Rates and Mechanisms of Coastal Erosion in the Bay of Fundy

芬迪湾海岸侵蚀的速率和机制

• 批准号: RGPIN-2017-04554
• 负责人: Hill, Paul
• 金额: $ 2.33万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653581
• 关键词: Rates; Mechanisms; Coastal; Erosion; Bay

Coastal erosion associated with rising sea levels and increased storminess threatens infrastructure in Canada and around the globe. Models of risk are evolving to incorporate the episodic nature of coastal erosion, but these efforts to establish firmer, evidence-based definitions of risk require frequent, high-resolution surveys of the coast, which until recently have been costly and logistically difficult. The emergence of Structure-from-Motion (SfM) technology, however, enables rapid, low-cost, accurate surveys of the coast, which is opening new avenues for investigation of episodic erosion. ***SfM constructs 3-D surfaces from overlapping photographs. The name comes from the ability of SfM to use images collected by a moving camera with positions that are unknown at the time of image capture. This ability has enabled the use of unmanned aerial vehicles (UAVs) for collection of photographs for SfM reconstruction of coastal morphology. The use of UAVs to conduct low-cost repetitive coastal surveys with SfM forms the core of the measurement approach in the proposed research.***The specific focus of the research is on rates and mechanisms of coastal erosion in the Minas Basin of the Bay of Fundy, Canada. Two projects will measure cliff erosion rates and the factors that control them, and another will examine rates and mechanisms of sediment storage and removal from side channels during periods of low and high stream discharge.***Cliff erosion in the Minas Basin threatens infrastructure, but it also determines the ecologically important sediment texture of the seabed. A recent study in my group showed that cliff retreat rates over the past 20 years are almost 50% larger than during the previous 30 years. I plan to employ frequent UAV-based SfM surveys, combined with measurements of rainfall, wind, and water level to investigate the underlying causes of observed increases in the rate of coastal retreat.***Suspended sediment concentration in the Minas Basin affects habitat in the water column by influencing the light field. Sediment concentration increases fivefold in the winter for reasons that are under investigation. One potential source of sediment to the Basin is erosion of mud from side channels during periods of high stream discharge. It is difficult to estimate volumes of sediment released during high discharge events with conventional methods, because the muds in side channels are dangerous to traverse. I plan to use UAV-based SfM surveys of the Belmont River in Nova Scotia to constrain conditions under which significant erosion and infilling occur in side channels and to constrain the volume of sediment involved.***Canada is faced with accelerating rates of coastal erosion. The proposed research will benefit Canada by developing and implementing new strategies for low-cost surveying of coastal morphology that are essential to building informed understanding of the rates and mechanisms of coastal change.*****

海平面上升和暴风雨加剧导致的海岸侵蚀威胁着加拿大和全球各地的基础设施。 风险模型正在不断发展，以纳入海岸侵蚀的偶发性，但这些建立更坚定、基于证据的风险定义的努力需要对海岸进行频繁、高分辨率的调查，而直到最近，这种调查成本高昂，而且在后勤上也很困难。 然而，运动结构（SfM）技术的出现使得快速、低成本、准确的海岸调查成为可能，这为间歇性侵蚀的调查开辟了新的途径。 ***SfM 从重叠的照片构建 3D 表面。 该名称源自 SfM 能够使用移动相机收集的图像，这些图像的位置在图像捕获时是未知的。 这种能力使得能够使用无人机 (UAV) 收集照片以进行海岸形态的 SfM 重建。 使用无人机通过 SfM 进行低成本重复海岸调查构成了拟议研究中测量方法的核心。***该研究的具体重点是米纳斯湾盆地海岸侵蚀的速率和机制加拿大芬迪。 两个项目将测量悬崖侵蚀率及其控制因素，另一个项目将研究在低流量和高流量期间沉积物储存和从侧河道清除的速率和机制。***米纳斯盆地的悬崖侵蚀威胁着基础设施，但它也决定了海底沉积物的重要生态结构。 我的团队最近的一项研究表明，过去 20 年的悬崖撤退率比过去 30 年几乎增加了 50%。 我计划频繁采用基于无人机的 SfM 调查，并结合降雨量、风力和水位测量，以调查观察到的沿海退缩率增加的根本原因。***米纳斯盆地的悬浮沉积物浓度影响了栖息地通过影响光场来改变水柱。 冬季沉积物浓度增加五倍，原因正在调查中。 流域沉积物的潜在来源之一是高流量期间侧河道泥浆的侵蚀。 用传统方法很难估计高流量事件期间释放的沉积物量，因为侧河道中的泥浆穿越很危险。 我计划使用基于无人机的 SfM 对新斯科舍省贝尔蒙特河进行调查，以限制侧河道发生严重侵蚀和填充的情况，并限制所涉及的沉积物量。***加拿大面临着海岸侵蚀速度加快的问题。 拟议的研究将通过制定和实施沿海形态低成本调查新战略而使加拿大受益，这对于建立对沿海变化速率和机制的知情理解至关重要。*****