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8. Output Data Dictionary
This page contains descriptions of the primary output data from the NWC Inundation Mapping codebase. This page will be updated over time as the codebase evolves.
This file contains HAND-derived variables describing the channel/overbank geometry and corresponding synthetic rating curve attributes for each flowline.
Standard Outputs in each hydroTable.csv
Variable | Description | Units |
---|---|---|
AREASQKM | Catchment area (HydroID catchment) | square kilometers |
BedArea (m2) | Inundated ground-surface area | square meters |
discharge_cms | Calculated discharge from Manning's equation (modified if barc_on or vmann_on or adjust_src_on = True) |
cubic meters per second |
feature_id | Common identifier value for each NWM Flowline | |
HUC | Unique watershed hydrologic unit code (HUC8) | |
HydraulicRadius (m) | Inundated hydraulic radius (reach-averaged) (modified if barc_on = True ) |
meters |
HydroID | NWC FIM unique identifier for stream segments/catchments | |
LakeID | Unique identifier for lake water bodies (values = -999 represent a non-lake segment) | |
LENGTHKM | Length of HydroID flowline (pixel-to-pixel calculated distance) | kilometers |
ManningN | Manning's roughness (includes any adjustments applied - see barc_on , vmann_on , & adjust_src_on ) |
unitless |
NextDownID | Common identifier of the next downstream flowline (HydroID) | |
Number of Cells | Number of HAND cells inundated at a given stage | |
order_ | Strahler stream order value (obtained from USGS NHD Flowline attributes) | |
SLOPE | Channel thalweg longitudinal slope | unitless |
stage | River height above the HAND-derived catchment outlet | meters |
submitter | Text identifier for tracking the source of the most recent observation data provided to the localized calibration/optimization routine | |
SurfaceArea (m2) | Water surface area of inundated cells | square meters |
TopWidth (m) | Reach averaged width of the water surface (inundated area / stream length) | meters |
Volume (m3) | Water-occupied volume (modified if barc_on = True ) |
cubic meters |
WetArea (m2) | Water-occupied cross-section area (reach-averaged) (modified if barc_on = True ) |
square meters |
WettedPerimeter (m) | Water-occupied wetted perimeter (reach-averaged) | meters |
Additional Output Variables appended during Synthetic Rating Curve Post-processing
Variable | Description | Units |
---|---|---|
adjust_ManningN | Manning's roughness value calculated during localized calibration/optimization routine (computed from observations) | |
adjust_src_on | Boolean identifying if localized calibration/optimization adjustments are applied to the ManningN variable | |
barc_on | Boolean identifying if bathymetry adjustment is applied to the discharge calculation (True=applied; False=not-applied) | |
chann_volume_ratio | Channel (vs. overbank) ratio of the total inundated volume | unitless |
default_discharge_cms | Previous value of discharge_cms (differs from discharge_cms when adjust_src_on=True ) |
|
default_ManningN | Previous value of ManningN (differs from ManningN when adjust_src_on=True ) |
|
last_updated | Date/time stamp identifying the most recent observation data provided to the localized calibration/optimization routine | |
orig_discharge_cms | Original calculated discharge from Manning's equation (prior to rating curve modifications) | cubic meters per second |
orig_HydraulicRadius (m) | Original inundated hydraulic radius (reach-averaged) (prior to rating curve modifications) | meters |
orig_ManningN | Default Manning's roughness (FIM3 applies initial value of 0.06 globally) | unitless |
orig_Volume (m3) | Original water-occupied volume (prior to rating curve modifications) | cubic meters |
orig_WetArea (m2) | Original water-occupied cross-section area (reach-averaged) (prior to rating curve modifications) | square meters |
vmann_on | Boolean identifying if variable/composite roughness is applied (True=applied; False=not applied) |
Multiline layer containing DEM-derived stream segments with crosswalked NWM feature_id attribute. Attributes:
Variable | Description | Units |
---|---|---|
areasqkm | Catchment area (HydroID catchment) | square kilometers |
feature_id | Common identifier value for the corresponding NWM Flowline | |
fid | Unique ID key | |
From_Node | Upstream node ID | |
HydroID | NWC FIM unique identifier for stream segments/catchments | |
LakeID | Unique identifier for lake water bodies (values = -999 represent a non-lake segment) | |
LengthKm | Length of HydroID flowline (pixel-to-pixel calculated distance) | kilometers |
ManningN | Default ManningN value (channel) | |
max_thal_elev | Maximum thalweg elevation value within the HydroID catchment | meters (NAVD88) |
med_thal_elev | Median thalweg elevation value within the HydroID catchment | meters (NAVD88) |
min_thal_elev | Minimum thalweg elevation value within the HydroID catchment | meters (NAVD88) |
NextDownID | Common identifier of the next downstream NWM Flowline (feature_id) | |
order_ | Strahler stream order value (obtained from USGS NHD Flowline attributes) | |
S0 | Channel thalweg longitudinal slope | unitless |
src_calibrated | Boolean attribute identifying whether any localized calibration has been applied to the synthetic rating curve | |
To_Node | Downstream node ID |
Multipolygon layer containing a catchment polygon for each HydroID stream segment with crosswalked NWM feature_id attribute. Attributes:
Variable | Description | Units |
---|---|---|
areasqkm | Catchment area (HydroID catchment) | square kilometers |
feature_id | Common identifier value for the corresponding NWM Flowline | |
fid | Unique ID key | |
From_Node | Upstream node ID | |
HydroID | NWC FIM unique identifier for stream segments/catchments | |
LakeID | Unique identifier for lake water bodies (values = -999 represent a non-lake segment) | |
LengthKm | Length of HydroID flowline (pixel-to-pixel calculated distance) | kilometers |
max_thal_elev | Maximum thalweg elevation value within the HydroID catchment | meters (NAVD88) |
med_thal_elev | Median thalweg elevation value within the HydroID catchment | meters (NAVD88) |
min_thal_elev | Minimum thalweg elevation value within the HydroID catchment | meters (NAVD88) |
NextDownID | Common identifier of the next downstream NWM Flowline (feature_id) | |
order_ | Strahler stream order value (obtained from USGS NHD Flowline attributes) | |
S0 | Channel thalweg longitudinal slope | unitless |
src_calibrated | Boolean attribute identifying whether any localized calibration has been applied to the synthetic rating curve | Boolean |
To_Node | Downstream node ID |
Relative elevation model raster with pixel values representing the height above nearest drainage (Note: negative values removed and masked to the HUC boundary)
Raster with pixel values representing the catchment HydroID value
Multipoint layer identifying point locations where stream segments are split based on lake boundaries and input threshold distance.
Hydro-conditioned digital elevation model raster (i.e. includes pit removal, levee burn-in, thalweg elevation conditioning, etc.)
Raster of flow direction from each grid cell to one of its adjacent or diagonal neighbors (D8), calculated using the direction of steepest descent.