An assessment of the impact of urbanization and land use changes in the fast-growing cities of Saudi Arabia     

Abdullah F. Alqurashi  Lalit Kumar 《国际地球制图》2019,34(1):78-97

Understanding rates, patterns and types of land use and land cover (LULC) changes are essential for various decision-making processes. This study quantified LULC changes and the effect of urban expansion in three Saudi Arabian cities: Riyadh, Jeddah and Makkah using Landsat images of 1985, 2000 and 2014. Seasonal change of vegetation cover was conducted using normalised difference vegetation index, and object-based image analysis was used to classify the LULC changes. The overall accuracies of the classified maps ranged from 84 to 95%, which indicated sufficiently robust results. Urban area was the most changed land cover, and most of the converted land to urban was from bare soil. The seasonal analysis showed that the change of vegetation cover was not constant due to climatic conditions in these areas. The agricultural lands were significantly decreased between 1985 and 2014, and most of these lands were changed to bare soil due to dwindling groundwater resources.  相似文献   

内蒙古高原等地湖泊表层沉积物孢粉与植被覆盖度定量关系研究          下载免费PDF全文

陈东雪  王维  刘立娜  姜亚娟  李岩岩  牛志梅  马玉贞  何江 《干旱区地理》2019,42(5):1011-1022

过去植被覆盖度重建在长尺度气候模拟和陆地生态环境演变机制研究等方面具有重要意义。基于现代过程的孢粉—植被覆盖度转换函数研究，可为利用孢粉地层数据重建过去植被覆盖度变化提供一条新的途径。以内蒙古高原等地39个湖泊和7个水库中心的表层沉积物孢粉组合与归一化植被指数（NDVI）为研究对象，利用加权平均偏最小二乘法（WA-PLS）、局部加权加权平均法（LWWA）和最佳类比法（MAT）分别建立了孢粉—NDVI转换函数；通过留一交叉检验法、自助法和空间自相关性等检验，筛选出最优模型并应用于古地层孢粉数据，实现定量重建过去植被覆盖度变化。结果表明：MAT和WA-PLS模型均受到空间自相关性的显著影响，而LWWA模型则是建立孢粉—NDVI转换函数的最优模型。与已有类似转换函数表现能力的对比表明，本研究建立的转换函数具有较强的可靠性和应用潜力。基于本研究转换函数重建的内蒙古辉腾锡勒（HTL）区域全新世植被覆盖变化与孢粉重建的植被变化具有很好的一致性，进一步印证了本研究转换函数的较强潜力，均表现出对降水变化的响应更为显著。  相似文献   

An analysis of snow cover patterns in a small alpine catchment     

G.schl Bl  R. Kirnbauer 《水文研究》1992,6(1):99-109

Snow cover patterns in a 9.4 km² basin in the Austrian Alps are examined during spring and summer 1989. Digital mono-plotting from oblique aerophotographs is used for mapping. on the basis of a square grid with 25 m spacing, snow cover as mapped during nine surveys is analysed as a function of elevation and slope. During winter conditions the snow cover is found to be much better related to these terrain features than during the late ablation period.  相似文献   

BOOK REVIEWS     

《The Professional geographer》1984,36(3):376-412

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.  相似文献   

云场中云簇的测量     

罗钢 《成都信息工程学院学报》1996,(3)

使用云分割法和最近累积分布函数法，通过蒙特卡罗模拟和陆地卫星资料研究了卷云覆盖频率与云簇型式的依赖关系。结果表明：由于云分布“核态”的尺度依赖于云网格的尺度，云分布“模态”不能很好地描述云尺度大小分布，这里云尺度大小是指云覆盖量最大时的尺度权重（是云尺度大小的函数）。同时也表明卷云的“模型”尺度与云网格尺度之间关系最小，对任何给定的云尺度分布，“最小模态尺度”是唯一的。在云的组成具有相同尺度及与较大尺度云重迭的云场中，“最小模态尺度”与云覆盖频率分布的形状有关。云尺度分布引起的簇的形式不同于云中心区云簇的形式，其原因是“有效”的云尺度大小取决于网格区域的大小，并且是由云簇决定的，有效的云尺度是由云覆盖频率分布形状反算得到的  相似文献   

九寨沟的湖泊植被     

张宁  李恒  费勇  王立松 《山地学报》1988,(4)

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。  相似文献   

Inclusion of ice cover in a storm surge model for the Beaufort Sea     

M. B. Danard  M. C. Rasmussen  T. S. Murty  R. F. Henry  Z. Kowalik  S. Venkatesh 《Natural Hazards》1984,2(2):153-171

Storm surges in the Beaufort Sea present a severe problem for navigation as well as for offshore oil drilling activities. Influence of ice cover on storm surges in the Beaufort Sea is examined making use of a numerical model as well as a set of observations.The automated shallow-water model of Henry has been modified to incorporate ice cover and is adapted to the Beaufort Sea. The leading edge of the permanent ice is calculated from the loci of identifiable points. Generalized similarity theory is employed to compute wind stresses. Simulations are made using model-predicted ice concentrations and observed ice concentrations. Ice motion is relatively small in units of model grid distance (approximately 18 km) during surges. Spherical effects are important and should be included in future adaptations of the model. Comparison of the computed surges with observed surges for eight different events showed reasonable agreement.  相似文献   

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

Alberto Rondón  Eugenio Sanhueza 《Journal of Atmospheric Chemistry》1990,11(3):245-254

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.  相似文献   

基于降水条件的城镇化与植被覆盖协调发展研究     

温小洁  姚顺波  赵敏娟 《地理科学进展》2018,37(10):1352-1361

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。  相似文献   

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

David T. Y. Wong  William S. Osborne  Stephen D. Sarre  Bernd Gruber 《International journal of geographical information science》2018,32(5):1006-1025

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.  相似文献