Relationship between degrees, percent slope, and ratio to express slope gradient.
Slope gradient is a key factor in influencing the relative stability of a slope. It determines the degree to which gravity acts upon a soil mass. Slopes are often irregular and complex, with gradients varying greatly throughout a given shoreline profile. Each slope profile section should be treated as a separate management and restoration site unit. Slope gradient can be expressed in several ways. The table and slope determination formulas below illustrate three commonly used notations.
|
DEGREES
|
PERCENT (%)
|
RATIO (H:V)
|
|
 |
|
2.5
|
5.0
|
|
|
|
5.7
|
10.0
|
10:1
|
|
|
10.0
|
17.6
|
|
|
|
14.0
|
25.0
|
4:1
|
|
|
18.0
|
33.5
|
3:1
|
|
|
19.3
|
35.0
|
|
|
|
20.0
|
36.4
|
|
|
|
24.2
|
45.0
|
|
|
|
26.1
|
49.0
|
|
 |
|
26.6
|
50.0
|
2:1
|
|
|
30.0
|
57.7
|
|
|
|
33.0
|
66.7
|
1.5:1
|
|
|
35.0
|
70.0
|
|
|
|
38.6
|
80.0
|
|
|
|
42.0
|
90.0
|
|
|
|
45.0
|
100.0
|
1:1
|
|
|
55.0
|
142.8
|
|
|
|
60.0
|
173.2
|
|
|
|
|
|
|
|
| Adapted from: A Guide for Management of Landslide – Prone Terrain in the Pacific Northwest (1991) Land Mgmt. Handbook 19. B.C. Ministry of Forests. |
|
Corrected From: Urban Riparian Inventory and Assessment Guide (1998) Oregon Div of State Lands. |
By Elliott Menashe (greenbeltconsulting.com) 2004
Written by Elliott Menashe of Greenbelt Consulting, an environmental education, assessment, and management service in the Pacific Northwest.
This material is available for use by non-profit organizations and public education. All other uses or repurposing requires the permission of the author. This information is protected by Copyright © Law 2004.
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