Land cover and topographic controls on groundwater recharge on the Oak Ridges Moraine

土地利用和气候变化对水文过程和水资源有重大影响。我将研究这些变化如何影响安大略省南部对环境敏感的橡树岭Moraine地区的地下水补给和径流--这是一种关键的地区性水文地质资源。冰河正在经历土地利用和气候变化，其水文影响尚不清楚。这在一定程度上是由于排水盆地向溪流储存和释放水的能力存在不确定性。Moraine上的相邻溪流排放的地下水数量差异很大，目前尚不清楚这是由于补给、地下储存和释放特性的差异，还是两者兼而有之。这种变化性还表明，在以溪流形式离开之前，水在盆地中的停留时间存在差异。在预测地表水文变化(由于土地利用和/或气候变化)是否以及何时可能引起径流响应时，关于水停留时间的数据至关重要。 我们预测地表和地下水对土地利用和气候变化的反应的能力，在一定程度上取决于我们对这些变化如何控制水的渗透、补给和排放的了解。这项工作将研究从城市到森林的土地利用在渗透和补给方面的差异，特别是以洼地为重点的补给的潜力。这是当山坡径流进入地形凹陷并渗入时产生的。它导致洼地比邻近高地的补给更多和更快，这对水和污染物向更深的地下水流动以及地下材料过滤污染物的能力具有重要影响。冰冻的地面在雨雪融化向洼地的转移中起着关键作用；然而，在莫雷纳丘陵地带的丘陵地貌上，这一过程的经验证据是缺乏的。将开发具有成本效益的方法来估计冰原的土地使用和特定地形条件的补给。将为这些土地用途确定冻土开发，以评估土地用途变化可能如何改变补给。盆地储存补给输入的能力将从详细的三维地质数据中获得，水停留时间将从环境示踪剂中得出。数据将用于对土地利用和气候变化的补给响应的模型预测，结果将有助于评估入渗、水停留时间和径流之间的耦合。以实地和模拟为基础的综合办法将把以洼地为重点的补给的潜力与排水流域的储水量和相关的水停留时间联系起来，并将评估气候和土地利用变化可能如何改变这种联系。这些结果将是地下水模型的关键投入，而地下水模型是橡树岭、莫雷恩和加拿大其他地区可持续水资源管理的关键组成部分。

Land use and climate changes have major implications for hydrologic processes and water resources. I will study how such changes impact groundwater recharge and streamflow on the environmentally-sensitive Oak Ridges Moraine in southern Ontario - a key regional hydrogeologic resource. The Moraine is undergoing both land use and climate change, the hydrologic implications of which are unclear. This is partly due to uncertainty in the ability of drainage basins to store and release water to streams. Adjacent streams on the Moraine discharge greatly different amounts of groundwater, and it is not known whether this results from differences in recharge, subsurface storage and release properties, or both. This variability also suggests differences in residence time of water in the basin before it leaves as streamflow. Data on water residence times is critical when predicting if and when surface hydrologic changes (due to land use and/or climate change) may induce a streamflow response. Our ability to predict surface and subsurface water response to land use and climate change partly depends on our knowledge of how such changes control water infiltration, recharge, and discharge. This work will study differences in infiltration and recharge for land uses ranging from urban to forest, and particularly the potential for depression-focused recharge. This is produced when hillslope runoff enters topographic depressions and infiltrates. It leads to greater and faster recharge in depressions than on adjacent uplands, with important implications for water and contaminant movement to deeper groundwater, as well as the capacity of subsurface material to filter contaminants. Frozen ground is critical in the transfer of rain and snowmelt to depressions; however, empirical evidence for this process on the Moraine’s hummocky landscape is lacking. Cost-effective methods will be developed to estimate recharge for the Moraine’s land use and specific topographic conditions. Frozen soil development will be determined for these land uses to assess how recharge may be altered by land use change. Basin capacity to store recharge inputs will be obtained from detailed 3-d geologic data, and water residence times will be derived from environmental tracers. Data will be used in model predictions of recharge response to land use and climate changes, and results will help assess coupling between infiltration, water residence times and streamflow. The integrated field- and modelling-based approach will link the potential for depression-focused recharge with water storage and release from drainage basins and associated water residence times, and will assess how such linkages may be modified by climate and land use changes. These results will be key inputs for the groundwater models that are critical components of sustainable water resource management on the Oak Ridges Moraine and elsewhere in Canada.