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

河流三角洲的各种形状被认为主要取决于下游过程，如海洋盆地的波浪和潮汐力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提出了一项理论和实地研究，研究泥沙负荷和泥沙类型以及源区地形如何控制三角洲。S台地形态与内部地层学。利用Delft3D（一种基于形态动力学物理的模拟三维流体流动和泥沙输运的模型）进行的一系列数值实验，将通过改变每年一次洪水的母河的泥沙通量和粒度分布，扩展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。数值预测将与代表建模结果终端成员的现代三角洲的岩心、连续航空摄影、测深和探地雷达数据集进行比较。候选三角洲包括路易斯安那州和萨斯喀彻温省的蜡湖三角洲和苔藓三角洲，加利福尼亚湾西海岸的El Coyote扇三角洲，现有的数据将通过有限的实地工作来补充，佛罗里达州阿巴拉契科拉附近的更新世陆架边缘三角洲，以及犹他州白垩纪铁龙三角洲和豹舌三角洲等古代三角洲。更好地理解和预测三角洲台地和地层学，可以提高我们在全球和局部海平面上升导致的泥沙进给量和类型变化以及可容纳空间创造速度变化的情况下预测海岸线演变的能力。本研究产生的更广泛影响：牵头PI？他与国家地球表面动力学中心的合作将确保这项工作将有助于恢复密西西比三角洲和扭转土地流失趋势所需的科学研究。这项工作也将成为两名研究生的论文题目和两名本科生的论文资助。所有学生都将受益于接触到一个需要整合地貌学、泥沙运输、水动力学和形态动力学建模的问题。

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.