RAPID: Morphological Effects of Extreme Sea-Level Anomalies

对该项目的非技术性说明，解释了该项目的意义和重要性。海岸侵蚀是一个国家和全球的重要问题。随着越来越多的人居住在海岸，预测风暴和其他天气系统如何改变海岸线的景观变得越来越重要。这个快速项目将在海平面上升和厄尔尼诺现象期间从俄勒冈州海岸线收集密集的现场数据，这将使海滩运动和侵蚀的数字模型更加准确。海岸过程的数值模型被联邦/州政府机构、当地规划者和咨询公司广泛用于一系列工程和规划应用；因此，提高这些模型中形态演变的定量准确性有可能改善许多产品和服务的质量。该项目的技术说明这一快速项目将在俄勒冈州奈塔茨滨海小区实施海滩和沙丘地形测量活动，以量化极端海平面异常对海滩形态的影响。有待检验的假设是：1)在厄尔尼诺期间，俄勒冈州向海角方向的沿海地区的大部分沙丘海岸线是否会比正常年份多经历大约10-15%的萨伦格风暴影响尺度的碰撞。沿海沙丘也将比一般年份经历更多的“冲刷”；2)南部沿海地区将遭受严重侵蚀，受到的影响比北部更大。沿海沉积物输送的梯度将从沿海单体南端侵蚀数万立方米的沙子，这些沉积物被近岸和向北输送；3)风暴后和异常期结束时向海滩供应跨岸沉积物，启动沙丘的恢复阶段，根据海滩地形测量学，这将在空间上高度可变，但将与沿海沉积物输送的当地梯度密切相关。虽然对海平面异常和厄尔尼诺事件如何影响美国西海岸的海滩和沙丘有一个普遍的感觉，但现有的数据集很少，岸上沉积物输送的速度和机制也没有很好的记录。这项研究将量化每次风暴事件期间海滩流失的沉淀量，并随后跟踪整个冬季和春季海滩恢复的空间和时间趋势。

A non-technical description of the project, which explains the project's significance and importanceCoastal erosion is a problem of national and global importance. As more people live along the shore, it is becoming increasingly vital to forecast how storms and other weather systems can alter the landscapes of coastlines. This RAPID project will collect intensive field data from the Oregon coastline during a period of elevated sea level and El Niño conditions that will make numerical models of beach movement and erosion more accurate. Numerical models of coastal processes are widely used by federal/state government agencies, local planners, and consultancies for a range of engineering and planning applications; accordingly, enhancing the quantitative accuracy of morphological evolution in these models has the potential to improve the quality of many products and services. A technical description of the projectThis RAPID project will implement a beach and dune topographic surveying campaign in the Netarts littoral cell, Oregon to quantify the impacts of extreme sea level anomalies on beach morphology. Hypotheses to be tested are whether 1) the majority of the dune-backed coastline within Oregon's headland-bound littoral cells will experience the "collision regime" of the Sallenger storm impact scale approximately 10-15% more during El Niño than during normal years. Dunes along the coast will also experience the "overwash regime" significantly more than during a typical year; 2) the southern extent of littoral cells will experience significant erosion and will be more impacted than the north. Gradients in longshore sediment transport will erode on the order of tens of thousands of cubic meters of sand from the southern ends of littoral cells with that sediment being transported both offshore and northward; and 3) Cross shore sediment supply to the beach following storms and at the end of the anomalous period, initiating the recovery phase for the dunes, will be highly spatially variable based on beach morphometrics, but will be strongly correlated to local gradients in longshore sediment transport. Although there is a general sense of how sea level anomalies and El Niño events impact beaches and dunes along the U.S. West Coast, there are few data sets available and the rates and mechanisms of onshore feeding of sediment are poorly documented. This research will quantify the sediment volume lost from the beach during each storm event and subsequently track the spatial and temporal trends in beach recovery throughout the winter and spring.