ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS”, Bangkok, May 23-25, 2001 
65 
contaminants risk can be mapped in Arclnfo coverages. Each 
converage is linked to an attribute table so that information is 
available on the individual features, or records, of the theme. 
Maps can be created to convey geographic features and 
relationships along with the results of a data analysis. Besides 
data-mapping advantage, GIS also has the ability to query 
specific information in a theme and dynamically link external 
database. 
The general GIS-supported framework is showed in Fig. 4. 
GIS USEJUNTERFACE 
3.1 The Digital Base Design 
It consists of two major components: a spatial database and a 
tabular database. The spatial database contains the GIS shape 
files and coverages of geographic features related to regional 
and facility information. These features are topologically 
referenced to the real world. The regional information required 
by spatial database can be obtained from various source, it’s 
always a time consuming and tedious search work. Most of 
these sources contain Arclnfo coverages in export format 
(*.e00), which can be imported into ArcView using build-in 
lmport71 command. 
Obstacles exist when big-scale coverages are not available 
from Internet sources, federal or local department. Fortunately, 
options available for building a facility database. One method is 
first through aerial mapping to produce orthophotos, and then 
digitize features from the orthophotos. It is accurate but very 
expensive. Digitizing the facility features using existing maps or 
photographs is the alternative that is easy-taken and was 
employed in the research process. Through accessing to a 
digitizing tablet, layering coverage can be accomplished 
directly with the Digitizer extension in ArcView (Fig. 5). 
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Tabular database contains information about environmental 
measurements at the site, such as contaminants concentration 
data, groundwater levels, sampling position, soil profiles and 
so on. An efficient form of organizing data is through the use of 
a relational database. The database is stored in one file, but 
this file can contain multiple tables, all of which relate to the 
particular subject but contain different data related to that 
subject. However, the current capabilities of ArcView do not 
provide an efficient way to link multiple tables since each 
feature can have only one associated record. Under such 
circumstance, Microsoft Access was used to create the 
relational database. Interrelationship within tables was 
established to link each other, which could be used to execute 
query function to create new relationships (Fig. 6). 
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3.2 Customized Graphic User Interface 
ArcView’s Advanced Customized Graphic User Interface 
operation allows the user to create self-demand user interface 
with more flexible and realizable function. Through executing 
easy event-driven Avenue script “System.Execute”, the 
groundwater transport model simulator BIOF&T could be called 
externally by ArcView. The results from BIOF&T simulator can 
be compiled and saved as Text Delimited Format, which can 
be sequently imported to MS Excel to proceed the risk analysis 
using proposed environmental risk assessment methodology. 
3.3 Connecting Spatial and Tabular Database and 
Spreadsheet 
The predicted concentration data resulting from the 
groundwater simulator and sampling data were imported to 
Excel spreadsheet to process the calculation step of 
environmental risk analysis. When the calculation was done, 
the risk results were connected with MS Access through the 
“Get External Data” function. Advanced ArcView Database 
dynamically link function allows the user to import selected 
sets of data from another database utility into GIS using an 
Open Database Connectivity (OBDC) driver and build-in data 
management system which use Structured Query Language 
(SQL). The imported data can then be joined to an existing 
coverage or used to create a new coverage with Avenue 
scripts or Add Event Theme command in ArcView. 
The Spatial Analyst extension of ArcView was used to 
interpolate grid surface and contours between point 
measurements. For each figure, the contours of risk level for 
individual risk and overall risk level were created using Inverse 
Distance Weighting (IDW) interpolation scheme, which 
interpolates a values for each point in the study area using the 
inverse distance squared between the location of the current 
point and the measurement location as a weighting parameter 
(Fig. 7).