Scale-dependent lithological variations and their control on water resources and flooding in the Eden Valley

伊甸谷规模相关的岩性变化及其对水资源和洪水的控制

• 批准号: 2128217
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2128217
• 关键词: Scale; dependent; lithological; variations; their

The Eden Valley (Cumbria, UK) has been involved in two of the worst flooding events this century. It is also an important local water resource. The River Eden courses over a complex geological terrain. Rising on the volcanic rocks of the Lake District, it flows over the Carboniferous limestones of the north Pennines and on to the Permo-Triassic sandstones in the Vale of Eden, a largely rural area where agriculture and tourism are the main sources of income. Comprising the Penrith Sandstone Formation and the Sherwood Sandstone Group, the Permo-Triassic sandstones lie in a fault-bounded basin (approximately 50 km long and 5-15 km wide) and are the region's primary aquifers. Their structure, however, is highly complex due to the heterogeneous nature of the rocks, due to primary and secondary lithological variation. Consequently, an improved understanding of this complexity and its influence on water flow is needed to manage the aquifer's potential as a water resource, and understanding its role in flooding. A key part of this is the role of low permeability features, which are highly scale-dependent. These include the occurrence of thick silicified (depositions of silica) layers. Individual units are relatively small but can form discontinuous bands up to tens of metres thick that extend over several kilometres (Fox, 2016) and affect groundwater recharge and water level dynamics (Lafare et. al., 2016). Another important feature, the Armathwaite dyke, an igneous intrusion that crosses the entire Eden valley, appears to act as a major barrier to groundwater flow on a variety of scales. With increased awareness of this scale dependent complexity, there is a need to incorporate this knowledge into a new hydrogeological conceptual model of the region that can be tested using groundwater flow models, which are able to reproduce groundwater level and surface water flow responses and provide new insights for the management of this geological system and its role in the wider Eden valley. A key aim of the research will be to demonstrate the importance of heterogeneity at a variety of scales in controlling flow in Permo-Triassic sandstones. Not only will this improve our understanding of the relationship between scale dependent geological features and groundwater response, due to their widespread occurrence elsewhere in the UK and internationally, this work is highly transferrible. The basic outline of the project will be to:- Collate available geological data and, working with BGS geologists, enhance a geological model to develop hydrogeological conceptual models;- Encapsulate the conceptual understanding into regional and local scale numerical models of groundwater flow that simulate flow processes and observation borehole hydrograph response;- Examine how this scale-dependent heterogeneity controls groundwater flow and influences water resources and flooding in the catchment ReferencesFox K (2016). Development of a numerical groundwater model of the Eden Valley, using conceptual understanding derived from seasonal trend decomposition. MSc thesis, Imperial College London.Lafare AEA, Peach DW & Hughes AG (2016) Use of seasonal trend decomposition to understand groundwater behaviour in the Permo-Triassic Sandstone aquifer, Eden Valley, UK. Hydrogeology Journal. 24 (1), 141-158.

伊登谷（英国坎布里亚郡）已经卷入了本世纪最严重的两次洪水事件。也是当地重要的水资源。伊甸河流经复杂的地质地形。它发源于湖区的火山岩，流经北奔宁山脉的石炭纪石灰岩和伊甸谷的二叠纪-三叠纪砂岩，伊甸谷是一个主要的农村地区，农业和旅游业是主要的收入来源。二叠纪-三叠纪砂岩包括Penrith砂岩组和舍伍德砂岩组，位于一个有断层的盆地（约50公里长，5-15公里宽）中，是该地区的主要含水层。然而，由于原生和次生岩性变化，岩石的异质性，其结构非常复杂。因此，需要更好地了解这种复杂性及其对水流的影响，以管理含水层作为水资源的潜力，并了解其在洪水中的作用。其中一个关键部分是低渗透率特征的作用，这是高度依赖于规模的。这些包括厚硅化（二氧化硅沉积）层的出现。单个单元相对较小，但可形成长达数十米厚的不连续带，延伸数公里（Fox，2016年），并影响地下水补给和水位动态（Lafare et.例如，2016年）。另一个重要的特征是阿玛斯韦特堤坝，一个贯穿整个伊登谷的火成岩侵入体，似乎是各种规模地下水流动的主要障碍。随着人们对这种规模依赖的复杂性的认识的提高，有必要将这种知识纳入一个新的水文地质概念模型的区域，可以使用地下水流模型进行测试，这是能够重现地下水位和地表水流量的反应，并提供新的见解，这个地质系统的管理及其在更广泛的伊登谷的作用。该研究的一个主要目的是证明非均质性在控制二叠-三叠系砂岩流动的各种尺度上的重要性。这不仅将提高我们对尺度相关的地质特征和地下水响应之间关系的理解，由于它们在英国和国际上的广泛存在，这项工作是高度可转移的。该项目的基本大纲将是：-整理现有的地质数据，并与英国地质调查局的地质学家合作，加强地质模型，以开发水文地质概念模型;-将概念理解纳入区域和地方规模的地下水流数值模型，模拟水流过程和观测钻孔水文线响应;- 研究这种尺度依赖的异质性如何控制地下水流并影响集水区的水资源和洪水2016年）。利用从季节趋势分解得出的概念性理解，开发伊登谷的地下水数值模型。硕士论文，帝国理工学院伦敦。Lafare AEA，Peach DW & Hughes AG（2016）使用季节趋势分解来了解英国伊登谷二叠纪-三叠纪砂岩含水层中的地下水行为。水文地质学杂志. 24（1），141-158。