Low water levels and hydrological droughts
The intensification of low water periods due to climate change threatens water availability and quality, compromising various human uses and damaging aquatic ecosystems.
In southern Quebec, water shortages have already been observed, with consequences such as:
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Surface water and groundwater supply difficulties for some municipalities and residents with private wells
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Higher water treatment costs, notably due to lower dilution factors
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Bans on outdoor water use
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Irrigation problems for farmers
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Various consequences for boating
The CASCADES project documents, analyzes and projects the consequences of water scarcity in terms of their cascading effects on the well-being of human populations and ecosystems.
The CASCADES project suggests that, in the absence of adaptation or anticipation in the integrated management of water resources, all the consequences already experienced during previous episodes of water scarcity will be exacerbated in the coming decades. The impacts will be especially marked in the St. Lawrence lowlands, affecting the areas south of the St. Lawrence River (Montérégie, the Eastern Townships, central Quebec and Chaudière-Appalaches) in particular.
Water quality
During low water periods, the contaminant dilution capacity of rivers and lakes may become insufficient due to reduced water flow. That can result in water contamination, as the pollutant load of rivers and lakes remains the same despite the reduced volume of water.
In addition, lower water levels combined with rising temperatures encourage the growth of algae and cyanobacteria, increasing the contamination risk of wells, drinking water intakes, beaches, wildlife and plant habitats, and other environments.
The drinking water supply
The reduced availability and quality of water resulting from more severe low water periods can affect the intake capacity of waterworks and engender costs for some municipalities that will need to adapt their drinking water production, treatment and distribution systems.
Impacts on ecosystems
The most worrying consequences of severe low water levels for ecosystems are reduced water quality and changes to fish habitats. Alterations to the physical and chemical parameters of water, such as temperature increases, lower O2 and variations in the natural pH of watercourses, can have an impact on aquatic species. Combined with increasing eutrophication, all these factors are likely to profoundly alter the biological richness of watercourses and generate major imbalances in aquatic populations.
Impacts on other human uses
Hydrological droughts and low water levels will also increase pressure on water supplies for various economic activities such as agriculture, industry, tourism, shipping and energy generation. Climate change may also increase the water demand on these sectors precisely at times when water levels are at their lowest.
For example, drought can force farmers to limit their crop irrigation activities, thereby reducing yields. They may also turn to alternative water sources, which can entail additional costs and constraints. Livestock watering issues may also arise.
This research project provided an initial estimate of the potential economic impacts of low levels in the St. Lawrence River on six major sectors: ecological services, shipping, hydroelectricity production, tourism, drinking water and waterfront properties. At the same time, the project enabled the development of expertise and collaboration on the issues and challenges of adapting to low water levels in the St. Lawrence.
Water availability and usage conflicts
Declining water availability could increase constraints and complicate the management of different water uses in the province. In the long run, this situation could increase tension between the various water users.
The RADEAU 1 and 2 projects were funded by the Ministère de l'Agriculture, des Pêcheries et de l’Alimentation (MAPAQ) and the 2013-2020 Climate Change Action Plan. They enhanced and structured the existing data used to categorize the water balance of 11 regions in current and future climates. They also proposed recommendations for the development of intervention strategies to mitigate or avoid water use conflicts in agriculture in Quebec.
