Mississippi Floods by Anuradha Mathur and Dilip da Cunha, Yale University
Press, 拢35/$45, ISBN 0300084307
MARK TWAIN thought the flooding of the Mississippi was triggered by heavy
rains pouring into the 鈥渓awless stream鈥�. He was wrong, say landscape designers
Anuradha Mathur and Dilip da Cunha. The culprit is the artificial levees along
the mighty river, which constrict the flow. For more than a century the US Army
Corps of Engineers pursued a levees-only policy, straightening and embanking the
stream to speed its flow, scour its bed and keep a channel open for navigation.
But floods occurred more frequently and spread widely as the levees rose.
In 1927 the Mississippi submerged an area almost as large as Belgium and the
Netherlands, and destroyed 160,000 homes. After that, the engineers began to
rethink. They built an experimental model, measured capacities of different
watercourses and dug overflow channels. They planned meanders and cut-off lakes
in the Mississippi-Yazoo Delta to hold flood water, weirs to control an outfall
down the Atchafalaya floodway into the Gulf of Mexico, and designed a spillway
above New Orleans to divert overflows into Lake Pontchartrain. At the mouths of
the Mississippi and its distributaries, jetties constrict current and flush away
silt at entrances to the navigable waterway.
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The imaginative illustrations are a delight, capturing the dynamic qualities
of a landscape in perpetual flux. To convey this shifting scene, the authors
have overlaid maps from different dates and juxtaposed slices of photographs to
represent the changeable terrain of Mississippi mud and water.