Understanding, and adapting to, the potential impacts of climate change on salinity levels in the Fraser River is essential for the future of food production in Delta. A new study that models the effects of climate change and dredging on the future availability of irrigation water for Delta farmers, provides data and projections to help assess the risks and inform planning and decision-making for farmers and government alike.
Delta farmers are dependent on irrigation drawn from the Fraser River to grow their crops. This irrigation water is brought in through carefully managed intakes on the river, filling a network of irrigation ditches before being used on the fields. Salt water has always flowed up the river at high tide and the irrigation intakes are managed accordingly. However, with climate models predicting lower volumes of water flowing downstream during summer, combined with rising sea levels, the “salt wedge” is anticipated to push further up river in the future. This poses a management challenge for the agricultural water supply, creating the risk of contamination from salt water.
“Without good data, we would just be anecdotally saying that we think salinity is going to get worse with climate change and dredging,” says Bruce May, a cranberry farmer and Chair of the Delta Farmers’ Institute’s (DFI) Committee on Irrigation and Salinity. “If we have a model that can show us what is going to happen with different scenarios, we can adjust and maybe change our intake operations somewhat. It is always good to be able to anticipate problems.”
The Delta Farmers’ Institute and the Corporation of Delta partnered with the BC Agriculture & Food Climate Action Initiative to commission a study on the potential impacts of climate change and dredging on salinity in the Fraser River. The study used hydraulic modeling to predict and analyze salinity levels based on low river flow and sea level rise scenarios. While the Port of Vancouver has publicly stated that there are no plans for deeper dredging in the river, the potential for this to change in the future is cause for concern with Delta’s agricultural producers; as a result, dredging practice scenarios were incorporated into the study parameters.
The study identified long-term and near-term impact on salinity by measuring and modeling the number of hours per day (24-hour period) that water was of sufficiently low salinity that it could be used for irrigation. With the current intake at 80th Street, the daily water availability ranges between 24 hours, for normal and wet years, to 4 hours for a dry year.
Looking at near-term impacts over the next 10 to 25 years, the study projected that increasing sea level rise of 0.3m could reduce daily irrigation water availability under low river flows by up to 25 percent. During periods of more extreme low flows, sea level rise impacts are anticipated to further reduce irrigation water availability windows. Longer-term (50-100 years), the modeled impacts of the salt wedge become increasingly severe with respect to irrigation water availability. In all cases (near and long term) increased dredging levels are expected to have substantial effects on irrigation water availability.
“This is the future of farming. Without irrigation water I don’t see agriculture being viable in Delta,” says May. “With this study, we now understand each of these issues and the sensitivity that the salt water wedge has to the different variables we are facing. The next phase of the work, the monitoring, will tell us under which circumstances we can expect to have a problem.”
The effect of climate change on the future availability of irrigation water from the Fraser River was identified as an area of concern in the Delta Adaptation Strategies plan. Completed in 2013, this plan was the result of a collaborative process that brought together Delta’s agricultural producers, and local and provincial government partners, to evaluate potential climate change impacts on local agricultural production, and to develop strategies and actions to address the associated challenges.
A collaborative process to implement priority actions has been underway since autumn of 2013.
This project assists in delivering actions in the Delta Adaptation Strategies related to the function of irrigation intakes and improving understanding of the potential impacts of climate change on irrigation water supply. Funding for this study is part of a $300,000 investment in the implementation of the Delta Regional Adaptation Strategy by the federal and provincial governments through Growing Forward 2, a federal-provincial-territorial initiative.
The BC Agriculture and Food Climate Action Initiative was established by the BC Agriculture Council in 2008, and is led by an advisory committee of agricultural producers, food processors and representatives from various government agencies. The Initiative has been supported by the Investment Agriculture Foundation of BC with funding provided by the governments of Canada and British Columbia through Growing Forward 2.
Learn More: To read the full report, visit: http://www.bcagclimateaction.ca/wp/wp-content/media/DeltaFraser-River-Salinity-Modeling-and-Monitoring-Report-2016.pdf
For more information on The Delta Regional Adaptation Strategy, visit: http://www.bcagclimateaction.ca/adapt/regional-strategies/
For more information on Growing Forward 2 programs in British Columbia, visit: http://www2.gov.bc.ca/gov/topic.page?id=EB8322DE53664C7289317829FA25360E
For more information on Growing Forward 2, visit: http://www.agr.gc.ca/eng/about-us/keydepartmental-initiatives/growing-forward-2/?id=1294780620963
Communications Coordinator BC Agriculture & Food Climate Action Initiative