Appropriate Incorporation of Groundwater Flow Features and Processes in Small- to Large-Scale Hydrologic Models

地下水在水文循环中起着至关重要的作用，因为它是可用淡水的最大组成部分。GW是我们最重要的淡水资源，提供饮用水和粮食安全，维持地表水体（SW），并保持生物多样性。因此，诊断和预测水文变化的数值模型应适当考虑GW流量及其与SW的相互作用。然而，在现有的建模软件之间如何处理这种相互作用存在很大的差异，需要进行研究，因为模型结果可能会对规划，水资源管理和政策产生重大影响。这个为期3年的项目的总体目标是通过构建可能影响SW流量的不同复杂性的模型，对安大略南部（S-ON）两个代表性流域的水文模型中GW流量特征和过程的适当结合进行评估。项目目标包括调查：1）水文模型应考虑的地下物质的总深度; 2）应包括的地下地质异质性的垂直和/或水平分辨率;以及3）如何在大规模水文模型中表示GW提取/注入。这项研究将通过修改现有的原型HydroGeoSphere（HGS）模型来进行，该模型是Aquanty公司最近建造的。（Aquanty）和加拿大地质调查局（GSC），它们是项目合作伙伴。具体来说，将根据S-ON HGS模型创建桤木溪流域（ACW）和格兰德河流域的嵌套和/或独立模型。通过将模拟结果与来自监测威尔斯的现有数据和来自计量站的水文过程图进行比较，对不同复杂程度的HGS模型进行性能评估，从而实现项目目标。各利益攸关方可利用总体结果来评估在小到大规模水文模型中是否适当纳入GW流量特征和过程。所获得的知识将有助于实现该团队的总体目标，即提供风险管理解决方案，这些解决方案以领先和创新的决策工具为基础，以管理加拿大的淡水资源。

Groundwater (GW) plays a vital role in the hydrologic cycle as it is the largest component of available freshwater. GW is our most critical freshwater resource providing drinking water and food security, sustaining surface water (SW) bodies, and maintaining biodiversity. Therefore, diagnosing and predicting hydrologic changes with numerical models should appropriately account for GW flow and its interactions with SW. However, there are large differences in how this interaction is treated among existing modelling software requiring research as model results can have significant impacts on planning, water management, and policy. The overall goal of this 3-year project is to assess the appropriate incorporation of GW flow features and processes within hydrologic models for two representative watersheds in southern Ontario (S-ON) by constructing models of varying complexities that could impact SW flow. Project objectives include investigations of: 1) the total depth of subsurface materials that hydrologic models should consider; 2) the vertical and/or horizontal resolution of subsurface geologic heterogeneity that should be included; and 3) how GW extraction/injection are represented in large-scale hydrologic models. The research will be conducted by modifying the existing, prototype HydroGeoSphere (HGS) models of S-ON recently built by Aquanty, Inc. (Aquanty) and the Geological Survey of Canada (GSC), which are the project partners. Specifically, nested and/or standalone models for the Alder Creek Watershed (ACW) and the Grand River Watershed will be created from the S-ON HGS models. Project objectives will be achieved by performance assessment of HGS models of varying complexities by comparing simulation results with existing data from monitoring wells and hydrographs from gaging stations. The overall results could be utilized by various stakeholders to assess the appropriate incorporation of GW flow features and processes in small- to large-scale hydrologic models. The knowledge gained will help achieve the team's overarching goal to deliver risk management solutions informed by leading-edge and innovative decision-making tools to manage freshwater resources in Canada.