Late Holocene Cliff Retreat in Del Mar, CA, Revealed From Shore Platform 10 Be Concentrations and Numerical Modeling
Late Holocene Cliff Retreat in Del Mar, CA, Revealed From Shore Platform 10 Be Concentrations and Numerical Modeling
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海岸平台 10 Be 浓度和数值模拟揭示了加利福尼亚州德尔马的全新世晚期悬崖撤退
DOI：
10.1029/2022jf006855
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Shadrick, J. R.
中科院分区：
文献类型：
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作者：
Clow, T.;Willenbring, J. K.;Young, A. P.;Matsumoto, H.;Hidy, A. J.;Shadrick, J. R.
岩石海岸悬崖退缩对沿海社区和基础设施构成危害，在海平面上升等因素下，这种危害可能会加剧。不幸的是，对撤退率的限制通常仅限于来自过去 100 年的图像和地图的限制。在这里，我们使用新开发的海岸平台剖面演化和宇宙放射性核素产生的耦合模型，该模型考虑了相对海平面（RSL）上升、风化、材料阻力和波高衰减的影响，来模拟加利福尼亚州德尔马的悬崖在千年时间尺度上的退缩及其潜在驱动因素。我们展示了使用狭窄海岸平台的地形和水深测量以及从悬崖底部延伸至 125 m 的 9 个宇宙成因 10Be 浓度的有限数据集的能力，以获得模拟的悬崖退缩率，从过去两千年到 100 年前，该退缩率稳定在 5.0 至 12.5 cm yr−1 范围内。这些速率与现代约 2-19 cm yr−1 的后退速率一致。在全新世晚期，南加州的 RSL 上升保持相对稳定，这可能解释了这一时期模拟的悬崖后退率相对稳定的原因。我们还探讨了风化、材料阻力和波浪侵蚀功效的相对影响，发现风化和波浪驱动的侵蚀对于复制该位置的测量数据都是必要的，后者对模型的接受度有更强的控制，这表明波浪可能提供了一种可能的机制，RSL的上升可能通过这种机制影响南加州的沿海悬崖侵蚀。
Rocky coast cliff retreat presents a hazard to coastal communities and infrastructure that is potentially amplified under rising sea level conditions, among other factors. Unfortunately, constraints on retreat rates are typically limited to those derived from imagery and maps spanning the last ∼100 years. Here, we use a newly developed coupled model of shore platform profile evolution and cosmogenic radionuclide production that considers the influence of relative sea level (RSL) rise, weathering, material resistance, and wave height decay to model cliff retreat over millennial timescales and its potential drivers in Del Mar, California. We demonstrate the ability to use topographic and bathymetric measurements from a narrow shore platform along with a limited data set of nine cosmogenic10Be concentrations extending ∼125 m from the cliff base to obtain modeled cliff retreat rates that steadily range from 5.0 to 12.5 cm yr−1over the last two millennia until 100 years before present. These rates are consistent with modern retreat rates of about 2–19 cm yr−1here. RSL rise in Southern California remained relatively constant during the late Holocene, potentially explaining the relatively stable modeled cliff retreat rate over this time. We also explore the relative influence of weathering, material resistance, and wave erosion efficacy and find that both weathering and wave‐driven erosion are necessary to replicate the measured data at this location, with the latter exerting a stronger control on model acceptance, suggesting that waves may provide a possible mechanism by which RSL rise may influence coastal cliff erosion in southern California.