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Wetland Classification and Mapping of the Kenai Lowland, Alaska
Map Unit Descriptions Ecosystem: Riparian Map Unit: Reb
Extent: 90 wetland polygons; 1031.1 ha; 0.73% of wetland area; 0.55% of wetland polygons. |
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 An Reb stream reach dammed by a road on in the City of Kenai (polygon 899).
An Reb reach dammed by beavers in the upper Anchor River Watershed (polygon 908). All but the very highest beaver dams in the Upper Anchor River Watershed were breached by the autumn 2002 floods. |
Wetland Indicators Type: Stream Average depth to water table: 40.2 cm; n=6 Organic layer thickness: 79.0 cm; n=6 Average depth to redoximorphic features: 74 cm; n=2 Common Soils: STARICHKOF, SLIKOK, MOOSE RIVER, KILLEY, DOROSHIN Common Plant communities: Barclay willow / Bluejoint - Field horsetail Beaked sedge – Water horsetail
NWI: Stream: R2US3,4(b). Valley wetlands: PSS1/EM1H,F(b) HGM: Stream: Low Gradient Natural Stream-single thread. Valley wetlands: Lotic Slope Throughflow. |
| Accuracy assessment: 25 polygons interpreted as Reb on aerial photographs were field checked. 19 remained Reb; 5 were revised to Rel; 1 was revised to RB. | |
Reb units are in Rosgen's (1996) 'E' stream category. E streams are slightly entrenched, pool-dominated sluggish streams with thickly vegetated banks. They occur on surfaces deposited by larger processes. On the Kenai Lowlands those larger processes occurred when glaciers occupied more of the landscape, leaving behind lakebed, drainageway and kettle surfaces. REb reaches are characterized by full to overflowing banks, usually caused by an obstruction; human created (e.g. logging debris), or natural (e.g. beaver dam). Features causing elevated reach levels are transient. These reaches may be sinuous (sinuosity greater than 1.3), like typical E streams, or not. They are encountered primarily on lakebeds and low gradient relict drainageways. If the water level has been elevated for a sufficient time, snags and dead shrubs characterize the floodplain margin, and plant communities are changing. Bed material is fine grained mineral, or organic material. Reb units can occur anywhere, but were most common in the higher reaches, above treeline.
After the floods that occurred during October and November of 2002, the character of many Reb streams changed. Beaver dams breached, so E streams that were dammed became free-flowing and are now exhibiting B and C stream characters. Their beds were scoured, creating more riffles, and exposed cobbles and gravels. No new dam building activity was observed on many former upper watershed Reb streams during the following summer. Reb units can change rapidly: Road building is on the increase, and culverts continue to fail. Where we observed Reb units not present on the 1996 aerial photography, or units no longer bankful, we mapped them, otherwise the map reflects conditions in September, 1996 when the photography was taken.
E streams are considered "evolutionary" (Rosgen, 1996). Many of these steams should probably be re-examined to observe whether or not they: 1) changed during the floods, 2) return to their former character, or 3) begin to evolve into a different stream type. The floods may have been one of the first big episodes in the long term evolution of these streams. The glacial till these streams now flow across will eventually be left as a terrace as the stream valley becomes entrenched into underlying bedrock over time. Then the till terrace will erode into the stream, a deep V-shaped valley will form, then perhaps glaciers will return and reset the process.
Fifty foot habitat protection area
Fourteen streams in the project area are 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.
Floodplain regulation
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."
