Geoscience Reference
In-Depth Information
Figure 15-18.
Lower portion of Mississippi River delta as surveyed in 1839 by the Bureau of Topographical
Engineers. Note prominent passes and bays; Bay Ronde and Garden Island Bay have been largely ini lled. Compare
with previous i gure; 5-minute lat/long grid; adapted from Morgan and Andersen (1961, pl. 2).
70s (Dugan 2005). Substantial wetland losses
took place. Since the 1980s, however, new
policies attempt to balance multiple, sustain-
able uses of wetlands for timber, i sh and
shelli sh, wildlife, and recreation. Wetland
losses have slowed, but still continue.
• Oil and gas production - Since World War
II, Louisiana has become a major source for
oil and gas production both on- and off-
shore. In order to accomplish inland produc-
tion, many canals have been cut through
marsh and swamp to service drilling and
production rigs, which has allowed rapid
water exchanges. Extraction of subsurface
l uids leads eventually to suri cial subsid-
ence. Many scientists believe this is the
primary cause for rapid increases in relative
sea level (10-15 mm per year) along the
Louisiana coast (Morton, Bernier and Barras
2006; Milliken, Anderson and Rodriguez
2008).
Among these factors, most are widespread
and intractable in terms of effecting any signii -
cant changes
-
eustatic rise in sea level, sedi-
ment compaction and starvation, and hurricane
