城市化进程下南昌市城区水系格局与连通性分析

针对当前城市化引起的水系结构单一化、河流连通性减弱以及水生态环境等问题,以南昌市城区为例,选取1990年、2000年、2010年3期遥感影像图像,分析城市化影响下土地利用的变化;基于1958年地形图与2010年江西省水系图,通过GIS提取两期南昌市城区水系图,选取数量特征和结构特征指标进行水系格局分析,并引入图论理论讨论两时期的水系连通性。结果表明:(1)20 a间城镇用地面积增加174.73 km~2,水域面积减少34.04 km~2。研究区水域面积随城镇用地增加而缩减;(2)城市化进程中,研究区河流水面率、河网密度和河频率均下降,支流发育薄弱,河网复杂度下降;(3)赣江以北水系连通度降低,赣江以南区域水系连通度提升。该研究将为城市化地区河流水系保护提供支持与参考。

ANALYSIS OF WATER SYSTEM STRUCTURE AND CONNECTIVITY IN THE CENTER OF NANCHANG UNDER THE URBANIZATION PROCESS

The effect of urbanization on the stream structure and connectivity has been a hot topic nowadays.At present,fast urbanization has caused many environmental problems,such as the simplification of water system structure,decreasing connectivity of river and degrading water quality.Three remote sensing images in 1990,2000 and 2010 in the center of Nanchang were processed and classified for the analyses on the spatial and temporal characteristics of underlying lands.The river systems were extracted by GIS based on the topographic maps in 1958 and 2010,and the influence on the stream structure was analyzed using quantitative and structural index;The graph method was used to analyze the changes in river connection.The results showed that:(1)During the 20 years,the urban land area increased by 174.73 km2,and the water area decreased by 34.04 km2.The water area decreased with the increase of urban land;(2) The water surface rate,river network density and frequency were found to decrease.Tributary development was also found to decrease during the urbanization process;(3) The connectivity of water system reduced at the north of the Ganjiang River but increased at the south.