subject: Shoes Bags Sales [print this page] We found that about 10 percent of the water that is applied is lost below the vine rooting zone and does not have contact with the soil and vine roots," said Eve Hinckley, who worked on the project for her PhD thesis in the department of geological and environmental sciences at Stanford. "This is a conservative estimate."fashion
The problem lies in deep cracks that are a chronic feature in the clay-rich soils of the areaDue to the physical and chemical properties of these soils, they naturally swell when wet and shrink as they dry, producing cracks. Hinckley says that tendency is exacerbated by the weekly cycle of irrigating during the growing season, when vines are typically watered for 4 hours a week. Under a regular regimen of swelling and shrinking, the cracks become more pronounced and water speeds through them without interacting with the soil.fashion shoes
Hinckley is presenting her results at the fall meeting of the American Geophysical Union on Dec. 16.
She gathered her data by burying devices called lysimeters about 16 inches down in the soil -- just below the root zone of the vines. That is also the depth to which many of the deep cracks penetrate in the vineyard where she did her study. The lysimeters captured water flowing through the soil, giving her data on the volume, chemical composition, and residence time of water in the soil.
The speedy passage of so much water through the cracks in the soil affects more than just the job of getting enough water to the vines. There are significant consequences on either end of that rapid flow. Upstream, it means that more water has to be stockpiled each winter than the vines are actually usinggiuseppe zanotti.
All the water needed to sustain the vines through the summer has to be captured for each vineyard by the grower during the preceding winter. Most of that water is diverted from rivers and streams that are temporarily swollen -- in a good year -- by the winter rains. A lesser portion comes from rain falling directly into the reservoirs and runoff from adjacent slopes.
"You will often see a string of reservoirs coming off of a stream," Hinckley said. "The lowest one has the first water rights. When it's full, the grower closes it off and then the next grower up the slope is allowed to fill." In a winter with low rainfall, sometimes the higher reservoirs in the string never fill completely.
"Diversions are a pretty big deal up in the (river) system," Hinckley said. "And that is what has been a concern to the public, because it is siphoning water from the supply that would be going to groundwater recharge or to streams, where fish may be spawning." Chinook salmon and steelhead trout both spawn in the Napa River and its tributaries.
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