A full-scale study of Darcy-Weisbach friction factor for channels vegetated by riparian species

In this article, an open channel flow resistance equation, deduced applying dimensional analysis and incomplete self-similarity condition for the flow velocity distribution, was tested using measurements carried out in a full-scale channel equipped with three types of riparian plants (Salix alba L., Salix caprea L. and Alnus glutinosa L.). In the experimental channel, having banks lined with boulders, the vegetation branches were anchored in a concrete bottom. For each species, the measurements were carried out with plants having different amounts of leaves, different plant density and plant area index. The relationship between the scale factor Γ of the velocity profile and the Froude number was separately calibrated by measurements carried out without and with vegetation. The component of Darcy-Weisbach friction factor corresponding to the riparian vegetation f_v was calculated as the difference between the measured friction factor value (channel grain roughness + vegetation) and that calculated for the channel without vegetation in the same hydraulic conditions. Using these f_v values, the relationship between the scale factor Γ and the Froude number was calibrated. In this last relationship, a scaling coefficient a varying with the investigated vegetation type was introduced. This coefficient, as expected, gives the highest friction factor values for vegetation having branches with leaves. The theoretical flow resistance law, coupled with the relationship for estimating the Γ function having a scaling coefficient different for each investigated vegetation type, allowed an accurate estimate of the Darcy-Weisbach friction factor (errors less than or equal to 20% for 82.6% of the investigated cases). Finally, for the investigated vegetation species that are characterized by a condition with few leaves or leafless, the scaling coefficient a resulted strongly related to the bending stiffness. This analysis demonstrated that the highest Darcy-Weisbach friction factors correspond to vegetation species characterized by the highest values of bending stiffness. The friction factor values calculated for this last condition are characterized by errors that were less than or equal to ±20% for 90.6% of cases.     

BOOK REVIEWS

Book Reviewed in this article: Introduction to Climatology for the Tropics . J. O. Ayoade. Conservation and Management of Natural Resources in the United States . Charles F. Bennett. The Keeping of Animals: Adaptation and Social Relations in Livestock Producing Communities . Riva Berleant-Schiller and Eugenia Shanklin, ed. The Evolution of Geographic Thought in America: A Kentucky Root Wilford A. Bladen and Pradyumna P. Karan, eds. Latin America: Geographical Perspectives , 2nd ed. Harold Blakemore and Clifford T. Smith, ed. The Rural Real Estate Market. Department of Geography Publication Series, No. 18 . Chris Bryant. Urban Geomorphology in Drylands . R. U. Cooke, D. Brunsden, J. C. Doornkamp, and D. K. C. Jones with contributions by J. Griffiths, P. Knott, R. Potter, and R. Russell. Italian Geography, 1960–1980. Meeting of the Status of the Geographic Research in Italy, 1960–1980. Treated under the auspices of Consiglio Nazionale delle Ricerche and organized by Istituto di Geografia Umana della Facoltà di Lettere e Filosofia dell'Università degli Studi di Milano , Giacomo Corna Pellecrini and Carlo Brusa, eds. The Changing Fenland . H. C. Darby. The Future for the City Centre . R. L. Davies and A. G. Champion, eds. Saudi Arabia, Energy, Developmental Planning, and Industrialization . Ragaei El Mallakh, Dorothea H. El Mallakh, eds. For We Are Sold, I and My People: Women and Industry in Mexico's Frontier . Maria Patricia Fernández-Kelly. The Great Lakes Forest: An Environmental and Social History . Susan L. Flader, ed. Regional Transformation and Industrial Revolution: A Geography of the Yorkshire Woolen Industry . Derek Gregory Crime in City Politics . Anne Heinz, Herbert Jacob and Robert L. Lineberry, eds. Revitalizing Cities . H. Briavel Holcomb and Robert A. Beauregard. Cartographic Relief Presentation . Eduard Imhof. H. J. Steward, Trans. Soviet Union: A Geographical Survey . S. V. Kalesnik and V. F. Pavlenko, ed. Cognition and Environment . Stephen Kaplan and Rachel Kaplan. Environmental Protection: The International Dimension . David A. Kay and Harold K. Jacobsen, eds. Mathematical Programming Methods for Geographers and Planners , James Killen. Gentrification Amid Urban Decline: Strategies for America's Older Cities . Michael H. Lang. The North Atlantic Sulphur System . Risto Laulajainen. The Jerusalem Cathedra: Studies in the History, Archaeology, Geography and Ethnography of the Land of Israel, Vol. 2 . Lee I. Levine ed. Jerusalem and Detroit: Recreation Planning and Management . Stanely R. Lieber and Daniel R. Fesenmaier, eds. Heartland and Hinterland: A Geography of Canada . L. D. McCann, ed. Scarborough Where We Live: The Residential Districts of Minneapolis and St. Paul . Judith A. Martin and David A. Lanegran. California: The Geography of Diversity . Crane S. Miller and Richard S. Hyslop. Palo Alto The Dilemma of Amazonian Development . Emilio F. Moran, ed. Boulder Nuclear Waste: Socioeconomic Dimensions of Long-Term Storage . Steve H. Murdock, F. Larry Leistritz, and Rita R. Hamm, eds. Boulder Communism and the Politics of Inequalities . Daniel N. Nelson, ed. The Los Angeles Metropolis . Howard J. Nelson. Dubuque An Historical Geography of Urban System Development: Tidewater Virginia in the 18th Century . James O'Mara. Procedures and Standards for a Multipurpose Cadastre . East Asia: Geographical and Historical Approaches to Foreign Area Studies . Clifton W. Pannell, ed. Dubuque Mackinder: Geography as an Aid to Statecraft . W. H. Parker. Beyond the Urban Fringe: Land Use Issues of Nonmetropolitan America . Rutherford H. Platt and George Macinko, eds. Recreation Geography of the USSR . V. S. Preobrazhensky and V. M. Krivosheyev, eds. Missouri: A Geography . Milton D. Rafferty The Invisible Farmers: Women in Agricultural Production . Carolyn E. Sachs. Cayman Islands Seashore Vegetation: A Study in Comparative Biogeography . Jonathan D. Sauer. Hillslope Materials and Processes . Michael J. Selby. Housing in Britain: The Post-War Experience . John R. Short The Study of Population: Elements, Patterns and Processes . George A. Schnell and Mark Stephen Monmonier. Columbus The Soviet Union: A Systematic Geography . Leslie Symons, ed. The Ottoman Slave Trade and Its Suppression . Ehud R. Toledano. The Impact of Recession on Industry, Employment and the Regions, 1976–1981 . Alan R. Townsend. Landslides and Their Control , 2nd ed. Quido Záruba and Vojtech Mencl. Translated from the Czech by H. Zárubová and V. Mencl.     

综合物探在东罗（坑口）火电厂灰渣堆置场勘察中的应用

东罗火电厂灰渣堆置场的选址，以场地堆置灰渣后是否对客兰水库造成污染为前提。广西地质测井中心利用综合物探方法对场地的水文地质、工程地质和环境地质进行勘察评价。经工作，圈定了第四系土层和七条岩溶发育带，确定了一正断层位置，在四个钻孔中充电确定了地下水的流速和流向（主要为北西向和正北方向）。最后认为，场地堆置弃渣后，对位于南南东方向的客兰水库没有造成污染，为选址决策和施工设计提供了依据     

BOOK REVIEWS

Books Reviewed in this article: Lob Trees in the Wilderness . Clifford and Isabel Ahlgren . Satellite Microwave Remote Sensing . T. D. Allan , ed. Sunbelt Cities: Politics and Growth Since World War II . Richard M. Bernard and Bradley R. Rice , eds. Legacy of Minneapolis: Preservation Amid Change . John R. Borchert , David Gebhard , David Lanegran , and Judith A. Martin . Bloomington, MN: Preparing a Historic Preservation Ordinance. Richard J. Roddewig . The Mountains of Northeastern Tasmania, A Study of Alpine Geomorphology . Nel Caine . Introductory Cartography . John Campbell . Englewood Cliffs, NJ: Changing Climate . Manual of Remote Sensing, Second Edition . 2 Vols. Robert N. Colwell , ed.-in-chief; David S. Simonett and John E. Estes , vol. eds. Remote Sensing in Meteorology, Oceanography and Hydrology . A. P. Cracknell , ed. Multidimensional Scaling . Mark L. Davison . Environmental Karst . Percy H. Dougherty , ed. The Urban Environment . Ian Douglas . Geomorphology of Europe . Clifford Embleton , ed. An Introduction to South Asia . B. H. Farmer . Great Geological Controversies . A. Hallam . Hazardous Waste Management: In Whose Backyard? Michalann Harthill , ed. Energy for Subsistence . Margaret Haswell . Perspective on Ratzel's Political Geography . James M. Hunter . Economic Deposits and their Tectonic Setting . Charles S. Hutchison . Energy Risk Assessment . Herbert Inhaber . Discovering the Vernacular Landscape . John Brinckerhoff Jackson . Climate and Energy Systems: A Review of Their Interactions . Jill Jäger . Dilemmas in Regional Policy . Antoni Kuklinski and J. G. Lambooy , eds. California Farmland: A History of Large Agricultural Landholdings . Ellen Liebman . The Spatial Organization of New Land Settlement in Latin America . Jacob O. Maos . Dark Continent: Africa as Seen by Americans . Michael McCarthy . Westport, CT: Climatology: An Introduction . John E. Oliver and John J. Hidore . Columbus, OH: The Geography of Warfare . Patrick O'Sullivan and Jesse W. Miller . The Expanding City. Essays in Honour of Professor Jean Gottmann . John Patten , ed. Scotland's Environment During the Last 30,000 Years . Robert J. Price . Integrated Urban Models . S. H. Putman . Development and the Environmental Crisis: Red or Green Alternatives? Michael Redclift .     

九寨沟的湖泊植被

九寨沟湖泊植被的特点是;湖泊植物区系属北温带植物区系的一部分;植物群落类型仅有挺水和沉水两大群落类型,群落生态系列极不完整;湖泊植被大体仍保持着自然性和原始性;植物群落生存的水深较大(种子植物可生长在水深6.0米处,轮藻群落可在水深11.0米的湖床上发育),本文对九寨沟13个湖泊植物群落的组成、结构进行了描述。     

Seasonal variation of gaseous HNO3 and NH3 at a Tropical Savannah site

Gaseous nitric acid and ammonia were sampled with annular denuders at a forest savannah site from April to December 1987. The analysis of the extract was made spectrophotometrically and by a selective electrode for NO₃ ^– and NH₄ ⁺, respectively. Higher concentrations were observed during the vegetation burning period at the end of the dry season. In the studied savannah area, large soil emissions of NO occur during the rainy season, although very low concentrations of HNO₃ (0.035 ppb) and also of particulate NO₃ ^– (0.43 g m^-3) were observed; it is likely that NO_x are lost by fast vertical transport to the upper troposphere. During the nonburning period, the average concentration of NH₃ was 2.7 ppb, which is much lower than values given in the literature for the tropical America atmosphere. The concentrations of HNO₃ and NH₃ were always below the values needed to produce ammonium nitrate aerosols.     

基于降水条件的城镇化与植被覆盖协调发展研究

为探讨城镇化发展与植被覆盖状况的协调发展关系,本文以黄河中上游的144个县域单元为研究对象,基于2000、2005、2010及2015年4期的县域经济发展数据及MODIS-NDVI数据,通过门槛回归模型,以影响研究区域植被覆盖最主要的降水因素作为门槛变量,具体分析不同降水条件下城镇化发展对植被覆盖的影响,并提出以保护植被覆盖为基础的差异化城镇化发展策略。结果表明：①随着城镇化的推进,植被覆盖会进一步遭到破坏,但降水因素在城镇化影响植被覆盖的过程中可发挥显著的正向调节作用,从而促进城镇化与植被覆盖的协调发展;②实现城镇化与植被覆盖的协调发展,不仅取决于自身的降水条件,还依赖于当地的生态工程建设及产业结构优化升级等多种因素。其中,退耕还林(草)政策的实施可加速植被覆盖的修复进程,提高区域环境的生态承载力,有效缓解城镇化发展带给植被覆盖的负面影响;③第二产业在经济发展中的比重增加会给植被覆盖带来严重威胁,阻碍城镇化与植被覆盖的协调发展,尤其是在年均降水量较少且生态脆弱的地区。     

Remotely sensed agricultural modification improves prediction of suitable habitat for a threatened lizard

The geographical distribution of a species is limited by factors such as climate, resources, disturbances and species interactions. Environmental niche models attempt to encapsulate these limits and represent them spatially but do not always incorporate disturbance factors. We constructed MaxEnt models derived from a remotely sensed vegetation classification with, and without, an agricultural modification variable. Including agricultural modification improved model performance and led to more sites with native vegetation and fewer sites with exotic or degraded native vegetation being predicted suitable for A. parapulchella. Analysis of a relatively well-surveyed sub-area indicated that including agricultural modification led to slightly higher omission rates but markedly fewer likely false positives. Expert assessment of the model based on mapped habitat also suggested that including agricultural modification improved predictions. We estimate that agricultural modification has led to the destruction or decline of approximately 30–35% of the most suitable habitat in the sub-area studied and approximately 20–25% of suitable habitat across the entire study area, located in the Australian Capital Territory, Australia. Environmental niche models for a range of species, particularly habitat specialists, are likely to benefit from incorporating agricultural modification. Our findings are therefore relevant to threatened species planning and management, particularly at finer spatial scales.