上海陆域地区地下水采灌与地面沉降的时空特征

Space-time characteristics of exploitation and recharge of groundwater and land subsidence of Shanghai’s land area

上海市地面沉降防治已有显著成效,但在空间格局上地表变形的不均匀性较显著,地面沉降防治管理进入了分区管控的新时期.为配合分区管控,利用长时间序列的水位、地下水开采、分层标三类监测数据,结合区域地面沉降模型,探讨地下水采灌与地面沉降的时空特征.上海市经历了两次长时间大范围的地下水开采,每次旋回分别经历开采量从增加到逐渐减少(甚至回灌)两个阶段.第一旋回的时段是1860-1971年,地下水开采于1963年达到年度最大净抽水量,开采集中在核心区的浅部土层,导致了较严重地面沉降.第二旋回的时段是1972年至今,地下水开采于1998年达到年度最大净抽水量,开采层位集中在第四承压含水层.从1998年至2005年,此层逐渐减少地下水开采,未大量回灌,但地下水位抬升显著,说明此层地下水补给条件良好. 2006-2011年间,各土层的压缩已经大幅减小,宝山、嘉定和核心区的深部土层均有回弹,浅部土层虽然没有抬升,但压缩速率较小,最大沉降速率处于浦东区,为2.61 mm·a-1.

The prevention and control of land subsidence in Shanghai has achieved remarkable results,but the uneven surface deformation in the spatial pattern is significant,and the prevention and control of land subsidence has entered the new era of zoning control. In order to cooperate with the district control,this paper uses the long-term sequence water level,groundwater exploitation and extensometer monitoring data,combined with the regional land subsidence model to explore the space-time characteristics of groundwater exploitation and recharge,and land subsidence. Shanghai has experienced two long-term and large-scale groundwater exploitation cycles. The pumpage of every cycle went through increasing to decreasing. The period of the first cycle was from 1860 to 1971. In 1963,the groundwater exploitation reached the annual maximum net pumping volume. The mining concentrated in the shallow layers of core area,resulting in more serious land subsidence. The period of the second cycle is from 1972 to present. The groundwater exploitation reached the annual maximum net pumping volume in 1998,and the mining concentrated in the fourth confined aquifer. From 1998 to 2005,groundwater exploitation of this layer gradually reduced,and was not recharged too much. However,the groundwater level rose significantly. It indicated the groundwater recharge condition of this layer is good. During 2006 to 2011,the compression of layers has been greatly reduced. The deep layers in Baoshan,Jiading and core areas have rebounded. Although,the surface layer has not risen,the compression rate was small,the maximum sedimentation rate was 2.61 mm·a-1 in Pudong.