Assessing risks of eutrophication by urban stormwater runoff under climate change

在整个加拿大，气候变化正在增加城市洪水的频率和强度。反过来，传统的雨水管理(SWM)系统正在向接收水体提供更多的城市高峰营养负荷。营养物质的过度富集会刺激富营养化和淡水水生生态系统中藻类水华的发生。在城市化和气候变化加剧的情况下，受损的水生生态系统的恢复成本可能会变得令人望而却步。因此，应根据下游生态风险设计和改造SWM系统，以最大限度地减少未来与营养有关的影响。然而，由于缺乏对城市水流路径上营养物质的去向和运输的预测性了解，目前没有评估在气候变化下接受水对城市雨水养分输入的脆弱性的框架。由于认识到气候适应战略的必要性，以最大限度地减少城市生态影响，拟议的研究将侧重于对城市水资源管理系统中养分循环的量化理解，并为下游生态系统制定风险评估框架。这一框架将能够为考虑到气候变化下的水质目标的水资源管理设计提供信息。为了实现这一目标，我们将结合实验室实验、野外采样和由学生和博士后进行的城市生态水文模型。这项研究符合NSERC的“水：健康、能源、安全”的研究主题，有助于“确保安全的社区供水系统”。由于这项研究将提高对水资源管理决策和生态系统影响之间联系的理解，因此对参与制定和实施流域管理计划、水资源管理指南和环境法规的利益相关者来说很重要。这些利益相关者包括但不限于安大略省环境和气候变化部、保护当局和市政当局，所有这些都是我们的合作伙伴。为城市水资源管理系统设定积极主动的养分减少目标将为加拿大未来节省数十亿美元的恢复成本。

All across Canada, climate change is increasing the frequency and intensity of urban flooding. In turn, conventional StormWater Management (SWM) systems are delivering increased urban peak loadings of nutrients to receiving water bodies. Nutrient over-enrichment stimulates eutrophication and the occurrence of algal blooms in freshwater aquatic ecosystems. Restoration costs of impaired aquatic ecosystems under increased urbanization and climate change may become prohibitive. SWM systems should therefore be designed and retrofitted on the basis of downstream ecological risks to minimize future nutrient-related impacts. However, because of the lack of predictive understanding of the fate and transport of nutrients along urban flowpaths, there is currently no framework for assessing the vulnerabilities of receiving waters to urban stormwater nutrient inputs under climate change. Motivated by the recognition of the need for climate-adaptive strategies to minimize urban ecological impacts, the proposed research will focus on the quantitative understanding of nutrient cycling within urban SWM systems, and develop a risk assessment framework for downstream ecosystems. This framework will be capable of informing SWM designs accounting for water quality targets under climate change. To achieve this goal, we will combine laboratory experiments, field sampling, and urban ecohydrological modeling carried out by students and a postdoctoral fellow. The research fits NSERC's research topic "Water: Health, Energy, Security", contributing to "Ensuring secure community water systems". Because the research will improve the understanding about linkages between SWM decisions and ecosystem impacts, it is important to stake-holders involved in the development and implementation of watershed management plans, SWM guidelines, and environmental regulations. These stakeholders include, but are not limited to, the Ontario Ministry of Environment and Climate Change, conservation authorities, and municipalities, all of which are among our partners. Setting proactive nutrient reduction targets for urban SWM systems will save Canada billions of dollars of future restoration costs.