Researchers from CRREL and the US Army Corps of Engineers Coastal Hydraulics Lab in Vicksburg, MS visited Yakutat and the Hubbard Glacier to conduct a complete bathymetric mapping and LiDAR topography survey of the Gilbert Point terminus area. The work utilized an advanced Multi-beam Bathymetric mapping system, a precision 2-D current profiler and a long range ground-based LiDAR scanner all tied together to simultaneously map the submarine environment and tidewater glacier terminus. These data will provide a precision base map that will serve as a spring board for future oceanographic, marine geophysics and monitoring efforts. These efforts were funded by the USACE Alaska District.

more

A group of researchers from CRREL and the US Army COE New England District visited the monitoring sites at Gilbert Point and Haenke Island to service all monitoring equipment and download high-resolution imagery collected hourly over the summer. All equipment at both locations was in top working order and no major repairs were needed at this time. The sites are showing signs of wear and next Spring some repairs to the towers and cables will be made to make sure no major problems incur.

Spring is finally nearing and it looks as if the monitoring equipment at Hubbard Glacier and Haenke Island survived the long cold winter. Our upgrades to the power systems last season worked as we hoped they would and power was never an issue, even during the darkest months. The glacier terminus near Gilbert Point should be at a point where it is advancing and we hope the laser ranging unit will begin to return valid data very soon. Measurements are begining to appear but difficult to determine if the measurements are valid or not. The laser ranging unit is only capable of about 1000 m range in good conditions. A team of researchers from CRREL, the New England Corps of Engineers and the Alaska District COE will return in late April to install an updated laser ranging system and a new high resolution imaging camera, which is a joint effort between our research team and the Extreme Ice Survey organization, an effort spear headed by James Balog and National Geographic.

more

During the Week of September 22nd maintenance visits were made to the Gilbert point ice monitoring system and the Haenke Island meteorological station. Team members included individuals from CRREL, the New England District COE, and the Alaska District COE office in Anchorage, the Geophysical Institute at the University of Alaska Fairbanks and a film crew for The History Channel. No significant modifications or upgrades were made outside of standard maintenance to ensure proper functionality through the winter months. Both sites were in good operating order except for minor bear damage to a solar panel at Gilbert Point.

more

USACE personnel were recently notified by local boat captain Mark Sappington of sediment above the low tide limit in front of the tidewater terminus in the region between Disenchantment Bay and Russell Fjord. A reconnaissance flight of the glacier conducted on August 31, 2007 with local US Forest Service personnel confirmed this observation. A low, broad mound of sediment was visible above tidewater along one portion of its terminus (see Photo). Upon analysis of oblique aerial photos taken through te course of the summer season and discussions with glaciologist from CRREL the likely source of the sediments has been identified as a preferential subglacial water outlet discharging at the terminus margin. These outlets are capable of depositing large amounts of sedimentary materials and remain active throughout the summer melt seasons.

Continued monitoring of the terminus of Hubbard Glacier indicates that the glacier is currently in a temporary period of retreat. Even though the glacier is considered to be advancing, the well documented tidewater glacier cycle has shown that they typically advance from mid winter to late spring and typically retreat to a stable position during the late summer to early winter. According to the monitoring data, Hubbard Glacier has retreated a total of 70 m during the month of August leaving the gap 310 meters wide between Disenchantment Bay and Russell Fjord on August 31, 2007.

During this current period of retreat, the sediment observed appears to pose no immediate threat of closing the gap between Disenchantment Bay and Russell Fjord. The continued build up of material in front of the glacier could have consequences once the glacier begins its annual period of advancement. USACE personnel, along with personnel from CRREL and the University of Alaska Fairbanks, are planning to perform further monitoring and data collection efforts to determine the potential implications if sediment remains to build. Available satellite imagery, aerial photos from future reconnaissance flights, and the terminus monitoring data will be analyzed to document changes in the sediment and the position of the glacier terminus. A site visit scheduled for October will allow better assessment of sediments as well as water depths in the surrounding area. After the analysis of data collected during this site visit, a reassessment of the potential effects of the sediment on closure of the gap between Disenchantment Bay and Russell Fjord will be made.

more