BEACH EROSION STUDIES 



Beach erosion control studies of specific localities are usually made 

 by the Corps of Engineers in cooperation with appropriate agencies of the 

 various States by authority of Section 2 of the River and Harbor Act 

 approved 3 July 1930. By executive ruling the costs of these studies are 

 divided equally between the United States and the cooperating agencies. 

 Information concerning the initiation of a cooperative study may be ob- 

 tained from any District or Division Engineer of the Corps of Engineers. 

 After a report on a cooperative study has been transmitted to Congress, a 

 summary thereof is included in the next issue of this Bulletin. Summaries 

 of reports transmitted to Congress since the last issue of the Bulletin 

 and lists of completed and authorized cooperative studies follow. 



SUMMARIES OF REPORTS TRANSMITTED TO CONGRESS 



BELLE PASS TO RACCOON POINT, LOUISIANA 



The purpose of the investigation was to determine the best method of 

 preservation or stabilization of the offshore islands comprising the study 

 area. Two groups of low barrier beach islands about 1/2 mile wide separate 

 Timbalier Bay, Terrebonne Bay, Lake Pelto and Caillou Bay from the Gulf of 

 Mexico. The length from Belle Pass at the mainland end of the chain to 

 Raccoon Point at the west end of the Isles Deinieres chain totals about 47 

 miles. The Timbalier chain is about 20 miles long and the Isles Dernieres- 

 Wine Island chain about 24 miles long. The islands consist generally of 

 sandy beaches backed by low dunes, thence low marshy areas. They are un- 

 inhabited and undeveloped except for well activities of the oil industry. 

 The State owns East Timbalier Island and the western half of Timbalier 

 Island. The remainder of the study area is privately owned. 



Tides in the Gulf of Mexico in the area are diurnal, their mean range 

 being 1.3 feet. Although specific storm tide data were not available, 

 general historical information indicated that the islands have been com- 

 pletely inundated on several occasions. Over the period of record, the 

 mainland near Belle Pass and the eastern end of East Timbalier Island have 

 receded at a rate of about 100 feet per year. However, the north shore of 

 the island is also moving toward the mainland, low sections are filling 

 and the spit is extending westward. The gulf shore of the east end of 

 Timbalier Island has receded at an average rate of 35 feet per year, but 

 the shore of the western portion has advanced gulfward indicating a proc- 

 ess of orienting Timbalier Island to the same alignment as East Timbalier 

 Island. The west end of Timbalier Island has also extended westward into 

 Cat Island Pass. The changes in these islands indicate a predominant 

 westward littoral drift. Isles Dernieres have receded at an average rate 

 of about 25 feet per year. They have extended westward, indicating a 

 westward littoral drift, but have also extended eastward probably due to 

 the tidal current effect of Wine Island Pass. These islands have generally 

 deteriorated, indicating a lack of supply of material. 



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