but relatively low amplitude (maximum is 0.87 m). Signatures of the other two 

 hurricanes are not observable in the data set. On average, major hurricanes 

 can be expected to strike this portion of the Texas coast about four times every 

 100 years (Bodine 1969). A total of about 25 major and minor hurricanes have 

 made landfall on the Matagorda Peninsula (about 100 km long) in the last 150 

 years. Thus, occasionally, wave conditions will be substantially more extreme 

 than are reflected in this data set. 



The shore-normal direction along the coastline at the mouth of the Colorado 

 River is approximately 155 deg. A substantially greater portion of the waves 

 approach the coastline from the 65- tol55-deg quadrant (from the left for 

 someone standing on the beach looking offshore) than from the 155- to 245-deg 

 quadrant, as is shown in the wave rose in Figure 13. 



MEAN WAVE HEIGHT f\| 







270 : 



i90 



LEGEND 

 0.21 M. 

 "Q.ia'iA.' 

 ■ o'64'mT 

 "■0.85"m.' 



PERCENTAGE 

 OF SAMPLES 



0-02:5 I 1 



2-10:! c^^^ 

 10-15/t Ejga 



COLORADO RIVER 

 <^ MAY 90 - SEP 92 



Figure 13. Wave rose for the mouth of the Colorado River, TX. The shore- 

 normal direction is approximately 155 deg 



This predominant wave direction is also seen in the angular distribution of 

 the deep water wave energy flux (wave power), a parameter related to the long- 

 shore sediment transport. Wave power is the energy transmitted across a 

 vertical plane perpendicular to the direction of wave advance per unit length of 

 wave crest. The formula, from the Shore Protection Manual (SPM 1984), is: 



30 



Chapter 4 Data Observations and Analyses 



