate read range (10–300 m) and low cost with in‐flood detection but require more testing. Video monitoring of wood passing on the surface of a river is successfully implemented. For a single flood on the Ain River (France), wood transport rates are an order of magnitude higher on the rising limb of the hydrograph than on the falling limb. Overall, the techniques improve the ability to gather the data needed to understand wood transfer processes and calibrate budgets of wood in rivers. Copyright © 2009 John Wiley & Sons, Ltd.     

The job of the river

Earth scientists have traditionally conceptualized rivers and streams as geomorphic machines, whose role is to transfer sediment and to sculpt the landscape. Steady‐state relationships between sediment supply and transport capacity have traditionally been considered normative in fluvial systems. Rivers are hydrological entities, however, whose function is to redistribute excess moisture on land. The geomorphic work of the river – erosion, transport, deposition, etc. – is a byproduct of the hydrological job of the river. There is therefore no reason to expect any particular relationship between sediment supply and transport capacity to develop as a normative condition in fluvial systems. The apparent steady‐state equilibrium slope adjustments of rivers are a byproduct of four basic phenomena: (1) hydraulic selection, which favors channels and branching networks over other flux patterns; (2) water flows along the available path of least resistance; (3) energy dissipation; and (4) finite relaxation times. Recognizing converging trends of stream power or slope and sediment supply as common (but far from inevitable) side effects rather than self‐regulation has important implications for interpreting and predicting fluvial systems, and for river management and restoration. Such trends are variable, transient, contingent, and far from universal. Where they occur, they are an emergent byproduct of fundamental physical mechanisms, not a goal function or attractor state. Copyright © 2009 John Wiley & Sons, Ltd.     

Climate change and sediment flux from the Roof of the World

Potential rises in global temperature are likely to have major impacts on high altitude environments, including glacier recession and permafrost degradation. In turn, these could have far‐reaching impacts on riverine sediment flux. Such impacts are emerging in the Himalayas and Tibet Plateau region, one of the world's largest and most environmentally‐sensitive cold regions. Closer monitoring is urgently required to track changing trends of sediment load from the interactions of glacial recession treat, rainfall changes and human interventions, and to study the implications of such changes for the large Asian river systems of the region. Copyright © 2010 John Wiley & Sons, Ltd.     

西格二线关角隧道浅埋砂层段施工技术及力学效应研究

关角隧道是西（宁）格（尔木）二线的控制性工程,在隧道入口处存在长约450 m的砂层,施工难度较大。由于在3台阶施工中出现了冒顶事故,故提出了4台阶施工的设想,并利用三维数值计算模拟了4台阶开挖支护过程,揭示了隧道的空间变形、地表沉降和初支受力特征。通过与3台阶施工模拟结果对比证实了4台阶方案的优越性;现场施工和变形量测结果表明,采用大拱脚断面形式和超短四台阶施工方案,施作长大水平超前管棚、设置临时钢横撑、缩短仰拱封闭距离等是保证大断面浅埋砂层隧道安全施工的有效方法,对其他类似工程施工提供了宝贵的工程经验。     

对常用大地坐标系间坐标转换方法的评价

常用坐标系间的相互转换对于现代工程应用有着十分重要的意义。实现坐标转换,需要若干公共已知点。然而,实际工程应用中,公共已知点的坐标信息一般难以获取,尤其是点的高程信息。针对该问题,本文利用实际数据,比较分析了在公共点无高程信息时,常用大地坐标系间坐标转换的4种方法（四参数法、多项式拟合法、高程迭代法、改化坐标法）在转换精度和其他方面的优劣。结果表明,4种方法都有着比较高的转换精度,而改化坐标法有着无需分带、单次迭代、仅需3个公共点、精度较高、精度指标一致的综合优势。     

BOOK REVIEWS

Book reviewed is the article: Small-State Security in the Balkans . Aurel Braun. South American Development: A Geographical Introduction . Rosemary D. F. Bromley and Ray Bromley. Interregional Migration, National Policy and Social Justice . Gordon L. Clark. Marketing Architectural and Engineering Services . Weld Coxe. A Geography of the Third World . J. P. Dickenson, C. G. Clarke, W. T. S. Gould, R. M. Prothero, D. J. Siddle, C. T. Smith, E. M. Thomas-Hope, and A. G. Hodgkiss. Wildlife and Man in Texas: Environmental Change and Conservation . Robin W. Doughty. At the Sea's Edge . William T. Fox. Englewood Cliffs Geography and Ecology . I. P. Gerasimov. Urbanization in Contemporary Latin America. Critical Approaches to the Analysis of Urban Issues . Alan Gilbert in association with Jorge E. Hardoy and Ronaldo Ramírez, eds. The Coming of the Transactional City . Jean Gottmann. College Park Visions of City and Country: Prints and Photographs of Nineteenth-Century France . Bonnie L. Grad and Timothy A. Riggs. Worcester Soviet Geography Today: Physical Geography . N. A. Gvozdetskiy, ed. Adaptive Responses of Native Amazonians . Raymond B. Hames and William T. Vickers, eds. Urban and Regional Industrial Research: The Changing UK Data Base . Michael Healey, ed. Cuando se Acaban los Montes . Stanley Heckadon Moreno. A Panama Forest and Shore: Natural History and Amerindian Culture in Bocas del Toro . Burton L. Gordon. Pacific Grove Mozambique: From Colonialism to Revolution, 1900–1982 . Allen Isaacman and Barbara Isaacman. Soviet Natural Resources in the World Economy . Robert G. Jensen, Theodore Shabad, and Arthur W. Wright, eds. The Changing Geography of the United Kingdom . R. J. Johnston and J. C. Doornkamp, eds. Pluralism and Political Geography—People, Territory and State . Nurit Kliot and Stanley Waterman, eds. Landmarks Preservation and the Property Tax . David Listokin. Irrigation Horticulture in Highland Guatemala: The Tablón System of Panajachel . Kent Mathewson. Her Space, Her Place: A Geography of Women . Mary Ellen Mazey and David R. Lee. Man, A Geomorphological Agent . Dov Nir. Dordrecht The Book of America: Inside the 50 States Today . Neal R. Peirce and Jerry Hagstrom. Rivers . Geoffrey E. Petts. Proceedings, United States/Australia Workshop on Design and Implementation of Computer-Based Geographic Information Systems . Donna Peuquet and John O'Callaghan, eds. Outdoor Recreational and Resource Management . John Pigram. Remaking the City: Social Science Perspectives on Urban Design . John S. Pipkin, Mark La Gory and Judith R. Blau, eds. The Crust of Our Earth: An Armchair Traveler's Guide to the New Geology . Chet Raymo. Englewood Cliffs Concepts and Themes in the Regional Geography of Canada J. Lewis Robinson. Vancouver Secondary Cities in Developing Countries: Policies for Diffusing Urbanization . Dennis A. Rondinelli. Beverly Hills Legal Foundations of Environmental Planning , Vol 1. J. G. Rose. Can We Delay a Greenhouse Warming? Stephen Seidel and Dale Keyes. Mobilizing Human Resources in the Arab World . R. Paul Shaw. Prairie Mosaic: An Ethnic Atlas of Rural North Dakota . William C. Sherman. The Future of Conflict in the 1980s . William J. Taylor, Jr. and Steven A. Maaranen, eds. The Visual Display of Quantitative Information . Edward R. Tufte. U.S. 40 Today: Thirty Years of landscape Change in America . Thomas R. Vale and Geraldine R. Vale. Madison Silent Violence: Food, Famine and Peasantry in Northern Nigeria . Michael Watts. Readings in Historic Preservation: Why? What? How? Norman Williams Jr., Edmund Kellogg and Frank Gilbert, eds.     

河北省涞水县野三坡国家地质公园：地质遗迹的地质意义和4期节理的导控作用

野三坡国家地质公园位于太行山断隆与燕山“台褶带”的结合部,两构造单元以紫荆关大断裂为界。公园内地质遗迹丰富,其地质内涵是华北地质的精髓。发育4期宏大构造节理,分别与印支期华南板块、燕山期伊佐奈歧板块、华北期太平洋板块和喜马拉雅期印度板块的挤压有关。4期节理,特别是喜马拉雅期南北向“追踪张节理”,对园区构造地貌景观的形成起着关键作用。     

Research progress of international rivers in China

China possesses over 110 international rivers and lakes, among which 41 are major ones and 15 are of great importance. With the highest concentration of international rivers, the northeast, northwest and southwest regions of China enjoy abundant transboundary resources and pose complicated ecological security issues. Following the 1950s, relevant studies on international rivers fall into three periods: 1) the planned economy period of the 1950s–1980s when border development and basic research were scant; 2) the reform and opening-up period from 1980 to the end of 20th century. Along with the drive of economic globalization and regional cooperation, development of international rivers was thriving, which filled blanks in the research and narrowed gaps with international standards. Relevant studies also provided national and local governments with important scientific grounds for making decisions; 3) since the start of the 21st century, China has integrated its international river studies across sectors and across international borders. Now both government and scientific institutions pay great attention to transboundary environmental issues.     

人为季节性河流的初步研究

由于人类引水量的激增,我国北方的一些天然常流河频繁断流,已经成为季节性河流。文中提出了人为季节河的概念,在分析天然常流河与天然季节河的形成条件的基础上,查明了人为季节河形成的敏感带和在这种敏感带中,常流河向季节河转化的条件。