Levee systems are an important part of California’s water infrastructure, engineered to provide resilience against flooding and reduce flood losses. The growth in California is partly associated with costly infrastructure developments that led to population expansion in the levee protected areas. Therefore, potential changes in the flood hazard could have significant socioeconomic consequences over levee protected areas, especially in the face of a changing climate. In this study, we examine the possible impacts of a warming climate on flood hazard over levee protected land in California. We use gridded maximum daily runoff from global circulation models (GCMs) that represent a wide range of variability among the climate projections, and are recommended by the California’s Fourth Climate Change Assessment Report, to investigate possible climate-induced changes. We also quantify the exposure of several critical infrastructure protected by the levee systems (e.g. roads, electric power transmission lines, natural gas pipelines, petroleum pipelines, and railroads) to flooding. Our results provide a detailed picture of change in flood risk for different levees and the potential societal consequences (e.g. exposure of people and critical infrastructure). Levee systems in the northern part of the Central Valley and coastal counties of Southern California are likely to observe the highest increase in flood hazard relative to the past. The most evident change is projected for the northern region of the Central Valley, including Butte, Glenn, Yuba, Sutter, Sacramento, and San Joaquin counties. In the leveed regions of these counties, based on the model simulations of the future, the historical 100-year runoff can potentially increase up to threefold under RCP8.5. We argue that levee operation and maintenance along with emergency preparation plans should take into account the changes in frequencies and intensities of flood hazard in a changing climate to ensure safety of levee systems and their protected infrastructure.

中文翻译：

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加州受堤防保护的关键基础设施在气候变暖时面临洪水灾害的变化

堤防系统是加州水利基础设施的重要组成部分，旨在提供抵御洪水的能力并减少洪水损失。加利福尼亚州的增长部分与导致堤防保护区人口膨胀的昂贵的基础设施开发有关。因此，洪水灾害的潜在变化可能会对堤防保护区产生重大的社会经济后果，尤其是在气候变化的情况下。在这项研究中，我们研究了气候变暖对加利福尼亚堤防保护区洪水灾害的可能影响。我们使用来自全球环流模型 (GCM) 的网格化最大日径流，该模型代表了气候预测之间的广泛可变性，并得到加利福尼亚第四次气候变化评估报告的推荐，调查可能的气候引起的变化。我们还量化了受堤防系统保护的几个关键基础设施（例如道路、输电线路、天然气管道、石油管道和铁路）遭受洪水的影响。我们的结果提供了不同堤防洪水风险变化的详细图景以及潜在的社会后果（例如人员和关键基础设施的暴露）。与过去相比，中央山谷北部和南加州沿海县的堤防系统可能会发现洪水灾害的增加幅度最大。预计中央山谷北部地区的变化最为明显，包括比尤特、格伦、尤巴、萨特、萨克拉门托和圣华金县。在这些县的堤防地区，根据未来的模型模拟，在 RCP8.5 下，历史 100 年径流可能会增加三倍。我们认为，堤坝运营和维护以及应急准备计划应考虑到气候变化中洪水灾害频率和强度的变化，以确保堤坝系统及其受保护基础设施的安全。