That sinking feeling: Levees hurt lowlands, push sea toward city

[IDemo]

Geologists call it subsidence. Swampers say the salt marsh trembles and floats where the toe of Louisiana slips toward Havana, bleeding soil from 31 states. Layers of compacted mud weigh down the butter-soft lowlands. Ponds become estuaries. Barrier islands erode, exposing beachfront. The shore migrates, and so does the mile-wide river that carved in its time five paths to the ocean.

Curling and coiling like a snake in a sandbox, the Mississippi giveth and taketh away. It fans alluvial silt, then leaps to a new location, building, destroying.

No dam or system of levees can hold that mudscape in motion. Yet hold we must. For the sake of 2.1 million Louisianans on 3.3 million acres of marshland. For the nation's largest fin and shell fishery. For nine ports, 3,000 miles of shipping channels, 16,000 miles of pipelines, 180,000 licensed saltwater sport fishermen, and a $4 billion a year tourist industry. For 70 percent of the winged commuters on the Great Mississippi Flyway. For 15 percent of America's oil and 20 percent of its natural gas.

Holding Louisiana has vexed the nation's pre-eminent builders since the U.S. Army Corps of Engineers first assumed control of the New Orleans levees in 1917. As Louisiana recedes, however, the agency confronts a conundrum beyond the dam-it, ditch-it tradition: how to let the world's third-ranking river approximate the rhythms of nature — to meander and spread its mud blanket across a collapsing delta, to nourish without disrupting navigation or risking a serious flood.

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[greenman3610]

1. this is critical

in the coming rush of government spending on this
area, billions of dollars will become available
for rebuilding flood control and levees.
But we must rethink what we are doing,
as the current levee system was built with
no appreciation of the ecological
role of the river's flow.

Anyone who urges second thoughts on
how this is to be done will
be shouted down and accused of
"lack of compassion" by the Halliburtons
who are eager to spend all those billions..

[alarimer]

2. absolutely right

The river needs to follow a more normal course and some of that sediment needs to be brought to the wetlands. There had been some experiments at diverting part of the river flow to the welands and in those areas they are not losing land at nearly the rate elsewhere. I think it is a place called Carnavon. Plus healthy wetlands filter water, act as a buffer against storm surge and provide habitat for animals.