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Full Water-Cycle Monitoring in an Urban Catchment Reveals Unexpected Water Transfers (Detroit MI, USA)
Citation:
Hoard, C., R. Haefner, W. Shuster, R. Pieschek, AND S. Beeler. Full Water-Cycle Monitoring in an Urban Catchment Reveals Unexpected Water Transfers (Detroit MI, USA). JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION. American Water Resources Association, Middleburg, VA, 56(1):82-99, (2020). https://doi.org/10.1111/1752-1688.12814
Impact/Purpose:
Utilities and wastewater managers make a lot of assumptions about how stormwater and wastewater conveyance networks (pipes) work and don't work. When the system is functioning well, wastewater is carried through the combined sewer pipe network to the wastewater treatment plant. During a rainfall event, stormwater volume increases on top of what the wastewater pipe normally carries. Therefore, a goal in urban water management is to reduce the volume of stormwater runoff in urban systems and the effect of combined sewer overflows into receiving waters. So, we responded by putting into place landscape features to detain and infiltrate water, but also set up a comprehensive monitoring program to see where this stormwater goes - does it go into the soil, into the pipe network (which is leaky), or elsewhere. We found that monitoring is essential to trace these flows, and understand how effective management is, and how "leaky" the urban water cycle can be. These results impact on maintaining and efficient wastewater collection and conveyance system, quantifying impacts of green infrastructure, and ultimately benefits to public health as reduced combined sewer overflows in American communities.
Description:
A goal in urban water management is to reduce the volume of stormwater runoff in urban systems and the effect of combined sewer overflows into receiving waters. Effective management of stormwater runoff in urban systems requires an accounting of various components of the urban water balance. To that end, precipitation, evapotranspiration, sewer flow, and groundwater in a 3.40-hectare sewershed in Detroit, Michigan were monitored to capture the response of the sewershed to stormwater flow prior to implementation of stormwater control measures. Monitoring results indicate that stormflow in sewers was not initiated unless rain depth was 4 mm or greater. Evapotranspiration removed more than 40 percent of the precipitation in the sewershed whereas pipe flow accounted for 8.4 to 85 percent of the losses. Flows within the sewer that could not be associated with direct precipitation indicate an unexpected exchange of water between the leaky sewer and the groundwater system, pathways through abandoned or failing residential infrastructure, or a combination of both. Groundwater data indicate that groundwater flows into the leaky combined sewer rather than out. This research demonstrates that urban hydrologic fluxes can modulate the local water cycle in complex ways which affect the efficiency of the wastewater system, effectiveness of stormwater management, and, ultimately, public health.
URLs/Downloads:
DOI: Full Water-Cycle Monitoring in an Urban Catchment Reveals Unexpected Water Transfers (Detroit MI, USA)
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