Reach-scale geomorphic characteristics influencing post-fire river response in mountain streams, Colorado, USA

Numerous 3rd-order mountain catchments within the Cache la Poudre (Poudre) River basin in the Colorado Front Range, USA burned severely and extensively during the 2020 Cameron Peak fire. Many of these catchments experienced debris flows and flash floods triggered by convective storms after the fire. The downstream effects of the debris flow sediment varied along a continuum from attenuated and largely contained within the catchment, through contributing to a pre-existing debris fan at the catchment outlet, to releasing substantial volumes of water and sediment to the Poudre River. We conducted longitudinally continuous surveys within seven of these catchments to measure reach-scale characteristics. These characteristics quantify the reach-scale geomorphic, vegetation, and burn characteristics, with a particular focus on elements that introduce inter- and intra-reach spatial heterogeneity including channel planform, beaver modified topography, the distribution of channel and floodplain l..., We conducted a longitudinal reach survey within each study catchment. The survey started at the drainage divide, moving downhill to find the first evidence of channelization and follow it to the stream head. We followed the river downstream, defining the boundaries between reaches by field-observed relative valley and channel geometry using a Garmin GPSMAP 66st and a Garmin eTrex10 with 3-m horizontal accuracy. Within each reach I documented burn status, vegetation type, basal area, channel planform, channel bedform, bankfull width, floodplain width, number of channel and floodplain jams, and number of beaver berms. Burn status was documented categorically in the field as burned, unburned, or mixed. Vegetation type was noted categorically as conifer, willow, aspen, or herbaceous based on the species present, where herbaceous denoted a lack of trees rather than implying that there was no herbaceous vegetation where other species were present. Basal area of the river corridor forest was m..., , # Data from: Reach-scale geomorphic characteristics influencing post-fire river response in mountain streams, Colorado, USA

Reach-scale parameters collected in the field during longitudinal surveys. Each reach is a segment of river corridor that has common geometry (i.e. continuous valley width, slope, etc) or is bounded by the confluence with a tributary. Data were collected in the summer of 2023 at sites that burned in the Cameron Peak fire in 2020.

## Description of the data and file structure

ReachVariableKey: a table that defines each of the variables for each reach including category, variable name, units if applicable, description of methods, and format.

ReachData: a file with variables for each reach.

Reach boundaries are coordinates for the upstream point of each reach. The downstream boundary is the upstream reach coordinate of the next most downstream reach. Reaches are numbered using reach IDs which are made up of a site code (LBC for Little Beaver Creek) and a number i...