Linking storm water management ponds & urban streams: function and ecological impacts

风暴会导致大量的水排入城市的溪流和河流，可能导致洪水、侵蚀，并将大量的沉积物和营养物质从陆地表面转移到河流和湖泊中。为了减少洪水事件和侵蚀，并捕获沉积物和营养物质，加拿大各地广泛使用了雨水管理（SWM）池塘（在大多伦多地区有大约2000个池塘在运行）。各池的设计特点不同，会对池出水水质产生影响。底吸式池塘可能从温度较低的较深的水中排出，但可能缺乏溶解氧，并且氯化物含量很高，这两种情况对水生生物都是有害的。池塘将沉积物、营养物和污染物困在池塘里。定期清除池塘中的沉淀物是维持其功能所必需的，但也很昂贵。因此，池塘的设计和维护可能是决定池塘条件和污水如何影响溪流和河流的重要因素。我们会广泛调查池塘的设计和维修对池塘内水质的影响，以及池塘内可能形成的生态群落，以及污水水质对接收溪流的生态群落的影响。例如，较高的水温和营养物质可能导致有害藻华的发展，这可能对经常出现在SWM池塘的狗和儿童的健康造成危害。我们的工作将一组池塘的持续性能联系起来，以确定污水对接收溪流和河流的影响。我们将研究池塘的设计和维护如何影响溪流周边植物、底栖无脊椎动物和鱼类群落，包括处于危险中的水生物种，我们将评估这些池塘的累积影响，因为许多池塘位于许多相对较短的溪流中。获得的知识将允许更好的设计，并确定具有成本效益的维护计划，以提高效率并减少生态影响。

Storms can result in large amounts of water draining into urban streams and rivers, potentially resulting in flooding, erosion, and transfer of large amounts of sediments and nutrients from the land surface into rivers and lakes. To reduce flooding events and erosion and to trap sediments and nutrients, storm water management (SWM) ponds are used extensively (>2000 ponds are in operation within the Greater Toronto Area) across Canada. The ponds have different design features that may influence water quality of pond effluent. Bottom-draw ponds may drain from deeper waters that are cooler in temperature, but may lack dissolved oxygen and have highly elevated levels of chloride both conditions are detrimental to aquatic life. Ponds trap sediment, nutrients, and contaminants within the ponds. Periodic removal of sediment from ponds is necessary to maintain their function, but is also expensive. As a consequence, both pond design and maintenance may be important factors determining conditions within the ponds and how effluent impacts streams and rivers.We will conduct a broad survey of how pond design and maintenance may be impacting the water quality within ponds and the resulting ecological communities that may develop within those ponds, and the impacts of effluent water quality on ecological communities of receiving streams. For example, higher water temperatures and nutrients may contribute to the development of harmful algal blooms that may present health hazards to dogs and children that may frequent SWM ponds. Our work links the ongoing performance of a subset of ponds to determine the impacts effluent has on the receiving streams and rivers. We will examine how pond design and maintenance impacts stream periphyton, benthic invertebrate, and fish communities, including aquatic species at risk, and we will assess cumulative impacts of these ponds given numerous ponds are located and drain into relatively short lengths of many streams. Knowledge gained will allow better design to be incorporated and to determine cost-effective maintenance scheduling that improves efficacy and reduces ecological impact.