Channel Switching in Fluvio-Deltaic Systems Draining Land Ice; Clyde River, Baffin-Island as a Type-Location

北极海岸带沉积物供应模型预测，由于气候变暖，沉积物流入量将显著增加。 然而，估计仍然是不确定的，因为：1）数值气候-沉积模型没有模拟罕见的高能事件; 2）河流输送系统的横向变化，即，由于气候变暖引起的河道转换和河漫滩沉积增加而导致的更高的排放量以前没有被模拟。 预计这些模型的局限性对地形相对平缓的流域具有最重要的影响，例如，内陆陆地冰盖的河流。 该项目提议改进气候驱动的水文模型HydroTrend，以纳入低频高强度事件，如冰川湖溃决。HydroTrend输出的模拟高分辨率流量和输沙量序列可以直接输入我们的三维沉积模型SedFlux 3D。 以前的理论实验表明，增加泥沙供应是导致通道开关的主导因素，并对河流-三角洲系统进入近海的渗透率具有重要意义。 这两个概念将测试对现场数据的克莱德河，东巴芬岛，排水的巴恩斯冰帽。 气象站提供的区域水文和气象数据与航空照片和卫星图像判读相结合，为水文趋势提供了所需的投入。 将对克莱德河的粒度趋势、河漫滩沉积和河道尺寸的实地测量结果与SedFlux 3D的输出结果进行比较。 北极河流系统对气候变化的反应是气候变化假设情景的一个基本未知的组成部分。改进后的模型将允许对高能事件的影响进行系统测试，否则很难量化，因为高北极的测量记录相对较短。此外，该模型将加强对流入海洋的沉积物通量的预测。 从更广泛的角度来看，该项目为冰川学模型和三维沉积模型的整合开辟了新的视野。在国家科学基金会主办的关于"社区沉积模型战略“的会议上，冰川学和沉积模型之间的联系被认为是能够而且应该取得重要科学进展的领域之一。克莱德河形成了一个独特的现代环境，但在冰川条件下，它是整个美国东缘的代表性“典型位置”。现今近海地层结构在很大程度上取决于末次冰期的沉积作用。 改进的浅海岸带地层结构模型将有助于海岸管理。

ABSTRACT OPP-0240823OvereemModels of sediment supply to the Arctic coastal zones predict pronounced increase of sediment influx as a result of a warming climate. Yet estimates are still uncertain, because: 1) the numerical climate-sedimentary models do not model rare high-energy events; 2) lateral changes in the fluvial transporting system, i.e., higher discharges due to climatic warming inducing channel switches and increased floodplain sedimentation, have previously not been modeled. It is expected that these model limitations have the most important implications for drainage basins with relatively gentle topography, for example, rivers draining a hinterland land-ice cap. This project proposes to advance the climate-driven hydrological model, HydroTrend, to incorporate low-frequency high-magnitude events, such as glacial lake outbursts. Simulated high-resolution discharge and sediment load series, which is output from HydroTrend, can directly be fed into our three-dimensional sedimentary model, SedFlux3D. Previous theoretical experiments show that increased sediment supply is a dominant factor in causing channel switches and of significant importance for progradation rates of fluvio-deltaic systems into the offshore. These two concepts will be tested against field data of Clyde River, East Baffin Island, which drains the Barnes Ice Cap. Regional hydrological and meteorological data from weather stations in combination with aerial photograph and satellite image interpretation yields the required input for HydroTrend. Field measurements of grain size trends, floodplain sedimentation, and channel dimensions of the Clyde River will be compared with output of SedFlux3D.Intellectual merit and broader impact. The response of Arctic river systems to climate change is a largely unknown component of climate change scenarios. The improved models will allow systematic testing of the impact of high-energy events, which is otherwise hard to quantify, because of the relatively short measurement records in the High Arctic. Furthermore, the model will enhance predictions of sediment flux into the ocean. In a wider perspective, the project opens up new horizons to the integration of glaciological models and three dimensional sedimentary models. At the NSF sponsored meeting on 'A Strategy for a Community Sediment Model', the link between glaciological and sedimentary models was recognized as one of the areas where important scientific progress can and shall be made. The Clyde River forms a unique present-day setting, but is a representative 'type-location' for the entire U.S. east margin under glacial conditions. The present offshore stratigraphic architecture depends heavily on the sedimentary processes during the last glacial period. Improved models of the stratigraphic architecture of the shallow coastal zone will facilitate coastal management.