城市化进程下北京平原渗流场与地面沉降发展演化模拟

北京地面沉降已有60多年的历史,其发生发展与半个多世纪城市的快速扩张密不可分.从整个北京平原地下水系统出发,梳理多年时间序列(1950-2015年)的城市发展规模、人口、水资源及开采动态等数据,结合遥感技术解译不同年代北京平原的不透水面变化,分析其对降雨入渗补给量的影响;构建整个北京平原含水层-弱透水层三维结构系统,借助PMWIN软件建立区域尺度的地下水流-地面沉降耦合模型,利用长期水位及沉降观测数据对模型进行识别验证;开展长时间序列的北京平原地下水水头场与地面沉降演化模拟,研究快速城市化进程下北京平原多层含水层系统渗流场演变与地面沉降响应特征.研究表明:长时间尺度区域地下水流场-地面沉降演化模拟基本再现了地面沉降形成和发展演化的过程;北京地下水开采历史与地面沉降发展历史具有一致性,而不同沉降区地面沉降发展受地下水开采和城市发展双重控制,是二者综合作用的结果.

Numerical study on evolution of groundwater hydrodynamics and land subsidence under the process of metropolitan urbanization in Beijing Plain,China

Ground subsidence in Beijing has a history of more than 60 years, which has close relationship with the rapid expansion of Beijing City in the past half a century. In this paper, based on the groundwater flow system of the entire Beijing Plain, a large amount of data of urban development scale, population, and water dynamics over a multi-year time series (1950s-2015s) has been combed, and the impervious covers of the Beijing Plain in different years are interpreted so as to analyzes the changes of rainfall infiltrations into groundwater systems by using remote sensing technology.After generalized a three-dimensional aquifer-aquitard structural system in the entire plain, a regional model coupling multi- groundwater flow with land subsidence model with PMWIN software, which is identified and verified by converging long-term water level and subsidence observation data. Long-term evolution simulation of groundwater hydrodynamics and land subsidence have been performed to study the evolution of the water cycle and the response characteristics of land subsidence in a multi-layer aquifer system in the Beijing Plain under rapid urbanization.The results show that the long-term evolution simulation coupling groundwater flow and land subsidence basically reproduces the process of formation and development of land subsidence.The history of groundwater abstraction in Beijing City is consistent with the history of land subsidence development. Moreover, the land subsidence developments in different subsidence areas are mainly controlled by groundwater abstraction and metropolitan urban development.