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Wetland Classification and Mapping
of Seward, Alaska
Map Unit Descriptions Ecosystem: Kettle Map Units: K1-3; K31; K13
Seward Area Extent: K1-3: 8 wetland polygons; 32.8 acres K31: 1 wetland polygon; 2.1 acres K13: 1 wetland polygon; 1.1 acre |
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A K1-3 peatland near the Snow River. The pools with emergent buckbean represent the K1 component, the low-lying areas dominated by tufted bulrush that connect pools represent the K2 component. The shrubby area in the right foreground is K3.
A K13 wetland in a low spot on the ice scoured bedrock north of Bear Lake. A season-variable central pool with the floating aquatic plant, bur-reed, occupies the center, with a fringe of bluejoint reedgrass. |
Wetland Indicators Type: Peatland with small pond Average depth to water table: 20 cm Organic layer thickness: 131 cm Average depth to redoximorphic features: n/a Common Soils: Typic Cryohemists Common Plant communities: K1: Open water Water horsetail (Equisetum fluviatle) Buckbean (Menyanthes trifoliata)
K2: Fewflower sedge - tall cottongrass (Carex pauciflora - Eriophorum angustifolium) Tufted bulrush - tall cottongrass (Tricophorum caespitosum - Eriophorum angustifolium)
K3: Bluejoint reedgrass (Calamagrostis canadensis) Fewflower sedge - dwarf birch (Carex pauciflora - Betula nana) |
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NWI: L1UB1 or PEM2H if shallow (K1); PEM1Bg (K2); PSS1,3&4Bg (K3) HGM: Terrene Basin groundwater-dominated Throughflow (headwater) |
These uncommon wetlands are small ponds (K1) with a sedge-dominated and shrubby peatland fringe (K2 and K3 respectively). If the open water portion of the wetland is dominant it is named K13, and if a broad peatland fringe surrounds a small pond it is named K31. If roughly concentric zones of pond, sedge-dominated peat and shrubby peat occur the wetland is named K1-3. They are found in low spots on ice-scoured bedrock. Sometimes a season-variable central pool is surrounded by bluejoint reedgrass over a mineral soil, as at the K13 wetland pictured above.
Kettle Ecosystem wetlands are hydrologically connected at or near the surface to streams and eventually Resurrection Bay. Seward area Kettles are primarily encountered on the large rock drumlin northeast of town. They also occur in low spots on other ice-scoured bedrock knobs, especially above the South Fork of the Snow River.
