|Goodrich, David - Dave|
Submitted to: American Society Of Civil Engineers Watershed Management Conference
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2005
Publication Date: 7/19/2005
Citation: Goodrich, D.C., Canfield, H.E., Burns, I.S., Semmens, D.J., Hernandez, M., Levick, L.R., Guertin, D.P., Kepner, W. 2005. Rapid Post-Fire hydrologic watershed assessment using the AGWA GIS-based hydrologic modeling tool. Proc. ASCE Watershed Manage. Conf., July 19-22, Williamsburg, VA., 12p., CD-ROM. Interpretive Summary: Numerous large wildfires have occurred throughout the Western United States in the last five years. The damage caused by these wildfires to watershed land cover and soils can be catastrophic. This is turn, can greatly influence how runoff is generated when rain storms occur over a watershed. Severe flooding and erosion can often result after a watershed is burned. To mitigate these effects, land and agency managers often attempt to reseed burned watersheds and install sediment traps shortly after a wildfire. To best target these measures, land managers need to estimate where post-burn runoff will be most severe. A computer model that simulates the processes of runoff and erosion over large watersheds is essential for this task. These models can often require significant data preparation and input to use them. To expedite this task we have developed the AGWA (Automated Geospatial Watershed Assessment hydrologic modeling tool (see: www.tucson.ars.ag.gov/agwa). This tool uses nationally available spatial data sets and several watershed runoff and erosion models. With this tool and a post-fire burn-severity map, land managers can compare the differences in runoff and erosion before and after a fire and thus more accurately deploy mitigation measures. In this presentation AGWA capabilities were demonstrated on the 2003 Aspen fire which occurred north of Tucson, Arizona.
Technical Abstract: Rapid post-fire watershed assessment to identify potential trouble spots for erosion and flooding can potentially aid land managers and Burned Area Emergency Rehabilitation (BAER) teams in deploying mitigation and rehabilitation resources. These decisions are inherently complex and spatial in nature and require a distributed hydrological modeling approach and extensive data requirements. Geospatial tools and readily-available digital sources of pre-fire land cover, topography, and soils combined with rainfall-runoff and erosion models can expedite assessments if properly combined, provided a post-fire burn-severity map is available. The AGWA (Automated Geospatial Watershed Assessment) hydrologic modeling tool was developed to utilize nationally available spatial data sets and both empirical (SWAT) and more process-based (KINEROS2) distributed hydrologic models (see: www.tucson.ars.ag.gov/agwa). Through an intuitive interface the user can select a watershed outlet, perform model discretization and paramterization, and model execution. Model simulation results are imported back into AGWA for graphical display. AGWA can difference results from pre- and post-fire model simulations and display the change on the modeled watershed. This allows managers to identify potential problem areas where mitigation activities can be focused. An overview of AGWA and an application of it to the 2003 Aspen fire north of Tucson, Arizona are discussed herein.