Geoscience Reference
In-Depth Information
Input Raster
- Topomap
- SRTM
- ASTER
(DEM)
Raster D8 Flow
Direction
Resample,
convert to point
Resample,
convert to point
Concept
+
New Equations
Vector
limitations
Vector
Convert to *.CSV
- D16 Algorithm
Tool.exe
- D16 Flow Dir
Input
XYZ
D8 Algorithm
Flow Direction
Comparison Testing
·
Topographic Map (3D
Visualization)
·
SRTM (Generalization)
·
ASTER (Swamp Area)
Output:
Comparison
results
Fig. 8
A framework for developing and comparing D16 algorithm with D8
• Wilson ( 2002 )—''D8 cannot be used to model the water flow direction diver-
gence in ridge area''.
• Miller ( 2010 )—D8 is not a suitable method for sub-catchment identification.
• Tarboton ( 1997 ):
- Less options available with a huge separated range angle (Discretization of
D8 flow into only one of eight possible directions, separated by 45).
- D8 introduces no dispersion, but at the expense of grid bias.
Furthermore, D8 algorithm was also not able to detect other state of water
which is with no direction (swamp or stagnant areas) that lead to produce false
flow direction information for a certain area. Thus, D8 will produce flow direction
result in which may be trapped toward the other pointed neighbouring flow arrows
as illustrated in Fig. 1 .
 
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