Reservoir and Flow Routing Model Transect Data Collection Water Resources Study Planning Meeting January 25, 2012 Prepared by 1

Study Objectives Locate and update 1980’s river transects Perform flow routing in the middle Susitna River downstream from the Watana dam site Model Susitna River from RM 184 (Watana dam site) to RM 75 (Sunshine gage is at RM 83.9) Determine flow rate and water level variations at downstream cross-sections based on reservoir operations and long-term time-series data 2

Data Collection 3 About 100 cross-sections mostly at 1980’s locations to the extent they can be located Added to 1980’s cross-sections mainly below confluence Deleted some 1980’s cross-sections mainly near Devils Canyon dam site 15 to 500 points per cross-section Survey up to the woody vegetation line Horizontal and vertical datum control Include staff gages where specified, record water line No flow measurements Photographs and substrate and vegetation description

Models and Methods 4 HEC-RAS – detailed river hydraulics  Includes backwater  Develops rating curves at cross-sections HEC-ResSim – reservoir and river system modeling  Includes reservoir operations and downstream flow routing  Muskingum-Cunge 8-point flow routing  Water levels from HEC-RAS rating curves  Attenuation and local inflows  Long-term time series data

How Results Will Be Used 5 Potentially applicable to several types of studies  River temperature  Aquatic and riparian habitat  Ice processes  Others Flow rates Water levels Rate of change Comparison to 1980’s results