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Enhancing spatial weather dynamics in the LANDIS-VELMA model linkage to assess the effects of wildfire on water quality
Citation:
Venable, Karretta AND JohnM Johnston. Enhancing spatial weather dynamics in the LANDIS-VELMA model linkage to assess the effects of wildfire on water quality. 2023 AMS Annual Meeting, Denver, CO, January 08 - 12, 2023.
Impact/Purpose:
This focus of this research is the development of a coupled landscape widlfire model (LANDIS-II) with and eco-hydrology model (VELMA). The coupled LANDIS-VELMA will combine the strengths of both models, providing unique capabilities for linking spatial and temporal dynamics of fire spread and fuel consumption (LANDIS-II), with the ability to simulate multi-scale hydrological and biogeochemical controls on water quality and quantity dynamics (VELMA). Important aspects of developing the linked model include calibrating LANDIS-II using a past wildfire event and incorporation of a sediment transport submodel in VELMA to complement existing capabilities for assessing impacts of fire on fate and transport of nutrients and contaminants within watersheds.
Description:
Wildfire activity in western US forests has increased over the last two decades, resulting in increased solids and nutrient loadings to streams, and in some cases threatening drinking water supplies. These increases are attributed to rainfall events and the distribution of water throughout the watershed. Modeling the influence of riparian biomass on watershed dynamics is essential for the protection of aquatic ecosystem health and drinking water quality by understanding interactions between climate, land use change, and complex hydrodynamic-biogeochemical processes. To fully assess these tradeoffs across media requires an integrated modeling platform. The Hayman Fire of 2002, one of the largest and most devastating wildfires in Colorado's recorded history, served as the study area for the linked model application. We utilized the VELMA eco-hydrologic model and the LANDIS plant community model to simulate the Hayman Fire pre- and post-fire conditions. Best performance of prior linked LANDIS-VELMA simulation calibrations, using one weather station and NLDAS daily runoff as validation, had an NSE of 0.663 during 2000 to 2006. The best annual performance of all 6 linked simulations ranged between 0.891 and 0.978 during 2006 in Brush Creek. Postfire, increased runoff and elevated concentrations of carbon and nitrogen impaired the drinking water source quality. Complex terrain in the Front Range generally enhances orographic lifting, promoting extreme differences in localized precipitation events and distribution of water across the region. This research focuses on optimizing the NSE for the case study area through a gridded network of weather drivers and streamflow data using the US EPA’s Hydrologic Micro Services (HMS) Rest API and GDAL with python.
