Analyzing the Magnitude, Variability, and Governance of Infrastructure-Mediated Flows in Urban Watersheds

Georgia State University Research Foundation, Inc., Atlanta GA

Investigators

Abstract

This project investigates how the water cycle within urban watersheds is altered by exchanges of water between the landscape and human infrastructure. The project demonstrates a new framework for analyzing urban water budgets that synergistically integrates qualitative analysis of knowledge, perceptions, and governance of water resources and infrastructures. This research will generate important new knowledge about how infrastructure-mediated flows (IMFs), including inter-basin transfers (IBTs) and the infiltration and inflow (I&I) of rainfall and groundwater into sanitary sewer pipes, fundamentally alter the hydrology of watersheds. The research will reveal how these IMFs strain the capacity of wastewater treatment systems and evaluate how this new knowledge can enhance the effective governance of transboundary water resources. The broader societal impacts of this research include enhancing STEM education and the inclusion of underrepresented groups in STEM fields. The project also includes a summer workshop with local K-12 teachers aimed at integrating concepts of urban hydrology and water governance into curriculum. The project provides research training for undergraduate and graduate students at Georgia State University, a national leader in supporting the educational accomplishments of underrepresented minority students, and elements of the project will be integrated into the curriculum for undergraduate and graduate courses. The U.S. population is becoming increasingly urbanized, resulting in dramatic impacts on urban watersheds and contributing to multiscalar and transboundary water governance challenges. Water withdrawals for municipal consumption have increased greatly, often necessitating politically contentious inter-basin transfers of water. Aging water infrastructure is conducive to infiltration and inflow, whereby a high volume of water permeates sanitary-sewers through pipe fractures and discontinuities. This unnecessarily increases inflow to wastewater treatment plants, while reducing streamflow in local watersheds. Inter-basin transfers and infiltration and inflow remain difficult to quantify, resulting in disparate perceptions of their magnitude and importance. This project answers three fundamental questions about the magnitude, variability, and governance of infrastructure-mediated flows (IMFs) in urban watersheds: (1) how do IMFs impact urban watershed hydrology; (2) how are these impacts perceived and managed by governance authorities and stakeholders; and (3) how will governance decisions be impacted by improved hydrologic characterization of IMFs? The methodology includes a novel formulation of the urban water budget with explicit quantification of the impact of inter-basin transfers and infiltration and inflow. A possible solution is using data representing meteorological variables, potable water flows, sanitary sewer flows, and land-cover characteristics. These data are widely available and promote maximum transferability of the approach. The solution of the urban water budget will be informed by qualitative data gathered from utility managers and water resource stakeholders, thereby leveraging local expertise. The perceptions of IMFs, and responses to new knowledge about them, will be characterized through an iterative set of interviews with managers and stakeholders. Inferences will be made via qualitative-thematic analysis of interview transcripts and quantitative analysis of Likert-scale survey responses. The findings of this project will inform conceptualizations about urban water management and urban sustainability. To demonstrate the utility of this new method and approach, this study focuses on the South River Watershed within the broader Atlanta, Georgia metropolitan area, while the methodological approach and results are applicable across a broad array of urban watershed in the United States. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.