Long-term trends in groundwater recharge and discharge in a fractured bedrock aquifer – past and future conditions

Abstract

2015): Long-term trends in groundwater recharge and discharge in a fractured bedrock aquifer -past and future conditions , Canadian Water Resources Journal / Revue canadienne des ressources hydriques,In the context of climate change, it is important to understand possible future projections and historical trends of groundwater recharge, flow, and discharge to surface reservoirs. Knowledge of a vast range of possible conditions is required to fully appreciate the variability of the hydrologic cycle and hence the long-term vulnerability of groundwaterdependent habitats. This research investigates historical trends for a groundwater-surface water interacting system that supports a fragile ecosystem in southern Quebec. A transient model was developed using MODFLOW to simulate sitewide groundwater flow for the study area. The model was used to simulate past hydrogeological conditions (1900-2010) using a new data set of available precipitation (rain and snowmelt) and temperature. This data set was used to simulate the overall groundwater budget and to determine groundwater discharge (river baseflow and spring flow) in the study area. This allows for the quantification of century-long trends in flow data, as well as the extreme maximum and minimum flows over 110 years. Recharge was variable, ranging from 41 to 197 mm/year over the study period. Lower recharge rates from 1950 to 1965 induced marked effects on spring flow. Although the trend is not statistically significant, there appears to be, for the second half of the study period , a tendency towards a reversal to an increase for recharge, hydraulic heads, spring flow and baseflows. A longer time series would be necessary to confirm this tendency. The simulated historical trends are compared with flow projections for future scenarios . The confirmation that the natural system has been subjected to a wide range of climatic conditions over the last century helps to inform about its resilience. This study highlights the utility of groundwater flow modeling using historical climate data sets to gain a better understanding of long-term trends for climate change-related hydrogeological and ecohydrological studies.Dans un contexte de changements climatiques, il est important d'analyser les projections futures possibles et les tendances historiques des écoulements d'eau souterraine (recharge, flux, apports aux eaux de surface). La prise en compte d'une vaste gamme de conditions possibles est nécessaire afin d'apprécier pleinement la variabilité du cycle hydrologique et, conséquemment, la vulnérabilité à long terme des habitats qui dépendent des eaux souterraines. Cette recherche examine les tendances historiques d'un système aquifère-eaux de surface qui soutient un écosystème fragile dans le sud du Québec. Un modèle transitoire a été développé en utilisant MODFLOW pour simuler l'écoulement des eaux souterraines dans la zone d'étude. Le modèle a été utilisé pour simuler les conditions hydrogéologiques passées (1900-2010) en utilisant des données de précipitation disponible au...

A review of simulated climate change impacts on groundwater resources in Eastern Canada

“…In the same location, Levison et al (2014b) The results showed that summer low flows events will generally be more severe and longer for all scenarios and all watersheds: Q 2-7 changed by -54% to -6%, Q 10-7 changed by -63% to -9%, and Q 5-30 changed by -56% to -8%. Levison et al (2016) also investigated long-term trends in groundwater recharge and discharge for the Covey Hill Natural Laboratory using the MODFLOW model. The authors compared the simulated responses of the groundwater system using observed and simulated data from 1900 to 2010 and also used projected climate data for 2041-2070.…”

“…At that scale, most of the studies of the last decade have been implemented with integrated models(Colautti 2010;Sultana and Coulibaly 2011;Sulis et al 2011;2012;Cochand 2014;Levison et al 2014b). Groundwater flow models are still used(Levison et al 2014a;Kurylyk et al 2014;Lemieux et al 2015;Levison et al 2016), but they necessitate simplifications in the recharge processes or the coupling of a recharge model to a groundwater flow model (e.g.,Kurylyk et al 2014;…”

Groundwater–surface water interactions in Canada

“…Understanding the connections between recharge and discharge is crucial to implementing better management and conservation methods. Levison et al (2016) investigated groundwater recharge and discharge through rivers and springs in the Covey Hill area of southern Quebec, at the northernmost extension of the Adirondack Mountains (Potsdam Group of the Covey Hill Formation). The improved understanding of how the natural system responded to a wide range of climatic conditions over the last century provides insight into its resilience to future climate change.…”

“…Groundwater flow modeling and particle tracking are integrative approaches which require abundant data to describe the studied conditions; data are usually acquired through aquifer characterization. Models can be used to understand flow directions to surface features (Marchildon et al 2016) and to quantify groundwater discharge to rivers and springs (Levison et al 2016). They are particularly relevant to understanding past and future conditions, which can be linked to climate change scenarios, as illustrated by Levison et al (2016).…”

“…Models can be used to understand flow directions to surface features (Marchildon et al 2016) and to quantify groundwater discharge to rivers and springs (Levison et al 2016). They are particularly relevant to understanding past and future conditions, which can be linked to climate change scenarios, as illustrated by Levison et al (2016). Distinct insight into current conditions and a clearer understanding of changing conditions in groundwatersurface water interactions can also be gained through the interpretation of policy statements (Bradford 2016).…”