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.

EPSRC：塞缪尔·沃尔（Samuel Woor）：EP/L016036/1水（排放）和沉积物进入河流控制其流量的性质。出院可能会因降雨量和强度的变化而直接传输到河流系统，或通过影响植被覆盖的径流的因素而间接地传播到河流系统。由于环境对气候变化的反应，例如增加或减少植被，进入河流的沉积物量可能会有所不同。由于对不断变化的环境条件的敏感性，河流系统和其中存储的沉积物可以充当长时间的过去环境和气候变化的重大记录（在许多情况下，数以万年的时间）。景观已经发生了重大变化，因为气候变化，例如降水量，蔬菜覆盖，植被覆盖或消失。这样的变化可能会导致出院和沉积物输入到河流系统中，从而在其集水区内给社会和工业带来了许多风险。像加拿大西部这样的快速冰川静修处的中纬度地区可能特别容易受到气候变化的影响，导致下降系统洪水，土壤侵蚀和渠道形态的变化。最近的河流洪水强调了不列颠哥伦比亚省的风险，特别是2021年11月的极端洪水事件估计是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。它们在数学上将沉积物和水的输入与河流形态计量学特性的预期变化（例如通道的陡度）联系起来，这对于预测这些驱动因素的变化对于预测未来的变化很有用。但是，缺乏从不同环境环境中河流系统中长期变化的现场研究限制了可以广泛应用数值模型期望的一般关系的程度。不列颠哥伦比亚省中南部的汤普森河（Thompson River）提供了一个绝佳的机会，以发展河流进化的长期记录，以响应变化的排放和沉积物通量，这些通量可以定量重建。这是因为该地区在最后一个冰河时代结束后的冰盖撤退后的最后15,000年中经历了重大的气候和环境变化。该项目将使用各种野外和实验室方法，以约会汤普森河（Thompson River）采样的沉积物年龄，然后估算过去的排放和沉积物通量量以及过去的河流形态计量学。然后将这些数据之间的关系与最近的数值建模研究进行比较，以测试其对汤普森河的适用性，并评估持续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，该地区对过去的环境变化几乎没有研究，并且与该地区的历史和考古学理解有关。