attributed to the construction of levees. Otiier areas suffering land loss were 

 abandoned delta lobes long before the construction of artificial levees. The Corps is 

 faced with making an overall evaluation of each individual project with regard to its 

 potential contribution to coastal erosion. 



Donald Landry: The Corps of Engineers performed a study of the barrier islands in the 

 I960's and concluded that the cost-benefit ratio did not justify expenditures for 

 barrier island protection. However, this analysis did not take into account the 

 benefits regarding protection of marshlands inside the islands. Of what benefit are 

 the islands in protecting interior wetlands from erosion? 



Murray Hebert: From admittedly unscientific studies of land-loss maps it does appear 

 that where barrier islands have been eroded away the interior marsh has eroded 

 much more rapidly than where it is still protected by barrier islands. 



I have the feeling that the islands absorb a tremendous brunt of the sea. For 

 instance, where a gap has opened between Timbalier and East Timbalier islands one 

 can almost see a channel opening through Lake Barre to Montegut. A community of 

 600 Indians in this area is now cut off by road just on a high tide. 



Dag Nummedal: It is possible that this is mainly an effect of subsidence. A numerical 

 model study of Moriches Inlet, Long Island, concluded that the change in storm surge 

 would be imperceptible given the quadrupling of the size of an inlet. A similar study 

 in Galveston Bay related to deepening the entrance channel for deepwater draft 

 vessels also concluded that it would have little or no effect on flooding in the bay. 



Johannes van Beek: The opening of large bays behind the islands has increased the rate 

 of erosion of interior wetlands because of increased fetch for wind waves. This 

 would be happening even if the barrier islands remained as they are . 



Charles Groat: Subsidence, then, is a double villain because in addition to directly 

 causing erosion of wetlands it may have the effect of increasing the water depth and 

 thus the erosive powers of waves generated in the bays. 



Irving Mendelssohn: The lack of ability to answer the simple question of the degree to 

 which island erosion affects marsh erosion illustrates the need for more research on 

 basic processes. Unfortunately, we hear that legislators say we have enough studies 

 and action is what we need. I feel this is a short-sighted viewpoint and I think our 

 inability to answer this question exemplifies that. 



Murray Hebert: Perhaps in place of studies we can use monitoring. People themselves 

 have gotten tired of the word "studies" and legislators, because they represent 

 people, have also become tired of the word. Nonetheless we need to continue to 

 work with the scientific community to monitor our efforts and to better understand 

 the main causes of erosion. 



I might add that there are over 2,000 oil and gas wells inside the barrier islands 

 in Terrebonne Parish. If the barrier islands erode there structures will become 

 vulnerable to the sea, because they were not designed as offshore structures. Some 

 of these fields are old and it would not be feasible to place offshore type platforms 

 in these areas. Because there are about 15,000 jobs in Terrebonne Parish directly or 

 indirectly resulting from the oil industry, the problem is of tremendous importance 

 to our economy. 



211 



