Data Results and Discussion 



The loss of the two DWGs placed outside the harbor significantly reduced the 

 value of some of the other data obtained during the monitoring effort. The DWGs 

 were deployed to obtain incident wave data that were required for correlation with 

 wave heights inside the harbor, wave runup, and wave overtopping data. Since 

 incident wave data were not obtained, these elements of the monitoring effort could 

 not be validated or verified based on the physical modeling and/or numerical tools 

 used in their predictions. 



When working in an environment with a high-energy wave climate like St. Paul 

 Harbor, extra precautions should be taken to ensure that data are collected. More 

 appropriate anchoring of the gauge mounts and/or devices hard-wired to shore to 

 obtain real-time data should be considered. Additional costs will be required, of 

 course, and should be included when estimates for the monitoring program are 

 prepared. In addition, when working at a remote site such as St. Paul Harbor, 

 logistical problems are a factor. Equipment and supplies must be shipped and, in 

 most cases, delivery times are uncertain. Shipping costs also are significantly higher 

 when working in a remote environment, and equipment and materials are not readily 

 available. 



Wave height data obtained inside the harbor in the lee of the main breakwater are 

 presented in Table 2. Gauge No. 276 was closest to the harbor entrance tied to the 

 Unisea's bow, and gauge No. 277 was tied to the vessel's stem. Maximum signifi- 

 cant wave heights obtained during the period of record were 0.58 m (1.9 ft). Even 

 though a correlation cannot be made with incident incoming wave characteristics, it 

 is known that storms occurred during the monitoring period. In the three- 

 dimensional model investigation of St. Paul Harbor, a range of extreme storm wave 

 conditions were tested from several directions with maximum significant wave 

 heights of 0.79 m (2.6 ft) predicted in the lee of the breakwater. Direct correlations 

 caimot be made for specific incident waves; however, it appears the prototype and 

 model data are in agreement. Model wave heights are slightly higher than those in 

 the prototype, but the prototype may not have experienced an extreme storm from as 

 critical a direction as the events tested in the model. 



Results of the wave hindcast model are presented in Table 3 for the dates and 

 times indicated. Output was generated to correlate with the dates and times that 

 wave runup and overtopping were obtained. Wave hindcast results revealed 

 maximum significant incident wave heights of 5 m (16.4 ft). Data indicated that 

 storms with wave heights in excess of 3 m (10 ft) occurred on 11-12 November, 

 14-15 November, 25-26 November, and 10 December 1994. Initial results revealed 

 that trends were estabhshed in that larger waves generally occurred with higher 

 wave runup values and smaller waves occurred with lower runup. The absolute 

 values of the wave heights, however, appeared low. These values will be discussed 

 in more detail after presentation of wave runup and overtopping results. 



Wave runup data secured for the St. Paul Harbor main breakwater, using the 

 videotape methodology developed, are presented in Table 4 for the times and dates 



30 



Chapter 2 Monitoring Program 



