Adaptive management of green stormwater infrastructure to reduce greenhouse gas emissions from urban watersheds

在世界范围内，雨水管理（SWM）系统正在扩大和改造，以应对城市化的负面影响，包括洪水增加，河流退化和接收水生生态系统的富营养化。在加拿大，雨水池塘（SWPs）是标准的SWM技术的新的发展，虽然其他绿色技术，特别是生物滞留系统（BRS），越来越多地使用。然而，这些技术是否也支持积极的气候效益仍然存在争议。例如，SWPs和BRS已被证明是温室气体（GHG）二氧化碳、甲烷和一氧化二氮的重要来源。然而，它们也会螯合碳（C），减少磷（P）等营养物质的地表径流，从而改变城市水生连续体和接收水体的营养限制模式，营养条件和温室气体交换。为了确定SWPs和BRS是否加剧或减轻气候强迫，因此必须在流域尺度上评估其净效应。拟议的项目将通过以下方式解决这一问题：（1）量化SWPs和BRS中控制温室气体交换、碳固存以及碳和磷化学形态和通量变化的尺度驱动因素和过程，（2）将由此产生的知识整合到城市流域耦合水文-生态地球化学模型中SWPs和BRS的稳健表示中，（3）利用模型模拟分析城市温室气体排放和养分磷输出对实施和管理绿色SWM基础设施的响应。我们将首先关注安大略南部的城市流域，SWPs和BRS的水文学和地球化学，我们已经广泛的特点，因此，奠定了基础，在加拿大各地扩大模型的应用。该项目的市政和工业合作伙伴将利用该项目的成果（1）实施干预措施，减少现有SWPs和BRS的温室气体排放，（2）制定绿色SWM战略，最大限度地减少气候缓解效益和其他关键服务之间的权衡，特别是水质保护。

Worldwide, stormwater management (SWM) systems are being expanded and retrofitted to counter negative impacts of urbanization, including increased flooding, stream degradation, and eutrophication of receiving aquatic ecosystems. In Canada, stormwater ponds (SWPs) are the standard SWM technology for new developments although other green technologies, especially bioretention systems (BRSs), are increasingly used. Whether these technologies also support positive climate benefits remains controversial, however. For instance, SWPs and BRSs have been shown to be significant sources of the greenhouse gases (GHGs) carbon dioxide, methane, and nitrous oxide. However, they also sequester carbon (C) and reduce the surface runoff of nutrients such as phosphorus (P), hence, altering nutrient limitation patterns, trophic conditions, and GHG exchanges along the urban aquatic continuum and in receiving water bodies. To determine if SWPs and BRSs exacerbate or mitigate climate forcing, their net effects must therefore be evaluated at the watershed scale. The proposed project will address this by (1) quantifying the landscape-scale drivers and processes within SWPs and BRSs that control GHG exchanges, C sequestration, and changes in the chemical speciation and fluxes of C and P, (2) integrating the resulting knowledge into robust representations of SWPs and BRSs in coupled hydrology-biogeochemistry models for urban watersheds, and (3) using model simulations to analyze the responses of urban GHG emissions and nutrient P export to the implementation and management of green SWM infrastructure. We will initially focus on urban watersheds in southern Ontario with SWPs and BRSs whose hydrology and biogeochemistry we have already extensively characterized, hence, laying the foundation for expanding the model applications across Canada. The project's municipal and industrial partners will use the project's outcomes to (1) carry out interventions that reduce GHG emissions from existing SWPs and BRSs, and (2) develop green SWM strategies that minimize trade-offs between climate mitigation benefits and other key services, in particular, water quality protection.