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Infiltration trench parameters

Hello, I am modifying the LID controls from the text editor to perform a sensitivity analysis

What is the meaning of the fifth parameter assigned to infiltration trench surface layer and the fourth parameter to underdrain layer?

;; Type/Layer Parameters
;;-------------- ---------- ----------
IT-0.5%   IT
IT-0.5%   SURFACE   0            0          0.25       0.5      5
IT-0.5%   STORAGE   2000    0.67    40          0 
IT-0.5%   DRAIN        0            0.5       0            6

Thank you.

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  • Thanks, that was interesting about the canOverflow logic - it was something I missed viewing the code before.  I am adding a collage image of the LID possibilities


  • The parameters for the Surface layer for LID modeling in SWMM 5 (the numbers are the column number on the input line):


  • The parameters for the Underdrain layer for LID modeling in SWMM 5 (the numbers are the column number on the input line):


    • Thank you very much, I found the following description on the executable file lid.c


      Infiltration trench: the fifth parameter is designated as "canOverflow"


      Underdrain: the fourth parameter represents the delay time

      But it is not specifically included in the LID CONTROL EDITOR. I am using the PCSWMM Model.
      Sorry for my English, thanks.


      //... for certain LID types, immediate overflow of excess surface water
      // occurs if either the surface roughness or slope is zero
      LidProcs[j].surface.canOverflow = TRUE;
      switch (LidProcs[j].lidType)
      case INFIL_TRENCH:
      case BIO_CELL:
      case RAIN_GARDEN:
      case GREEN_ROOF:
      if ( LidProcs[j].surface.alpha > 0.0 )
      LidProcs[j].surface.canOverflow = FALSE

      int readDrainData(int j, char* toks[], int ntoks)
      // Purpose: reads underdrain data for a LID process from line of input
      // data file
      // Input: j = LID process index
      // toks = array of string tokens
      // ntoks = number of tokens
      // Output: returns error code
      // Format of data is:
      // LID_ID DRAIN coeff expon offset delay

      • Thank you for reply , the fifth parameter is the  swale side slope.

        This is not available in the LID CONTROL editor. I must modify it in the text file, thanks.

        / Data Structures

        // LID Surface Layer
        typedef struct
        double thickness; // depression storage or berm ht. (ft)
        double voidFrac; // available fraction of storage volume
        double roughness; // surface Mannings n
        double surfSlope; // land surface slope (fraction)
        double sideSlope; // swale side slope (run/rise)
        double alpha; // slope/roughness term in Manning eqn.
        char canOverflow; // 1 if immediate outflow of excess water
        } TSurfaceLayer;

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