Research Feature
Effects of forest management and climate change on carbon loading in a major Atlantic Canadian source-water supply
Key messages

  • Dissolved organic carbon (DOC), naturally produced in great abundance in Atlantic Canadian forests, adds a costly step to source-water treatment.

  • Watershed managers at Halifax Water, the region’s water utility, endeavour to manage forests under their stewardship in a way that promotes water treatability.

  • This research aims to provide a better understanding of the relationships between forest management, climate and DOC concentrations in Nova Scotia watersheds. These findings should be transferrable to other temperate climates.

Summary

 Water utilities, including Halifax Water of the Halifax Regional Municipality in Nova Scotia, Canada, are facing increasing water treatment costs due to rising levels of carbon in their water supply. Found in water in both dissolved and non-dissolved forms, carbon comes from natural sources in forested watersheds and poses challenges as it is necessary and difficult to remove dissolved organic carbon (DOC) during the water treatment process. With DOC levels rising, Halifax Water is looking to forest management as a potential approach to mitigate increasing carbon loading, especially in the region’s largest water supply, the Pockwock watershed. Our research specifically aims to understand how different forest management regimes can influence carbon loading in source water supplies in a changing climate.

We tackled this research in the Pockwock watershed in three stages: (i) hydrologic characterization of the study area, (ii) determining the effects of forest management on living and dead carbon pools, and (iii) identifying relationships between how much carbon is in the forest versus how much carbon ends
up in the water. The first stage, understanding the area’s hydrology, involved extensive field work to build multi-year records of flow and DOC loading in several catchments in the Pockwock Watershed. The data from this field work contributed to the development of models that predict year-round hydrology of the Pockwock watershed. The second stage, determining the effects of forest management on carbon pools, also involved extensive fieldwork to study the forest composition of the watershed. These data were used to calibrate our understanding of regional forest growth and fed into carbon modelling that predicts the transformation of carbon from living to dead biomass though a forest’s lifecycle. The final stage uses data from the previous steps and will allow us to predict relative differences in source-water carbon loading under different forest management and climate regimes.

Our findings will provide watershed managers in Halifax and elsewhere with an understanding of the long-term implications of forest-management decisions on water carbon loading.


Publications

Foster DE, Duinker PN, Jamieson RC, Keys K, Steenberg JWN. 2024. Where does the carbon go? Long-term effects of forest management on the carbon budget of a temperate-forest water-supply watershed. Journal of Environmental Management. 352:120007. doi:10.1016/j.jenvman.2023.120007.
More than
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Photo: Working onsite with partner X.

Contributors

David E. Foster, PhD Candidate
Dillon Langelaan, MASc
James Aksenchuk, MREM
Destin Gardner, MREM
Charlotte Large, MREM
Meggie Letman, Research Associate
Megan Ansems, undergraduate
Carley Archibald, undergraduate
Abigail Bonnington, undergraduate
Connor Dearing, undergraduate
Jordan Haughn, undergraduate
Evan Muise, undergraduate
Peter Duinker, Dalhousie University
Rob Jamieson, Dalhousie University
James Steenberg, Nova Scotia Department
of Natural Resources and Renewables
Kevin Keys, Nova Scotia Department
of Natural Resources and Renewables