164
Figure 12. Comparison between computed flow
accumulation:
a) Flow accumulation computed by the aspect
based algorithm;
b) Flow accumulation computed by the form
based algorithm,
c) Flow accumulation computed by
ARC/INFO.
5.0 CONCLUSION
The proposed algorithms have demonstrated their ability to produce a better simulation for flow-
accumulation compared with the ‘eight direction’ algorithm which is commonly used in today’s GIS.
However, the results have to be statistically tested, by applying the different algorithms to
mathematically generated surfaces. Another challenge in future research will be focused on appropriate
algorithms for generating drainage network and introduction of more environmental variables into the
hydrological modelling processes.
6.0 REFERENCES
Eklundh, L. and Pilesjo, P. (1990). Regionalization and spatial estimation of Ethiopian mean annual
rainfall, International Journal of Climatology , Vol. 10, pp 473-494.
ESRI (1991). Cell-based Modelling with GRID , Environmental System Research Institute, Redlands, CA.