occur. Structural stream improvement projects should supplement, not supplant, proper land management practices, as recommended by Raleigh and Duff (1980).
If stream or river erosion control, channel stabilization, streambank protection, or streambed modifications are necessary, ''soft engineering" approaches, such as bioengineering techniques for bank stabilization and repairs, should be considered first, where appropriate, in preference to the use of "hard engineering" approaches that rely on dams, levees, channelization, and riprap.
To effect the restoration of floodplains, bottomlands, and riparian habitats, dikes and levees that are no longer either needed or cost-effective should be razed to reestablish hydrological connections between riparian and floodplain habitats and associated rivers and streams.
Classifications systems for land use and wetlands (i.e., in the Classification of Wetlands and Deepwater Habitats of the United States by Cowardin et al., 1979, should explicitly designate riparian environments and floodplains that retain their periodic connections to rivers (and hence their ecological, hydrological, and recreational functions and values as part of river-floodplain ecosystems).
Some types of restoration, characterized as "working with the river" or "letting the river do the work," are effected when a major, channel-altering flood occurs. Other types of restoration are designed to protect against the scouring action of high flows or to provide a refuge for organisms during periods of extreme low flow (droughts). It is important to conduct event-triggered sampling (during the event, in some cases; immediately after, in others) to determine whether the restoration is meeting the design criteria.
Event-triggered monitoring or surveillance should be planned in advance as part of restoration programs that are designed to convey, resist, or use floods or other extreme events.
Some well-intentioned restoration projects have failed because fluvial and biological processes were not adequately taken into account in the design and implementation of the projects. The public has become increasingly aware of the need for aquatic restoration (as