Influence of Ice Processes on fluvial sediment transport

拟议的研究将测量和模拟河冰过程对泥沙输运的影响。 由于气候变化、土地利用变化和/或河流发展，预测河流形态和生境的变化需要沉积物输运的知识。 然而，很少有人知道在河冰存在的泥沙输运。 特别是，很少有研究评估了春季河冰崩解期间的泥沙输运，而此时泥沙输运可能最为激烈。 冬季冰覆盖加拿大的河流，但缺乏了解的冰过程对泥沙输运的影响，阻碍了加拿大河流的形态和栖息地的变化预测能力。拟议研究的案例研究将是下纳尔逊河（LNR）。 该研究的支持组织是马尼托巴水电和哈奇有限公司，自2005年以来一直在测量LNR的泥沙输运（悬移质和推移质），但几乎没有在冬季进行测量，因为冰盖和冰过程会影响泥沙输运。 拟议的工作包括两年的数据收集和随后开发改进的数值模型。 在第一年，声学多普勒海流剖面仪（ADCP）的速度剖面和悬浮泥沙样品将通过在可行的LNR位置的冰盖上切割的孔进行采集。 ADCP声学后向散射强度将与测得的悬浮泥沙浓度相关，从而为ADCP测量悬浮泥沙浓度开发本地校准曲线。 在第二年，在两条河流的位置，将采取连续的时间序列上看ADCP和冰剖面测量，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迁移，预计冰破裂期间的沉积物迁移最为剧烈。 这些数据集将用于进一步开发和验证河流冰和沉积物输运过程的物理模型和数据驱动模型。 由此产生的模型将是有价值的冰在整个加拿大的河流泥沙输运过程的影响进行评估。

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.