From Minutes to Millennia: Transient Responses in Groundwater Systems

点击翻译按钮获取中文摘要

Globally, groundwater is the source of one third of all freshwater withdrawals. In many environments, natural groundwater discharges sustain baseflow to rivers, lakes and wetlands during periods of low or no rainfall. Despite these vital contributions to human welfare and aquatic ecosystems, a paucity of studies on the relationship between climate and groundwater severely restricted the ability of the Intergovernmental Panel on Climate Change (IPCC) to assess the interactions between groundwater and climate change in both its third and fourth assessment reports. Most climate change impact studies conducted to date have modeled groundwater systems as a snapshot in time (2020s, 2050s) over a 100-year projection window. Little research has been undertaken on the transient (time-varying) responses of these systems, and even less on the computationally challenging problems involving episodic and very long-term change. Moreover, most groundwater models continue to be calibrated using time-averaged observations (representing assumed steady-state conditions) or short-duration transient data (e.g. pumping tests) and, therefore, the uncertainty in long-term predictions is high. This research will explore the dynamics of groundwater systems using transient modeling in order to better understand aquifer responses to climate stresses that act over short and long time frames, from minutes to millennia, and attempt to better constrain the range of hydraulic properties suitable for regional-scale hydrogeological studies through model calibration to transient datasets. Significant insight will be gained concerning the sensitivity of the system to the parameters that control the aquifer response, and thus, aid in quantifying the uncertainty in future projections. This contribution is crucial for determining the sustainability of the groundwater resource as noted by the Council of Canadian Academies' report in 2009 on "The Sustainable Management of Groundwater in Canada" and for establishing appropriate monitoring networks to detect change.********