Environmental Engineering Reference
In-Depth Information
Bedrock channels tend to be incised below the surrounding slopes and uplands. Because bedrock
channel incision commonly occurs over the course of centuries to millennia, channel instability resulting
from bed incision is not as widespread a problem among bedrock channels as among alluvial channels.
However, there are conditions under which rapid bedrock channel incision may create hazards. As listed
in Table 3.4 the average rate of bedrock channel incision ranges from 0.5 to 1000 mm/kyr, depending on
the bedrock, the flow in the channel, and the bed gradient.
Table 3.4
Published long-term average rates of bedrock channel incision (after Schumm and Chorley, 1983; and
Wohl and Grodek, 1994)
Rate
(cm kyr
-1
)
Time range
of incision
Drainage
area (km
2
)
Lithology
Location
Climate tectonics
Source
Sierra Nevada,
California, U.S.
Pliocene-
Quaternary
9
granite, andesite
35,000
arid, uplift
Huber, 198l
Miocene-
Quaternary
Larson et al.,
1975
30
sedimentary
Colorado, U.S
11,800
semiarid, uplift
Pliocene-
Quaternary
7
metamorphic
Colorado, U.S.
semiarid, uplift
Scott, 1975
Goldberg,
1976; Schwarcz
et al., 1979;
Yair et al., 1982
Nahal Zin,
Israel
45-130
sedimentary
1,540
hyperarid, uplift
Quaternary
Nahal Paran,
Israel
Wohl and
Grodek, 1994
10
sedimentary
3,600
hyperarid, uplift
Quaternary
Hamblin et al.,
1981
30
basalt, limestone
Utah, U.S.
9,900
semiarid, uplift
Quaternary
9.5
sedimentary
Arizona, U.S.
68,500
semiarid, uplift
Quaternary
Rice, 1980
Jalisco,
Mexico
Pliocene-
Quaternary
23-25
basalt
arid, uplift
Righter, 1997
suggested average
rate of bedrock
channel incision in
middle latitudes
15
Pitty, 1971
Harden and
Colman, 1989
25-47
sedimentary
Utah, U.S.
115,000
semiarid, uplift
Quaternary
igneous and
metamorphic
Leland et al.,
1995
1,000
Pakistan
260,000
semiarid, uplift
Quaternary
Fourth River
Department,
2006
20
th
-21
st
century
shale and fine sand
stone
60,000
Taiwan, China
Wet and tropical
Mediterranean,
uplift
Merritts et al.,
1994
70-180
sedimentary
California, U.S.
655
Holocene
Rosenbloom
and Anderson,
1994
sedimentary,
intrusive igneous
Mediterranean,
uplift
<25
California, U.S.
10-20
Quaternary
Kauai, Hawail
U.S.
seasonal tropical to
semiarid, uplift
Pliocene-
Quaternary
Seidl et al.,
1994
0.5-8
basalt
0.1-90
Kauai, Hawail
U.S.
seasonal tropical to
semiarid, uplift
Pliocene-
Quaternary
Seidl et al.,
1997
40-100* basalt
0.1-90
humid temperate,
uplift
50-690
sedimentary
Montana, U.S.
1,420
Quaternary
Foley, 1980
Search WWH ::
Custom Search