• View from Sourdough Mountain Overlook  A view looking down onto Diablo Lake. Photo Credit: NPS/Michael Silverman, 2010.

    North Cascades

    National Park Washington

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  • State Route 20 closed at Mile Post 134, Ross Dam

    After a brief closure at Newhalem due to an avalanche and unstable conditions, SR 20 has re-opened to its normal winter closure point at MP 134, Ross Dam. The highway will remain closed from Ross Dam to MP 171 (Silver Star Creek) until spring re-opening. More »

  • Ross Dam Haul Road Closure Continues

    A short segment of the Ross Dam Haul Road between the Diablo Lake suspension bridge and the tunnel remains closed to public use due to continued recovery following a March 2010 landslide. The closure will remain in effect through 2014. More »

  • Notice of planned work for the Cascade River Road, fall 2014

    Visitors planning to access the park via the Cascade River Road after Labor Day should be advised that the Park Service is planning a fall closure of this road at Eldorado Creek (3 miles before the end of the road) in order to perform permanent repairs. More »

Methodology

Spring stake placement

Figure 5.  Spring stake placement using the steam drill.

Methods used to monitor these glaciers follow procedures established by the U.S. Geological Survey during more than 40 years of monitoring South Cascade Glacier, which are similar to methods used to monitor glaciers world wide (Ostrem and Brugman, 1991). In sum, the surface mass balance of these glaciers is monitored using a two-season approach to calculate mass (water) gained and mass lost on a seasonal basis. These glaciers gain most of their mass by surface accumulation of snowfall during the winter, when the park receives approximately three-fourths of its annual precipitation. Likewise, most of the melting (ablation) occurs at the surface, and by monitoring surface changes we account for approximately 90% or more of the annual change of a glacier's mass.



Our methods require us to visit each glacier at least two times annually. In late-April, when the accumulation season is ending, we probe thickness of the snow pack across the surface of the entire glacier. At the same time, we use a backpack-mounted steam drill to melt holes 8-9m into the glaciers (Figure 5). Four to five stakes per glacier are placed in these holes and are used to monitor the amount of the previous winter's snow, as well as underlying firn and ice that melts through the following summer. North Klawatti and Noisy glaciers have five stake stations, while the others have only four stations as a result of size and topographic characteristics. A late September visit is used to measure final melting and remove the stakes (Figure 6, 7). Mid-summer measurements are used to provide additional data on rate and processes of melting (Figure 8). Measurements taken at the stakes are averaged across the entire glacier to determine mass balance.
 
Stake removal

Figure 6.  Fall stake measurements and stake removal on lower North Klawatti Glacier.

We monitor the area of these four glaciers by taking aerial photographs (Figure 1-4) and making detailed large-scale maps every 10 years. Many people have asked why we don't just monitor changes in the area or terminus activity of these glaciers. The reason we don't exclusively monitor area is because glacier movement is a complex process influenced by the steepness of the mountainside a glacier rests on, the absence or presence of water at the base of the glacier, ice thickness, and other factors (Figure 9). Thus, changes in size of a glacier may not give a clear signal of the relationship between the glacier and climate, or allow for the monitoring of more subtle variations. Monitoring glacial melt also allows us to monitor glacial influence on lakes, wetlands and streams. Long-term trends in glacier area were assessed using old maps, moraine mapping, and aerial photographs obtained in 1998.
 
Figure 7 and 8
Figure 7.  Fall probing on Silver Glacier,  Figure 8.  Mid-summer probing on upper Sandalee Glacier.
 
Figure 9 Thumbnail
Figure 9.  Glacier Ecosystem Conceptual Model shows the relationship of monitored glacier characteristics (shaded box) to the surrounding landscape and ecosystem.

Did You Know?

Cascading stream

The North Cascades are well known for the abundant waterfalls that lace the mountains. Two of the best known waterfalls are Gorge Falls between Newhalem and Diablo along State Route 20 and Rainbow Falls in the Stehekin Valley.