Three dimensional numerical modeling of land subsidence in Shanghai
Shanghai city has been suffering land subsidence caused by overly exploitation of ground water since 1921, which is a serious problem for this coastal city with altitude of 2.2–4.8 m above mean sea level. The largest cumulative land subsidence amounted to 2.6 m in the downtown area. Measures to...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2015-11-01
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Series: | Proceedings of the International Association of Hydrological Sciences |
Online Access: | https://www.proc-iahs.net/372/443/2015/piahs-372-443-2015.pdf |
Summary: | Shanghai city has been suffering land subsidence caused by overly
exploitation of ground water since 1921, which is a serious problem for this
coastal city with altitude of 2.2–4.8 m above mean sea level. The largest
cumulative land subsidence amounted to 2.6 m in the downtown area. Measures
to decrease the ground water exploitation, change the pumping aquifers, and
increase aquifer artificial recharge have been used to mitigate land
subsidence since 1961. It is necessary to develop a proper numerical model
to simulate and predict land subsidence. In this study, a decoupled
three-dimensional (3-D) finite element land subsidence model including a 3-D
ground water flow model and a 3-D geo-mechanical model was developed to
simulate the 3-D deformation of the aquifer systems in the center area of
Shanghai. The area of downtown Shanghai is 660 km<sup>2</sup>, with 10 million
inhabitants, dense high buildings, and 11 metro lines. The simulation spans
the period from 1979 to 1995. Two different assumptions have been tested on
the side boundary, i.e., precluding the three components of the
displacement, or assuming a free-displacement condition. The distribution of
calculated land subsidence and horizontal displacements in different
aquifers was analyzed. The computed vertical displacement fitted well with
the available observations. It has been verified that the two different
assumptions on the lateral boundaries in the geo-mechanical model caused
different results just limited on nodes close to boundary. The developed 3-D
land subsidence model is reasonable and can be used to simulate and predict
3-D movement of aquifer systems in the center area of Shanghai, which could
provide scientific support to local government in controlling land
subsidence and differential movements of the land surface. |
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ISSN: | 2199-8981 2199-899X |