SOIL AND WATER CONSERVATION ENGINEERING USING A 3-D GIS 
Mu-Lin Wu, Professor 
Civil Engineering Department, National Pingtung Institute of Polytechnology 
P. O. Box 17-164, Taichung, Taiwan 40098, R. O. C. 
Julius E. Kuo, Department Head 
Mu Sheng Liu, Branch Chief 
Der-Ren Song, Specialist 
Taipei Water Resource Commission 
5, Lane 45, Sec. 1, Peihsing Road, Hsin-Ten, Taipei County, Taiwan 23101, R. O. C. 
Commission IV 
ABSTRACT: 
Taipei Water Resource Commission is in charge of soil and water conservation for the headwater in Taipei 
City. 9096 of drinking water for a four-million population is controlled by the Commission. A 3-D GIS has 
been developed in the last three years. This paper discusses how soil and water conservation engineering can 
be facilitated by the GIS. A 80% to 90% automatic process was pursued. 3-D drawings, calculations, and 
paper work can be obtained from a personal computer. All drawings were then built into the 3-D data base. 
3-D animation of a proposed conservation engineering can be obtained as well. 
KEY WORDS: Soil and water conservation engineering, 3-D modeling, Animation. 
1. INTRODUCTION 
Taipei Metropolitan is an area with population 
exceeding 4 millions. About 90% of its drinking water is 
provided by the Taipei Water Resource Commission. 
Water and soil conservation at Taipei Water Resource 
Commission is a very important task. A 3-D GIS has 
been developed in the last three years(Wu, 1990). 
Remote sensing can be implemented to monitor 
landslides and landuses in the two watersheds(Wu, 
1991). However, water and soil conservation 
engineering is still a time consuming process, especially 
in the design process. Both drawing and calculations are 
labor intensive. This paper will discuss how a GIS can 
make the drawing and calculation process a semi- 
automatic process. Site selection of a water and soil 
conservation engineering can be reviewed by a GIS to 
insure that its benefit can be at a very high level. Solid 
modeling and animation can be performed before the 
construction taking place. 
2. METHOD 
2.1 Field Surveying 
Field surveying is performed by a traditional approach. 
Its drawing and calculation process is very easy. Digital 
contour maps and slopes as well as a road map can be 
extracted from the existing data base. Those survey 
data can be inserted into the contour map for further 
interpolation in order to generated a very large scale 
contour map and digital terrain model. The whole 
process can be automatic because of the digital terrain 
model software packages which are components of a 
self-developed GIS. 
2.2 A Design Process 
A drawing has to be digitized or redrawn as a new CAD 
710 
drawing file. Then an interface will be developed to 
make an automatic drawing process. A designer can 
change several parameters which were controled by an 
interface program in order to gei a drawing wiui a 
specific width, height, and thickness. All interface 
programs were written in C and Visual BASIC. All 
interface programs were made in an order-only process. 
That is, it is only made by request from an engineer. 
Calculations were performed by a CAD package or by 
C and BASIC programs with human interactions. Areas 
of cross sections, cutting, and banking require that a 
user delineates the boundary, then an automatic 
process can be performed. 
3-D, front view, and side view drawings are 
automatically performed and stored into a predefined 
drawing format. Dimensioning is an editing process. 
Paper work at the final stage is performed by a word 
processor in a windowed environment. Interface 
programs to make the whole process automatic are now 
easy to write because of the Visual BASIC. One user 
can add new funtions to the interface programs in a 
very short period of time. 
2.3 Three-Dimensional Modeling 
Three-dimensional modeling is performed by a 
commercial animation program. A proposed site and its 
water and soil conservation engineering can be 
displayed in three dimensions. This process requires a 
little bit of practice. All solid models are stored as 
image files which can be displayed on a color monitor 
by mouse clicking. Solid models were generated as a 
single frame in an animation process. Irregular 
triangulated networks of a site or construction body 
must be generated firstly either by digital terrain model 
packages or by a self-developed program.