Research: Susitna dam project

Future glacier and runoff changes in the Susitna drainage basin

Background

Mt Deborah (12,339 ft; 3,761 m a.s.l.) in the upper part of the drainage basin, April 2012

The project is part of the Susitna-Watana Hydro study plan that includes a large portfolio of studies to provide relevant background information for the federal licensing process for the possible construction of a large dam for hydropower with a 42-miles long reservoir in the Susitna basin in central Alaska.

Goals

The goal of our project is to assess the effects of future climate change and associated glacier wastage on the river runoff in the Susitna basin. The specific goals are to;

• develop a hydrological modeling framework that includes the effects of glacier wastage and glacier retreat on runoff in the Susitna basin,
• quantify the glacier mass changes until 2100,
• project future river runoff using the newly developed tool in a set of climate projection scenarios until 2100
• analyze the response of the Susitna River to climate change with respect to annual runoff, seasonality and peak flows.

The product of this work will be a series of glacier and river runoff scenarios for the Susitna basin until the year 2100.

Our modeling efforts will rely on two existing models. First the glacier response will be simulated using the glacier melt and runoff model DETIM. Second, we use the physically-based and spatially distributed hydrological model Water Balance Simulation Model WASIM-ETH to simulate the hydrological processes outside the glacier.

The Susitna basin

The drainage basin of the proposed dam with measuring sites

The Susitna River basin covers 50,700 km2 and includes 15% glaciers. The permafrost is sporadic or discontinuous although seasonal freeze and thaw cycles affect the entire basin. Long-term (<60 yrs) stream flow observations from the USGS are available at five locations in the basin. The Susitna Hydroelectric Project was originally proposed in the 1960’s. Hence, the region has been extensively investigated including a wealth of published data until the early 1980s.

Field work

Our project includes glacier and hydrological field work. We have installed 2 detailed meteorological stations, one on a mountain ridge and one on the Westfork Glacier, in addition to 10 temperature stations distributed over different glaciers and elevations, and 5 stations in the tundra. In addition we measure the glacier mass balance and snow distribution in the basin. At about 20 sites across the glacierized area we measure snow depth in spring and drill ablation stakes into the ice to monitor glacier melt. In fall we return to measure the stakes. We also measure snow depth by helicopter-based snow radar.

Last update: May 2013