Figure 6. General view of 3-D model 



through the entrance, thus providing harbor circulation. Other currents will move 

 westerly along the north side of the detached breakwater, then seaward across the 

 harbor entrance. Maximum velocities of 2.2 mps (7.2 fps) occurred inside the 

 harbor during periods of severe storm wave attack. Typical current patterns and 

 magnitudes for the recommended improvement plan are shown in Figure 9. 



A crushed coal tracer material was used in the model to determine qualitatively 

 the general movement and subsequent deposits of sediment. The material was 

 selected in accordance with the scaling relations of Noda (1972). For Plan 47, 

 sediment generally moved southerly along the shoreline and some material migrated 

 into the harbor through the opening between the detached breakwater and the 

 shoreline. Some material also moved westerly along the seaside of the detached 

 breakwater and migrated seaward across the harbor entrance. Typical tracer 

 movement and subsequent deposits are shown in Figure 10. Material penetrating 

 into the harbor did not deposit in the proposed mooring area in the lee of the 

 detached breakwater. 



Two-dimensional (2-D) model study 



During 1987, a 2-D model study of proposed breakwater extensions at St. Paul 

 Harbor, AK, (Ward 1988) was conducted at WES to: 



a. Evaluate overall stability of the proposed breakwater. 



b. Determine wave runup and overtopping characteristics when the breakwater 

 is exposed to a range of design wave and water level conditions. 



Chapter 1 Introduction 



