Wetland Classification and Mapping
of Seward, Alaska
Map Unit Descriptions
Map Component: RD4C
Seward Area Extent: 11 wetland polygons; 1109.5 acres
Jap Creek, an RD4C, as it empties across its broad alluvial fan.
Type: Stream channel, a water of the US, but not a wetland.
Depth to water table: >61 cm at the one spot measured on 24 August 2006
Organic layer thickness: 0 cm
Average depth to redoximorphic features: n/a
Common Soils: Typic Cryofluvents
Common Plant communities: bare gravel and flowing water
HGM: Middle Gradient natural river (or stream)-multiple thread (braided)
RD4C are the channels of the large glacier-fed braided streams and rivers around Seward. Bed material is dominated by gravel, with some sand and cobbles. These are the most extensive areas mapped around Seward. Braided stream systems carry large amounts of material during frequent floods. As floodwaters subside the material is deposited, resulting in streambed aggradation; as much as several feet during a larger event. When the bed aggrades, it becomes higher than the surrounding valley, so the stream channel often shifts to a lower position. Because of this process, which dominates most of the valley floors and alluvial fans in the Seward area, prediction of where a stream channel might be following a flood event is probably impossible. The area mapped as RD4C is expected to change following floods.
The Snow River is a glacier-fed braided stream with a gravel dominated bed. It floods every two to four years when meltwater that has accumulated in a glacier-dammed lake drains. Bedload transport, deposition, and channel shifting processes occur there too, but on a more regular basis.
Sawmill and Glacier Creeks behave as RD4 streams, but lack extensive channel braiding.
Fifty foot habitat protection area
The Resurrection River is covered under Kenai Peninsula Borough's Anadromous Streams Habitat Protection Ordinance. Many activities require a permit, or are prohibited within 50 feet of these streams. For a list of the streams, rationale for the ordinance, and details on obtaining a permit, visit the link highlighted above.
From The Kenai Borough website:
"The Kenai Peninsula Borough manages a Floodplain Ordinance that addresses proper development to reduce flood risks and lessen the economic losses caused by flood events. The ordinance provides building standards for construction projects within the floodplain to ensure the availability of flood insurance through the National Flood Insurance Program. These building requirements also are intended to minimize or prevent damage when flood events occur. The ordinance requires floodplain development permits for all projects in floodplains."
|Contact: Mike Gracz Kenai Watershed Forum Homer Field Office Old Town Professional Center 3430 Main Street Suite B1 Homer, AK 99603 907-235-2218||
12 February 2007 15:24