Geology Reference
In-Depth Information
Table 9.5
Model output for the chisel plough management system for a 1000-year period.
Contributing
area (ha)
Discharge
volume (m
3
y
−
1
)
Sediment
yield (t y
−
1
)
Sediment yield
(t ha
−
1
y
−
1
)
Sediment
Delivery Ratio
Precipitation volume
in contributing area (m
3
y
−
1
)
64.61
107,239
1549.6
24
0.843
663,677
Runoff volume
(m
3
y
−
1
)
Soil loss
(kg y
−
1
)
Sediment
deposition (kg y
−
1
)
Sediment
yield (kg y
−
1
)
Length
(m)
Width
(m)
Hillslopes
Field area (ha)
H1
17,900
398,487
24,557
373,929
12.2
325
376
H2
20,188
449,379
27,693
421,686
13.8
325
424
H3
8435
134,267
509
133,758
4.7
125
376
H4
9511
151,390
574
150,817
5.3
125
424
H5
9512
151,407
574
150,834
5.3
125
424
H6
11,053
163,001
737
162,265
6.4
150
424
H7
9802
144,549
654
143,895
5.6
150
376
H8
8435
134,267
509
133,758
4.7
125
376
H9
6101
57,309
23
57,287
3.2
75
425
H10
5383
50,567
20
50,547
2.8
75
375
Discharge
volume (m
3
y
−
1
)
Sediment
yield (t y
−
1
)
Channels
Length (m)
Width (m)
C1
6215
55
425
2
C2
20,690
281
425
2
C3
29,819
507
425
2
C4
26,447
448
375
2
C5
56,342
936
275
2
C6
18,353
249
375
2
C7
95,468
1451
200
3
C8
5483
49
375
2
C9
107,239
1550
81
2
many cities in Oklahoma, Kansas and Missouri
experiencing similar rainfall amounts and major
flooding. Flows into three of the reservoirs on the
Osage river during runoff from that storm period
were the highest on record.
Monthly and yearly outputs from hillslopes and
channels are also available. Individual hillslopes
may be modelled separately from the Watershed
version and daily delivery of sediment and water to
the various channels can be calculated. For hills-
lopes, a graphical output that allows plotting of
nearly every input or output is available.
The average annual sediment yield from indi-
vidual hillslopes (Table 9.8) and channels was
used to compute where detachment and deposi-
tion occur in the channel system (Table 9.9). As
shown in Table 9.9, on average, deposition
occurred in the channels when erosion rates and
sediment yields from hillslopes were high. When
erosion rates and sediment yields from hillslopes
were low, detachment occurred in these chan-
nels. Deposition rates in the channels averaged
nearly 900 t ha
−1
of channel area (total channel
area
0.6 ha) for the moldboard plough system,
and nearly 400 t ha
−1
for the chisel plough system.
Detachment rates were small, averaging 7.3 t ha
−1
of channel area for the permanent grass, and 7.8 t
ha
−1
for the no-till system.
Based on these results, there should be less
maintenance of the channels for the no-till or
=
