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动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提出了一个理论和实地研究如何沉积物负荷和类型，从而源地形，控制三角洲？的平面形态和内部地层。利用Delft3D数值模拟三维水流和泥沙输移过程，通过改变一年一次洪水波作用下的河流泥沙通量和粒径分布，扩展了前期工作的参数空间，最后一组试验将考虑波浪和潮汐的影响。数值预测将进行比较，核心，连续航空摄影，测深，和地面穿透雷达数据集从现代三角洲代表端元的建模结果。候选三角洲包括路易斯安那州和萨斯喀彻温省的瓦克斯湖和莫西三角洲，以及加州湾西海岸的El Coyote扇三角洲，现有数据将通过有限的野外工作进行补充，更新世陆架边缘三角洲，如佛罗里达州的阿巴拉契科拉，以及古老的三角洲，如犹他州的白垩纪费隆和豹舌三角洲。更好地了解和预测三角洲平面和地层的能力，可以提高我们的能力，预测海岸线的演变，面对沉积物的饲料量和类型的变化，以及由于全球和当地海平面上升的可容纳空间的创造率的变化。本研究产生的更广泛影响：主要研究者？美国国家地球表面动力学中心的参与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。这项工作也将是论文的主题和两名研究生和两名本科生的论文的财政支持。所有的学生将受益于接触到一个问题，需要整合地貌，泥沙输运，流体动力学和形态动力学建模。

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.