1. Lecture 06: Digital Terrain Analysis II
Topics:
Network Extraction
Slope partition
References:
Chapter 2 by L.E. Band in Beven and Kirkby, 1993, pp

2. 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)

3. (Upstream Drainage Area. UDA) (D8 versus MFD from Qin et al. 2005)
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)

4. 4.2 Derived products (continued…)
2) Drainage network extraction:
(The Drainage network Figure)
3) Slope partitioning:
(The shaded relief calculation Figure)