Environmental Impact Statement
EFDC Hydrodynamic Model
ADCP Data Processing
ADCP Data vs. Model Comparisons
The Kotzebue Airport (OTZ) is currently in the process of conducting a Runway Safety Area Improvement Alternatives Study (RSAIAS). As part of that process an Environmental Impact Statement (EIS) is required to be conducted. The main objectives of the study were to determine the existing hydraulic and hydrodynamic situations for the coastal and near shore areas of Kotzebue Airport, including the existing coastal circulation patterns and sediment transport; and to evaluate the impacts to these processes for each of the various options of runway extension. The results of this assessment were incorporated into the Final EIS. Three EFDC hydrodynamic models were generated. A coarse grid model was developed covering most of the Kotzebue Sound, Hotham Inlet and Selawik Lake. This model was used to determine the boundary condition that was required by the medium grid model (MGM). The MGM was then nested into the coarse grid model. This model was calibrated to the measured water surface elevations and discharge data from two ADCPs that were collected over a four month period in 2008. The fine grid scale model (FGM) was nested into the MGM. The FGM was designed to provide the necessary grid resolution in the vicinity of Kotzebue Airport. This allowed detailed assessment of the hydrodynamics around the various runway extension options. The following figure shows the coarse scale coastal model location map and bathymetry as well as bed shear stress results from the FGM.