利用长时序流域不透水面数据集探索城市增长模式——以秦淮河流域为例

南京作为秦淮河下游的中心城市，在快速城镇化进程中面临着下垫面条件急剧变化带来的生态环境效应。不透水面作为衡量区域城镇化发展状况的关键指标，搭建了城市开发与环境质量的桥梁，可为当前空间治理与统筹城乡发展提供新的研究视角。在我国海绵城市建设背景下，以南京所在的秦淮河流域为研究区，通过半自动决策树分类模型从1988～2017年9景卫星影像提取流域基础不透水面数据集，利用多重滤波器构建连续变化的不透水地表，采用扩展强度指数和景观扩展指数定量分析30 a秦淮河流域不透水面时空扩展特征与城镇增长模式，揭示流域内城市发展轨迹及其成因。研究结果初步表明：(1)流域城镇化进程十分迅速。不透水面占比从1988年的3.09%增至2017年的26.49%，特别是2006年以来不透水面处于快速扩展期；(2)流域内不同城市的不透水面扩展进程差异明显。初期集中在南京城区和江宁城区，进入21世纪后则以江宁区、溧水区和句容市为主；(3)“多核扩展”和“点—轴扩展”是秦淮河流域城镇形态组建和增长的主要模式。初期以城区边缘式扩张为主，后期逐渐转向填充式增长，城镇一体化水平不断提升；(4)流域不透水面扩展是自然环境、经济发展...

Exploring the Urban Growth Patterns Using Long-time Series Impervious Surface Dataset in the Qinhuai River Basin

As the central city of the lower reaches of the Qinhuai River Basin （QRB）， Nanjing has been suffering from ecocological envirnoment effects due to great changes in underlying surfaces under rapid urbanization processes. Impervious surfaces， one of the key indicator of regional urbanization， can bridge urban development and environment quality， which provide a new perspective of spatial goverance and coordination of urban and rural development. Under the sponge city concept，we extracted the impervious surfaces of multi-temporal Landsat images through the semi-automatic decision tree classification model in the QRB， China from 1988 to 2017. To extract the continuously changing impervious surfaces， we made full use of temporal， spatial and spectral characteristics through multi-filter methods to further improve the classification accuracy. We then explored the characteristics of impervious surface expansion， including the area， intensity， landscape expansion types of the QRB during the past 30 years. The results show that the QRB experienced rapid urbanization in the study period， and the impervious surface percentage increased from 3.09% in 1988 to 26.49% in 2017. Before 2006， the QRB kept extending mainly at a lower and medium speed in the urban cores of Nanjing city and built-up of Jiangning district. After that， it began to expand at a high speed， being located in the Jiangning district， Lishui District and Jurong city. The QRB was a constellation model in 1988， however， its shape of the impervious patches turned to be simpler with higher compactness based on the “multi-core expansion” around the urban core as well as the “point-axes expansion” along the main transportation lines.The impervious surface expansion in the basin showed an obvious spatial heterogeneity. Economic development， government behaviors， traffic infrastructure development and natural environmental conditions hadgreat impacts on the impervious surface expansion in the QRB. The urban-rural integration was constantly improving with higher patch infill growth.