» water 
a lake 
  
  
  
3. GEOGRAPHIC INFORMATION SYSTEMS 
FOR TANFA LAKE 
Geographic information systems for Tanfa lake are 
written in several computer languages such as C++, 
Delphi. Data input and output, inquiry, manipulation, 
and analysis can be implemented in an all Chinese 
computer system. The whole systems are user friendly 
because of Windows 95 Chinese version providing an 
easy personal computer operating system. 
3.1 Databases 
All maps were digitized into a personal computer and 
converted into several map formats, both vector format 
and raster format. Topographic maps consist of five 
sheets of 1:5000 orthophoto maps, one sheet of 1:25000 
map. All orthophoto maps were scanned sheet by sheet 
and built into the databases as image files. Geological 
maps were generated based on field investigation. 
Attributes such as water quality, rain falls, land parcel 
ownership information, land category were stored in 
relational databases. Inquiry of the databases is simple 
and quick. Statistical charts can be drafted on a computer 
monitor by mouse clicking only. In the mean time, all 
statistical charts can be obtained as a color printer output 
by a mouse clicking on a color monitor. Geographic 
information systems have several different capabilities 
such that inquiry, and data entry, data manipulation can 
be performed simultaneously. 
3.2 Computers and Its Peripherals 
Only personal computers were required. Personal 
computers peripherals such as printers, plotters, scanner 
can be used. Pentium II processors are highly 
recommended. At least 64 MB of RAM, high quality of 
color monitors with 1024X768 full colors display 
capability, hard disks having more than 4 GB capacity 
are basic requirements for personal computers 
implemented at here. 
3.3 Software 
Word processing programs, spread sheet programs, 
CAD, image editing packages are recommended. 
Commercial geographic information system packages are 
not required but they can work as companions. Delphi is 
a powerful package that one technician at TPGWRD can 
add new functions to the developed GIS in one hour 
training. Modifying existing application modules and 
adding new functions in order to solving problems that 
may encounter before, in the process, and after a new 
dam site construction are quite simple. 
4. REMOTE SENSING APPLICATIONS 
Five sheets of orthophoto maps at scale of 1:5000 serve 
as the basic remote sensing materials and they can be 
extracted on a color monitor for further analysis with all 
other maps (figure 3). All maps are stored in the same 
coordinate system as the orthophoto maps and are 
registered to a common spatial reference system. Land 
uses investigation and local environmental impact 
assessment are mainly done on the ground but some jobs 
can be done on a color monitor. All maps are stored both 
in raster and vector formats such that raster 
implementations of overlay and vector implementations 
of overlay are system functions provided by GIS. In 
short, that remote sensing applications are performed in 
two simple steps, say, right mouse clicking and left 
mouse clicking. Zoom-in, zoom-out, overlay, maps 
extraction, inquiry, data manipulation, and output 
generation can be performed accordingly. 
5. CONCLUSIONS 
Water resource development at Tanfa lake, especially for 
a new dam site selection, is not a simple job. 
Applications of remote sensing and geographic 
information systems for water resource development at 
Tanfa lake did not try to solve all problems in hand but 
tried to make the whole process easier than traditional 
approach. It was without questions that a dam site 
selection process requires more software packages in 
addition to remote sensing and GIS. Human judgement 
and expertise is the major component that water resource 
development can be successful. However, applications of 
remote sensing and geographic information systems for 
water resource development can make the whole job 
easier in terms of data entry, data manipulation, overlay, 
inquiry, and output generation. 
6. REFERENCES 
Chrisman, N. 1997. Exploring Geographic Information 
Systems. John Wiley & Sons, Inc. 298 pages. 
Henderson, K. 1996. Database Devlopers Guide with 
Delphi 2. SAMS Publishing / Borland Press. 857 pages. 
Reisdorph, K., K. Henderson. 1997. Teach Yourself 
Borland C++ Builder in 21 Days. SAMS Publishing / 
Borland Press. ( Chinese edition ). 
Swan, T. 1996. Delphi 32-Bit Programming Secrets. IDG 
Books. 738 pages. 
Thurroff, P. et al. 1997. Delphi 3 Supper Bible. Waite 
Group Press. 1312 pages. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 759