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Morphodynamics and sedimentology of the tidally-influenced fluvial zone (TIFZ)

受潮汐影响的河流带（TIFZ）的形态动力学和沉积学

基本信息

批准号：
NE/H007954/1
负责人：
Philip Ashworth
金额：
$ 37.76万
依托单位：
University of Brighton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH007954%2F1
关键词：
Morphodynamics sedimentology tidally influenced fluvial

项目摘要

All rivers across the globe that exit to the ocean contain a zone, which can be 100s of kilometres long, which is transitional between river and tidal environments (termed here the Tidally-Influenced Fluvial Zone, or TIFZ). This zone is one of the most complex environments on the surface of the Earth because it is an area where both river flow and tidal currents are significant, and these competing forces vary daily, seasonally and annually. These regions are important to mankind and form some of the areas of highest population density: they are strategically important in the present day because these zones are at the interface of competing demands for shipping, aquaculture, land reclamation and nature conservation. Thus in order to better maintain, manage and protect these fragile zones, we must understand how and why these regions change and what factors control such change. Additionally, the sediments of ancient TIFZs may contain significant volumes of hydrocarbons which are increasingly the target for many energy companies. For example, the Athabasca oil sands form the largest petroleum deposit on Earth and these bitumen tars are locked up with ancient TIFZ sediments. Understanding the internal nature of such TIFZ sediments is thus of paramount importance when attempting to extract the maximum quantity of oil (or gas) from such ancient hydrocarbon reservoirs - we need to know what controls the geometry and internal characteristics of these reservoirs, and thus better plan efficient and maximal hydrocarbon extraction strategies. Thus all of these interests in both modern and ancient TIFZ environments depend on a detailed knowledge of the fluid flows in these areas, how such flows transport their sediment and critically how the form (or morphology) of these environments changes through time. However, due to the extraordinary challenges of working in such a complex and dynamic environment, few high-resolution, spatially-representative, field datasets exist and remarkably little work has been undertaken on the diagnostic internal sedimentary structure of such TIFZ deposits. Additionally, whilst there has been progress on the mathematical modelling of estuarine flow and sediment transport, these models remain largely untested. There is therefore a pressing need to link the processes and deposits of the TIFZ through an integrated study of their flow, morphology and sediment movement to quantify the key processes and how these are represented within the subsurface sedimentary record. This proposal outlines an integrated field and mathematical modelling study that seeks to achieve a step-change in our understanding of the TIFZ, using the very latest techniques in field survey and mathematical modelling. These techniques will yield unrivalled high-resolution datasets of bathymetry, flow, sediment transport and sedimentary structure that will then be used to construct and validate new numerical models of the TIFZ. This will ultimately allow evaluation of key unknowns with respect to the TIFZ, such as how such environments evolve under changing scenarios of tidal and fluvial contributions associated with sea-level change, and whether it is possible to differentiate between 'fluvial' and 'tidally' influenced deposits. Such results will transform our understanding of how such TIFZ zones behave in modern environments and critically how these changes may be recognized within ancient sedimentary successions.

全球所有流入海洋的河流都有一个区域，这个区域可能长达100公里，是河流和潮汐环境之间的过渡地带（这里称为潮汐影响河流带，简称TIFZ）。这个区域是地球表面最复杂的环境之一，因为它是一个河流流量和潮汐流都很重要的地区，这些相互竞争的力量每天、季节和每年都在变化。这些地区对人类很重要，形成了一些人口密度最高的地区：它们在当今具有重要的战略意义，因为这些地区处于航运、水产养殖、土地复垦和自然保护等竞争需求的交汇处。因此，为了更好地维持、管理和保护这些脆弱区域，我们必须了解这些区域如何以及为什么发生变化，以及哪些因素控制了这种变化。此外，古老的tifz沉积物可能含有大量的碳氢化合物，这些碳氢化合物越来越多地成为许多能源公司的目标。例如，阿萨巴斯卡油砂形成了地球上最大的石油矿床，这些沥青焦油被锁在古老的TIFZ沉积物中。因此，当试图从这些古老的油气藏中提取最大数量的石油（或天然气）时，了解这些TIFZ沉积物的内部性质是至关重要的——我们需要知道是什么控制了这些油气藏的几何形状和内部特征，从而更好地规划有效和最大限度的油气提取策略。因此，所有这些对现代和古代TIFZ环境的兴趣都取决于对这些地区流体流动的详细了解，这些流动如何运输沉积物，以及这些环境的形式（或形态）如何随时间变化。然而，由于在如此复杂和动态的环境中工作所面临的巨大挑战，目前很少有高分辨率、具有空间代表性的现场数据集，而且对TIFZ矿床的内部沉积结构进行诊断的工作也非常少。此外，虽然在河口水流和泥沙运输的数学模型方面取得了进展，但这些模型在很大程度上仍未经检验。因此，迫切需要通过对TIFZ的流动、形态和沉积物运动的综合研究，将TIFZ的过程和沉积物联系起来，以量化关键过程，以及这些过程如何在地下沉积记录中表现出来。该建议概述了一项综合的实地和数学模型研究，旨在利用最新的实地调查和数学模型技术，逐步改变我们对TIFZ的理解。这些技术将产生无与伦比的高分辨率数据集，包括水深测量、水流、沉积物输送和沉积结构，然后将用于构建和验证TIFZ的新数值模型。这最终将有助于评估TIFZ的关键未知因素，例如，在与海平面变化相关的潮汐和河流贡献的变化情景下，这些环境是如何演变的，以及是否有可能区分受“河流”和“潮汐”影响的沉积物。这些结果将改变我们对TIFZ带在现代环境中如何表现的理解，以及如何在古代沉积序列中识别这些变化。