基于Landsat影像的西宁市不透水面格局演变过程

Evolution of Impervious Surface Pattern in Xining City Based on Landsat Imagery

不透水面是衡量城市化进度的重要指标,准确地掌握不透水面的时空变化特征对城市协调发展以及规划布局有重要的指导意义。以西宁市为列,基于2001、2009、2017年landsat TM/OLI影像,采用增强型归一化差值不透水面指数提取不透水面信息,并结合不透水面覆盖率的变化、不透面面积年均增长率的变化、圈层理论及景观格局指数等分析近20年间西宁市不透水面的时空格局演变,旨在揭示新型城镇化背景下不透水面的时空变化规律。结果表明:①2001~2017年间西宁市不透水面扩张显著,总面积由41.58 km^2增长到96.23 km^2,年均增长率高达8.22%;②城北区不透水面面积增长率位于四区之首,城中区增长率最低;③不透水面主要分布在距城中心14 km 2区域,且不透水面由城中心向周边呈显著扩张态势,距离城市中心越远,不透水面面积增长速度越快;④不透水面内部斑块正趋于完整化、规则化发展,最大斑块所占比例(LPI)不断增加,优势度不断上升,人类活动对其空间特征的干扰作用在不断加强。

Impervious surface is an important indicator to measure the progress of urbanization.Accurate understanding of the temporal and spatial characteristics of impervious surface has important guiding significance for urban coordinated development and planning layout.Based on Xining City,the enhanced normalized difference impervious surface index was used to extract impervious surface information based on 2001,2009 and 2017 landsat TM/OLI images,and combined the change of impervious surface coverage rate,the change of average annual growth rate of impervious surface area,theory of circle layer and landscape pattern index to analyze the spatial and temporal pattern evolution of impervious surface in Xining City in the past 20 years,aiming to reveal the spatial and temporal change rule of impervious surface under the background of new urbanization.The results show these as follows.①During the study period,the impervious surface expansion of Xining City was significant,the total area increased from 41.58 km 2 to 96.23 km 2,and the average annual growth rate was as high as 8.22%;②The growth rate of impervious surface area in Chengbei District is the first in the four districts,and the growth rate in the urban area is the lowest;③The impervious surface is mainly distributed in the 14 km 2 area from the center of the city,and the impervious surface area is significantly expanded from the center of the city to the surrounding area.The farther away from the city center,the faster the impervious area grows;④The plaque inside the impervious surface is becoming more complete and regularized,the proportion of the largest plaque(LPI)is increasing,and the dominance is rising.The interference of human activities on its spatial characteristics is constantly strengthening.