Agriculture Reference
In-Depth Information
Well drained
Intermittent
saturation
1
Water
table
Moderately
well drained
2
Imperfectly
drained
3
Poorly
drained
Ver y
poorly
drai n ed
Levee
4
Zon e of permanent sa t uration
Ri v er
5
Hydrological sequence of soils from 1 to 5
(a)
Well drained
Moderately
Imperfectly
Poorly
Very poorly
well drained
drained
drained
drained
0
Rusty
mottles
around
roots
Uniform
Dark
peaty
colors
Uniform
25
colors
Mottles
Uniform
“oxidized”
colors
Prominent
mottles
Pre-
dominantly
blue-grey
Much
mottling
in a
dark-grey
matrix
grading
50
into
blue-grey
matrix
Orange
mottles,
grey matrix
75
(b)
Figure 1.11
(a) Section of a slope and valley bottom showing soil drainage classes. (b) Soil profiles,
with changing morphology, that correspond to the drainage classes of Figure 1.11a (White
1997). Reproduced with permission of Blackwell Science Ltd.
The gradient of a slope (expressed as a percent) can be measured from a con-
tour map (as the vertical interval divided by the horizontal distance between con-
tours). The slope angle
(alpha) is related to the gradient by
Gradient tan
(1.1)
The angle
is measured with an inclinometer.
 
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