Abstract: Salinity is increasing in freshwater reaches of rivers around the globe, including in the Delaware River Basin, located in the mid-Atlantic region of the United States. This study estimates the causal effect of land use changes on in-stream salinity concentrations in the Delaware River Basin. A 1% increase in urbanized areas increases salinity by 3 mg/L, or about 16%. Freezing precipitation, which leads to salt from deicing applications, also increases salinity, particularly in watersheds with developed land uses. Simulating salinity levels based on land use and climate projections indicates that, even in a warming climate with reduced deicing, more development increases in-stream salinity.
Keywords: Urbanization; Land management; Water pollution

Stormwater runoff is a growing source of urban water pollution, costing cities billions of dollars. We investigate peer effects in a voluntary residential green stormwater infrastructure program that mitigates stormwater runoff. Our identification strategy exploits households’ relative position in eligible sewersheds, generating plausibly exogenous variation in eligible peers. Peer adoption causes a 0.2% increase in the annual adoption probability, a 66% increase relative to the mean. The policy reduces compliance costs by $85–235 million, of which roughly 40% is due to peer effects. Contrary to prior claims, we find no evidence that adoptions increase neighborhood property values.

This study investigates the relationship between historical redlining and increased urban flood risk, particularly affecting marginalized communities. Redlining by the Home Owners Loan Corporation (HOLC), which assessed neighborhood creditworthiness, is linked to higher flood exposure in low-elevation areas. Analyzing HOLC maps for 160,000 homes across four US states using spatial and econometric models, the study finds redlined neighborhoods are 7.6% more likely to flood, with a 0.31% higher flood risk for homes Post-Hurricane Sandy, property values in these areas reflected the complex interplay of flood risk, housing prices, and gentrification. The findings highlight the enduring impact of discriminatory housing policies on disaster vulnerability and the nuanced effects on property values.

This project focuses on developing workflows and tools to assess multi-hazard flood risks for U.S. Navy Bases along the coast, with the initial application at the Patuxent River Naval Base on the Chesapeake Bay. Coastal communities, including military installations, are exposed to multi-hazard flooding events, exacerbated by expanded coastal infrastructure and varied flood drivers. These risks arise from both tropical cyclones (TCs) and extratropical cyclones (ETCs), leading to storm surges, riverine (fluvial) flooding, and precipitation-driven (pluvial) runoff. The region around the Patuxent River Naval Base is susceptible to these combined flood risks and serves as a pilot study to develop the approach.

Traditional risk management strategies, often focused on TCs, overlook the diverse nature of flooding, especially the impacts of ETCs and the compound effects of fluvial and pluvial factors besides storm surges and waves. This oversight can be important for locations like the Patuxent River Naval Base, where operational schedules and economic considerations are both important considerations that are impacted from flooding. Given the dynamic nature of coastal flood risks, exacerbated by climate change, there is a need for a comprehensive assessment approach. This approach must integrate multi-flood hazard modeling with current engineering practices and research advancements to be successful. The aim of this project is not only to evaluate economic losses but also to consider operational disruptions, improving decision-making tools for strategic planning and mitigation efforts under changing climate conditions at the naval air base.