The effects of interim flow operations from Glen Canyon Dam on Colorado River sand bars in the Grand Canyon, Arizona
- Northern Arizona Univ., Flagstaff, AZ (United States). Geology Dept.
- Northern Arizona Univ., Flagstaff, AZ (United States). NPS Cooperative Parks Studies Unit
- Glen Canyon Environmental Studies, Flagstaff, AZ (United States)
Discharges from Glen Canyon Dam (GCD) affect the geomorphology and stability of downstream alluvial sediment deposits. To protect downstream resources, the US DOI mandated interim flow criteria (IFC) on 1 August, 1991. The IFC consist of reduced daily fluctuations (226--566 m[sup 3]/s) and reduced ramping rates (42.5--57 m[sup 3]/s/hr), the primary objective of which is to maintain sediment storage in the river system by minimizing sediment transport. This study was initiated to determine the effectiveness of the IFC in achieving this objective. The authors examined whether reduced daily fluctuations lead to subaerial sand bar erosion and increased subaqueous sediment storage. They collected and analyzed topographic and bathymetric survey data from sand bars throughout the Colorado River corridor in Sept/Oct, 1991 and in Oct/Nov, 1992 to compare changes in sand bar morphology. They examined changing topography due to GCD operation in what they termed the hydrologically active zone (HAZ), that portion of the sand bar exposed to daily dam operations (142--900 m[sup 3]/s stage elevations). Volumes within the HAZ and profiles across this zone were generated from these sediment deposits. Their preliminary results show that, in general, erosion of sediment at higher bar elevations was coincident with deposition along lower parts of the bar platform. The observed response to IFC elevation in order to maintain sediment deposits for Colorado River corridor bio-diversity (e.g., fisheries habitats). 88% of sand bars that showed significant volume gain were preceded by significant volume loss, implying that antecedent conditions are an important factor in sand bar response to GCD operations. Sediment transport capacity was reduced as evidenced by increased sediment storage in recirculation zones and sediment infilling of eddy return channels. The authors conclude that IFC are achieving their primary objective of maintaining sediment storage within the river corridor.
- OSTI ID:
- 5188517
- Report Number(s):
- CONF-9305259-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
Similar Records
A review of proposed Glen Canyon Dam interim operating criteria
DETERMINING THE TRIBUTARY SEDIMENT CONTRIBUTION TO EXPERIMENTAL FLOOD DEPOSITS ON THE COLORADO RIVER IN MARBLE CANYON, GRAND CANYON, ARIZONA
Related Subjects
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
ALLUVIAL DEPOSITS
DEPOSITION
EROSION
COLORADO RIVER
DAMS
ENVIRONMENTAL EFFECTS
ARIZONA
GEOMORPHOLOGY
HYDROELECTRIC POWER PLANTS
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGY
NORTH AMERICA
POWER PLANTS
RIVERS
STREAMS
SURFACE WATERS
USA
130600* - Hydro Energy- Environmental Aspects
540350 - Environment
Aquatic- Site Resource & Use Studies- (1990-)
580000 - Geosciences