Monday, June 6, 2011

Securing the California Delta's levees before a major earthquake


California infrastructureSecuring the California Delta's levees before a major earthquake

Published 7 January 2011
In the event of a major earthquake or flood and many levees failing simultaneously in California's Sacramento-San Joaquin River Delta, as many as 515,000 residents and 520,000 acres of land would be in immediate danger; the long term effects could be even more widespread, as nearly 28 million residents depend on the Delta for water and irrigation; California lawmakers have increasingly turned their attention to securing the Sacramento-San Joaquin River Delta's levees, but experts say that only little progress has been made
After witnessing the destructive potential of broken levees during Hurricane Katrina, California lawmakers have increasingly turned their attention to securing the Sacramento-San Joaquin River Delta’s levees so they can withstand a major earthquake. Observers say that little progress has been made.
The levees surrounding the Sacramento-San Joaquin River Delta hold back the largest estuary on the Pacific Coast of the United States, provide 76 percent of the fresh water supply used for drinking and irrigation in California, and keep major cities and infrastructure dry.
Miller McCune reports that in the event of a major earthquake or flood and many levees failing simultaneously, as many as 515,000 residents and 520,000 acres of land would be in immediate danger. The long term effects could be even more widespread – nearly twenty-eight million residents who depend on the Delta for water as well as irrigation for farm lands stretching as far south as San Diego would lose access to their major source of water for months or even years.
The U.S. Geological Survey (USGS) predicts a 63 percent chance that an earthquake of magnitude 6.7 or greater along the Hayward fault line will occur by 2038. The Hayward fault lies only forty miles west of the delta, while at least six other fault lines lie even closer.
Earthquakes are only part of a long list of dangers that threaten the levees. Rising sea levels, increased rainfall, and even beavers pose real dangers – it is believed that in 2004 a beaver caused a levee breach that took six months and more than $90 million dollars to clean up.
Geography, physics, and history have put a gargantuan strain on one of California’s most important pieces of infrastructure. Situated between the San Francisco Bay and the Sierra Nevada Mountains, the levees must protect against both the surging salt water of the bay and the fresh water rushing downstream from the mountains.
Engineer Jay Lund fears that the Delta could easily become a salty marsh. On Lundpredicted that if nothing is done, “the levees will fall down, the saltwater will come in, and you will not be able to pump water from the delta.”
Climate change is straining the levee on both sides with rising sea levels in the bay and a decrease in snowfall that has resulted in increased rain and engorged rivers. To make matters worse, much of the land protected by the levees actually rests as much

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