8267

• UCREFRP Catalog Number: 8267
• Author: Elliott, J. G. and L. A. Hammack.
• Title: Geomorphic and Sedimentologic Characteristics of Alluvial Reaches in the Black Canyon of the Gunnison National Monument, Colorado.
• USFW Year: 1999.
• USFW - Doc Type: Water-Resources Investigations Report 99-4082,
• Copyright Material: NO

Table 1. Streamflow characteristics for the Gunnison River downstream
from the Gunnison Tunnel, U.S. Geological streamflow-gaging station 09128000
[Recurrence interval, in years, equals reciprocal of exceedance probability, calculated with
annual instantaneous discharge peak; streamflow duration in percentage of time specific
discharge is equaled or exceeded calculated with daily mean discharge; ft3/s, cubic foot
per second; %, percentage]
Recurrence interval
Discharge Pre- Post-
(ft3/s) regulation regulation
1911-65 1966-94
(years) (years)
500
1,000
1,140
2,000
2,200
3,000
4,000
5,000
5,140
6,000
7,000
8,000
9,000
10,000
11,000
12,000
13,000
14,000
15,000
16,000
17,000
18,000
19,000
20,000
1.01
1.04
1.09
1.17
1.18
1.30
1.50
1.70
2.0
2.5
3.2
4.4
6.0
8.0
11
16
24
35
55
90
1.01
1.02
1.18
1.25
1.65
2.5
4.0
4.2
6.0
10
16
24
35
50
75
100
Streamflow duration
pre- Post-
regulation regulation
1911-65 1966-94
(% time) (% time)
80 80
51 65
28 47
26 42
19 17
18 12
14 4.0
11 1.2
7.9 0.72
7.5 0.70
5.8 0.60
4.1 0.46
2.8 0.28
1.9 0.13
1.2 0.03
0.8
0.5
0.3
0.16
0.09
table 2. A complete set of photographs taken from
these locations is in the possession of the NPS Water
Resources Division in Fort Collins, Colorado, and
selected photographs are presented in the appendix at
the end of this report.
Geomorphic Surveys
Surveys were made of the study reaches with a
total-station laser theodolite to quantify geomorphic
features, high-water elevations, channel cross-section
characteristics, and river gradient. Data from these
surveys also were used as input to one-dimensional,
water-surface profile models and sediment-entrain-
ment potential calculations. The Warner Point study
reach (fig. 4) was approximately 3,000 ft long and was
surveyed in 1990, 1994, and 1995. Twelve channel
cross sections were surveyed in the Warner Point reach
and were used to calibrate the one-dimensional, water-
surface profile model. Hydraulic-geometry character-
istics and sediment-entrainment potential were calcu-
lated at 8 of the 12 cross sections. Geomorphic
features surveyed included streambanks, alluvial bars,
and overflow channels between the bars and adjacent
talus slopes.
10 Geomorphic and Sedimentologic Characteristics of Alluvial Reaches in the Black Canyon of the Gunnison National Monument,
Colorado