1400 ‎(2)‎

• UCREFRP Catalog Number: 1400
• Author: Simons, D. B., et al., ed.
• Title: Proceedings
• USFW Year: 1980.
• USFW - Doc Type: Workshop on Downstream River Channel Changes Resulting From Diversions or Reservoir Construction.
• Copyright Material: NO

The sediment transport capacity can be estimated by applying the
modified Meyer-Peter, Muller equation using limited measured data. The
sediment loading to the stream due to construction activities can be
estimated by applying an on-site soil erosion model (Simons et al.
1977) .

The morphological changes in the system are dynamic in nature and
should be evaluated in both qualitative and quantitative terms. The
altered water and reduced sediment flows downstream of the reservoir
will probably induce degradation or aggradation depending on the sedi-
ment retention capacity of the reservoir. The altered flow and the
clear water release from the reservoir will probably degrade the down-
stream channel; however, the extent of degradation is dependent on the
flow rate, particle size, channel shape, and downstream controls.

The degradation or aggradation of the river system, or both, can be
estimated by applying an acceptable water and sediment routing method
such as the one developed by Li and Simons (1979). This method routes
sediment by size fraction and has been verified in many field applica-
tions. The new equilibrium morphological conditions can be further
checked by utilizing the Shields criteria (Simons and Senturk 1977)
considering the armoring effect. After the morphological changes have
been evaluated, the hydraulic parameters related to fisheries such as
top wi dth, velocity, flow depth, and substrate can be determi ned by
applying an acceptable model.

An initial thermal study should be conducted. A more detailed
analysis must be performed if significant changes in the thermal regime
are detected by the initial study. This analysis would consider the
thermal routing in the system. A mathematical model would be required
to conduct this detailed analysis. A candidate" for use is the Colonell
(1976) model, which was developed by modifying the Massachusetts
Institute of Technology model (MIT Model). The model was based on the
simultaneous solution of appropriate equations for the conservation of
mass and energy. Related hydrodynamic and thermodynamic processes
include 1) internal radiation absorption, 2) heat sources and sinks. 3)
advective heat transport, and 4) convection and diffusion. In order to
account for cold region conditions, the model can be modified to
consider ice cover during the winter months.

The general approach to the complicated problems involved in the
study of downstream river channel change is 1) to consider the signifi-
cance of the physical and biological environment, 2) to conduct
sensitivity analysis for evaluating the relative importance of the
physical processes and data, 3) to adhere to the project schedule, and
4) to provide a factual, practical, efficient1 and effective solution.

DATA BASE

The data required to conduct the required hydrologic, hydraulic,
sedimentation, and morphological analysis generally will include:

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