Rates and Trends of Coastal Change in California and the Regional Behavior of the Beach and Cliff System
Rates and Trends of Coastal Change in California and the Regional Behavior of the Beach and Cliff System
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DOI：
10.2112/08-1006.1
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发表时间：
2009-05-01
影响因子：
--
通讯作者：
Richmond, Bruce
中科院分区：
文献类型：
--
作者：
Hapke, Cheryl J.;Reid, Dave;Richmond, Bruce
美国地质调查局（USGS）最近完成了一项关于加州海岸线变化和悬崖退缩的分析。这是第一次对西海岸海岸的海岸变化进行区域性、系统性的测量。计算了750 km以上海岸线的长期（近似120年）和短期（近似25年）海岸线变化率，并对350 km海岸线生成了70年的悬崖退缩率，结果表明，加州40%的海滩在长期内受到侵蚀。这一数字在短期内增加到66%，表明许多海滩已转向慢性侵蚀状态。长期和短期的全州平均净海岸线变化率分别为0.2米/年和-0.2米/年。长期的加积信号可能与该州某些地区的大型沿海工程项目和其他地区河流的大量沉积物有关。悬崖退缩评估得出全州平均值为-0.3 m/y。结果发现，北方加州具有最高的整体撤退率，这是受侵蚀热点与大型沿海滑坡和slumps.The数据库建立的海岸线变化和悬崖撤退分析的一部分，进一步调查，以检查动态的海滩/悬崖系统。相关性分析确定了海岸地貌和海滩/悬崖系统的行为之间的密切关系。高起伏海岸地区表现出负相关性，表明较高的悬崖后退率与较低的海岸线侵蚀率相关。相比之下，低到中等起伏的海岸显示出很强的正相关性，其中高海岸线变化的地区对应于高悬崖撤退的地区。
The U.S. Geological Survey (USGS) recently completed an analysis of shoreline change and cliff retreat along the California coast. This is the first regional, systematic measurement of coastal change conducted for the West Coast. Long-term (similar to 120 y) and short-term (similar to 25 y) shoreline change rates were calculated for more than 750 km of coastline, and 70 year cliff-retreat rates were generated for 350 km of coast.Results show that 40% of California's beaches were eroding in the long term. This number increased to 66% in the short term, indicating that many beaches have shifted toward a state of chronic erosion. The statewide average net shoreline change rates for the long and short term were 0.2 m/y and -0.2 m/y, respectively. The long-term accretional signal is likely related to large coastal engineering projects in some parts of the state and to large fluxes of sediment from rivers in other areas. The cliff-retreat assessment yielded a statewide average of -0.3 m/y. It was found that Northern California has the highest overall retreat rates, which are influenced by erosion hot spots associated with large coastal landslides and slumps.The databases established as part of the shoreline change and cliff-retreat analyses were further investigated to examine the dynamics of the beach/cliff system. A correlation analysis identified a strong relationship between the geomorphology of the coast and the behavior of the beach/cliff system. Areas of high-relief coast show negative correlations, indicating that higher rates of cliff retreat correlate with lower rates of shoreline erosion. In contrast, low-to moderate-relief coasts show strong positive correlations, wherein areas of high shoreline change correspond to areas of high cliff retreat.