Influence of Ice Processes on fluvial sediment transport

拟议的研究将测量和模拟河流冰过程对沉积物运输的影响。由于气候变化、土地利用变化和/或河流发展，预测河流形态和栖息地的变化需要了解沉积物的迁移。然而，人们对河冰存在时的沉积物运输知之甚少。特别是，很少有研究评估了河流冰春季崩解期间的泥沙输送，而此时泥沙输送可能最为剧烈。冬季冰覆盖了大多数加拿大河流，但缺乏对冰过程对沉积物运输影响的了解阻碍了预测加拿大河流形态和栖息地变化的能力。拟议研究的案例研究将是纳尔逊河下游（LNR）。这项研究的支持组织是马尼托巴水电和哈奇有限公司，他们自2005年以来就测量了LNR的沉积物运输（悬浮载荷和河床载荷），但在冬季，当冰盖和冰过程会影响沉积物运输时，几乎没有测量过。拟议的工作包括两年的数据收集和随后改进的数值模型的发展。在第一年，声学多普勒电流剖面仪（ADCP）的速度剖面和悬浮沉积物样本将在可行的LNR位置通过在冰盖上切割的孔进行采集。ADCP声后向散射强度将与测量的悬沙浓度相关，从而建立ADCP测量悬沙浓度的局部校准曲线。在第二年，将在两个河流地点进行连续的时间序列观测ADCP和冰剖面仪测量，包括冰盖形成和破裂的时期。这将是世界上第一次连续测量冰破裂期间的沉积物运输，届时沉积物运输预计将是最强烈的。这些数据集将用于进一步开发和验证基于物理和数据驱动的河流冰和沉积物运输过程模型。由此产生的模型对于评估冰对加拿大各地河流中沉积物输送过程的影响将是有价值的。

The proposed research will measure and model the influence of river ice processes on sediment transport. Knowledge of sediment transport is required for prediction of changes to river morphology and habitat, due to climate change, changes in land-use, and/or river development. However, little is known about sediment transport in the presence of river ice. In particular, very few studies have assessed sediment transport during spring break-up of river ice, when sediment transport can be most intense. Winter ice covers most Canadian rivers, but the lack of understanding of influence of ice processes on sediment transport impedes ability to predict morphological and habitat change in Canadian rivers. The case study for the proposed research will be the Lower Nelson River (LNR). The supporting organizations of the research are Manitoba Hydro and Hatch Ltd, which have measured sediment transport (suspended load and bed load) in the LNR since 2005, but almost no measurements have been taken in winter months when an ice cover and ice processes can affect sediment transport. The proposed work includes two years of data collection and subsequent development of improved numerical models. In the first year Acoustic Doppler Current Profiler (ADCP) velocity profile and suspended sediment samples will be taken through holes cut in the ice-cover at feasible LNR locations. The ADCP acoustic backscatter intensity will be correlated with measured suspended sediment concentrations, such that a local calibration curve is developed for ADCP measurement of suspended sediment concentration. In the second year, at two river locations, continuous time series of up-looking ADCP and ice profiler measurements will be taken, including the periods of ice-cover formation and break-up. These will be the world's first continuous measurements of sediment transport during ice break-up, when sediment transport is expected to be the most intense. These data sets will be used to further develop and validate both physically-based and data-driven models of river ice and sediment transport processes. The resulting models will be valuable for evaluating the influence of ice on sediment transport processes in rivers throughout Canada.