Topographic Change, Occupancy Maps, and Classified Raster Products for the 180° Experimental Alluvial Fan

This archive contains the topographic and activity-mapping data products used to analyse the 180° experimental alluvial fan presented in the manuscript. The experiment was run under constant water and sediment supply, and digital elevation models (DEMs) were collected at 30-minute intervals after stopping the flow and allowing the fan surface to drain. These DEMs were used to generate DEMs of Difference (DoDs), which quantify preserved erosion and deposition over consecutive 30-minute windows. To complement the topographic record, occupancy maps were generated from optical-flow analysis of overhead imagery. For each 30-minute window, 1-minute activity masks were summed and divided by 30 so that each pixel records the fraction of 1-minute intervals during which it was active. These occupancy maps therefore capture both the spatial extent and the temporal persistence of visible surface motion across the fan surface. Classified rasters were then produced by comparing the occupancy-derived activity footprint with the thresholded DoD footprint for the same 30-minute interval. Each classified raster distinguishes three classes: overlap between the two methods, DoD-only change, and activity-only areas where optical flow detected motion but no net topographic change was preserved above the DoD threshold. Together, these files document the paired process-outcome framework used in the study and allow users to examine where activity occurred, where it produced measurable topographic change, and where the two records diverged. The archive is organized to preserve the full analysis sequence, from raw DEMs to processed DEMs, DoDs, occupancy rasters, classified rasters, summary tables, and the R Markdown workflow used to generate the DEM- and DoD-based products. Contents of the zip file 01_raw_dem180deg: raw DEMs for all surveyed 30-minute intervals 02_modified_dems: preprocessed DEMs cropped to the fan extent, transformed to the local apex-centred coordinate system, and masked to remove areas outside the analysed fan surface 03_DoD: DEMs of Difference generated from consecutive DEM pairs for each 30-minute interval 04_DOD_Plots: hillshade maps with overlaid erosion and deposition for each DoD 05_Occupancy_Raster: 30-minute occupancy rasters derived from 1-minute optical-flow activity masks 06_Classified_Raster: classified rasters comparing occupancy footprints with thresholded DoD footprints 07-CSV_files: summary tables containing DoD metrics and related analysis outputs Fan_DEM_DoD_workflow.Rmd: R Markdown workflow for DEM preprocessing, DoD generation, plotting, and metric calculation