中文摘要：

以石羊河流域古浪县城区为研究区，选取2000、2010年两期土地利用现状数据及Landsat TM/ETM＋影像为数据源，利用NDBI-NDVI提取古浪县建成区面积并计算相关指标，并解译各时期功能用地信息．在此基础上，借助ArcGIS10．0和Fragstats3．3软件分析研究城镇空间趋势演变特征，对古浪县城镇演变特征展开研究．研究结果表明：①古浪县主要功能用地面积总体呈现减少趋势，以农用地面积减少最为显著，其他功能用地变化相对较小．②2000～2010年古浪县中心城区面积持续增长，城区用地共增加35．96 km2，扩张为原来的1．89倍．中心城区平均每年扩张3．59 km2，扩张强度指数为8．91％．③中心城区空间扩张主要在原城镇建成区的基础上扩张，东西向空间扩张最为明显；城镇空间中心点及城镇空间集中趋势整体向东北方向变迁．

英文摘要：

Choose Gulang county which located in Shiyang River Basin as the study area , and select two periods Landsat TM/ETM+images from 2000 to2010 as data resources ,the NDBI-NDVI is extracted to calculate Gulang city centre area.Besides,other landuse types in different period are also interpreted using GIS software .On the basis above, the software ArcGIS 10.0 and Fragstats3.3 are used to analyze the evolution of urban spatial characteristics.The results showed that:①The main landuse type of Gulang county showing an overall decreasing trend such as farm land , its area decreased the most significant .Relatively the other landuse types changed slight .②From2000 to 2010, Gulang county city center area continues to grow , the urban land area increased 35.96 km2, which expanded 1.89 times than the original area .City center expand about 3.59 km2 every year ,and its average expansion intensity index is 8.91%.③The spatial expansion of urban central area is main happened in the original basis and expand along the city edge .the most obvious expand direction is east and west ,and the urban center point and spatial central tendency are changed to northeast as whole .