Network Extraction

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Lecture 06 Digital Terrain Analysis II
Topics
Network Extraction Slope partition
References
Chapter 2 by L.E. Band in Beven and Kirkby, 1993,
pp. 13-42
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Lecture 06 Digital Terrain Analysis II
Outlines
4. Network extraction and slope partition
(Digital Elevation Model Figure) 4.1 Flow
direction and flow routing 4.1.1
Determining local flow direction (LFD)
1) Methods (a) D8
algorithm
(The D8 Figure) (b) MFD
algorithms Quinn et al.
1991 (The Quinn
Equation) Qin et al.
2005 (The Qin
Equation)
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2) Issues Pits (The
Pits Figure) Flat areas
Undefined directions 4.1.2 Flow accumulation
surface (Upstream Drainage Area.
UDA) Comparison of UDA from D8 and
MFD (D8 versus MFD from Qin et al.
2005) 4.2 Derived products 1) Wetness
index w ln (a/tan ?) (a
UDA per contour length) (The
Wetness Figure)
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4.2 Derived products (continued) 2)
Drainage network extraction (The
Drainage network Figure) 3) Slope
partitioning (The shaded relief
calculation Figure)