This report presents observations and findings of the 2009 Greater Moose’s Tooth 1 (GMT1) Alpine Satellite Project Spring Breakup and Hydrologic Assessment conducted by Michael Baker Jr., Inc. at the request of ConocoPhillips Alaska. The assessment supports the Alpine Development Project and Alpine Satellite Development Plan, and is the fifth year of study in the Fish Creek Basin.
Observations and measurements of water surface elevation were recorded at nine locations associated with the proposed GMT1 pad and access road. Both the proposed pad and access road lie within the Fish Creek Drainage Basin (FCB) of the National Petroleum Reserve, Alaska (NPR-A). The nine monitoring locations included seven small drainages along the access road corridor, the proposed pad site, and the Ublutuoch River at the proposed road crossing.
The 2009 GMT1 breakup was characterized by relatively low water surface elevations throughout the monitoring area, with small stream flooding conditions primarily due to local melt. The timing of the 2009 breakup of the Ublutuoch River and area small streams was earlier than the historical average by approximately four days. The 2009 Ublutuoch River peak water surface elevation was slightly below average and peak discharge was slightly above average compared to those on record since observations began in 2001.
The peak water surface elevation at the Ublutuoch River crossing occurred on May 29 and was measured at 8.45 feet British Petroleum Mean Sea Level (BPMSL) at river mile (RM) 6.8. The 2009 peak water surface elevation was approximately two feet lower than the maximum peak observed over the historic record. The peak water surface elevation recurrence interval is 1.5 years, based on stage frequency analysis calculations.
The Ublutuoch peak discharge occurred shortly after peak stage, early on May 30, and was estimated to be 1,990 cfs with a WSE of 8.45 feet BPMSL. The 2009 peak discharge has a recurrence interval of 4 years, based on the Ublutuoch River flood frequency analysis.
