高强度人类活动下河网水系时空变化分析——以浦东新区为例

Dynamic Changes of River Network under Intensive Human Activities:A Case of Pudong New Area,Shanghai Municipality

基于遥感资料和GIS分析,对2000年～2003年浦东新区河网(包括河流、池塘、养殖鱼塘)与其他土地利用类型之间相互转变数量特征,河网水系的变化强度、河网流失强度的区域分异特征进行了描述和分析,对河网缩减机制进行了初步探讨.研究结果表明:①2000年～2003年,浦东新区河网水系发生了很大变化,主要表现为水域面积减少和河网密度的快速降低,其中河流面积净减少449hm2,年平均流失率4%,河流密度年平均缩减率为5%;②城市化不同发展程度对河网水系有不同的影响规律,城市化率很高的主城区,河网水系稳定,变化很小;城市化水平较低的城市边缘区,城市化进程迅速,河网水系缩减迅速;城市化水平低,远离市区,建设用地新增速度慢的地区河网水系变化小;③河网缩减具有显著的区域分异特征,流失的主体部分集中在城乡交替地带,同城市扩展同步.

River network protection is not paid enough attention in the process of rapid urbanization, leading to fiverway tamping, river network reduction and water environment destruction. Moreover, there are few relevant researches on spatial-temporal change mechanism of river network caused by intensive human activities. This research attempted to reveal the dynamic change trends and spatial-temporal distribution characteristics of river network in Pudong New Area by depicting and analyzing the intensity of fiver loss and relating transformation modes based on the multi-temporal remote sensing data of aero photographs and relevant social-economic statistics. Firstly, the water quantity in Pudong New Area has experienced dramatic changes with the remarkable reduction of water body and the density of river network from 2000 to 2003. For instance, in these three years, the total net reduction of river body is 449 hm^2 with an annual reduction rate of 4% ; and the average reduction rate of river density is 5 %. The transformation from water body to urban land use acted as the main contributions to the changes of both quantity and density of river network. Secondly, different urbanization levels and speeds have different effects on the river network. The disappeared rivers are mainly located in the urban fringe and near to the major roads, where the urbanization is intense, reflecting the violent encroachment of urbanization to river network. Quite on the contrary, the water body located in the downtown didn＇t experience the dramatic changes, and in some remote areas which featuring a relative slow constructional land growth, the intensity of river network changed little. Thirdly, the regional differentiation of decrease in fiver network is obvious. It can be concluded that the major parts of river network losses are mainly located in the intersectional of urban and suburban areas. The distinct trends of the decrease in river network appear by turns with the distance increases from the downtown, which means it changes from very slow to fast, very fast, slow, then to very slow, urbanization speed with the river reflecting a close relationship between the urbanization level and network decreasing soeed.