Groundwater Recharge within the Agricultural Landscape in a Changing Climate

由于需求增加、土地使用的变化和不确定的气候，淡水资源的可持续管理在全球范围内变得更具挑战性。对水平衡进行量化是流域管理的一个基本组成部分，涉及人类和生态使用的清洁水的供应。区域水平衡的一个主要组成部分是地下水补给，它直接控制地下水库的补给、地表污染物的负荷以及地表水基流的时间和规模。由于地下水补给的高度可变性，很难测量和量化，并且具有高度的不确定性。补给的规模、时间和空间分布受到土地使用、地形环境、地下地质和季节性气候条件的影响，特别是在大多数补给发生的农村地区。随着最大限度地提高作物产量的需求日益增加，目前正在区域范围内实施农业排水管理，包括安装广泛的瓦片排水网络，这对农业景观内的水平衡产生了重大影响。在许多北方国家，地下水资源广泛取自这些农村地区，通常取自补给模式复杂的起伏冰川地形。此外，气候变暖的影响从根本上影响了补给动态，但人们对此知之甚少。拟议的研究计划包括三个主要组成部分。第一个研究瓷砖和浅层地下水流动系统之间的相互作用，在一系列的地下和气候条件下，特别侧重于地下水补给。详细的现场调查和遗留数据集将被整合到先进的数学模型中，以评估各种旨在揭示瓷砖排水沟和浅层地下之间复杂相互作用的方案。在第二部分中，将通过实地调查和先进的模拟工具对低地形环境中极端降水事件后形成的低压集中补给现象的影响进行量化，以调查这些补给现象对含水层和公共供水井脆弱性的潜在影响。最后一部分将把前两节的见解纳入区域分析，分析瓦片排水、洼地集中补给和气候变化对地下水补给的综合影响，特别强调区域水平衡和地下水资源的可持续性。总体结果将有助于水资源管理人员了解在农业排水管理和气候变化的影响下，区域水平衡如何变化，并为未来的水资源管理政策提供信息。

Summary The sustainable management of freshwater resources has become more challenging globally as a result of increasing demand, changes in land use and an uncertain climate. Quantifying the water balance is a fundamental component of watershed management with respect to the availability of clean water for both human and ecological use. A major component of the regional water balance is groundwater recharge, which directly controls the replenishment of subsurface reservoirs, the loading of surface contaminants and the timing and magnitude of surface water base flow. Due to the highly variable nature of groundwater recharge, it has been difficult to measure and quantify and is associated with a high degree of uncertainty. The magnitude, timing and spatial distribution of recharge is influenced by land use, topographic setting, subsurface geology and seasonal climatic conditions, particularly within rural regions where the majority of recharge occurs. With the increasing need to maximize crop production, agricultural drainage management is being implemented at a regional scale, including the installation of extensive tile drainage networks, which significantly influence the water balance within the agricultural landscape. In many northern countries, groundwater resources are extensively drawn from these rural regions, commonly from undulating glacial terrain where recharge patterns are complex. In addition, the impacts of climate warming are fundamentally influencing recharge dynamics in ways that are poorly understood. The proposed research program includes three main components. The first examines the interaction between tiles and the shallow groundwater flow system under a range of subsurface and climatic conditions with a specific focus on groundwater recharge. Detailed field investigations and legacy data sets will be integrated into advanced mathematical models to evaluate a wide range of scenarios designed the reveal the complex interaction between tile drains and the shallow subsurface. In the second component, the influence of depression focused recharge phenomena, which form following extreme precipitation events in low topographic settings, will be quantified through field investigations and advanced simulation tools to investigate the potential impact of these recharge phenomena on aquifer and public supply well vulnerability. The final component will integrate insight from the first two sections into a regional analysis of the combined influence of tile drainage, depression focused recharge and climate change on groundwater recharge with a specific emphasis on the regional water balance and the sustainability of groundwater resources. The overall results will assist water managers in understanding how the regional water balance is changing under the influence of managed agricultural drainage and climate change and inform future water management policy.