C,.=Logun(X +1) + (6) 
where X, is conservation measure factor. 
5. MODEL IMPLEMENTATION 
The implementation has two functions: 1) to 
produce a soil erosion map covering 3120 km for 
the local government; and 2) to finish the research 
of computerized soil erosion mapping. The model 
implementation on a computer was undertaken on 
a 200 km? subarea, since the hardware platform 
used was a PC-386 which was unable to support 
large quantity data manipulation. 
5.1 Manual Application 
After the six factors were made into thematic 
maps, they were then converted to semi- 
transparent hard copies. We were able to evaluate 
the soil erosion intensity on these maps polygon 
by polygon. Finally, a total area with 3120 km“ 
was mapped which was highly approved by the 
local governments. 
5.2 Application in Raster Format 
A total of 200 km? of the thematic maps were 
input into PC ERDAS 7.3. An accurate map of 
soil erosion was produced. However, the resulting 
map needed smoothing because the raster format 
modeling was based on pixel by pixel, which gave 
the map a “noisy” appearance. 
5.3 Application in Vector Format 
This application was carried out on PC 
ARC/INFO using vector format data. The 
researchers noticed that the evaluation must be 
based on the land use layer, because this model 
theoretically assumed that soil erosion 
mechanisms differ from land use. The output in 
this research was satisfactory, and the result is 
illustrated in Figure 6. 
5.4 X-Window Package 
For easier mapping, this model was incorporated 
into a small software which reads ERDAS .lan file 
and produces raster format data. This package was 
programmed at UNIX X-Window Toolkit 
Intrinsic level, so it can be loaded on any UNIX 
and LINUX system. Likewise, the resulting map 
needs to be “cleaned” since it is in raster format. 
6. DISCUSSIONS AND CONCLUSIONS 
RASEAM was proven to be a practical approach 
to soil erosion mapping suitable for use in rough 
terrain area. The designation of a ranking system 
for the six factors is simple and easy to operate, 
without requiring expensive time consuming 
experiments. It requires minimal field work to 
establish the factor ranking scheme and to 
implement the model, which is particularly 
suitable for remote sensing and GIS mapping 
activities. 
RASEAM can be used in any rough area by 
modifying ranking tables for each factor. It will 
be not necessary to modify the modeling rationale, 
but only modify the ranking tables to address 
different problems. It will be easy and inexpensive 
to apply this approach in the other places. 
RASEAM is a runoff focused soil erosion model, 
so it does not work well for wind erosion and 
gravity erosion issues. For runoff erosion types, it 
did not specify the terms of sheet erosion, rill 
erosion and gully erosion, but handled this 
problem through a slope grading design because 
the researchers assumed that soil erosion 
characteristics are relevant to slopes. 
7. ACKNOWLEDGMENTS 
The authors are grateful to the following people 
who made contributions to this research: 
Dr. Paul Mausel, Indiana State University, USA, 
for help in article review. 
Mr. R. B. Tucker, Hunting, England, for his 
discussions on soil and parent material ranking. 
822 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996 
Prof. 
discus 
Miss I 
on ER 
Mr. 1 
Englar 
data in 
Mr. H 
Remot 
their c 
manua 
Mrs J 
Agricu 
soil erc 
Profess 
Agricu 
Mr. Y: 
Zhaoho 
Researc 
design 
]itea TH 
of Scier 
Soil C« 
Shaanx 
à. Si 
Soil an 
Report 
Sensing 
Power I 
3 ants IE 
Prospec 
Fertilize