NED ROZELL ALASKA SCIENCE
- NED ROZELL ALASKA SCIENCE
(Published: August 1, 2004)
Photo by NED ROZELL A fish wheel turns on the Tanana River on a smoky
July afternoon. The Tanana, fed by water from melting glaciers and
other sources, was flowing bank to bank while other Interior streams
and rivers without glacial sources were trickling near-record lows.
Click on photo to enlarge
Here's one for the only-in-Alaska file: In mid-July 2004, wildfires
and floods were both consuming an Alaska state forest at the same
East of Delta Junction, the Gerstle River had overflowed its banks,
slicing through a gravel road and flooding a portion of Tanana Valley
State Forest. Farther north, a wildfire was turning thousands of
acres of spruce trees and tundra in the forest to smoke and ash.
While many Interior rivers that depend on snowmelt, springs and
rainfall shrank during summer 2004, rivers fed by glaciers swelled
and shifted in their channels. Supplied by Alaska Range glaciers, the
Gerstle River forced itself out of its bed and through a road used by
area farmers and Native villagers.
"Like a lot of glacial streams, the Gerstle flushes lots of gravel
down its bed at high flow, so much that the river is almost higher
than the surrounding ground," said Al Edgren, the state forester for
the region, who was monitoring both the flood and the nearby forest
fire. "Since the surrounding area is almost lower than the river,
there's a big sheet of water across the state forest land."
The water had cut through a 14.5-mile road in six places, Edgren
said. Flows of glacial water up to 6 feet deep on the road prevented
people from traveling to a Native community at Healy Lake.
"Right now, they'll have to fly in," Edgren said.
In 2004, Fairbanks had the second-warmest June in 100 years of
weather records, according to the Alaska Climate Research Center.
Records were also topped at one of the longest-monitored glaciers in
A weather station at 4,855 feet next to Gulkana Glacier recorded new
high-temperature readings for both May and June, according to Rod
March, a glaciologist with the U.S. Geological Survey. The glacier's
weather station recorded an average daily temperature of 39.5 degrees
F for May (compared with the normal reading of 34.2 and the previous
record of 39.1) and 50.9 degrees for June (compared with the normal
reading of 41.5 and the old record of 47.1). The thermometer next to
the glacier that registered all-time highs this summer has been
recording since 1967.
The rise in temperature also showed in the increased flow of Phelan
Creek, which drains the glacier, March said. The June flow readings
taken from a gauge on the stream showed it at the highest levels
since technicians installed the instrument in the late 1960s.
Floods during the warmest part of summer will be more common if
Alaska continues to experience record high temperatures, and the
washing out of roads might be another consequence of a changing
climate. Adding to the strangeness is that while some glacial rivers
spill over their banks, rivers nearby will shrink at the same time.
"The Tanana could be at flood stage while at the same time the Chena
could be experiencing record low flows," said Ed Plumb, a hydrologist
with the National Weather Service.
Ned Rozell is a science writer at the Geophysical Institute,
University of Alaska Fairbanks. He can be reached at
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