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

analysis. One should keep in mind when reading these papers that given
the techniques currently available for analysis of river channel change,
the "science" of river engineering must be supplemented by subjective
judgements based on years of field experience with rivers. The papers
collected in these proceedings provide an exposure to the "artll of river
system analysis that is not normally found in the technical literature.

MAJOR PROBLEMS THAT REQUIRE DETAILED ANALYSIS

The major effects imposed by di vers ions or reservoi r construction
that must be evaluated are as follows:

1. Determine conditions on the watershed such as climatology,
hydrology, land use, possible land use changes, soil types,
the geometry and topography of the system, and the exi stence
of man-made or natural controls or both.

2. Determine the characteristics of the proposed reservoir
including its volume, geometry, its stage-volume and stage-
area curves, the operational plan for the reservoir, its
trapping efficiency, and its uses such as irrigation, power,
or recreation.

3. Evaluate the impact of the reservoir on flow in the study
reach. The type of hydrographs normally experienced will
depend on operation of the reservoir, probably reducing peak
flows and increasing base or minimum flows

4. The water released from the reservoir will be transporting
less sediment at the point of release than natural flows and
this change in water quality may induce degradation, bank
erosion, head cutting in tributaries, and possibly may induce
growth of aquatic plants that may effect flow condi t ions,
water losses, and water qua 1 i ty.

5. Evaluate the impacts of changed flow conditions on river form,
the sequence of riffles and pools, lateral migration, and the
bed material.

6. The modification of flows will cause changes in channel regime
such that the aquatic habitat of the river may be affected, at
least until a new equilibrium is established.

7. The storage and modi fi ed release of water from the reservoi r
may cause changes in the natural temperature conditions in the
reach below the dam.

8. The reduction in peak flows and base flows will cause changes
in the hydraulic characteristics and possibly in the stream
morphology that may alter the fish spawning environment.

9. Impacts of the reservoi r on groundwater condi t ions near the
reservoir may be significant and should be investigated.

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