Evaluation of Coastal Response to Sea-Level Rise from Holocene Stratigraphic Records: A Step Towards Coastal Forecasting

从全新世地层记录评估海岸对海平面上升的响应：迈向海岸预测的一步Antonio Rodriguez和John B。安德森政府间气候变化专门委员会的共识是，由于全球变暖，海平面上升的速度将在未来加快。 海平面上升速度加快将对世界海岸产生若干不利影响，例如湿地丧失和海岸侵蚀加速，但这些变化的程度仍然无法预测。 应通过审查全新世期间海岸变化的地质记录，改进对未来海平面上升率的海岸反应预测，当时海平面上升的速度与未来预测的速度相似。 海岸对海平面上升的反应最好的记录是在下切河谷中发现的。 将检查和比较三个墨西哥湾海湾（特别是移动的湾、加尔维斯顿湾和科珀斯克里斯蒂湾）的下切河谷填充物。 这些海湾位于不同的气候带内，并由形态上不同的河流系统供水。 从所有三个海湾的初步数据已经确定了一个情节的快速海岸线撤退发生在全新世。 在加尔维斯顿湾，这一事件导致河口环境向陆地移动了数十公里，屏障岸线被淹没并搁浅在大陆架上作为银行（希尔德银行）。 该假设是，在海岸沉降和河流流量的速度的变化是不是观察到的海岸后退事件的原因。 通过收集每个海湾的高分辨率地震、沉积物岩心（长达30米）和古生物学数据，以确定洪水面，将对这一假设进行检验。 从植物碎片和铰接软体动物采样在许多位置以上和以下的整个倾角轴的洪水面在每个海湾内的放射性碳年龄的日期将限制事件的时间和沿海变化的速度。 海湾之间洪泛面的相关性，加上沉积和压实速率的计算以及从底部泥炭沉积物生成海平面曲线，将有助于区分气候变化和海平面事件的沉降。 这项工作将有助于量化沿海对强迫机制的反应，并将创建适合于通过后报测试沿海预报模型的数据集。

AbstractEvaluation of Coastal Response to Sea-Level Rise from Holocene Stratigraphic Records: A Step Towards Coastal ForecastingAntonio Rodriguez and John B. Anderson The consensus of the Intergovernmental Panel on Climate Change was that the rate of sea-level rise will increase in the future as a result of global warming. An increased rate of sea-level rise will have a number of adverse impacts on world coasts, such as wetlands loss and accelerated coastal erosion, but the magnitude of these changes remains unpredictable. Predictions of coastal response to future sea-level rise rates should be improved by examining the geological record of coastal change during the Holocene, when sea level was rising at rates similar to future predictions. The best records of coastal response to rising sea level are found in incised fluvial valleys. Incised valley fill from three Gulf of Mexico bays, specifically Mobile Bay, Galveston Bay, and Corpus Christi Bay will be examined and compared. These bays are located within differing climatic belts, and are fed by morphologically distinct fluvial systems. Preliminary data from all three bays has identified an episode of rapid shoreline retreat that occurred during the Holocene. In Galveston Bay, this event resulted in the estuarine environment being shifted tens of kilometers landward and the barrier shoreline being submerged and stranded on the continental shelf as a bank (Heald Bank). The hypothesis is that variations in the rate of coastal subsidence and river discharge were not the cause of the observed coastal backstepping events. The hypothesis will by tested by collecting high-resolution seismic, sediment core (up to 30 m-long cores), and paleontologic data from each bay to identify flooding surfaces. Radiocarbon age dates obtained from plant fragments and articulated mollusks sampled at numerous locations above and below the entire dip axis of flooding surfaces within each bay will constrain the timing of the events and the rates of coastal change. Correlation of flooding surfaces between the bays, together with calculations of sedimentation and compaction rates and the generation of sea-level curves from basal peat deposits, will aid in distinguishing variations in climate and subsidence from sea-level events. This work will help quantify coastal response to forcing mechanisms, and will create data sets appropriate for testing coastal forecasting models by hindcasting.