[Fires] Adding Rate of Spread as output based on Rothermel's model

[angehung5]

I have a python script to calculate the rate of fire spread (ROS) using Rothermel's approach (Rothermel 1972; Andrews 2018). I reclassify the 13 standard fuel types (Table 8a in Andrews 2018) into 4 (grass, brush/slash, timber/hardwood, logging slash).

Input:

• Fuel type
• Fuel moisture (%)
• Terrain slope
• Wind speed (ft/min)

Output:

• Rate of spread (ft/min)

The full parameter list can be found in /groups/ESS/whung/canopy_wind/rothermel_spread.py
Prescribed fuel parameters (e.g. total fuel loading (W0)) are adapted from the Table 8a in Andrews (2018). Fuel bulk density (rho) and pack ratio (beta) are calculated from W0 and fuel bed depth instead of using the static values.

Example of ROS:

After discussed with @drnimbusrain, we think it will be great to extend canopy-app's capability by adding ROS calculation based on Rothermel's model. To add this function, several things needed to be think of:

• Map fuel categories/parameters based on VIIRS AST
• How to get fuel moisture content - There were some presentations on AMS fire meeting about getting fuel moisture approximation from humidity. We may contact them for details
• Get terrain slope
• How to apply it to operational system? How to relate the grid cell by grid cell ROS to the overall fire spread - Maybe check RFS-Fire?

[drnimbusrain]

Amazing Wei-Ting!!! Can't wait to get working on this.

…

On Tue, Jul 25, 2023, 12:52 PM Wei-Ting Hung ***@***.***> wrote: I have a python script to calculate the rate of fire spread (ROS) using Rothermel's approach (Rothermel 1972 <https://www.fs.usda.gov/rm/pubs_int/int_rp115.pdf>; Andrews 2018 <https://www.fs.usda.gov/rm/pubs_series/rmrs/gtr/rmrs_gtr371.pdf>). I reclassify the 13 standard fuel types (Table 8a in Andrews 2018) into 4 (grass, brush/slash, timber/hardwood, logging slash). Input: - Fuel type - Fuel moisture (%) - Terrain slope - Wind speed (ft/min) Output: - Rate of spread (ft/min) The full parameter list can be found in /groups/ESS/whung/canopy_wind/rothermel_spread.py Prescribed fuel parameters (e.g. total fuel loading (W0)) are adapted from the Table 8a in Andrews (2018). Fuel bulk density (rho) and pack ratio (beta) are calculated from W0 and fuel bed depth instead of using the static values. Example of ROS: [image: rothermel_test] <https://user-images.githubusercontent.com/107704243/255969963-4bde4b48-a0af-44d8-bc7f-290a13741cf2.jpg> After discussed with @drnimbusrain <https://github.com/drnimbusrain>, we think it will be great to extend canopy-app's capability by adding ROS calculation based on Rothermel's model. To add this function, several things needed to be think of: - Map fuel categories/parameters based on VIIRS AST - How to get fuel moisture content - There were some presentations on AMS fire meeting about getting fuel moisture approximation from humidity. We may contact them for details - Get terrain slope - How to apply it to operational system? How to relate the grid cell by grid cell ROS to the overall fire spread - Maybe check RFS-Fire? — Reply to this email directly, view it on GitHub <#81>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGLFYNSY2CUQFIW5UC4VXZ3XR72VPANCNFSM6AAAAAA2XLHNRU> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[angehung5]

A great discussion with Patrick today! Few ideas about adding ROS calculation to canopy-app.

1. It should be easier to code up my python ROS model into canopy-app in its entirety. We could map VIIRS vtype classification fuel types based on Scott and Burgan 2005 paper, something like what we did for the plant shape function. A simple classification but should be enough for our scale.

2. Also, we could run Rotherel's model over a range of conditions (e.g. more case studies) to get functional linear/exp or some fit equations to more simply use in canopy-app as a function of midflame wind speed.

[drnimbusrain]

Great Wei-Ting! I think ultimately we could pursue both options in canopy-app for easy comparison of speed and accuracy of the different approaches.

…

On Thu, Aug 3, 2023, 8:00 PM Wei-Ting Hung ***@***.***> wrote: A great discussion with Patrick today! Few ideas about adding ROS calculation to canopy-app. 1. It should be easier to code up my python ROS model into canopy-app in its entirety. We could map VIIRS vtype classification fuel types based on Scott and Burgan 2005 paper <https://www.fs.usda.gov/rm/pubs_series/rmrs/gtr/rmrs_gtr153.pdf>, something like what we did for the plant shape function. A simple classification but should be enough for our scale. 2. Also, we could run Rotherel's model over a range of conditions (e.g. more case studies) to get functional linear/exp or some fit equations to more simply use in canopy-app as a function of midflame wind speed. — Reply to this email directly, view it on GitHub <#81 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AGLFYNQQ72V4JUPITSWQVZ3XTQ3QFANCNFSM6AAAAAA2XLHNRU> . You are receiving this because you were assigned.Message ID: ***@***.***>

[drnimbusrain]

@angehung5 I've been thinking, dependent on issue #66 and adding PAVD profiles to canopy-app, if we can advance the ROS developments in canopy-app to include a new index we develop. I am thinking of how critical the vertical vegetation distribution and gaps (i.e., the PAVD) could be for identify events of rapid vertical (and related faster horizontal) fire spread. I think this could be very useful in our UFS developments/proposals in canopy-app. It could be called something like the Fire Vertical Vegetation Index (FVVI), or just Fire Vertical Index (FVI), or similarly Vertical Fire Index (VFI). Essentially, it would depend on vegetation type, PAVD distribution, Fire Intensity, Flame Height, etc., and the "VFI" would be higher if there are relatively high values extending from forest canopy top to surface, , thus indicating the potential for rapid vertical fire spread and crowning, thus increasing potential for faster horizontal ROS. In fact, the Rothermal model (used in WRF-FIRE that is to be implemented in UFS) does not apply to crown fires in overstory trees, and is a significant limitation thus for calculating the ROS in large fires. Thus, I think we could develop something like a "VFI", include it as a diagnostic, and also use it to somehow advance the ROS calculations (assuming we also base it on Rothermal as the base formulation) in canopy-app for UFS. I think we could/should use the mechanistic FRaME model and heat transfer from flames through vegetation strata to help develop the VFI parameterization.