Assessing stormwater reduction using green infrastructure: Niagara River Greenway Project (Buffalo, NY) Active

Study Summary

In many urban watersheds, including Buffalo, New York, stormwater (excess rainfall or snowmelt that isn’t absorbed by the ground) can cause problems such as flooding, erosion, and sedimentation; property and habitat damage; harm to fish and aquatic organisms; and decreased water quality. Many communities are considering the use of urban stormwater control measures to mitigate these problems.  Green infrastructure uses natural processes to reduce or delay peak flows and volumes of stormwater runoff by retaining, detaining, and infiltrating water and by enhancing evapotranspiration.

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The USGS is partnering with the City of Buffalo, the EPA and University at Buffalo to assess the effectiveness of green infrastructure to reduce the volume of stormwater runoff and limit the risk of combined sewer overflows in the Niagara River Area of Concern (AOC). An area of 21 city blocks along Niagara Street is undergoing redevelopment to reconnect residential land-use to the waterfront and implement a safer corridor for pedestrians and bicyclists. Green infrastructure, such as storm planters and sand filters, are being incorporated into the project to attenuate and reduce stormwater runoff. Initial plans for the Niagara Street redevelopment have the potential to reduce the volume of stormwater runoff by 16 million gallons per year.

Study objectives

The USGS has been monitoring flow in selected storm sewers since 2016. The initial phase of green infrastructure installation was completed in 2021.

 The primary objective of this study is to quantify changes in storm-sewer flow resulting from the installation of green infrastructure stormwater control measures. Secondary goals are:

• Improving the understanding of rainfall, runoff, and infiltration relationships in an urban area.
• Correlation of meteorological variables such as precipitation depth and intensity, hydrologic fluxes, and antecedent dry days to pre- and post-construction stormwater discharge and volume.
• Development and calibration of a model for extrapolation of monitoring results to the larger sewershed.
• Increasing spatial resolution of hydrologic data collected in the study area by adding more water-level monitoring and sewer-flow-monitoring sites.

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Study description

This study will occur in three phases:

1. Monitoring

• Gather existing groundwater, meteorological, sewer flow, and other relevant data from the Buffalo Sewer Authority (and other sources).
• Install continuous-monitoring sites to measure sewer flow (pre- and post-green infrastructure installation).
• Install observation wells to measure groundwater levels
• Install meteorological equipment to measure ET, precipitation, and soil moisture.
• Install monitoring equipment to measure runoff volume at each green infrastructure installation with the help of the Buffalo Sewer Authority and Watts Engineering.

2. Analysis

• Evaluate water level, sewer flow, and meteorological data to determine the effectiveness of the green infrastructure practices at attenuating and reducing stormwater runoff.

3. Modeling

• Develop a model of rainfall runoff and infiltration for both pre-and post-green infrastructure implementation.
• Use the runoff/infiltration model to construct an urban watershed model calibrated for the Niagara Street site. The urban watershed model has the potential to simulate the benefits of expanding green infrastructure into other areas of Buffalo that may be redeveloped.

Benefits

This study will be used to investigate the effectiveness and performance of green infrastructure over a range of hydrologic and hydraulic conditions, answering questions such as:

• To what extent can the reduction of stormwater runoff by green infrastructure be quantified?
• How do storm-sewer flows and groundwater levels respond to rainfall events? How can the installation of green infrastructure change this response?
• What is the water budget at this site before and after installation? How much stormwater is infiltrating into the soil versus leaving as runoff?
• Are there additional data that would help quantify the effectiveness of the proposed stormwater control measures, both here and at future sites?

This study also addresses two major challenges facing the Great Lakes Region: (1) mitigation of stormwater runoff impacts, and (2) urban revitalization and redevelopment of infrastructure in urban settings. The data collected through monitoring the effectiveness of these green infrastructure installations will be used to help design future stormwater control measures in urban projects across the Great Lakes region. Additionally, innovative methods for monitoring stormwater control measures will be developed during the course of this study, producing data that could improve the design, construction, and assessment of green infrastructure nationally.