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Stream and floodplain restoration in a riparian ecosystem disturbed by placer mining

January 1, 1994

Techniques for the hydrologic restoration of placer-mined streams and floodplains were developed in Denali National Park and Preserve Alaska, USA. The hydrologic study focused on a design of stream and floodplain geometry using hydraulic capacity and shear stress equations. Slope and sinuosity values were based on regional relationships. Design requirements include a channel capacity for a 1.5-year (bankfull) discharge and a floodplain capacity for a 1.5- to 100-year discharge. Concern for potential damage to the project from annual flooding before natural revegetation occurs led to development of alder (Alnus crispa) brush bars to dissipate floodwater energy and encourage sediment deposition. The brush bars, constructed of alder bundles tied together and anchored laterally adjacent to the channel, were installed on the floodplain in several configurations to test their effectiveness. A moderate flood near the end of the two-year construction phase of the project provided data on channel design, stability, floodplain erosion, and brush bar effectiveness. The brush bars provided substantial protection, but unconsolidated bank material and a lack of bed armour for a new channel segment led to some bank erosion, slope changes and an increase in sinuosity in several reaches of the study area.

Publication Year 1994
Title Stream and floodplain restoration in a riparian ecosystem disturbed by placer mining
DOI 10.1016/0925-8574(94)90041-8
Authors Kenneth F. Karle, Roseann V. Densmore
Publication Type Article
Publication Subtype Journal Article
Series Title Ecological Engineering
Index ID 70182197
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center