Geology topics

Research about East Fork River

Source-linked reports with geographic coverage including East Fork River.

4 recordsLinked to original sources

USGS2010

Bank stability and channel width adjustment, East Fork River, Wyoming

Frequent surveys of eight cross sections located in self-formed reaches of the East Fork River, Wyoming, during the 1974 snowmelt flood showed a close relation between channel morphology and scour and fill. Those cross sections narrower than the mean reach width filled at discharges less than bankfull and scoured at discharges greater than bankfull. Those cross sections wider than the mean reach width scoured at discharges less than bankfull and filled at discharges greater than bankfull. The accumulation and depletion of sand-sized bed material in a cross section was concentrated in the near-bank parts of the stream channel and thus significantly influenced bank stability and retreat. In those cross sections that scour at discharges greater than bankfull, the basal bank material is eroded and the banks become undercut and unstable. Conversely, in those cross sections that fill at discharges greater than bankfull, the basal bank material is covered by the accumulated sand-size material and is not eroded. Streambanks in these cross sections are moderately inclined and stable. A resurvey in the summer of 1980 of the cross sections located in straight reaches showed that those cross sections which scoured at discharges greater than bankfull had become 2–4 feet wider, whereas those cross sections which filled at discharges greater than bankfull were unchanged. Thus bank stability and to some extent the adjustment of stream channel width in the East Fork River study reach appears to be controlled by the processes of scour and fill.

Wyoming↗

USGS1997

Bedload and river hydraulics - Inferences from the East Fork River, Wyoming

During 1973-79, bedload data were collected in a sophisticated trap on a river of moderate size, the East Fork. The transport rate was measured most days through a full snowmelt season, and the rate was determined separately for eight zones across the channel width. The quantitative data are unique and unlikely to be repeated. Nor need they be, because as a result of this effort a practical bedload sampler was adequately tested against full river measurement. It was shown that bedload moves sporadically and randomly on the river bed. Therefore, transport rate is highly variable in short periods of time. There is also a wide variance from day to day. Yet, different rivers have transport rates, which are functions of discharge, depth, and sediment size, that are clearly distinct. Comparison of computed and measured transport rates indicates that a major problem remains: What grain size is representative of the bedload when there is a wide or heterogeneous particle-size distribution? Size of the bedload in motion may be very different from the size of bed material obtained from samples of the streambed. For general computation, the river channel slope may be averaged, and it may be assumed that water-surface slope does not change materially with changing discharge. Indeed, this generality is correct, in that, compared with depth, velocity, and width, slope is conservative at-a-station. However, in more detail, slope changes importantly with discharge in short reaches of channel, and those changes are very different in pool and riffle. These local changes in slope are not merely an aspect of a detailed longitudinal profile but involve cross-channel as well as down-channel components. The pool and riffle sequence involves not only undulation of bed elevation and bar formation on alternate sides of the channel, but alternation of the zone of superovulation of the water surface, and changing relation of watersurface slope to discharge. These details can be seen only in the full topography of the water surface. Riffles fill during high flow and scour at low flow. Changes in local water-surface slope illustrate this process. Pools are a storage zone for sediment in the low-flow season. Even though large volumes of sediment move, the distance moved is not large—in the East Fork River, sand of size 0.5-1 millimeter moved 650 meters during the 1979 snowmelt runoff season. Bedload transport is greatest over or near bars and not in the deepest part of the channel. Direct observation of the locus of sediment transport indicates that this locus moves from one side of the channel to the other in concert with the occurrence of alternate bars. Separately, data indicate that at constant stream power, transport rate increases as depth decreases.

Wyoming↗

USGS1978

Scour and fill in a stream channel, East Fork River, western Wyoming

Frequent soundings of 11 cross sections located on the East Fork River, western Wyoming, during a spring flood revealed two sequences of channel scour and fill. All sections either scoured or filled at the flood crests relative to their low-flow condition. The sections which scoured at high flow (called scouring sections) generally tended to fill at low flow. Conversely, the sections which filled at high flow (called filling sections) generally tended to scour at low flow. The critical discharge at which the character of a section changed from scouring to filling or vice versa was approximately the bankfull discharge. Therefore, at any discharge except bankfull, some sections were accumulating bed material (fill), while others were being depleted of bed material (scour). (Woodard-USGS)

Wyoming↗

USGS1976

Data for calibrating unsteady-flow sediment-transport models, East Fork River, Wyoming, 1975

In 1975, data to calibrate a one-dimensional unsteady-flow and sediment-transport routing model were collected on a reach of the East Fork River of western Wyoming. The reach, 3.1 miles (5 kilometers) in length, wan immediately upstream from a previously established bedload sampling station. Nineteen channel cross sections were sounded at regular intervals during the spring-runoff period. Four stage recorders provided continuous records of water-surface elevations. Samples of bed material at most of the cross sections were obtained prior to high water. Streamflow and sediment-discharge measurements were collected at four of the sections. The physiography and hydrology of the contributing watershed, the study reach, and the equipment and techniques used in data collection are described briefly. The bulk of the report is a presentation of data for the several-week period of late May to early June 1975, for which concurrent water discharge data, bedload transport and size data, and cross-section depth measurements were collected. In addition, some data collected in 1973 and 1974 and before and after the calibration period in 1975 are included for completeness.

Wyoming↗