The SWR Structures dialog box is used to define structures such as dams that control flow between reaches.
The SWR Structures dialog box is displayed by selecting Model|SWR Dialog Boxes|Structures...
There are two tabs on the SWR Structures dialog box: Structure Definition and Timing.
The Structure Definition tab is used to specify the properties of the structures and the Timing tab is used to define when the structures are used.
The table in the top half of the Structure Definition tab is used for specifying data that are used with many different structure types. The table in the bottom half of the Structure Definition tab will change depending on which row is selected in the table in the top half of the dialog box. The table in the bottom half of the dialog box is used for data that are only specified for a small number of structure types.
Structure Definition Tab
Upper Table
Name: Name is specified in the table in the upper half of the dialog box and is used to identify a structure in tables in the lower half of the dialog box and the Timing tab.
Reach (ISMODRCH, ISTRRCH): ISMODRCH identifies the number of the reach with which the structure is associated. ISMODRCH must be greater than zero and less than or equal to the number of reaches. ISMODRCH data can be specified in any order, but each structure must be assigned a unique reach number.
Connected Reach (ISTRCONN): ISTRCONN is the reach number to which a structure is connected. ISTRCONN must be less than or equal to the number or reaches and consistent with the reach connectivity. Values of ISTRCONN equal to zero indicate that the tailwater end of the structure is unconnected.
Flow Restrictions (ISTRDIR): ISTRDIR—an integer value that defines directional limits on flow for the structure. This variable is only specified if ISTRTYPE = 5, 6, 7, 8, 9, or 10.
•ISTRDIR < 0, Restriction of flow from ISTRCONN to ISTRRCH.
•ISTRDIR = 0, Bi-directional flow is allowed.
•ISTRDIR > 0, Restriction of flow from ISTRRCH to ISTRCONN.
Weir Discharge Coefficient (STRCD): STRCD is a weir discharge coefficient (dimensionless) for the structure entry. This variable is only specified if ISTRTYPE = 5, 6, 7, 8, 9, or 10.
Orifice Discharge Coefficient (STRCD2): STRCD2 is an orifice discharge coefficient (dimensionless) for the structure entry. This variable is only specified if ISTRTYPE = 5, 7, 9, or 10.
Submergence Exponent (STRCD3): STRCD3 is the dimensionless submergence exponent for the structure. A value of 0.5 is sufficient if specific data are not available for a structure. This variable is only specified if ISTRTYPE = 6, 7, 8, 9, or 10.
Structure Invert Elevation (STRINV): STRINV is the structure invert elevation (units of length) for the structure entry. This variable is only specified if ISTRTYPE = -2, 5, 6, 7, 8, 9, or 10.
Structure Width (STRWID): STRWID is the structure width (units of length) perpendicular to flow for the structure. This variable is only specified if ISTRTYPE = 5, 6, 7, 8, 9, or 10. If ISTRTYPE = 5 (culvert) and the culvert type is circular, STRWID is the diameter of the culvert. If ISTRTYPE = 5 and the culvert type is rectangular, STRWID is the culvert span.
Method for Specifying Initial Value (STRVAL): If ISTRTYPE = 12, tabular data from an external file can be used to define STRVAL. In this column you must specify whether you want to use a value or a tabfile for STRVAL.
Initial Value (STRVAL): STRVAL—a real number that is the inital flow rate (units of length3 per time) or gate opening (units of length) for the structure. If ISTRTYPE = 6 or 7, STRVAL is the gate opening for the stress period. This variable is only specified if ISTRTYPE = 3, 6, 7, 8, 9,10 or 12.
Initial Value Tabfile Name (STRVAL): If ISTRTYPE = 12, tabular data from an external file can be used to define STRVAL. The name of the external file is specified here. It will be used to define initial flow rate data for the stage-dependent boundary flux structure
SFR Segment (ISFRSEG): ISFRSEG is the SFR2 segment that (1) supplies downstream segment discharge to SWR1 reach ISTRRCH or (2) SFR2 segment that receives SWR2 surface-water control structure discharge.
SFR Reach (ISFRRCH): ISFRRCH is the SFR2 reach in SFR2 segment ISFRSEG that receives SWR2 surface-water control structure discharge. Any SFR2 reach number can be specified if ISTRTYPE=11. ISFRRCH is not read if SFR is not specified in the name file.
Lower Table 1
This table is displayed if ISTRTYPE = -2, 2, or 5.
Name: Name is specified in the table in the upper half of the dialog box and is used to identify a structure in tables in the lower half of the dialog box and the Timing tab.
Downstream Invert Elevation (STRINV2): STRINV2 is the downstream invert elevation (units of length) for the structure entry. This variable is only specified if ISTRTYPE = 5.
Culvert Type (STRWID): The Culvert type is only specified if ISTRTYPE = 5. It indicates whether the culvert is circular or rectangular and determines whether STRWID is the culvert diameter or culvert span.
Culvert Rise (STRWID2): STRWID2—a real number that is the culvert rise (units of length). This variable is only specified if ISTRTYPE = 5 and the culvert type is rectangular.
Specify Lengths (STRLEN and STRLEN2): The Culvert Length and Downstream Culvert Length are optional if ISTRTYPE = -2 or 2. Check this check box if you wish to specify them.
Culvert Length (STRLEN): STRLEN is the culvert length (units of length). This variable is only required if ISTRTYPE = 5 (culvert). This variable is optional if ISTRTYPE = -2 or 2 and defines the distance from ISTRRCH to the structure, otherwise STRLEN is internally set to one-half of the reach length (RLEN) of reach ISTRRCH.
Downstream Culvert Length (STRLEN2): STRLEN2 is the culvert length or distance from the center of the reach to the structure (units of length). This variable is optional if ISTRTYPE = -2 or 2 and defines the distance from ISTRCONN (the connected reach) to the structure, otherwise STRLEN2 is internally set to one-half of the reach length (RLEN) of reach ISTRCONN.
Manning's Roughness (STRMAN): STRMAN is the culvert Manning’s roughness coefficient. This variable is only specified ISTRTYPE = 5 (culvert).
Lower Table 2
This table is displayed if ISTRTYPE = 4 (Specified stage-discharge relation).
Elevation (STRELEV): STRELEV(i) is the elevation (in units of length) of the structure. By definition, the first of NSTRPTS values represents the lowest elevation; values for remaining points should be greater than the previous elevation.
Discharge (STRQ): STRQ(i) is the flow rate (units of length cubed per time) for the structure entry STRELEV(i).
A plot of the data in the table is displayed next to the table.
Lower Table 3
This table is displayed if ISTRTYPE = 1, 3, 8, 9, or 10 (Specified elevation excess volume structure, Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Name: Name is specified in the table in the upper half of the dialog box and is used to identify a structure in tables in the lower half of the dialog box and the Timing tab.
Control Type (CSTROTYP): CSTROTYP is used to set the SWR1 data type used to control structure operations. This variable is only specified if ISTRTYPE = 1, 3, 8, 9, or 10 (Specified elevation excess volume structure, Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
•CSTROTYP = STAGE, simulated SWR1 stages at a user-defined reach will be used to operate the structure.
•CSTROTYP = FLOW, simulated SWR1 flow at a user-defined reach connection will be used to operate the structure. A CSTROTYP = FLOW is not supported for ISTRTYPE = 1 (Specified elevation excess volume structure).
Control Reach (ISTRORCH): ISTRORCH defines the reach that will be used to operate the structure. This variable is only specified if ISTRTYPE = 3, 8, 9, or 10 (Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Connected Control Reach (ISTROQCON): ISTROQCON defines the reach connection for reach ISTRORCH that will be used to operate the structure. This variable is only specified if CSTROTYP = FLOW and ISTRTYPE = 3, 8, 9, or 10 (Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
When is Structure Operated (CSTROLO): CSTROLO is used to determine if a structure should be operated. This variable is only specified if ISTRTYPE = 3, 8, 9, or 10 (Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
•CSTROLO = GE, the structure will be operated when the STAGE in reach ISTRORCH or FLOW at the connection between reach ISTRORCH and ISTROQCON is greater than or equal to the specified structure criteria STRCRIT.
•CSTROLO = LT, the structure will be operated when the STAGE in reach ISTRORCH or FLOW at the connection between reach ISTRORCH and ISTROQCON is less than the specified structure criteria STRCRIT.
Method for Specifying Critical Value (CSTRCRIT): Choose whether you wish the critical value to be read from a tabfile or specified as a number.
Critical Value Tabfile Name (CSTRCRIT): This is the name of the tabfile used for the critical value data. The file must be listed in the SWR Tab Files dialog box as a Structure file.
Critical Value (STRCRIT): The critical value is either the control-elevation or control-flow criterion (STRCRIT – units of length or length3 per time) for the structure. (See CSTROTYP.) Tabular data cannot be used to define the control-elevation control-flow criterion for a structure if tabular data are used to define STRVAL. STRCRIT is evaluated in reach ISTRORCH to determine if a structure should be operated. This variable is only specified if ISTRTYPE = 1, 3, 8, 9, or 10 (Specified elevation excess volume structure, Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Control Offset Criterion (STRCRITC): STRCRITC is the control offset criterion (units of length or length3 per time) that must be evaluated in reach ISTRORCH prior to closing the structure. The closing elevation is calculated by adding STRCRITC and STRCRIT. This variable is only specified if ISTRTYPE = 3, 8, 9, or 10 (Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Initial Control Rate (STRRT): STRRT is pump startup rate (units of length3 per time2) or the opening rate (units of length per time or length3 per time2) of the operable structure. This variable is only specified if ISTRTYPE = 3, 8, 9, or 10 (Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Maximum Control Rate (STRMAX): STRMAX is the maximum discharge rate (units of length3 per time) or the maximum opening(units of length) of the structure. This variable is only specified if ISTRTYPE = 1, 3, 8, 9, or 10 (Specified elevation excess volume structure, Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
(Optional) Discharge Tabfile Name (CSTRVAL): CSTRVAL— a optional string variable that is used to set the flag (ISTRTSTYPE) determining if tabular data from an external file will be used to define the discharge (units of length3 per time) or gate opening (units of length) for the structure. The file must be listed in the SWR Tab Files dialog box as a Structure file. Tabular data cannot be used to define the gate opening or discharge for a structure if tabular data are used to define STRCRIT (see the description for CSTRCRIT). If a file name is not specified, the variable is ignored and STRVAL will be calculated using the defined structure operation data. This optional variable is only specified if ISTRTYPE = 1, 3, 8, 9, or 10 (Specified elevation excess volume structure, Pump, Movable crest weir (overflow gate), Gated spillway (underflow gate), or Generalized spillway equation).
Timing Tab
Starting time and Ending time are explained in the help for the MODFLOW Features tab.
For each time period, you must check the checkbox for a structure if it is active in that time period.
