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3. Climate Change Vulnerability Assessment <br />San Leandro 2021 Climate Action Plan Page 41 <br />likely to slide. In some cases, hillsides can become so saturated that slope failures result in a <br />mudslide (a mixture of soil and water moving downslope). Steeper slopes in the San Leandro Hills <br />are in high landslide susceptibility areas. <br />Landslides and mudslides can move fast enough to damage or destroy homes or other structures <br />in their path, block roadways (including evacuation routes), and injure or kill people caught in them. <br />The most vulnerable populations are those that may be unable to evacuate due to limited mobility, <br />lack of access to a vehicle, or language barriers that may prevent awareness of emergency <br />notifications. Those living on single-access roadways in the hilly portion of the City or those living <br />in less resilient housing may lose access to their homes if roadways or the structures are damaged <br />or destroyed by a landslide. Infrastructure, such as natural gas pipelines and water or wastewater <br />infrastructure, can break or malfunction if the soil supporting them fails. This can lead to disruptions <br />in energy delivery and water or wastewater services. <br />Sea-Level Rise <br />As global temperatures rise, glaciers and other land ice near the north and south poles melt. The <br />water flows into the ocean, increasing sea levels across the globe. Higher temperatures also cause <br />water to expand in oceans, causing further rising of sea levels. SLR is a gradual process, taking <br />place over years or decades. In California, guidance suggests that sea levels will increase by 6 to <br />10 inches in most places by 2030, 13 to 23 inches by 2050, and 41 to 83 inches by 2100.43 However, <br />it is possible that sea levels could rise faster than these projections.44 Along San Leandro’s bay <br />shoreline, sea levels are projected to rise approximately 24 inches by 2050 and as much as 84 <br />inches by 2100.45 <br />Rising sea levels can increase the frequency and severity of bay shoreline flooding. Since SLR <br />raises ocean levels, shoreline floods, such as king tides and storm surges, can reach further onto <br />land. For example, a storm that has a 1 in 10 chance of occurring in a given year (known as a 10- <br />year storm), can create a temporary increase in sea levels of approximately 28 to 30 inches. This <br />means that if sea levels rise by 24 inches during normal conditions, a 10-year storm event would <br />create a temporary SLR of around 52 inches.46 Bayshore flooding zones in 2050 and 2100 are <br />shown above in Figure 8. Higher sea levels can also give a “boost” to smaller floods that would not <br />have been large enough to flood dry land during normal conditions, making shoreline flooding more <br />frequent. <br />Eventually, sea level may increase enough to permanently flood low-lying areas in the eastern <br />portion of San Leandro along the bayshore. Homes within the Mulford Gardens, Marina Faire, and <br />Heron Bay neighborhoods are within the SLR inundation area. 47 SLR can increase residential <br />flooding in these neighborhoods, causing mold and mildew to grow. Eventually, homes in these <br />neighborhoods may become uninhabitable. Homes and structures built above sea level can still be <br />harmed if the higher levels of water erode the rock or soil supporting the structures, potentially <br />making them unsafe or at risk of collapse. <br />85