Issue link: http://winesandvines.uberflip.com/i/480754
72 P R A C T I C A L W I N E R Y & V I N E YA R D April 2015 B O O K E X C E R P T and people have been finding that space in the Central Valley. Increasingly, the region has been providing more afford- able housing, with former agricultural lands in the Central Valley floodplains being converted to housing develop- ments. Should floodwaters fill the Central Valley, they will submerge not just small towns, marshes and farm- lands but also major population centers in 10 to 30 feet of water. In 2009, over 6 million people lived in the Central Valley, many in densely populated cit- ies like Modesto, Fresno, Stockton and Sacramento, all of which face potential catastrophe should storms and floods like the ones in 1861–62 strike again. The recent trend in urban sprawl seems to dance on the edge of disaster: flooded fields are one thing, but flooded homes are quite another. The long history of megafloods in the Central Valley is virtually unknown to most residents today. Many new cit- ies and housing developments are pro- tected by a relatively primitive network of levees — some 6,000 miles of levees in all — that line the rivers. These levees are fragile, and they are the last—and in some cases only—line of defense against the potential floods spilling out from the Sacramento and San Joaquin rivers. The fragility of California's levees has repeat- edly been exposed in recent years. During the winter of 1986, floodwaters over- whelmed Folsom Dam on the American River and almost flooded Sacramento; in 1997, levees broke throughout the Central Valley, causing the largest evacuation in California's history; and in 2006, multiple levee breaks and massive flooding in the Central Valley made national news. The Delta The Sacramento-San Joaquin Delta is located inland of San Francisco Bay on the western edge of the Central Valley, at the confluence of the Sacramento and San Joaquin rivers. These rivers drain a watershed covering almost half the area of California, including the south- ern Cascade range to the north, the west- ern flank of the Sierra Nevada, and the eastern flank of the Coast Ranges. Wet winters bring huge volumes of water to the delta — a region now considered a disaster waiting to happen. The level of Mono Lake (feet above sea level) for the period 1850 to 2011. Diversion of inflowing streams began in 1941. Diversions were reduced in 1981, allowing the lake level to rise and the ecosystem to begin to recover. (Data from Mono Lake Commission website, plotted by B. Lynn Ingram.) Photo at left: Mono Lake, showing calcium carbonate "tufa tower" formations that originally formed beneath the lake but are now exposed aft er the water level dropped. The east- ern flank of the Sierra Nevada range is shown in the background. PHOTO BY D. J. DEPAOLO SUPPORT RESEARCH & WINE INDUSTRY NEEDS THROUGH THE A M E R I C A N V I N E YA R D FO U N D AT I O N P.O. Box 5779, Napa, CA, 94581 • T: (707) 252-6911 Visit our Web site at www.avf.org for information on funding and current research projects T E C H NO L O GY TO I M P R OV E I R R I G AT I O N E F F I C I E NC Y Dr. Andrew McElrone's research defines improvements in the Surface Renewal technique to more clearly evaluate the relationship between real vineyard evapotranspiration and traditional water status indicators such as midday leaf water potential. This valuable information will assist in the development of more efficient vine irrigation strategies and potentially reduce labor costs. For more information visit AVF.org or contact Dr. McElrone at ajmcelrone@ucdavis.edu. For a wealth of useful viticulture and enology research and information, visit AVF.org, ngr.ucdavis.edu, asev.org, iv.ucdavis.edu or ngwi.org Finding Solutions Through Research