Marketing Paragraph: Statement of Purpose: Wildfires are increasing due to extreme temperature and precipitation changes due to climate change. It is critical to understand how the landscape and groundwater processes respond and recover after fire. This work focuses on surface-groundwater interactions in different post-fire environments by monitoring infiltration, soil characteristics changes, water quality, runoff, and sediment discharge through soil column and hillslope experiments. We also used MODFLOW6 to model groundwater processes in burned and unburned conditions. This work will provide information about post-fire landscapes through a hydrologic lens and can aid in post-fire watershed management and rehabilitation work.
Full Abstract: Complete Proposal for Your Session:Wildfires impact the landscape, changing physical soil properties, vegetation structure, and the relative partitioning between interception, infiltration, runoff, and subsurface storage. This research contributes to understanding post-fire changes in surface and subsurface flows and water quality under a range of land use conditions. We constructed a rainfall simulator, and four experimental soil columns and four experimental hillslopes to represent burned conditions and hydrologic processes in urban, riparian, chaparral, and forested areas in the San Diego, California region. Hydrophobicity and hydraulic conductivity were measured before rainfall simulations in both setups. We measured soil water volume content and soil matric potential after rainfall at different depths of the soil columns. Infiltrated water was collected throughout the soil column experiment and analyzed for Dissolved Organic Carbon (DOC) and Total Dissolved Nitrogen (TDN). We also measured the experimental hillslope runoff rate, total excess runoff volume, and total sediment discharge. Soil water volume content and soil matric potential were measured after rainfall simulation at different depths of the hillslopes. Finally, we parameterized MODFLOW6 with our experimental measurements for burned conditions to predict groundwater flow in post-fire landscapes. Model simulations were compared with unburned conditions to investigate short- and long-term impacts on subsurface hydrologic processes. While we expect changes in soil properties that would decrease the infiltration rate and increase the rate of runoff in the short term due to post-fire hydrophobicity, less is known about subsurface processes. The results from this work have implications for managing landscapes, water quality, sediment discharge, and groundwater in watersheds prone to fire and for post-fire watershed rehabilitation.
Learning Objectives:
At the conclusion of this presentation, attendees will:
Identify and explain the key hydrological changes that occur in post-fire landscapes, such as increased runoff, erosion, and altered water quality.
Understand the mechanisms by which wildfires can alter groundwater recharge and subsurface flow patterns.
Critically evaluate the limitations of current modeling approaches in predicting post-fire hydrological changes.
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