(d) Sidecast dredging techniques should not be used in 

 maintenance of the outer bar channel at the entrance to Galveston Harbor, 

 because dredged material placed close to the channel will return quickly 

 to the channel and increase the shoaling rate in the outer bar channel. 



(e) Dredged material placed in the northeasterly one-third 

 of the existing disposal area, 3 miles off the outer end of the south 

 jetty, will return to the entrance channel; dredged material placed in 

 the remaining two-thirds moves generally to the east beach area south of 

 the south jetty and will not return to the channel. 



Cf) An anchorage area can be developed for deep-draft tank- 

 ers with only a slight increase in annual maintenance dredging. Elimina- 

 tion of the western 2,000 feet of anchorage tested in the model would 

 essentially eliminate maintenance dredging requirements. 



(g) The addition of a spur dike to the north jetty would 

 reduce shoaling in the outer bar channel by about 250,000 cubic yards 

 per year as a result of the increased impounding capacity of the revised 

 north jetty. This annual benefit would cease when the new impounding 

 area is filled, and economic justification of the spur dike appears 

 doubtful. 



(h) Reducing the width of the entrance channel from 800 

 to 600 feet would significantly reduce annual maintenance dredging, and 

 studies are necessary to determine if the lesser width would be satis- 

 factory for navigation. 



(i) Deepening the inner and outer bar parts of the entrance 

 channel to 46 and 48 feet, respectively, would increase average annual 

 maintenance dredging in the channel by about 100,000 cubic yards. This 

 increase would be partially offset by a reduction in the shoaling rate 

 in the anchorage area. 



(j) All three jetty extension plans tested caused signifi- 

 cant increases in the overall shoaling rate in the entrance channel. 



The recommended changes were constructed in the prototype. Figure 

 7-18 shows the prototype existing channel condition before construction 

 and the proposed channel relocation alinement. Figures 7-19 and 7-20 

 show the extent of scour and fill that occurred in model and prototype, 

 respectively, from the initial construction to the end of the second 

 year after construction. The navigation channel has been eliminated 

 from this comparison, because the realined channel was constructed and 

 two maintenance dredging operations were performed during this period. 

 Major changes in depth are concentrated in the abandoned channel, and 

 especially in the area used for dredged-material disposal. This com- 

 parison readily shows the increased tendency for shoaling of the aban- 

 doned channel in the prototype as compared to the model predictions. In 

 the area between the abandoned channel and the relocated channel, the 

 model indicates fill and the prototype indicates scour; however, all of 



