interface programs that make paper work so simple 
were written in Visual BASIC. 
3. RESULTS AND DISCUSSION 
3.1 Data Base 
Data base for Noname River Watershed consists of 
land parcel maps 74 sheets, topographic maps 48 
sheets, three-dimensional contour maps 48 sheets, 
slope maps 48 sheets. All are at a scale of 1:1,000. 
Every single sheet of map has graphic layers more than 
180. Slope land uses and suitability maps are at a scale 
of 1:5,000 and only 10 sheets are needed and all are 
available. They can overlay to one another both in two 
dimensions and three dimensions. The whole process is 
confined to this watershed. 
3.2 GIS Analysis 
Overlay analysis is simply a process of layer on and off. 
Slope maps and contours maps can be displayed in 
three dimensions by a single command. A 3-D display 
of an illegal slope land use site is very useful to review 
several different "what if' might happen in the near 
future such as, landslide. It is an overlay analysis that 
can provide the key land ownership information, that is, 
parcel numbers. Then a small program will display all 
attributes associated with a particular parcel number 
automatically. 
3.3 All Land Parcels Under Monitoring 
All illegal slope land uses were identified on a color 
monitor and their land parcel numbers were picked by 
a mouse and stored as a new file. This new file then 
serves as a basic file to meet needs in further 
management. A list of land owners who is confined to 
one more fine can be automatically displayed and 
printed out. A color photo can be displayed on a color 
monitor to indicate what happened on a particular site 
to decide what management prescription is needed. All 
paper work is performed on a table by table basis. That 
is, an interface program takes care a single table. The 
interface programs are very easy to be configured into 
different forms to meet different needs. 
In short, a GIS provides functions that will indicate 
parcel numbers for those illegal slope land use sites. A 
tine for the illegal slope land uses is issued 
automatically. One more fine is needed or not is also 
decided by a GIS. All paper work required to monitor 
illegal slope land uses is also an automatic process that 
needs user interaction. 
682 
4. CONCLUSION 
Management of illegal slope land uses in Taipei City is 
now performed by the use of geographic information 
system. Only limited functionalities were provided by a 
self-developed GIS. Interface programs have been 
developed to make the management process very 
simple and easy to use. No training is required. 
Interface programs are very easy to write that 
interaction of one single user can be made very 
smoothly. The whole process can adapt to users and 
organizational needs. Information content of the 
existing data base is very critical. Slope land uses maps 
and digital parcel maps of the whole Taipei City have to 
be created into the data base such that the whole 
process can be implemented to soil and water 
conservation problem in the city instead of only one 
watershed. 
5. REFERENCES 
Frank, A. U., M. J. Egenhofer, W. Kuhn, 1991. A 
perspective on GIS technology in the nineties. 
Photogrammetric Engineering and Remote Sensing, 
Vol. 57, No. 11, pp. 1431-1436. 
Mark, D. M., M. D. Gould, 1991. Interacting with 
geographic ^ information: A commentary. 
Photogrammetric Engineering and Remote Sensing, 
Vol. 57, No. 11, pp. 1427-1430. 
Wu, Mu-Lin, Ta neu Liao, 1991. Slope land uses 
investigation at Noname River Watershed, Wenshan 
District, Taipei City. Research Report, Bureau of 
Reconstruction, Taipei Municipal Government, 51 
pages.