Alluvial landscape evolution in response to deglaciation. A case study from the Thompson River, south-central British Columbia.

冲积地貌演化响应冰消作用。

• 批准号: NE/X007081/1
• 负责人: David Thomas
• 金额: $ 1.16万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX007081%2F1
• 关键词: Alluvial; landscape; evolution; response; deglaciation.

EPSRC : Samuel Woor : EP/L016036/1The amount of water (discharge) and sediment entering a river control the nature of its flow. Discharge may vary due to hydro-climatic changes, transmitted to river systems either directly via changes in rainfall amounts and intensities, or indirectly via changes in the size of glaciers or factors influencing runoff like vegetation cover. The amount of sediment entering a river may vary due to environmental responses to climatic change, such as increasing or decreasing vegetation. Due to this sensitivity to changing environmental conditions, river systems and the sediments stored within them can act as significant records of past environmental and climatic change over long periods of time (tens of thousands of years in many cases).Globally, landscapes are already undergoing significant changes as a result of climate change, such as changes in precipitation, vegetation cover, or the disappearance of glaciers. Such changes are likely to result in changes to discharge and sediment inputs into river systems, posing numerous risks to society and industry within their catchments. Mid-latitude regions undergoing rapid glacial retreat, like western Canada, are likely to be especially vulnerable to climate change with resulting down-system flooding, soil erosion and changes in channel morphology. Recent river flooding has highlighted the risks posed to British Columbia specifically, with the extreme flooding events of November 2021 being estimated as the most expensive disaster in the region's history. As such, understanding how river systems adjust to changes in their fundamental controls is increasingly important and requires more studies of their long-term variability. Models can also be used to help answer these questions. They mathematically relate amounts of sediment and water input to expected changes in the morphometric properties of rivers, such as the steepness of channels, which is useful for predicting future change given changes in these driving factors. However, a lack of field studies of long term changes in river systems from different environmental contexts limits the extent to which the general relationships expected by numerical models can be widely applied. The Thompson River, south-central British Columbia, provides an excellent opportunity to develop a long-term record of river evolution in response to changing discharge and sediment fluxes which can be quantitatively reconstructed. This is because the area has experienced significant climatic and environmental change over the last c.15,000 years following the retreat of ice sheets at the end of the last Ice Age. This project will use a variety of field and laboratory methods to first date the age of sediments sampled from the Thompson River and then estimate past discharge and sediment flux amounts as well as past river morphometry. Relationships between these data will then be compared to recent numerical modelling studies to test their applicability to the Thompson River and evaluate how continued climatic change may influence the landscape into the future. It will also provide new data on the age and long-term evolution of the landscapes of British Columbia, a region for which there are very few studies of past environmental changes, with potential wider relevance to historical and archaeological understandings of the region.

进入河流的水量（排水量）和泥沙量控制着河流的流动性质。流量可能因水文气候变化而变化，通过降雨量和强度的变化直接传递到河流系统，或通过冰川大小的变化或植被覆盖等影响径流的因素的变化间接传递到河流系统。由于环境对气候变化的反应，例如植被的增加或减少，进入河流的沉积物数量可能会发生变化。由于这种对环境条件变化的敏感性，河流系统和其中储存的沉积物可以作为过去很长一段时间（在许多情况下是数万年）的环境和气候变化的重要记录。在全球范围内，由于气候变化，景观已经发生了重大变化，例如降水、植被覆盖或冰川消失的变化。这种变化很可能导致河流系统的排放和沉积物输入发生变化，对其集水区内的社会和工业构成许多风险。正在经历冰川快速退缩的中纬度地区，如加拿大西部，可能特别容易受到气候变化的影响，从而导致下系统洪水、土壤侵蚀和河道形态的变化。最近的河流洪水特别突出了不列颠哥伦比亚省面临的风险，2021年11月的极端洪水事件被估计为该地区历史上最昂贵的灾难。因此，了解河流系统如何适应其基本控制的变化变得越来越重要，需要对其长期变异性进行更多的研究。模型也可以用来帮助回答这些问题。他们用数学方法将泥沙和水的输入量与河流形态特征的预期变化联系起来，比如河道的陡峭度，这对于预测这些驱动因素的未来变化很有用。然而，缺乏对不同环境背景下河流系统长期变化的实地研究，限制了数值模型所预期的一般关系能够广泛应用的程度。不列颠哥伦比亚省中南部的汤普森河提供了一个很好的机会，可以开发一个长期的河流演变记录，以响应变化的流量和沉积物通量，可以定量重建。这是因为在过去的大约15000年里，随着上一个冰河时代结束时冰盖的退缩，该地区经历了重大的气候和环境变化。该项目将使用各种实地和实验室方法，首先确定从汤普森河采样的沉积物的年龄，然后估计过去的流量和沉积物通量以及过去的河流形态测定。然后将这些数据之间的关系与最近的数值模拟研究进行比较，以测试它们对汤普森河的适用性，并评估持续的气候变化如何影响未来的景观。它还将提供有关不列颠哥伦比亚省景观的年龄和长期演变的新数据，该地区对过去环境变化的研究很少，可能与该地区的历史和考古理解具有更广泛的相关性。