Session 2A: Environmental (In)justice of SWI

June 11
2:15 - 3:45 pm

Choptank Ballroom

Equity Considerations in Saltwater Intrusion Adaptation
Tiana Noelani Thorp
University of Delaware

Saltwater intrusion (SWI) is a pervasive natural phenomenon that has gained worldwide attention as mankind faces climate change. The preliminary findings of our global overview of SWI impacts on infrastructure identified threats of SWI to ten types of infrastructure over the last decade on all seven continents in 66 countries. Adapting to climate change threats like SWI requires a reassessment of the decisions that led Western nations to their present environmental crossroads. The IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems highlights the need to incorporate Indigenous and local knowledge (ILK) into sustainable development risk management and decision making. This presentation explores essential SWI equity considerations that were highlightable Western blind spots in the global overview of SWI impacts on infrastructure. These include national sovereignty, colonial histories, helicopter research, and extractive “collaboration” with Indigenous peoples.

Implications of Sea Level Rise on Septic Systems and Private Wells
Andrew Lazur
University of Maryland Extension

Climate change and associated sea level rise (SLR) increasingly is being observed to be impacting important, yet “out of sight” underground infrastructure including septic systems and drinking water wells. Negative impacts on this infrastructure can result in serious environmental and public health issues and underserved communities are at greater risk. In the case of private drinking wells, SLR can degrade water quality by saltwater intrusion or by increased incidence of well head flooding. Subsequent elevated chloride concentrations can not only impact water taste, but also increases the corrosivity of water which subsequently increases heavy (lead, copper, and zinc) from plumbing, but also mobilizes other metals (cadmium, chromium, mercury) within soils to groundwater. Risk remediation can be implementation of relatively simple wellhead protection practices, utilization of existing water filtration systems selected for specific well water quality, and implementation of groundwater withdrawal management policy/strategies. Characteristics of coastal hydrogeology may influence the degree of well and water quality contamination by saltwater intrusion. Climate change impact on septic systems is complex with remediation and sustainable solutions presenting significant challenges. By design, septic systems rely on a prescribed soil quality and depth for a substantial portion of treatment of nutrients, organics, and pathogens. With SLR and elevated water table, the depth of soil is reduced, subsequently decreasing wastewater treatment effectiveness. Additionally, elevated chloride and sodium impacts important treatment characteristics of soil including structure and microbial communities. Elevated chloride and sodium can also interfere with the function of advanced treatment units by suspending organics and reducing beneficial microbial population. Strategies to remediate SLR impact on septic systems vary depending on site conditions and proximity to existing or planned sewer infrastructure. Local smart growth policy can play a role in future housing development. Connection to wastewater treatment plants (WWTP) is another strategy, though WWTP can be subject to SLR impacts and significant investment costs hinder expansion and will not serve all households. Existing onsite treatment technologies such as elevated soil dispersal systems, e.g. mounds or drip dispersal, or advanced treatment units are commonly employed in areas with elevated water tables and offer comparable or greater treatment to WWTPs. As with wells, low-income households and communities are especially faced with challenges in dealing with failing systems. As SLR impacts increase and the number of failing systems increase in the future, a commitment to truly innovative and alternative approaches are needed. These and other challenges and possible solutions will be discussed.

Surge, salt and saturation: Integrated simulation of sea water overwash, infiltration and salinization of coastal soils
Hanne Borstlap
University of Virginia

Rural communities on the Eastern Shore of Virginia (ESVA) are particularly vulnerable to effects of climate change including increases in the severity of coastal storms, droughts, and salinization from sea level rise and coastal surge intensity. Following previous research integrating surge inundation potential with freshwater flushing to assess salinization potential, we consider the interactions between saltwater inundation depths with watershed freshwater processes. We develop models that integrate event scale surge inundation dynamics with ecohydrological controls on surface and subsurface hydrologic flux. ADCIRC is first used to simulate current and potential future shoreline surge levels, and the extent and depth of seawater inundation of coastal areas. We conceptualize these levels as event based surface detention store dynamics, which are then input to a coastal watershed ecohydrological model. RHESSys estimates antecedent soil water and groundwater levels, assimilates the event based detention store dyamics and estimates the depth of salt water infiltration. RHESSys then simulates post surge event freshwater flushing to estimate long term impacts and vulnerability to surge events. The integrated model has been set up across multiple watersheds along the ESVA and Maryland. We discuss adaptation of both component models, challenges in simulating shallow groundwater in flat, irrigated coastal regions, and potential to assess both event dynamics and long term vulnerability in current and future climate and SLR scenarios.