ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
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2 MINING SUBSIDENCE AND ITS PROPERTIES 
As a typical damage to landscape and environment, mining 
subsidence has many important features, and those are the 
basis of further studies. In order to simulate and represent the 
shape and features of mining subsidence, its dynamic process 
and properties should be understood firstly. 
2.1 The dynamic of mining subsidence 
Mining subsidence is a typical spatio-temporal dynamic process. 
The mining activities were conducted underground and brought 
damage to rock directly, and then the stress change would 
spread in vertical and horizontal directions, finally, land over 
working space and goaf would subside and create other 
problems, and this procedure can be demonstrated by Fig. 1. 
1 ► 
Advancing direction 
Fig. 1 The relationship of mining and subsidence 
From Fig. 1 we can describe the dynamic process as follows: (1) 
before coal was mined, underground rock and ground surface is 
stable. (2) After mining begins, the balance of underground 
stress would be damaged and the force would spread to ground 
surface, but before point 1 was mined, no impact was created to 
point A on ground surface. (3) When 1 was mined, point A began 
to move at a low speed and with acceleration. (4) When point 2 
was mined, point A would subside with biggest values and begin 
decrease, but continue to move. (5) After point 2 was mined, 
point A would continue to move with a lower speed until it 
reaches a stable situation. So we can know that this process is 
complex and dynamic. 
We also can describe the procedure by Fig.2. From Fig.2, It can 
be known that the area of subsiding land is much larger than 
underground goaf by mining, and it looks like a basin, so it is 
called subsiding basin. 
2.2 The properties of mining subsidence 
It is well known that GIS applications should be based on the 
properties of geo-phenomena and its demands, so we would 
give discussions on them. 
Fig.2 The shape of subsiding basin and mining 
(1) Mining subsidence is a three dimensional (3D) dynamic 
process, so if we want to express and analyze it in GIS, 
multi-dimensional and dynamic model and methods are 
necessary. 
(2) It is influenced by several factors, including thickness of coal 
seam, mining depth, properties of rock and its force features, 
mining methods and others. When it is analyzed in GIS, different 
factor should be represent in different layer with different 
patterns, and the information should be easy to get and 
organize. 
(3) The subsiding land can be expressed by different land use 
and land cover, and it can be identified by spatial and attribute 
information. So it should be represented by spatial and attribute 
information with different methods, such as shapes, DLM, 
images and other forms. 
(4) It is a non-linear and non-even process, so the simulation 
can't be realized by GIS solely, and it should be based on the 
combination of spatial analyzing model and GIS. How to 
establish the model is a key issue, especially to non-linear and 
non-even process, the modeling methods based on statistics, 
experience, mechanism and rule should be used. 
(5) It obeys some laws and can be forecasted, so GIS can be 
used to simulate and forecast the land subsiding situation, but 
how to realize it is a important and difficult problem, especially 
how to represent the laws by GIS. 
(6) It will cause some further damages and problems, including 
water and soil loss, damage of construction, impact on water 
resource and land pollution. In GIS, mining subsidence would be 
integration with other problems, and it should be open to other 
field. Then, the data, information and model should obey certain 
standard and rules. 
From above properties, we can know that if we want to study 
subsidence in GIS, several key issues should be given more 
discussions, and in this paper emphasis would be paid on the 
spatial information collection and 3D representation of subsiding