Assessment Data Fields¶

This page describes the data fields in the segments and basins layers of the GeoJSON.zip and Shapefile.zip assessment results. (Note that the perimeter and basins data layers do not have data fields).

Segment ID¶

Field	Description
`SegmentID`	A unique integer identifier for each stream segment in the network. Segment IDs are sorted in ascending order, but may not be sequential. The Segment ID for a basin is the ID of the most downstream stream segment in the basin.

Likelihood, Volume, and Combined Hazards¶

The likelihood, volume, and combined hazard results are computed for a series of design storm scenarios. These design storms are selected by specifying a peak 15-minute rainfall intensity in millimeters per hour. The following table details the naming conventions for likelihood, volume, and combined hazard results for a generic design storm. The table uses the substitution iii to indicate the peak 15-minute rainfall intensity as an integer.

Note

Although the iii substitution uses three characters, real 15-minute rainfall intensities are not zero-padded, so may vary from 1 to 3 digits.

Field	Units or Range	Description
`H_iii`	Either 1, 2, or 3	Combined hazard class for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`H_iii_LG`	NA	Legend entry of the combined hazard class for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`P_iii`	From 0 to 1	Debris-flow likelihood for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`P_iii_LG`	NA	Legend entry of debris-flow likelihood for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`V_iii`	Cubic meters	Potential sediment volume for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`V_iii_LG`	NA	Legend entry for potential sediment volume for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`Vmin_iii`	Cubic meters	Lower bound of the 95% confidence interval of potential sediment volume for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.
`Vmax_iii`	Cubic meters	Upper bound of the 95% confidence interval of potential sediment volume for a design storm with a peak 15-minute rainfall intensity of `iii` mm/hour.

Rainfall Thresholds¶

The rainfall threshold model is run for a series of design probabilities. Additionally, the thresholds for each probability are modeled for 15-minute, 30-minute, and 60-minute rainfall durations. The following table details the naming conventions for the estimated rainfall thresholds. The table uses the substitution dd to indicate a rainfall duration (either 15, 30, or 60). The table also uses the substitution pp to indicate a design probability as a percentage.

Field	Units or Range	Description
`Rdd_pp`	Millimeters of accumulation	Peak rainfall accumulation over a `dd` minute interval required for a debris-flow probability of `pp` percent.
`Idd_pp`	Millimeters per hour	Peak `dd`-minute rainfall intensity required for a debris-flow probability of `pp` percent.
`Idd_pp_LG`	NA	Legend entry for peak `dd`-minute rainfall intensity required for a debris-flow probability of `pp` percent.

Hazard Model Inputs¶

Fields that record values used as inputs to hazard models.

Field	Units or Range	Description
`Terrain_M1`	From 0 to 1	Terrain variable for the M1 likelihood model. The proportion of catchment area that is both (1) burned at moderate or high severity, and (2) has a slope ≥ 23 degrees.
`Fire_M1`	Unitless	Fire variable for the M1 likelihood model. Mean catchment dNBR divided by 1000.
`Soil_M1`	Inches per hour	Soil variable for the M1 likelihood model. Mean catchment KF-factor.
`Bmh`	Square kilometers	Catchment area burned at moderate or high severity.
Relief	Meters	Watershed vertical relief.

Catchment Characteristics¶

Fields that characterize stream segment catchment basins.

Field	Units or Range	Description
`Area`	Square kilometers	Total catchment area.
`BurnRatio`	From 0 to 1	The proportion of catchment area that is burned.
`DevArea`	Square kilometers	The catchment area that is classified as human development.

Segment Characteristics¶

Fields that characterize stream segment flow paths. These fields are only included in the segments data layer, as they are not defined for the basins.

Field	Units or Range	Description
`ConfAngle`	Degrees	The mean confinement angle along a stream segment’s flow path.
`Slope`	Unitless gradient (rise over run)	The mean slope gradient along a stream segment’s flow path.