Characterising groundwater-dominated lowland catchments: the UK Lowland Catchment Research Programme (LOCAR)
Characterising groundwater-dominated lowland catchments: the UK Lowland Catchment Research Programme (LOCAR)
复制标题
描述以地下水为主的低地流域的特征：英国低地流域研究计划 (LOCAR)
DOI：
10.5194/hess-11-108-2007
复制
发表时间：
2007
影响因子：
6.3
通讯作者：
A. Binley
中科院分区：
文献类型：
--
作者：
H. Wheater;D. Peach;A. Binley
本文报道了英国一项重大举措，旨在解决对地下水为主的低地流域的水文生态响应的理解不足。介绍了该国家计划的范围和目标，并重点关注三组研究盆地之一——英格兰南部泰晤士河的支流庞/兰伯恩白垩流域。这项研究的动机是需要支持对河流系统的综合管理，这些系统具有较高的生态价值，并受到地下水抽取供水、扩散污染、土地利用和气候变化等压力的影响。提供了研究计划的概述以及有关这些流域水文功能的一些当前研究结果的重点。尽管白垩岩作为英国主要含水层很重要，但人们对水和溶质的地下运动的了解却很匮乏。双孔隙非饱和区中的溶质输运取决于难以观察的裂缝/基体相互作用；目前的实验和模型研究支持基质流的主导地位，并表明数十年养分负荷的时间历史的缓慢迁移正在发生。地下水流十分复杂；流域随季节变化且界限不明确，喀斯特特征在当地很重要。正在使用基于实验钻孔阵列的天然和人工地球化学示踪剂来研究地下水流动路径；溪流-含水层相互作用研究结合了地球物理学、钻孔阵列地球化学以及溪流和溶质的纵向剖面。与地质控制和岩溶特征相关的局部地下流入的复杂情况以及河道下方显着的纵向地下水流正在出现。讨论了管理影响。控制营养物质表面应用的策略预计在几十年内对地下水质量影响很小，并且已经开发了用于决策支持的新建模工具来代表这些影响。传统的建模方法受到地下系统复杂性的限制；集水区很难界定，因此追踪污染物到达河流受体的路径也存在问题。传统的分布式地下水模型难以捕捉地下水系统的关键方面。这就提出了重要的问题，涉及对常规用于决策支持的模型的信心以及建立在安全的科学基础上的流域管理所需的知识水平。
This paper reports on a major UK initiative to address deficiencies in understanding the hydro-ecological response of groundwater-dominated lowland catchments. The scope and objectives of this national programme are introduced and focus on one of three sets of research basins – the Pang/Lambourn Chalk catchments, tributaries of the river Thames in southern England. The motivation for the research is the need to support integrated management of river systems that have high ecological value and are subject to pressures that include groundwater abstraction for water supply, diffuse pollution, and land use and climate change. An overview of the research programme is provided together with highlights of some current research findings concerning the hydrological functioning of these catchments. Despite the importance of the Chalk as a major UK aquifer, knowledge of the subsurface movement of water and solutes is poor. Solute transport in the dual porosity unsaturated zone depends on fracture/matrix interactions that are difficult to observe; current experimental and modelling research supports the predominance of matrix flow and suggests that slow migration of a time-history of decades of nutrient loading is occurring. Groundwater flows are complex; catchments vary seasonally and are ill-defined and karst features are locally important. Groundwater flow pathways are being investigated using natural and artificial geochemical tracers based on experimental borehole arrays; stream-aquifer interaction research is using a combination of geophysics, borehole array geochemistry and longitudinal profiles of stream flow and solutes. A complex picture of localised subsurface inflows, linked to geological controls and karst features, and significant longitudinal groundwater flow below the river channel is emerging. Management implications are discussed. Strategies to control surface application of nutrients are expected to have little effect on groundwater quality for several decades, and new modelling tools for decision support have been developed to represent these effects. Conventional modelling approaches are limited by the complexities of the subsurface system; catchment areas are difficult to define, hence tracking pollutant pathways to stream receptors is also problematic. Conventional distributed groundwater models have difficulty in capturing key aspects of the groundwater system. This raises important questions concerning the confidence that can be placed in models as routinely used for decision support and the level of knowledge required for catchment management to be placed on a secure scientific foundation.