1958-2006年玛纳斯河流域水系结构时空演变及驱动机制分析

Temporal-spatial Evolution of Stream Construction and Its Driving Forces in Manas River Basin During 1958-2006

为了研究玛纳斯河流域水系结构演变状况,利用其1958、1976、1987、2006年4期遥感影像图,在ArcInfo支持下进行目视解译,根据解译结果,定量分析了水系长度、密度、分枝比、长度比和分维等参数的变化特征,并探讨其主要驱动因素。研究表明:1958-2006年玛纳斯河流域水系变化满足Horton定律,水网数目及河道平均长度随水网级别呈几何级数变化,并且水网密度、水系长度比、分枝比等参数持续增大;流域内绿洲地区水网密度高于南部源流山区与北部荒漠区,这种区域差异是由不同生态经济单元的自然生态环境类型、社会经济发展状况,综合发展需求及生态修复重建等方面共同决定的;玛纳斯河流域水资源量近50年来不断增加,人口数量持续攀升,耕地与绿洲面积不断扩大等因素是玛纳斯河流域水网结构演变的主要驱动力。然而耕地不能无限扩大,绿洲也不能过度扩张,要以水资源的承载能力为限,因此确定合理的绿洲面积,优化水系结构,提高水资源利用效率将成为今后研究的重点。

This paper analyzes dynamic changes of length,density,branching ratio,length ratio and fractal dimension of the river networks and their driving factors based on the visual interpre-tation of remote sensing image of Manas River Basin during 1958,1976,1987 and 2006 by using the software of Arc/Info.In the results,the changes of the river networks obey Horton’s law,with geometric changes of stream number and average length and with continuous increase of river den-sity,length ratio and branching ratio.River density of oases in the basin is higher than that in the southern mountainous areas and the northern deserts.This is determined by the eco-environment,social-economic,synconditions,integrated development and ecological restoration in those areas.The increase of water quantity,population,and areas of cultivated lands and oases are the main driving factors.The expansion of cultivated land and oases is limited by water carrying capacity,therefore,it will become the key tasks to make rational plans for oases,to optimize river system structure and to improve water use efficiency.