The orientation, shape, and stability of the Golden Gate sand waves

海洋沙波就像水下的沙丘。它们分布在世界各地的浅海环境中，如潮汐入口和潮汐滩。它们也存在于一些河口、海底峡谷和深海陆架环境中。它们对导航、海底电缆、管道和风力发电设施的设计和安置都很重要。例如，由于沙波的生长或迁移，埋在地下的管道或电缆意外暴露，可能导致灾难性的故障，导致高成本和破坏性的生态影响。沙波峰向航道的动态迁移会使航海图不准确，并对船舶和小船造成危险。该项目将使用模型研究金门沙波中的沉积物运输，金门沙波是地球上最引人注目的沙波场之一。该项目的更广泛影响包括提高对沙波动力学的理解，这将有助于为该地区的沉积物管理提供信息。该项目还将资助一名研究生。通过整合现有的多个高分辨率金门沙波现场调查和包含沿海地区流体动力学和沉积物输运等物理过程的校准数值模型，研究沙波的形状和动力学。该地区的水动力强迫主要是由潮汐引起的，并且由于旧金山湾的水流进出而表现出强大的潮汐射流。与海浪相结合，形成了复杂的高能沉积物输运模式和河床形态动力学。该项目的目标是评估一些假设，以解释在世界各地沙波的各个领域中发现的一些令人困惑的观察结果，例如：单个沙波的不对称形状及其与沙波迁移的关系；潮汐强迫与个别沙浪方向的动力学关系；以及在沙波场中偶尔出现和消失的新沙波峰。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Marine sand waves are like underwater sand dunes. They are found worldwide in shallow marine environments such as tidal inlets and tidal banks. They are also found in some estuaries, submarine canyons, and deep shelf environments. They can be important to navigation and the design and placement of submarine cables, pipelines, and wind power generation facilities. For instance, the unintended exposure of a buried pipeline or cable due to the growth or migration of sand waves can cause catastrophic failure resulting in high costs and destructive ecological impacts. The dynamic migration of sand wave crests into shipping channels can render navigational charts inaccurate and be hazardous to shipping and small boats. This project will use models to study sediment transport in the Golden Gate sand waves, one of the earth’s most striking field of sand waves. The project Broader Impacts include an improved understanding of sand wave dynamics that will help inform sediment management in the region. The project would also support a graduate student.The shape and dynamics of sand waves will be investigated through the integration of multiple existing high resolution field surveys of the Golden Gate sand waves and a calibrated numerical model that incorporates physical processes such as fluid dynamics and sediment transport in coastal regions. The hydrodynamic forcing in the region is due mainly to tides and exhibits a powerful tidal jet due to the flow in and out of San Francisco Bay. In combination with ocean waves this results in a complex and energetic sediment transport patterns and bedform morphodynamics. The goals of this project are to evaluate hypotheses to explain several perplexing observations found in various fields of sand waves worldwide, such as: the asymmetric shapes of individual sand waves and their relation to sand wave migration; the dynamics linking the tidal forcing and the orientation of individual sand wave crests; and the occasional appearance and disappearance of a new sand wave crest within a field of sand waves.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.