Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

Journal Article · Mon Jan 01 00:00:00 EST 1990 · United States Geological Survey, Professional Paper; (USA)

OSTI ID:6164625

Schmidt, J C; Graf, J B

Alluvial sand deposits along the Colorado River in Grand Canyon National Park are used as campsites and are substrate for vegetation. During high flows, both separation and reattachment deposits are initially scoured but are subsequently redeposited during flow recession. Sand is also exchanged between the main channel and recirculation zones. The rate of recession of high flows can affect the elevation of alluvial deposits that are left exposed after a flood has passed. Fluctuating flows that follow a period of steady discharge cause initial erosion of separation and reattachment deposits. A part of this eroded sand is transported to the main channel. Therefore, sand is exchanged between the main channel and recirculation zones and redistributed within recirculation zones over a broad range of discharges. Comparison of aerial photographs and reinterpretation of published data concerning changes of alluvial sand deposits following recession of high flows in 1983 and 1984 indicate that sand was eroded from recirculation zones in narrow reaches. In wide reaches, however, aggradation in recirculation zones may have occurred. In all reaches, the percentage of separation deposits that maintained a constant area was greater than for other deposits. Separation deposits, therefore, appear to be the most stable of the deposit types. Fluctuating flows between October 1985 and January 1986, which followed the higher and steadier flows of 1983 to 1985, caused erosion throughout the park. For separation deposits, erosion was greatest at those sites where deposition from the 1983 high flows had been greatest. The existing pattern of low campsite availability in narrow reaches and high campsite availability in wide reaches was thus accentuated by the sequence of flows between 1983 and 1985.

• OSTI ID: 6164625
• Journal Information: United States Geological Survey, Professional Paper; (USA), Vol. 1493
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
54 ENVIRONMENTAL SCIENCES
ALLUVIAL DEPOSITS
DEPOSITION
EROSION
COLORADO RIVER
AERIAL SURVEYING
ARIZONA
DISTRIBUTION
ENVIRONMENTAL TRANSPORT
EVALUATION
FLOODS
FLUCTUATIONS
HYDROLOGY
IMAGES
PHOTOGRAPHY
RECREATIONAL AREAS
SAND
DISASTERS
FEDERAL REGION IX
GEOLOGIC DEPOSITS
MASS TRANSFER
NORTH AMERICA
RIVERS
STREAMS
SURFACE WATERS
USA
VARIATIONS
580000* - Geosciences
540210 - Environment
Terrestrial- Basic Studies- (1990-)
540310 - Environment
Aquatic- Basic Studies- (1990-)