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Wetland Classification and Mapping
of the Kenai Lowland, Alaska
Map Unit Descriptions Ecosystem: Riparian Map Unit: AMT
Extent: 143 wetland polygons; 868.0 ha; 0.6 % of wetland area; 0.9% of wetland polygons. |
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An aerial photograph of the well-developed abandoned meander terraces and channels (AMT) along the Kenai River at about mile 12.5 (scale about 1:20,000). |
Wetland Indicators Type: Peat or Mineral Soil Average depth to water table: 59.0 cm; n=2 Organic layer thickness: 21.0 cm; n=1 Average depth to redoximorphic features: n/a Common Soils: TRUULI, MOOSE RIVER Common Plant communities: |
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Accuracy assessment: 21 polygons interpreted as AMT on aerial photographs were field checked. 18 remained AMT, 1 each were revised to: RB, SSC, SA. |
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The AMT map unit represents abandoned meander terrace and channel features. The channels were active sometime after retreat of glacial ice, but before modern times. Peatlands now typically occupy AMT's. The peat has built up since the channel was abandoned. The now- abandoned channels and terraces that comprise the AMT map unit probably developed when the river was larger, or during larger glacial outburst floods than presently occur. Some are probably more recent than others, but no reliable dates have been obtained.
AMT's have only been mapped along a few reaches of the three large glacier-fed rivers in the project area, the Kenai and Kasilof and Fox. Some especially well defined meander scrolls occupy the banks of the Kenai river just upstream of the Pillars, at about river mile 12.5.
