A daily compilation of significant news articles and comment
October 17, 2007
3. Watersheds -
Sinking Delta
Where tules replace corn, they grow soil. It's no quick fix, but it could save levees. -
Sacramento
Climate Change Reshaping
San Francisco Chronicle
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Sinking Delta
Where tules replace corn, they grow soil. It's no quick fix, but it could save levees.
Sacramento
By Matt Weiser - Bee Staff Writer
One side of the road is a farm field, with corn stretching in orderly and silent rows across hundreds of acres. It sits at least 5 feet lower than the road, a result of decaying peat soils that have made many Delta islands into deep bowls through a process called subsidence.
On the other side is a soggy marsh, its floor nearly level with the road. The marsh is thick with tules and cattails reaching 10 feet overhead. Songbirds and waterfowl rise between pockets of open water. The air is filled with chirping and quacking.
This side of the road was once a subsided bowl, too, and filled with corn. But 10 years ago, the U.S. Geological Survey converted it to marshland, allowing tules and other native plants to grow and die back with the seasons as they once did.
The experiment has revived the process that created the Delta's peat soils in the first place. Over 10 years it has slowly raised the ground surface more than 2 feet in places, and it could restore generations of decline in the Delta, the West Coast's largest estuary.
"I'm standing on 2 feet of accumulated material, and it didn't just squish down," said Robin Miller, USGS project chief at the Twitchell site, as she stepped off a plywood platform into a jungle of tules and cattails. A decade earlier, she would have dropped into thigh-deep water.
"When I first started doing this project 10 years ago ... I didn't expect the reversal to be so startlingly enormous."
Delta islands have been sinking below sea level ever since the first levees were built. Peat soil is fertile farmland, helping to make farms the Delta's economic heart.
But conventional farm practices have helped sink many Delta islands, which now survive only thanks to increasingly fragile levees.
Peat soil slowly decays when drained and exposed to air, especially when it's plowed over and over for farming, as it has been for more than 100 years.
Many Delta islands are now more than 20 feet below sea level, and continue to subside up to 1 inch per year. This slowly weakens surrounding levees, creating what scientists say is at least a 20 percent chance that multiple islands will flood in an earthquake within the next 25 years.
After such a quake, rebuilding at least some of these islands and forcing out seawater drawn in from
Restoring peat soils on some islands could avoid that catastrophe by raising the ground surface again and bolstering levees.
But it won't be a quick fix.
Roger Fujii, chief of the USGS Bay-Delta Program, will present results of the
Two test plots were started in 1997 with a few tules planted in each. Over time, plants filled the rest of the plots on their own.
One plot was maintained at a water depth of 10 inches, the other 22 inches. This ensures that as tules and other plants die, they accumulate in the water rather than decaying, drying up and blowing away with the wind.
New plants grow up through dead plants each year. The cycle repeats, creating successive layers of dead material.
Scientists working for the state Department of Water Resources estimate that if seven islands in the west Delta were converted to growing tules, they could be raised 11 feet by 2050.
"We're interested in moving the technology down the path to see if this can be implemented on larger scales," said Jerry Johns, DWR deputy director.
The expensive alternative is to keep building levees taller and wider. DWR estimates reinforcing levees on seven Delta islands would cost $8 billion.
Growing peat takes longer but looks like a cheaper fix. Converting seven islands to peat could cost $600 million. But 85 percent of that cost involves first grading the land flat, which could be avoided if islands were planted in stages following natural land contours.
Miller said the benefits don't take decades to accrue. Wildlife habitat improves immediately and grows richer each year. If an island floods early in the process, marsh plants might buffer waves within the island that could further damage levees.
There's also potential to reduce global warming by storing carbon dioxide from the atmosphere in new peat soils. If a market can be created to sell carbon credits in peat soil, this might cover restoration costs.
Researchers plan a larger project on
Fujii said Delta farmers could be growing peat soil one day instead of corn, wheat and tomatoes. They would be paid to store carbon in peat soil rather than to produce food.
"The vision is to create kind of a blueprint, so a farmer can take a corn field and convert it," said Fujii.
Some questions still need to be answered. For instance, drain water from the test plots might put more dissolved organic carbon and mercury into the Delta. These chemicals create harmful byproducts when water is treated for domestic consumption.
The potential for storing carbon dioxide in peat soils also needs to be measured precisely.
Fujii said a larger test project could provide these answers within five years.
Finally, there is a thornier question: How will growing peat affect the farm economy of the Delta and the people who live there?
Marci Coglianese, former Rio Vista mayor, acknowledged that farming has a mixed legacy in the Delta: It has degraded Delta islands, but revenue from growing food is also the primary source of money to maintain levees.
Putting farmers to work growing peat "could be a wonderful solution," she said, if there is an economy to support that.
"Those of us who are down here physically working and trying to maintain the Delta cannot stay if there is not a local economy," she said. "So we have to balance all of that. It is people who are the stewards of the land down here."#
http://www.sacbee.com/101/story/436685.html
Climate Change Reshaping
San Francisco Chronicle – 10/17/07
The
Sea ice fell well below the previous record, caribou are declining in many areas and permafrost is melting, according to the annual update of the State of the Arctic report.
"The bottom line is we are seeing some rapid changes in the
And unlike
Scientists have expected polar regions to feel the first impacts of global warming and the 2006 State of the Arctic report provided a benchmark for tracking changes. Wednesday's follow-up was the first update.
Winter and spring temperatures were all above average throughout the whole Arctic, said James Overland of NOAA's Pacific Marine Environmental Laboratory in
"This is unusual and looks like the beginning of a signal from global warming," Overland said in a telephone briefing.
If you go back 100 years, it would be warm in one part of the
Sea ice cover this year is 23 percent smaller than the past record low set in 2005 and 39 percent less than average, said Jacqueline A. Richter-Menge of the Cold Regions Research and Engineering Laboratory in
She noted that the amount of older ice in the
Vladimir E. Romanovsky of the Geophysical Institute at the
"This similarity of very different regions shows the changes are not local, they are on at least a hemispherical scale," Romanovsky said.
Mike Gill, of the Circumpolar Biodiversity Monitoring Program in
The herds are sensitive to changes in their range and sometimes have problems migrating in changing conditions, meaning that calving occurs before they get to new feeding grounds, resulting in higher mortality.
The tundra itself is "shrubifying," he said and the increased shrub cover over many regions affects habitat and local climate, since it tends to absorb more solar radiation.
The global goose population has been on the increase, he added, resulting in overgrazing in some areas.#
http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2007/10/17/national/w085311D84.DTL&type=politics
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