#INFOSWMM InfoSWMM InfoSWMM_SA

Rules and Ranges the for Hydrology Options in InfoSWMM and InfoSWMM SA

By Robert Dickinson / May 31, 2018

Subcatchment Hydrological (Modeling) – Data Table

This table contains all subwatershed data that is used to estimate the amount of runoff and pollutant yielding from Subwatersheds. For more information on each of the input (data fields) in this table, Subcatchment editor may be referred. The following table is in invert colors and shows the whole first row of the DB Table on separate rows in the image.

Field Description
Subcatchment ID User determined ID. It can only be changed with the Change ID command.
Raingage ID Specify Raingage ID used to input rainfall data to Subcatchment.
Receiving Node ID Node ID for node receiving rainfall hydrograph from Subcatchment.
Subcatchment Area Area of Subcatchment
Subcatchment Impervious (%) Percentage of the Subcatchment covered by impervious surfaces.
Subcatchment Width Characteristic width of the Subcatchment (feet or meters).
Subcatchment Slope (%) Slope of the Subcatchment.
Subcatchment Curb Length Total length of curbs in the Subcatchment (any length units). Used only when pollutant buildup is normalized to curb length.
Snow Pack ID Name of snow pack parameter set (if any) assigned to the Subcatchment.
Manning’s N for Imperv. Portion Manning’s N for overland flow over the impervious portion of the Subcatchment.
Manning’s N for Pervious Portion Manning’s N for overland flow over the pervious portion of the Subcatchment.
Depression Stor. for Imp. Portion Depth of depression storage on the impervious portion of the Subcatchment (inches or millimeters)
Depression Stor. for Perv. Portion Depth of depression storage on the pervious portion of the Subcatchment (inches or millimeters).
% of Imperv. Part w/o Dep. Stor. Percent of the impervious area with no depression storage.
Runoff Routing Destination Choice of internal routing of runoff between pervious and impervious areas:

  • IMPERV – runoff from pervious area flows to impervious area.
  • PERV – runoff from impervious flows to pervious area.
  • OUTLET – runoff from both areas flows directly to outlet.
% of Runoff Routed to Destination Percent of runoff routed between subareas.
LENGTH Characteristic length of the Subcatchment (feet or meters).
CNTRD_DIST Distance from centroid of Subcatchment to outlet (feet or meters).
NRCS_CN NRCS Curve Number
DCIA_LEVEL Directly Connected Impervious Area Level for CUHP method

  • Level 1 assumes that all roof gutters are disconnected from driveways, gutters and Stormwater conveyance elements.
  • Level 2 is for developments that already use Level 1 and do not have any curbs and gutters, including concrete swale gutters. All runoff from streets and parking areas is directed as sheet flow across grass surfaces. Intermittent curbs with frequent opening to the grass surface qualifies as Level 2.
CIA_RATIO Fraction of the impervious area that is directly connected to the drainage system.
RPA_RATIO Fraction of the pervious area that receives runoff from pervious area and unconnected impervious area.
TC Time of concentration (minutes).
WQCV Water Quality Capture Volume (watershed inches or millimeters).
WQCV_TIME The time it takes to fully drain the brim-full WQCV
Runoff Coefficient SDMRH only. (Note – There is a different Runoff Coefficient reported in HYDQUA.RPT. It is the total runoff from the Subcatchment divided by the total rainfall over the Subcatchment. It should always be between 0 and 1.)
Storage Coefficient Snyder UH and Clark UH. Represents storage effects of the watershed.
Empirical Coefficient Snyder UH only.
Conveyance Factor Espey UH only
Infiltration Model Use this to use a different infiltration model than the default model set in Simulation Options.
Depression Storage Average depth of depression storage across the Subcatchment. Can be used in NRCS methods to indicate Initial Abstraction (Ia).
Storage Coefficient Storage Coefficient for German Runoff
Reservoir Count Reservoir Count for German Runoff

Rules and Ranges the for Hydrology Options

Innovyze Hydrology Type Data Ranges and Default
Hydrology Type Data Type User Unit Internal Unit Valid Internal Range Default Internal Values
rain-depth
Colorado UH in or mm
DCIA level enumerator 1, 2, 3 1
hydraulic length double ft or m ft >= 1 50
centroid distance double ft or m ft >= 0 0
DCIA fraction double 0 <= & <= 1 0.2
RPA fraction double 0 <= & <= 1 0.75
time of concentration double minutes seconds >= 1 60
captured volume double rain-depth ft >= 0 0
Drainage time double hours seconds >= 0 12
NRCS/Delmarva
Curve Number double 40 <= & <= 100 75
hydraulic length double ft or m ft >= 1 50
time of concentration double minutes seconds >= 1 60
depression storage double rain-depth ft >= 0 0
Snyder UH
storage coefficient double 0.1 <= & <= 8 2
empirical coefficient double 0.1 <= & <= 1.0 0.5
hydraulic length double ft or m ft >= 1 50
centroid distance double ft or m ft >= 0 0
depression storage double rain-depth ft >= 0 0
Clark UH
storage coefficient double 0.1 <= & <= 10 1
time of concentration double minutes seconds >= 1 60
depression storage double rain-depth ft >= 0 0
Santa Barbara
time of concentration double minutes seconds >= 1 60
depression storage double rain-depth ft >= 0 0
Espey UH
hydraulic length double ft or m ft >= 1 50
conveyance factor double 0.6 <= & <= 1.3 1
depression storage double rain-depth ft >= 0 0
Modified Rational
time of concentration double minutes minutes >= 1 5
runoff coefficient double 0 <= & <= 1 0.5
storm duration double factor factor TC: > 0 1
hours hours Dur: >= 0
San Diego Rational
runoff coefficient double 0 <= & <= 1 0.5
time of concentration double minutes minutes >= 1 0.75
German Runoff
Storage constant double minutes minutes > 0 5
Reservoir count integer > 0 1
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