January 9, 2013 Dr. Gabriel J. Wolken, Future glacier and runoff changes in the Susitna drainage basin Alaska Division of Geological & Geophysical Surveys

Future glacier and runoff changes in the Susitna drainage basin

Dr. Gabriel J. Wolken, Alaska Division of Geological & Geophysical Surveys

The Alaska Energy Authority (AEA) has been authorized by the State of Alaska to develop the Susitna-Watana Hydroelectric Project on the Susitna River to serve the region's energy needs. Critical to any hydroelectric development is a firm understanding of the basin-wide contributions to river runoff and how these might change over time to influence the quantity and seasonality of flow into a hydroelectric reservoir. Although only about 4% of the upper Susitna watershed area (13,279 km²) is glacierized, these glaciers provide a significant portion of the total runoff in the upper Susitna drainage basin, and it is well documented that these glaciers, like most Alaskan glaciers, are retreating. Changes in glacier extent and volume, in response to climate warming and/or altered precipitation regimes, have the potential to substantially alter the quantity and seasonality of runoff. It is crucial, therefore, to simulate future changes in glaciers and the quantity and seasonality of runoff in order to properly evaluate the hydroelectric project's operational longevity and to assess potential protection, mitigation and enhancement measures.

In April 2012, the Alaska Division of Geological & Geophysical Surveys, along with collaborators from the University of Alaska Fairbanks, began a multi-year study of the hydrology of the upper Susitna drainage basin with a particular focus on modeling the effects of future glacier wastage and retreat on runoff. The study combines field measurements and computational modeling to provide estimates of future runoff into the proposed 81 km2 and 63 km-long reservoir of the Susitna-Watana Hydroelectric Project. In this presentation I will introduce the study and discuss its relevance to the hydroelectric project, talk about field activities from year-1, and present some early model calibration results.