Channel incision and water-table decline along a recently rormed proglacial stream, Mendenhall Valley, southeastern Alaska
Professional Paper
1760-E
By: Edward G. Neal
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- More information: USGS Index Page (html)
- Larger Work: This publication is Chapter E of Studies by the U.S. Geological Survey in Alaska, 2007
- NGMDB Index Page: National Geologic Map Database Index Page
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Abstract
Retreat of the Mendenhall Glacier, in southeastern Alaska, resulted in the formation of Mendenhall Lake, which has reduced the supply of coarse sediment to the proglacial Mendenhall River. Channel geometry surveys conducted in 1969 and 1998 over a 5.3 km reach of the Mendenhall River revealed reductions in mean bed elevations ranging from 0.4 to 1.5 meters based on cross sections replicated at 7 locations. Channel incision in the Mendenhall River is believed to be the result of a combination of factors resulting from localized and region-wide glacial retreat.
In addition to a reduction of river stage due to channel incision, a decline in water-table elevations of about 0.6 m during a 17-year period from 1984 to 2001 was identified in an observation well located 250 m from the incising stream channel. Water-table elevations 600 m from the incising channel in the adjacent alluvial outwash aquifer respond in phase to changes in river stage, indicating water-levels in the adjacent aquifer are declining in response to river-channel incision. This study suggests channel incision can rapidly lower water-table elevations for large distances in the adjacent aquifer, potentially modifying the hydrology to a degree capable of influencing adjacent surface-water features, such as off-channel wetlands and flood-plain side channels.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Channel incision and water-table decline along a recently rormed proglacial stream, Mendenhall Valley, southeastern Alaska |
| Series title | Professional Paper |
| Series number | 1760 |
| Chapter | E |
| DOI | 10.3133/pp1760E |
| Year Published | 2009 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Contributing office(s) | Alaska Science Center |
| Description | iv, 15 p. |
| Larger Work Type | Report |
| Larger Work Subtype | USGS Numbered Series |
| Larger Work Title | Studies by the U.S. Geological Survey in Alaska, 2007 (Professional Paper 1760) |
| Country | United States |
| State | Alaska |
| Other Geospatial | Mendenhall Valley |
| Online Only (Y/N) | Y |
| Google Analytic Metrics | Metrics page |