Collaborative Research: Catchments and Coastlines--The Influence of Sediment Load and Type on Delta Morphodynamics and Deposits

各种不同形状的河流三角洲被认为主要取决于下游过程，如洋盆的波浪和潮汐功率以及河流的能量通量，但最近的工作表明，上游控制，如负荷和沉积物类型(即粘性沉积物与非粘性沉积物)也可能是控制三角洲形态的主要因素。PI提出了一项关于沉积物负荷和类型，从而源地形如何控制三角洲-S平面地貌和内部地层的理论和现场研究。Delft3D是一种基于地形动力学的物理模型，模拟了三维流体流动和泥沙运动，通过改变一条每年一次洪水作用下母河的泥沙通量和粒度分布，扩展了早期工作的参数空间。最后一组实验将包括波浪和潮汐的影响。数值预测将与岩心、连续航空摄影、水深测量和来自现代三角洲的探地雷达数据集进行比较，这些数据代表了模拟结果的最终成员。候选三角洲包括路易斯安那州和萨斯喀彻温省的蜡湖和苔藓三角洲，以及加利福尼亚州海湾西海岸的El Coyote扇三角洲，那里已有的数据将得到有限的实地考察的补充，更新世陆架边缘三角洲，如佛罗里达州阿帕拉契科拉外海，以及古三角洲，如犹他州的白垩纪费龙和黑豹舌三角洲。更好地了解和预测三角洲平面和地层学的能力可以提高我们预测海岸线演变的能力，以应对由于全球和当地海平面上升而引起的沉积物供给量和类型的变化以及可容纳空间的创造速度的变化。这项研究产生了更广泛的影响：皮埃尔？S带头参与国家地球表面动力学中心的工作，将确保这项工作将有助于恢复密西西比河三角洲所需的科学，并扭转土地流失的趋势。这项工作也将是两名研究生的毕业论文选题和资助，以及两名本科生的论文资助。所有学生都将受益于一个需要综合地貌学、泥沙输运、水动力学和地貌动力学建模的问题。

The various shapes of river deltas were thought to be dependent mainly upon downstream processes, such as the wave- and tidal-power of the ocean basin and the energy flux of the river, but recent work has suggested that upstream controls, such as load and sediment type (i.e. cohesive vs. noncohesive sediment) may also be a major factor controlling delta morphology. The PIs propose a theoretical and field study of how sediment load and type,and thus source terrain, control a delta?s planform morphology and internal stratigraphy. A series of numerical experiments using Delft3D, a morphodynamic physics-based model simulating 3D fluid flow and sediment transport, will extend the parameter space of earlier work by varying sediment fluxes and grain size distributions of a parent river subject to one flood wave per year.A final set of experiments will include the effects of wave and tides. The numerical predictions will be compared to cores, serial aerial photography, bathymetry, and ground penetrating radar datasets from modern deltas representing end-members of the modeling results. Candidate deltas include Wax Lake and Mossy deltas of Louisiana and Saskatchewan, and El Coyote fan delta on the western coast of the Gulf of California, where already existing data will be supplemented by limited fieldwork, Pleistocene shelf-edge deltas such as off Apalachicola, FL, and ancient deltas such as the Cretaceous Ferron and Panther Tongue deltas of Utah. A better understanding and predictive capability of delta planform and stratigraphy could improve our ability to predict coastline evolution in the face of changes in sediment feed volume and type and changes in the rate of creation of accommodation space due to global and local sea level rise. Broader Impacts Resulting from This Study: The lead PI?s involvement with the National Center for Earth-surface Dynamics will ensure that this work will contribute to the science needed to restore the Mississippi delta and reverse the trend of land loss. This work will also be the dissertation topic and financial support for two graduate students and theses for two undergraduate students. All students will benefit from exposure to a problem requiring the integration of geomorphology, sediment transport, hydrodynamics, and morphodynamic modeling.