2014-028 - Approving General Plan Amendement No. 2014-01

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City of Santa Ana -Park View at Town and Country Manor Draft EIR Hydrology and Climate Change Adaptation - Sea Level Rise and Increased Flooding Impact 4.3 -9 The project would not be significantly impacted by climate change through a rise in sea levels or increased flooding. Impact Analysis Climate change could result in sea level rises and increased flooding, as explained in the following excerpts from a paper published by the California Climate Change Center (2006) and a paper sponsored by the California Energy Commission (Moser et al. 2009). Sea level rise is already affecting much of California's coastal region, including the Southern California coast, the Central California open coast, and the San Francisco Bay and upper estuary. During the past century, sea levels along California's coast have risen about seven inches. The rate of sea level rise observed at the gauges along the California coast is similar to the estimate for global mean sea level. Sea levels are likely to increase by up to 35 inches by the year 2100, depending on the magnitude of climate warming. Elevations of this magnitude would inundate coastal areas with salt water, accelerate coastal erosion, threaten vital levees and inland water systems, and disrupt wetlands and natural habitats. The combination of increasingly severe winter storms, rising mean sea levels, other climactic fluctuations like El Nino, and high tides is expected to cause more frequent and severe flooding, erosion, and damage to coastal structures. Many California coastal areas are at significant risk for flood damage. For example, the city of Santa Cruz is built on the 100 -year floodplain and is only 20 feet above sea level. Although levees have been built to contain the 100 -year flood, a 12 -inch increase in sea levels (projected for the medium warming range of temperatures) would mean storm surge- induced flood events at the 100 -year level would likely occur once every 10 years. Despite extensive engineering efforts, major floods have repeatedly breached levees that protect freshwater supplies and islands in the San Francisco Bay Delta as well as fragile marine estuaries and wetlands throughout the State. Continued sea level rise will further increase vulnerability to levee failures. Some of the most extreme flooding during the past few decades has occurred during El Nino winters, when warmer waters fuel more intense storms. During the winters of 1982 -1983 and 1997 -1998, for example, abnormally high seas and storm surges caused millions of dollars' worth of damage in the San Francisco Bay area. Highways were flooded as six -foot waves crashed over waterfront bulkheads, and coastal real estate was destroyed. Climate change will require major changes in flood management. In many regions such as the Central Valley, where urbanization and limited river channel capacity already exacerbate rising flood risks, flood damage and flood control costs could amount to several billion dollars. Research has shown that rapid greenhouse gas emission reductions cannot prevent substantial sea level rise because ocean waters store heat effectively and will expand for centuries, long after air Michael Brandman Associates 4.3 -13 H\Cl t(PN -Rn) 32]b327W3MMVB2]0030 Se 4B Hyd bUadWat Wity.d¢