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https://hdl.handle.net/11681/9330| Title: | Long-term modifications of perennially frozen sediment and terrain at East Oumalik, northern Alaska |
| Authors: | Geological Survey (U.S.) Lawson, Daniel E. |
| Keywords: | Alaska Permafrost Environmental impact Soils Erosion Thermal dcgradation Ground ice Thermokarst Frozen ground Ice wedges Tundra |
| Publisher: | Cold Regions Research and Engineering Laboratory (U.S.) Engineer Research and Development Center (U.S.) |
| Series/Report no.: | CRREL report ; 82-36. |
| Description: | CRREL Report Abstract: Camp construction and drilling activities in 1950 at the East Oumalik drill site in northern Alaska caused extensive degradation of ice·rich, perennially frozen silt and irreversible modification of the upland terrain. In a study of the long-term degradational effects at this site, the near·surface geology was defined by drilling and coring 76 holes (maximum depth of 34 m) in disturbed and undisturbed areas and by laboratory analyses of these cores. Terrain disturbances, including bulldozed roads and excavations, camp structures and off-road vehicle trails, were found to have severely disrupted the site's thermal regime. This led to a thickening of the active layer, melting of the ground ice, maw subsidence and thaw consolidation of the sediments. Slumps, sediment gravity flows and collapse of materials on slopes bounding thaw depressions expanded the degradation laterally, with thermal and hydraulic erosion removing material as the depressions widened and deepened with time. Degradational processes became less active after thawed sediments thickened sufficiently to slow the increase in the depth of thaw and permit slope stabilization. The site's terrain is now irregular and hummocky with numerous depressions. Seasonal thaw depths are deeper in disturbed areas than in undisturbed areas and reflect the new moisture conditions and morphology. The severity of disturbance is much greater at East Oumalik than at another old drill site, Fish Creek. The difference results primarily from differences in the physical properties of the sediments, including the quantity and distribution of ground ice. In areas similar to East Oumalik, the removal or severe compaction of the vegetative mat would cause similar adverse physical changes to take place over two to three decades and should therefore be avoided. |
| Rights: | Approved for public release; distribution is unlimited. |
| URI: | http://hdl.handle.net/11681/9330 |
| Appears in Collections: | CRREL Report |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| CR-82-36.pdf | 5.78 MB | Adobe PDF |  View/Open |