Study On Visualization Of Land Subsidence Due To Pumping Ground-water

Land subsidence due to pumping groundwater is one of the severe geological disasters and often occurs in prosperous areas due to the abused use of groundwater. In this thesis, the process of land subsidence was visualized by using professional programs (Mapbasic and IDL) in combination with studies on the mechanism of land subsidence and the subsidence calculations by FEM. The developed visualization program is able to illustrate the subsidence magnitude, drawdown and water table variation through charts, tables and animations. Work scope includes followings.(1) Given the incompressibility of water, a relation between specific elastic storage, compressibility modulus and deformation modulus was inferred by applying current related formulas.(2) To preliminarily develop a visual program projecting and illustrating land subsidence. Firstly, a GIS system embedding query and visualization sub-module was set up by using Mapbasic, a satellite product of Mapinfo. Data were imported into the GIS system to form a database, based on which the visual program is able to evaluate the subsidence distribution, drawdown and water table variation in researched areas by observing the color variations of contour charts and 3-D nephograms. The visual program is also able to demonstrate the variation of hydrological parameters in the process of pumping based on data in drillings, which aids the effect analyses of hydrological variation on subsidence.(3) To visualize a 3-D process of land subsidence by pumping. A program was compiled by using IDL, a visual tool. This program can import data and automatically play a 3-D animation of subsidence. Thus, the data variation in researched areas is well demonstrated, including the formations of subsidence funnels and drawdown funnels.