SWMM5 xsection.dat Summary

 The xsection.dat file contains tables of relative geometric properties for rounded cross-sections, which are used in the EPA SWMM5 (Storm Water Management Model) to model various shapes of drainage and stormwater cross-sections. These properties help determine flow characteristics such as area, width, hydraulic radius, section factor, and wetted perimeter at different flow depths.

Key Components of xsection.dat:

1. Cross-Section Geometry Tables:

   • The file includes tables for multiple types of cross-sectional shapes, such as circular, egg-shaped, horseshoe, gothic, catenary, semi-elliptical, and basket-handle shapes.
   • For each shape, the following tables are provided:
     • A_xxx: Represents the area divided by the full area versus the depth divided by the full depth (for a given shape).
     • Y_xxx: Represents the depth divided by the full depth versus the area divided by the full area.
     • W_xxx: Represents the width divided by the maximum width versus the depth divided by the full depth.
     • R_xxx: Represents the hydraulic radius divided by the hydraulic radius at full depth versus the depth divided by the full depth.
     • S_xxx: Represents the section factor divided by the section factor at full depth versus the area divided by the area at full depth.
     • N_Z_xxx: Number of equal intervals between 0.0 and 1.0 in the table for parameter Z and shape xxx.

2. Shape-Specific Tables:

   • Circular Shape: Includes parameters for standard circular cross-sections, which use Manning's equation to calculate flow.
     • Tables: A_Circ, R_Circ, Y_Circ, S_Circ, W_Circ.
   • Egg-Shaped Shape: Provides parameters for egg-shaped cross-sections.
     • Tables: A_Egg, R_Egg, Y_Egg, S_Egg, W_Egg.
   • Horseshoe Shape: Provides parameters for horseshoe-shaped cross-sections.
     • Tables: A_Horseshoe, R_Horseshoe, Y_Horseshoe, S_Horseshoe, W_Horseshoe.
   • Gothic Shape: Provides parameters for gothic-shaped cross-sections.
     • Tables: A_Gothic, R_Gothic, Y_Gothic, S_Gothic, W_Gothic.
   • Catenary Shape: Provides parameters for catenary-shaped cross-sections.
     • Tables: A_Catenary, R_Catenary, Y_Catenary, S_Catenary, W_Catenary.
   • Semi-Elliptical Shape: Provides parameters for semi-elliptical cross-sections.
     • Tables: A_SemiEllip, R_SemiEllip, Y_SemiEllip, S_SemiEllip, W_SemiEllip.
   • Basket-Handle Shape: Provides parameters for basket-handle shaped cross-sections.
     • Tables: A_BasketHandle, R_BasketHandle, Y_BasketHandle, S_BasketHandle, W_BasketHandle.
   • Semi-Circular Shape: Provides parameters for semi-circular cross-sections.
     • Tables: A_SemiCirc, R_SemiCirc, Y_SemiCirc, S_SemiCirc, W_SemiCirc.

3. Geometric Properties:

   • Each table contains values for a specific geometric property (e.g., area, width, hydraulic radius) as a function of flow depth, normalized to full depth and area.
   • These tables are used for hydraulic calculations, such as computing the flow, hydraulic radius, and wetted perimeter, and are essential for solving Manning's equation for flow in conduits and channels.

4. Key Parameters for Specific Shapes:

   • Circular Shape: Parameters such as the radius of the circle, wetted perimeter, and the area of the circle are calculated and normalized in the R_Circ and A_Circ tables.
   • Egg-Shaped Shape: Parameters for this shape are used to compute the flow characteristics in egg-shaped pipes and channels.
   • Horseshoe Shape: This shape is commonly used for stormwater culverts and is modeled using the A_Horseshoe and R_Horseshoe tables.
   • Gothic Shape: Used for unique stormwater and sewer applications, modeled using A_Gothic, R_Gothic, etc.
   • Semi-Elliptical and Basket-Handle shapes: Often used for specialized sewer systems, modeled using the respective geometric tables.

5. Full Depth and Section Factor:

   • Each shape has a corresponding section factor, which is used to calculate flow using Manning's equation.
   • The S_xxx tables provide the section factor relative to full section factor at full depth.

6. Manning’s Equation:

   • The file also supports the calculation of flow using Manning's equation for these cross-sections, considering the roughness coefficients (Manning's n values) for different parts of the cross-section.

7. Use in SWMM:

   • The tables in xsection.dat are critical for computing the flow, head, and other hydraulic characteristics of channels, pipes, and culverts in the SWMM model. They provide the necessary geometric data for different types of cross-sections, ensuring the model can simulate flow through diverse drainage structures accurately.

Summary:

The xsection.dat file in SWMM5 provides predefined tables for various cross-section shapes (such as circular, egg-shaped, horseshoe, and others) that are used to calculate hydraulic parameters such as area, wetted perimeter, hydraulic radius, and section factor at different flow depths. These tables are fundamental for modeling flow through stormwater and sewer systems, ensuring that the flow calculations are based on the correct geometry for each type of conduit or channel.+