不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,...不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,采用指标分析、重心轨迹偏移等方法探究不透水层空间扩展特征,并结合统计年鉴、DEM数据研究铜川市不透水层扩展驱动机制。结果表明:文中提出的基于决策树分类模型结合BCI和MBSI的方法对不透水层提取与验证数据的拟合优度达到0.88.铜川市的不透水层面积持续增加,面积从1986年的5.7 km 2增加到2017年的61.5 km 2,年均增长速度高达1.8%,特别是2007—2017年是快速城市化时期,增长面积占31 a变化总面积的69.3%.不透水层的重心呈先北后南的阶段性变化,1986—2002年向北移动,2002—2007年向南移动,2007—2017年继续向西南方向移动。通过对驱动力指标分析表明,经济及人口增长对不透水层扩展有着直接推动作用,矿产资源分布、地理环境限制和规划政策引导为影响研究区不透水层变化的主要因素。展开更多
DMSP/OLS nighttime light （NTL） image is a widely used data source for urbaniza- tion studies. Although OLS NTL data are able to map nighttime luminosity, the identification accuracy of distribution of urban areas （...DMSP/OLS nighttime light （NTL） image is a widely used data source for urbaniza- tion studies. Although OLS NTL data are able to map nighttime luminosity, the identification accuracy of distribution of urban areas （UAD） is limited by the overestimation of the lit areas resulting from the coarse spatial resolution. In view of geographical condition, we integrate NTL with Biophysical Composition Index （BCl） and propose a new spectral index, the BCl Assisted NTL Index （BANI） to capture UAD. Comparisons between BANI approach and NDVl-assisted SVM classification are carried out using UAD extracted from Landsat TM/ETM＋ data as reference. Results show that BANI is capable of improving the accuracy of UAD extraction using NTL data. The average overall accuracy （OA） and Kappa coefficient of sample cities increased from 88.53% to 95.10% and from 0.56 to 0.84, respectively. Moreover with regard to cities with more mixed land covers, the accuracy of extraction results is high and the improvement is obvious. For other cities, the accuracy also increased to varying de- grees. Hence, BANI approach could achieve better UAD extraction results compared with NDVl-assisted SVM method, suggesting that the proposed method is a reliable alternative method for a large-scale urbanization study in China＇s mainland.展开更多
文摘不透水层是指能够隔离地表水渗透到土壤的覆盖表面,以不透水层分布变化来研究铜川城市化进程。利用决策树分类结合生物物理成分指数(BCI)和裸土指数(MBSI)的方法对1986,1991,1996,2002,2007,2012和2017年的遥感影像数进行不透水层提取,采用指标分析、重心轨迹偏移等方法探究不透水层空间扩展特征,并结合统计年鉴、DEM数据研究铜川市不透水层扩展驱动机制。结果表明:文中提出的基于决策树分类模型结合BCI和MBSI的方法对不透水层提取与验证数据的拟合优度达到0.88.铜川市的不透水层面积持续增加,面积从1986年的5.7 km 2增加到2017年的61.5 km 2,年均增长速度高达1.8%,特别是2007—2017年是快速城市化时期,增长面积占31 a变化总面积的69.3%.不透水层的重心呈先北后南的阶段性变化,1986—2002年向北移动,2002—2007年向南移动,2007—2017年继续向西南方向移动。通过对驱动力指标分析表明,经济及人口增长对不透水层扩展有着直接推动作用,矿产资源分布、地理环境限制和规划政策引导为影响研究区不透水层变化的主要因素。
文摘DMSP/OLS nighttime light （NTL） image is a widely used data source for urbaniza- tion studies. Although OLS NTL data are able to map nighttime luminosity, the identification accuracy of distribution of urban areas （UAD） is limited by the overestimation of the lit areas resulting from the coarse spatial resolution. In view of geographical condition, we integrate NTL with Biophysical Composition Index （BCl） and propose a new spectral index, the BCl Assisted NTL Index （BANI） to capture UAD. Comparisons between BANI approach and NDVl-assisted SVM classification are carried out using UAD extracted from Landsat TM/ETM＋ data as reference. Results show that BANI is capable of improving the accuracy of UAD extraction using NTL data. The average overall accuracy （OA） and Kappa coefficient of sample cities increased from 88.53% to 95.10% and from 0.56 to 0.84, respectively. Moreover with regard to cities with more mixed land covers, the accuracy of extraction results is high and the improvement is obvious. For other cities, the accuracy also increased to varying de- grees. Hence, BANI approach could achieve better UAD extraction results compared with NDVl-assisted SVM method, suggesting that the proposed method is a reliable alternative method for a large-scale urbanization study in China＇s mainland.
