The Leeville oil field was mapped from 15-minute quadrangle maps made in 1957 by 

 the U.S. Geological Survey, and from an October 1978 EPA infrared aerial photograph 

 scaled to 1:24,000 with a Bausch and Lomb Zoom Transfer Scope. Because of distortion, 

 it was necessary to scale small areas of the oil field independently. Canals were placed 

 into one of five categories, depending on their morphology and exposure to boat activity 

 (Table 2), and their widths were measured on both maps. Widening rates exceeded the 

 smallest change discernible using measurements of 0.5 mm on 1:24,000 imagery (Tanner 

 1978). Analysis of variance was used to test for widening rate differences among canal 

 types. 



Table 2. Canal types in the Leeville, Louisiana oil field 



Morphology 



Type 



Description 





Major navigation canals 



(MNW) 





Oil field navigation 

 canals (OFNC) 



Nonmajor canals (NMC) 



Well -access canals 

 extending directly 

 off major navigation 

 water ways (Bayou 

 Lafourche and South- 

 western Louisiana 

 Canal ) 



Well -access canals 

 extending directly 

 off oil field naviga- 

 tion canals 



Well -access canals 

 well removed from 

 regular boat wake 

 exposure 



r" 



Side extensions on oil 

 field navigation canals 

 (SMNC) 



Well -access areas 

 that are widenings of 

 existing navigation 

 canal s 



\l 



r™^ 



Side extensions on 

 minor canal s (SNMC) 



Well -access areas 

 that are widenings of 

 existing canals in- 

 frequently exposed to 

 boat wakes 



63 



