通州区城市扩张对地面沉降的影响

The Influence of Urban Expansion of Tongzhou on Land Subsidence

地面沉降是一种不可补偿的永久性环境和资源损失.在北京"市府东移"的战略背景下,通州城区快速扩张、基础设施加速建设、人口急剧增多,都会对通州沉降漏斗的演变造成新的压力.本文基于ENVISAT ASAR(2003—2010年)和RADASAT-2(2010—2016年)两个时段的时间序列SAR影像,利用最新的永久散射体合成孔径雷达干涉测量(PS-In SAR)技术提取高精度的沉降数据,并结合地下水水位数据、土地利用数据,采用GIS空间分析方法,分析通州区地面沉降的时空演化特征及其成因.结果表明:1)2003—2010年,漏斗中心的最大年沉降速率为88.55 mm/a,2010—2016年的最大年均沉降速率达到127.58 mm/a,其沉降呈不断加重的趋势,这两个阶段的区域最大累积沉降量达到1 219.45 mm.2)2016年建设用地面积较2003年净增202.38 km2,达到433.85 km2,建设用地的主要转入来源为绿地.建成区的持续扩张、大量的生态用地被侵占,致使通州城区地面沉降加速演变.3)城市人口增多带来用水量的增加,导致地下水开采量的增加.四个水位监测点上的水位标高的均出现不同程度的下降且与沉降的趋势有很高的相关性.

Land subsidence is a loss of environment and resources which is unable to be compensated. Under the strategic background of new city subsidiary-center of Beijing,the center has expanded rapidly,the building speed of the infrastructure accelerates and the number of population in this area increases sharply,all of these have posed much pressure on the evolution of the settlement funnel. This paper employs Persistent Scatterers In SAR to detect and characterize spatiotemporal changes of ground subsidence,SAR datasets used for ground subsidence monitoring over the Tongzhou region including ASAR images acquired from 2003 to 2010 and RADARSAT-2 images acquired from2010 to 2016. The study also combines groundwater level data,land use data,and GIS spatial analysis methods to analyze spatial-temporal variations of the evolution and the causes of the land subsidence. Major findings are summarized as follows： 1） From 2003 to 2010,the maximum annual settlement rate of funnel center was 88. 55 mm/a and achieved 127. 58 mm/a in next six years. In the past two periods,the maximum cumulative subsidence reached 1 219. 45 mm,and the figure of subsidence of Tongzhou urban area increased continuously. 2） Compared with 2003,the area of construction land in 2016 increased to 433. 85 km^2,gained 202. 38 km^2 and the main source of construction land was green space. The continuous expansion of the built-up area and the occupation of a large number ecological land led to the accelerated evolution of ground subsidence in Tongzhou 3） The increase of urban population brought the increase of water consumption, which eventually led to the increase of groundwater exploitation. The water level elevation at the four water level monitoring points all decreased to varying degrees and had a high correlation with the trend of settlement.