9446

• UCREFRP Catalog Number: 9446
• Author: Stanford, J. A., J. V. Ward, W. J. Liss, C. A. Frissell, R. N. Williams, J. A. Lichatowich and C. C. Coutant
• Title: A General Protocol for Restoration of Regulated Rivers
• USFW Year: 1996
• USFW - Doc Type: Regulated Rivers
• Copyright Material: YES

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RESTORATION OF REGULATED RIVERS

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Figure 6, Simulated annual discharge (m3fs x 10, mean monthly flow) patterns in the Hanford Reach of the Columbia River, USA.
The same volume of water passed through the reach in each of the three scenarios (derived from US Geological Survey data. Reston,
Virginia, USA)

aggraded rivers and extensive scouring of floodplain surfaces occurs if revetments are breached, Recent
floods (1993-1995) of such magnitude in large rivers of western Europe, southern Scandinavia, Bangladesh
and the USA provided evidence of the value of vacating floodplains to reduce the human costs and exploit
natural flood pulsing (Sparks, 1995)
The strong inference for management is to protect uncolonized floodplains by re-establishing periodic
overbank flooding, allowing the river to rebuild habitats, Elsewhere, incentives will be needed to get people
to vacate floodplains so that revetments can be removed allowing reconnection of channels and floodplains.
If that is not practical or desired by stakeholders, development of strategies for reconnecting severed lowland
floodplain wetlands and backwaters by use of lateral flow control structures may be useful (Gore, 1985; Gore
and Shields, 1995), In situations where alluvial areas have been inundated, it may be possible to lower per-
manently the full pool level of the reservoir, allowing riverine cut and fill alluviation to reconfigure and
restore drowned floodplains. As in dam removal, this scenario requires careful evaluation because sediment
transport dynamics may be different from those that occurred prior to regulation,
Whereas peak flows are needed to restore natural habitat heterogeneity, usually stabilization of base-
flow fluctuations will also be needed to revitalize the varial zone of the channel (Figure I), Establishment
of sustained baseflows restores biodiversity and bioproduction in shallow water habitats, which are cri-
tically important to benthic insects that must emerge from the shorelines of rivers, and small fishes that
must reside on or near substratum in low velocity habitats (Perry and Perry, 1986; Weisberg et aI., 1990;
Travnichek el at" 1995),
Reregulation in most rivers can be accomplished without substantially compromising storage or hydro-
power (Figure 6), Peak flows are built from storage and runoff and released in concert with natural runoff
timing in the catchment (Figure 4), In wet years, peaks can be reregulated to approach floods of record,
?epending on the release capability of the dam, Very high flows are not needed every year to maintain
lllstream and floodplain habitats nor is the historical duration of floods likely to be required because