Bioretention for enhancing urban stormwater management

雨水是加拿大水道污染的主要来源，因为在到达接收水域之前，它会吸收大量沉积在陆地表面的悬浮固体、营养物质、有机物、重金属和其他污染物。低影响发展技术（lid）是现代雨水管理方法，可以改善雨水质量和减少雨水量。生物滞留就是其中一种技术，它涉及陆地表面的植被洼地。**自90年代首次使用以来，生物保留已被广泛实施，但主要是在特殊的方式和在温和和温暖的气候地区，这是加拿大大多数气候带的非典型。对去除污染物的基本过程的了解仍然缺乏，因此，可预测的生物保留设计所必需的实用工具也是如此。为了使工程从业人员有信心在加拿大使用这种技术，必须明确量化生物滞留在管理雨水数量和质量方面的好处，并开发设计生物滞留的实用工具。拟议的研究项目将结合计算机建模和在不同规模（空间尺度）和两个不同气候带开发的生物滞留设施收集的观测资料，以回答以下问题：i)在生物滞留中控制污染物（特别是营养物）去除的潜在过程是什么？ii)如何比较和评价不同水文条件（如不同大小降雨事件）和不同污染物负荷下的生物滞留性能？iii)如何将从不同规模的生物滞留设施获得的知识用于开发预测工具？iv)在不同的加拿大气候条件下，生物保留率如何表现？这些问题的答案将有助于开发可靠的方法来预测生物滞留的好处和优化生物滞留设计。该项目的研究结果不仅将为生物保持性提供有用的、明确的技术信息，而且将为生物保持性设计提供实用的、有用的工具。**

Stormwater is a major source of pollution in Canadian waterways because it picks up high amounts of total suspended solids, nutrients, organic matter, heavy metals and other pollutants that are deposited on the land surface, before reaching the receiving waters. Low Impact Development technologies (LIDs) are modern stormwater management methods that can improve stormwater quality and reduce stormwater quantity. Bioretention, which involves vegetated depressions in the land surface, is one of these technologies. ** Since its initial use in the 90's, bioretention has seen widespread implementation but primarily in an ad hoc manner and in regions of mild and warm climates, which are atypical of most climate zones in Canada. The knowledge of the underlying processes to remove pollutants is still lacking and hence, so are the practical tools necessary for predictable bioretention design. In order to equip engineering practitioners with the confidence to use such a technology in Canada, the benefits of bioretention in managing stormwater quantity and quality need to be clearly quantified, and the practical tools for designing bioretention need to be developed. The proposed research project will combine computer modelling with observations collected on bioretention facilities developed at different sizes (spatial scales) and in two different climate zones, to answer the following questions: i) What are the underlying processes controlling the removal of pollutants (especially nutrients) in bioretention? ii) How can bioretention performance under different hydrologic conditions (such as different size rain events) and different pollutant loads be compared and evaluated? iii) How can knowledge obtained from bioretention facilities at very different scales be used to develop predictive tools? iv) How does bioretention perform under varying Canadian climate conditions? The answers to these questions will lead to the development of reliable approaches for predicting the benefits of bioretention and optimizing bioretention design. The results from this project will not only provide useful and definitive technical information on bioretention, but the practical, useful tools necessary for bioretention design. **