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Natural infrastructure (NI) and nature-based solutions in urban riverscapes can provide a spectrum of environmental, societal, and economic benefits, but widespread implementation of NI strategies remain limited because of their context-dependent nature. Windows of opportunity have opened through legislation and funding to expand NI solutions that address flooding, water quality, air pollution, extreme heat, and environmental equity. System-level approaches may offer these projects a framework that is flexible yet holistic enough to streamline implementation. In fact, a systems approach is essential to realize the potential of NI for equitably achieving these goals, and a critical step includes identification of vulnerabilities (e.g., exposure to environmental harm). The purpose of this study was to support decision makers and managers in prioritizing their urban riverscapes with multiple vulnerabilities: flood risk, water quality, ecosystem function, and environmental inequity. We conducted an urban stream spatial multicriteria decision analysis (MCDA) case study with Charlotte–Mecklenburg Storm Water Services to support equitable and efficient stream reach, floodplain, and watershed planning. Our study assessed the social and ecological characteristics of the system and prioritized vulnerable watersheds and subbasins using a spatial MCDA. We developed an urban stream prioritization framework that could be tailored to complement existing management strategies and also more broadly implemented in other social–ecological systems. 

Urban flooding is a growing threat due to land use and climate change. Vulnerable populations tend to have greater exposure to flooding as a result of historical societal and institutional processes. Most flood vulnerability studies focus on a single large flood, neglecting the impact of small, frequent floods. Therefore, there is a need to investigate inequitable flood exposure across a range of event magnitudes and frequencies. To explore this question, we develop a novel score of inequitable flood risk by defining risk as a function of frequency, exposure, and vulnerability. This analysis combines high-resolution, parcel-scale compounded fluvial and pluvial flood data with census data at the census block group scale. We focus on six census tracts within Athens-Clarke County, Georgia that are highly developed with diverse populations. We define vulnerable populations as non-Hispanic Black, Hispanic, and households under the poverty level and use dasymetric mapping techniques to calculate the over-representation of these populations in flood zones. Inequitable risks at each census tract (approximately neighborhood scale) were estimated for multiple (e.g., 5-, 10-, 20-, 50-, and 100-year) flood return periods. Results show that the relatively greatest flood risk inequities occur for the 10-year flood and not at the largest event. We also found that the size of inequity is dynamic, depending on the flood magnitude. Therefore, addressing a range of events including smaller, more frequent floods can increase equity and reveal opportunities that may be missed if only one event is considered. 

Rapidly growing cities along the Interstate‐85 corridor from Atlanta, GA, to Raleigh, NC, rely on small rivers for water supply and waste assimilation. These rivers share commonalities including water supply stress during droughts, seasonally low flows for wastewater dilution, increasing drought and precipitation extremes, downstream eutrophication issues, and high regional aquatic diversity. Further challenges include rapid growth; sprawl that exacerbates water quality and infrastructure issues; water infrastructure that spans numerous counties and municipalities; and large numbers of septic systems. Holistic multi‐jurisdiction cooperative water resource planning along with policy and infrastructure modifications is necessary to adapt to population growth and climate. We propose six actions to improve water infrastructure resilience: increase water‐use efficiency by municipal, industrial, agricultural, and thermoelectric power sectors; adopt indirect potable reuse or closed loop systems; allow for water sharing during droughts but regulate inter‐basin transfers to protect aquatic ecosystems; increase nutrient recovery and reduce discharges of carbon and nutrients in effluents; employ green infrastructure and better stormwater management to reduce nonpoint pollutant loadings and mitigate urban heat island effects; and apply the CRIDA framework to incorporate climate and hydrologic uncertainty into water planning.