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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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