Integrated Water Cycle Management in the Great Lakes Basin under Changing Climate Conditions

Elisha Persaud, Jana Levison, Sarah Rixon, Scott MacRitchie

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: EcoSystem and Climate Change

ABSTRACT: Climate change is expected to affect temperature as well as the timing and amount of precipitation received within the Great Lakes Basin. An integrated monitoring and modelling approach is required to improve the current understanding of the water cycle components, especially groundwater-surface water interactions, and possible future conditions. The Parkhill Creek Integrated Climate Change Station in Southwestern Ontario, is highlighted as an example of integrated field data collection and subsequent hydro-climatic modelling as a framework for climate change impact assessment. This case is discussed in relation to the importance of hydrologic function and the policy implications of this framework.

RÉSUMÉ: On s'attend à ce que les changements climatiques affectent la température ainsi que le moment et la quantité de précipitations reçues dans le bassin des Grands Lacs. Une approche intégrée de la surveillance et de la modélisation est nécessaire pour améliorer la compréhension actuelle des composants du cycle de l'eau, en particulier les interactions eaux souterraines et eaux de surface, et les conditions futures éventuelles. La station de changement climatique intégrée de Parkhill Creek dans le sud-ouest de l'Ontario est soulignée comme un exemple de collecte intégrée de données sur le terrain et de modélisation hydro-climatique subséquente comme méthodologie pour l'évaluation de l'impact des changements climatiques. Ce cas est discuté en relation avec l'importance de la fonction hydrologique et les implications politiques de ce cadre. 1 GROUNDWATER-SURFACE WATER INTERACTIONS IN THE GREAT LAKES BASIN AND ANTICIPATED EFFECTS OF CLIMATE CHANGE The science behind climate change projections is continually evolving and there remains a large degree of uncertainty due to the unpredictable impact of future human decisions as well as complex feedbacks in the climate system (Kornelsen and Coulibaly 2014). Nonetheless, projected changes in seasonal temperature as well as changes in the amount and distribution of precipitation may lead to fundamental water cycle modifications including changes in the timing and magnitude of groundwater recharge and streamflow (e.g. Cunderlik and Simonovic 2005; Jyrkama and Sykes 2007; TRCA 2007; EBNFLO Environmental and CVC 2008; McBean and Motiee 2008; TRCA 2008; Wiley et al. 2010; Sulis et al. 2011; Rahman et al. 2012; Shifflett 2014). Potential impacts on groundwater-surface water interactions are particularly important in light of their already proven vulnerability to human disturbances and the impacts of development on water quality, quantity, and aquatic habitats (e.g. Hancock 2002; Roy and Malenica, 2013; Roy and Bickerton 2014; Peipoch et al. 2015). Moreover, these interactions play a large role in controlling flow to the Great Lakes. For example, baseflow contributions to the Great Lakes represent 22-42% of the basin water supply (Holtschlag and Nicholas 1998; Neff et al. 2005). Groundwater-surface water systems are inherently interconnected and should be assessed as a single domain (Winter et al. 1998). Furthermore, patterns in the magnitude and direction of such exchanges are complex and may show substantial spatial and temporal variability (e.g. Cey et al. 1998; Woessner 2000; Conant 2004; Coulibaly and Burn 2005; Cardenas et al. 2008; Ashworth 2012; Peterson et al. 2013; Ala-aho et al. 2015; Tian et al. 2015). As a result, in the assessment of climate change impacts, there is a need to incorporate an integrated monitoring and modelling approach moving forward (Sykes et al. 2016). 2 AN INTEGRATED MONITORING AND MODELLING APPROACH FOR ASSESSING CLIMATE CHANGE Hydrologic processes within a given watershed are governed by climate inputs, such as temperature and precipitation, and the influence of these factors on related variables such as runoff, infiltration, evapotranspiration, and recharge, and properties such as soil moisture, groundwater and surface water levels, and streamflow. Further to this is the hydrologic control exhibited by inherent properties of the watershed (e.g. land use, topography, and geology). When these external and internal factors are considered in combination, and under conditions of spatial and temporal variability, the ability to fully understand a watershed system may be associated with a large degree of complexity and uncertainty. Developing an appropriate strategy to examine the potential influence of climate change on water cycle components must first involve a clear understanding of the water budget in question, for which comprehensive

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