Integrating Urban Hydrology, Social Vulnerability, and Fluvial Ecosystem Modeling into Green Infrastructure and Stream Restoration Planning

This dissertation details research that advances green infrastructure (GI) and stream restoration modeling by integrating an equity objective into GI optimization, experimenting with a novel method of assessing restoration effects on dissolved inorganic nitrogen (DIN) uptake, and developing an integrated model for assessing the impacts of GI on in-stream DIN processing. Urban development has intensified stormwater runoff, flow velocities, and nutrient loads in streams, degrading natural channels and water bodies. To address these issues, stormwater GI and stream restoration are often cited as viable solutions. This dissertation enhances modern GI and restoration modeling in three areas. Chapter 1 explains the research motivations of chapters 2,3, and 4. Chapter 2 details the integration of a spatial social equity objective (LID/GI-Social vulnerability (SVI) index correlation objective) into a GI optimization model, that promotes equitable GI implementation in socially vulnerable areas. Chapter 3 presents a novel adaptation of the Small Streams Hydro-Biogeochemistry Simulator (SSHBS) to assess the impact of various riffle, pool, and meander configurations on DIN uptake dynamics in an urban stream reach. Chapter 4 introduces a watershed-channel hydraulic stream-ecosystem model that is integrated into a single open-source Python notebook to evaluate the effects of GI on in-stream DIN processing.
Chapter 2's analysis details the development of the LID/GI-SVI correlation objectives, which directs optimization algorithms towards runoff management and equitable GI distribution goals and allows for tradeoff analyses between local hydrologic and equity goals. Chapter 3's findings show how SSHBS can be a promising option for process-based assessments of stream restoration designs and how benthic area augmentation, riparian canopy removal, and multi-feature channel designs can enhance simulated net DIN uptake in streams. Chapter 4 highlights the usefulness of an integrated model with results showing that: A relatively low percentage (0.86%) of DIN that enters a local urban stream from the watershed is retained or removed by the stream; Stream zones with higher light combined with lower leaf-litter have greater potential net DIN uptake; Higher groundwater DIN concentrations combined with infiltration-based GI could result in elevated in-stream concentrations and export of DIN.