DOI: 10.5281/zenodo.17836579
title: Lidar mapping of post-wildfire debris flows from source to sink: 2025 Eaton Fire, Los Angeles County

description: This archive includes supplementary data and code for the following publication: 

Geyman, E.C., Chen, Z., Lindsay, D.N., DiBiase, R.A., and Lamb, M.P. Source-to-sink mapping reveals the dry origins of post-wildfire debris flows. Submitted for review. 2025.

This study analyzes (i) pre-fire, (ii) post-fire, and (iii) post-rainfall airborne lidar data over the Eaton Fire burn area (January 2025, Los Angeles County) to construct a source-to-sink sediment balance for post-wildfire sediment mobilization and debris flows. This analysis produces a spatially-explicit budget for sediment erosion and deposition, including an attribution for how much of sediment mobilization occurred through dry processes (pre-rainstorm) vs. wet processes (syn-rainstorm). See the above manuscript for details. 

The data can be viewed as a simple webmap at: https://egeyman.github.io/EatonFire-DebrisFlows/ 

 

README:

The dataset is organized into 4 folders:

 

1. Catchment statistics. 

2. Topographic change maps. 

3. Other GIS data. 

4. Matlab code.

 

The compressed size of the dataset is 1.9 GB and the uncompressed size is 5.3 GB. 

 

 

Each folder is described in more detail below.

 

1. Catchment statistics.

 

This folder contains an Excel (.xlsx) spreadsheet with summary statistics for each of the n = 25 catchments analyzed in the Eaton Fire burn area. The summary statistics include variables such as the catchment area, the latitude and longitude of the debris basin, the volume of material delivered to the debris basin during the Feb. 13 2025 storm event (which produced widespread debris flows), and the lidar-measured surface elevation and volume changes during the dry loading (pre-fire to post-fire) and rainstorm (post-fire to post-storm) phases. There is a separate tab in the spreadsheet (labeled 'basin_data_readme') that describes in detail each variable in the spreadsheet.

 

2. Topographic change maps. 

 

This folder contains 0.5 meter gridded geotiff files recording the surface elevation change (dz)  during the two phases:



The dry-loading phase (pre-fire to post-fire): "Eaton_dZ_BA_final.tif"

The rainstorm phase (post-fire to post-rainfall): "Eaton_dZ_CB_final.tif"


The dates of the analyzed airborne lidar surveys are:



Pre-fire survey: August-October, 2023

Post-fire survey: January 21, 2025

Post-rainstorm survey: February 20, 2025 


The Eaton Fire began on January 7, 2025, and the major debris-flow-producing rainstorm was on February 13, 2025. See manuscript for additional details about each airborne lidar dataset. In addition to the maps of surface elevation change, this folder contains a gridded 0.5 meter digital elevation model (DEM) (pre-fire USGS DEM) that is sampled to the same grid as the surface elevation change (dz) maps. This basemap DEM is useful for visualizing the dz maps; the dz maps are best visualized by plotting them as a semi-transparent layer over a hillshade DEM. A scale bar of -3 meters to +3 meters (dz) captures most of the range of observed topographic change. 

 

3. Other GIS data.

 

This folder contains georeferenced .tiff (geotiff) files of gridded datasets in the Eaton Fire burn area, as well as vector shapefiles (.shp) of polygon outlines of the mountain catchments and the debris basins. All geospatial data are in the projected coordinate system EPSG:6340 - NAD83(2011) / UTM zone 11N. The files available in the GIS_data folder are:



Eaton_NV5_flow_acc_1m.tif: Flow accumulation map calculated using the post-fire DEM, available for download here.

DEM_USGS1m_cropped.tif: 1 meter gridded digital elevation model (pre-fire), available for download on OpenTopography.

R_deposit.tif: Modeled ravel deposit thickness map, based on applying the 2D numerical ravel routing code from DiBiase et al. (2017) (see Methods section of manuscript for additional details).

USGS_Eaton_Basin_Modified_6340.shp: Polygon outlines of the analyzed catchments in the Eaton Fire burn area. The boundaries are modified from the catchment outlines published by the USGS as part of the Post-Fire Debris Flow Hazard Assessment.

LA_DB_poly_for_volume_calc_6340.shp: Polygon outlines of the accumulation zones in each debris basin. Used to calculate the debris basin deposition.

Eaton_dz_areas_omit.shp: Polygon outlines of zones in the Eaton Fire burn area that produced anomalous dz estimates. We mask out these regions of anomalous dz when computing the catchment-wide topographic change.

USGS_basin_mask.shp: Polygon outline covering the area of the mountain catchments analyzed in this study. 


The data in this folder are used by the Matlab scripts (see below) to produce the figures in the manuscript. 

 

4. Matlab code.

 

This folder contains the main script "Eaton_Fire_analysis.m", which analyzes the topographic change across the Eaton Fire burn area and produces the main figures in the manuscript. This code was written and tested on Matlab R2023b, and it requires functions from TopoToolbox, which can be downloaded here. The total time to run the Eaton_Fire_analysis.m script (start to finish) is 141 seconds on a 2024 MacBook Pro.