*        The 'G1' data line contains Extran weir data (Max of 60).

*============================================================================

*     G1 line     :

*     NJUNC(1)    : Junction number at which weir is located, or

*                   junction name (enter in single quotes).

*     NJUNC(2)    : Junction number to which weir discharges, or

*                   junction name (enter in single quotes).

*                   Note: To designate outfall weir, set NJUNC(N,2)

*                         equal to zero or ' ' (one space between quotes).

*                         In this case the boundary condition must be

*                         specified in the J1 lines for NJUNC(1).  Weir

*                         outfalls can't have flap gates.

*     KWEIR       : Type of weir.

*                   = 1 Transverse horizontal weir (exponent = 3/2).

*                   = 2 Transverse horizontal weir with tide gate.

*                   = 3 Side flow horizontal weir (exponent = 5/3).

*                   = 4 Side flow horizontal weir with tide gate.

*                   = 5 V-notch or triangular (exponent = 5/2).

*                   = 6 V-notch or triangular with tide gate.

*                   = 7 Trapezoidal (compound exponent)

*                   = 8 Trapezoidal with tide gate.

*     YCREST      : Height of weir crest above invert, ft [m].

*     YTOP        : Height to top of weir opening above invert

*                   (surcharge level), ft [m].

*     WLEN        : Weir length, ft [m].  Not used for V-notch weirs.

*     COEF        : Coefficient of discharge for weir.  If KWEIR = 7 or 8,

*                   COEF is for rectangular portion of weir.

*

*  Note, side flow weirs operate as transverse weirs for reverse flow

*  situations.

*

*  The following parameters are strictly optional for KWEIR < 5, and

*  they may be omitted from the G1 line without error. If one or more

*  of these four parameters are required and/or used, all four must be

*  entered.

*

*     ISUBEQ      : Submergence equation.

*                   = 0 Submergence equation used in previous versions of

*                       SWMM.

*                   = 1 Villemonte equation. (ref.  Handbook of Hydraulics

*                       Brater and King, 1976)

*     ENDCON      : Number of end contractions.  Only applies to KWEIR = 1,

*                   2, 7, and 8.  Weir length is reduced by 0.1*Head*ENDCON.

*     THETAV      : Angle in degrees of V-notch or trapezoidal end sections.

*                   See figures below for definition of THETAV

*     COEF2       : Coefficient for triangular portion of trapezoidal weir.

*                   Not used for KWEIR < 7.

*     Summary of equations used:

*

*        Free discharge  (Water elevation on downstream side of weir

*                         is below weir crest)

*               HEADW = water elevation on upstream side of weir above

*                       weir crest)

*           Transverse horizontal weir or side flow weir with reverse flow:

*               Q = COEF * WLEN * (1.0 - 0.1 * ENDCON * HEADW) * HEADW**1.5

*           Side flow horizontal weir

*               Q = COEF * WLEN * HEADW**1.66667

*           Triangular or V-notch weir                *<--THETAV--->*

*               Q = COEF * TAN(THETAV/2) * HEADW**2.5    *         *

*                                                         *     *

*                                                            *  _______YCREST

*           Trapezoidal

*               Q = COEF * WLEN * (1.0-0.1*ENDCON*HEADW) * HEADW**1.5

*                   +COEF2 * TAN(THETAV/2) * HEADW**2.5

*

*                              *<-THETAV/2->                        *

*                                *         |                      *

*                                  *       |                    *

*                                    *     |                  *

*                                      *   |                *

*                                        *                *

*                                          ************** ____________YCREST

*                                          <----WLEN---->

*

*          Weirs with tide gates subtract a head loss from the head on

*          the weir by applying above equations.

*          This head loss is computed using the ARMCO equation.

*              HLOSS = (4./GRVT)*VEL1**2*EXP(-1.15*VEL1/SQRT(HEADW))

*          where VEL1 is velocity through weir prior to applying correction.

*

*         Submerged weir - when water level on downstream side of weir

*                          exceeds weir crest.

*        Head1 = upstream water level above crest

*        Head2 = downstream water level above crest

*        Ratio = head2/head1

*        Power = Power used in weir equation (1.5 for transverse horizontal,

*                1.66667 for side flow horizontal , 2.5 for V-notch)

*

*       Correct for weir submergence.

*

*       Q corrected = CONST * Q uncorrected

*

*         Original version used linear interpolation through the following

*         points.       Q corrected = CONST * Q uncorrected

*                     RATIO      CONST

*                      0.0         1.0

*                      0.30        1.0

*                      0.75        0.9

*                      0.85        0.8

*                      0.95        0.4

*                      1.0         0.0

*

*      Villemonte Equation

*                      CONST = (1.0 - RATIO**POWER)**0.385

*

*      For trapezoidal weirs, the separate corrections are applied to both

*      "halves" of flow equation.

*      When weir goes into surcharge (e.g., depth of flow over weir 

*      exceeds YTOP) an orifice equation is used. The orifice coefficient 

*      is set such that the flow through the equivalent orifice after 

*      surcharge equals the flow over the weir prior to surcharge.

*

*

* NJUNC(1) NJUNC(2) KWEIR YCREST YTOP WLEN COEF ISUBEQ ENDCON THETAV COEF2

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