概念和词汇表
自然和基于自然的特色的机会
制定次区域适应计划为我们提供了一个契机，将生态及其他社区的协同效益纳入我们的适应方案。阿拉米达和奥克兰湾区从历史湾区向现代湾区转变，反映了自然过程与人类活动之间复杂的相互作用。随着海平面上升的加速，这些湾区的未来取决于有效的管理和修复工作，以平衡生态需求与城市发展。保护和恢复湾区对于减轻气候变化对该地区自然生态系统和人类社区的影响至关重要。
历史悠久的湾区：历史上，湾区是一片广阔的潮汐沼泽、泥滩和湿地，沿着旧金山湾的边缘延伸，包括阿拉米达和奥克兰周边地区。这些生态系统生物多样性丰富，养育了种类繁多的动植物物种。湾区充当了天然的缓冲区，吸收了洪水，并为包括候鸟在内的野生动物提供了重要的栖息地。
潮汐沼泽：潮汐沼泽在海湾地区占主导地位，其特点是耐盐植被和经常被潮汐淹没。它们在过滤水、截留沉积物和稳定海岸线方面发挥着至关重要的作用。
泥滩和湿地：这些区域位于低海拔地区，涨潮时被淹没，退潮时露出水面。它们为各种鱼类、无脊椎动物和鸟类提供了栖息地。
现代湾区 随着时间的推移，阿拉米达和奥克兰周围许多历史悠久的湾区由于城市发展、农业和基础设施项目而遭到改变或消失。大片潮汐沼泽被排干或填埋，尤其是在19世纪和20世纪，为城市、道路和工业设施腾出空间。
城市发展：阿拉米达和奥克兰等城市扩张至昔日的湿地区域，导致海湾地区的自然栖息地大幅减少。这种发展往往导致这些地区丧失其提供的生态系统服务，例如防洪和水过滤。
恢复工作：近几十年来，人们越来越认识到海湾地区的重要性。恢复项目旨在重建潮汐沼泽和湿地，以抵御海平面上升并恢复生态平衡。
海平面上升及其未来影响
Sea level rise, driven by climate change, presents a significant threat to the modern Baylands, particularly in low-lying areas around Alameda and Oakland. As sea levels continue to rise, these areas face increased risks of flooding, erosion, and habitat loss.
Increased Flooding: Rising sea levels lead to higher tides and storm surges, which can inundate low-lying areas, especially during extreme weather events. In Oakland, this threatens not only natural habitats but also urban infrastructure and communities.
Loss of Tidal Marshes: Many of the remaining tidal marshes in the Baylands are at risk of being submerged permanently as sea levels rise, unless they can migrate inland or be artificially raised.
Adaptation and Resilience: In response to these challenges, there are ongoing efforts to enhance the resilience of the Baylands through restoration and adaptation strategies. These include creating living shorelines, enhancing sediment deposition to raise marsh elevations, and planning for the migration of habitats inland.
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Tidal Marsh Restoration
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Description: Restoring and enhancing tidal marshes involves re-establishing native
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vegetation and hydrology in degraded or former marsh areas. This can help to stabilize
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the shoreline, reduce erosion, and provide a buffer against storm surges and high tides.
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Benefits: Tidal marshes can absorb floodwaters, reduce wave energy, and trap sediments, which can help to elevate the marsh surface in response to rising sea levels. They also provide critical habitat for wildlife.
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Living Shorelines
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Description: Living shorelines use natural elements like plants, sand, and rock to stabilize the coastline. Techniques might include planting native vegetation, installing biodegradable materials, and creating oyster reefs or other structures that mimic natural features.
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Benefits: Unlike traditional hard structures like seawalls, living shorelines can adapt over time to changing conditions. They help reduce erosion, improve water quality, and provide habitat for marine life.
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We will continue to:
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Engage local experts within the OAAC, Scientific Partners, and consultant team
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Use the green-to-gray spectrum, integrating nature-based features and hybrid solutions wherever feasible
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Learn from existing pilot projects, and identify where new pilot projects may be needed in the Subregion
海平面上升适应目标
适应海平面上升需要我们确定海岸线需要抬高的位置、抬高多少以及何时进行。为了确定近期（2080年）的新高度，我们从当前的高潮位开始。我们海岸线上一些最低的地区已经经历了沿海洪灾。然后，我们考虑当前百年一遇（年概率为1%）的海湾水位，该水位是在严重的沿海风暴期间观测到的。加上预计的海平面上升和干舷（一个缓冲区，用于解释海平面上升水位估算中的不确定性），我们得到了目标设计高程14.0英尺（NAVD88，用于测量高程的标准参考基准）。 对于我们海岸线的最低点（靠近高潮线的点），这意味着在短期内将边缘抬高约7.0英尺。较高的地区需要的抬高幅度较小，目标是在海岸线周围实现一致的保护水平。
Inland Flooding and Groundwater Rise
As our climate warms, the intensity of rainfall events is increasing and sea levels continue to rise. During rainfall events, precipitation infiltrates into the ground, reducing the capacity of the ground to absorb water from future storm events and temporarily raising the local groundwater table. As a result, localized flooding can occur, and it is more common with storms that happen back-to-back. Meanwhile, rising bay water gradually pushes the groundwater table closer to the surface. During a storm, this further limits the capacity of the ground to absorb rainwater. The groundwater table can also rise above the ground surface and create permanent ponding on the land in places that have historically remained dry, even long after storms have passed. Portions of this project area could experience this ponding (or “emergent groundwater”) with as little as 1 foot of sea level rise. Inland flooding is caused by rainfall and the rising groundwater table. When we build adaptation measures along the shoreline to protect against coastal flooding, we also need to address the risks of inland flooding. This can be done by increasing stormwater pipe and pumping capacity while also building green infrastructure to detain rainfall and emergent groundwater. These detention and conveyance systems slow flooding, provide space for temporary water storage, and remove pressure on drainage infrastructure until the storm has passed. Alameda Northern Watershed and Storm Drain System It is estimated that Alameda’s Northern Watershed requires an additional 37 acre-feet of stormwater detention to mitigate the current 100-year, 24-hour storm event. The water volume from this type of storm is estimated to increase by the following percentages in the coming decades. Proposed Detention Basins In both the Alameda and Oakland project areas, space for new stormwater detention area locations are being identified. Existing parks, such as Sweeney Park, could also be adapted to detain stormwater and still maintain current uses for play when detention is not needed. Green infrastructure basins provide additional benefits for habitat, parks, and streets when there isn’t an active storm. Where space is limited, green infrastructure may be combined with less visible gray systems.
概念适应策略
奥克兰海岸线概念性适应策略 根据所需的防护等级、可用空间大小、邻近土地和水域用途，以及改善公共领域和/或海岸线及潮间带栖息地带来的协同效益，可在海岸线沿线组合使用不同的适应措施，例如堤坝和海堤。 这些示例展示了两种可在从哈里森街到梅里特湖水道的海岸线上实施的策略，这些策略均考虑到了现有的海岸线状况和用途。这些策略及其他策略将经过进一步研究完善，并最终形成一个优选方案。 堤坝建于现有海岸线的14.0米高程。公共领域在退让线允许的情况下向内陆抬高。河口公园的设计将海岸线抬高至12.5米高程，以提供短期保护，并使其长期适应更高的海拔。铁路桥的防洪墙将在保护海岸线的同时，最大限度地减少对现有潮汐水道水质和功能的影响。防洪墙的建造高度将高于相邻的坡度，并且在铁路走廊有限的占地面积和通行权限制内可能难以实施。需要沿着水道至第七街的路段增建堤坝，以提供足够的防护。 堤坝建于向陆地方向14.0米高的堤坝。海岸线坡度较缓，以适应岩石潮间带、沼泽或砾石滩以及高地栖息地。河口公园的设计将海岸线抬高至12.5米，以提供短期防护，并使其能够长期适应更高的海拔。内河码头西桥的潮闸将为铁路桥和水道提供沿海防洪保护，使其不受铁路桥占地面积的限制（仅在涨潮时关闭，并随着时间的推移而逐渐关闭）。该位置的潮闸对水质和栖息地的潜在影响有待进一步研究。潮闸以北无需增建堤坝。潮闸附近海岸线（例如河口公园）的坡度将提高，以提供与潮闸相同的防护高度。 阿拉米达北部海岸线概念性改造策略 可根据所需的防护等级、可用空间大小、邻近土地和水域用途，以及改善公共领域和/或海岸线及潮间带栖息地带来的协同效益，沿海岸线组合使用不同的改造措施，例如堤坝和海堤。 这是一个可在阿拉米达北部海岸线这一段实施的策略示例，该策略考虑了现有的海岸线状况和用途。该策略及其他策略将不断完善，并发展成为首选方案。
