Friday, November 10, 2023

Detailed Overview of landuse_getWashoffQual Function in SWMM5 ๐ŸŒง️๐Ÿ”ฌ๐Ÿ“Š

 

Detailed Overview of landuse_getWashoffQual Function in SWMM5 ๐ŸŒง️๐Ÿ”ฌ๐Ÿ“Š

The landuse_getWashoffQual function in SWMM5 calculates the pollutant concentration in washoff from a specific land use. This function is a key component in modeling how pollutants are transported from urban surfaces during rainfall events. Here's an in-depth analysis of its workings:

Function Prototype ๐Ÿ“

  • Input:
    • i: Land use index.
    • p: Pollutant index.
    • buildup: Current buildup of the pollutant on the land use (measured in pounds or kilograms).
    • runoff: Current runoff rate on the subcatchment (feet per second).
    • area: Area of the land use (square feet).
  • Output: Returns the concentration of the pollutant in the washoff (mass per cubic feet).
  • Purpose: To determine the concentration of a pollutant that is washed off from a specific land use during a runoff event.

Calculation Process ๐ŸŒŠ๐Ÿงฎ

  1. Initial Checks:

    • Returns 0.0 if there is no washoff function or no runoff.
    • Returns 0.0 if there's a buildup function but no current buildup.
  2. Washoff Function Types:

    • Exponential Washoff (EXPON_WASHOFF):
      • The washoff concentration is calculated using an exponential function of runoff (converted to inches per hour or mm per hour) and the buildup, which is converted to concentration mass units.
      • The calculated concentration is then normalized by runoff and area.
    • Rating Curve Washoff (RATING_WASHOFF):
      • The washoff concentration is determined using a power function of the runoff volume (runoff rate multiplied by area) and an exponent.
    • Event Mean Concentration Washoff (EMC_WASHOFF):
      • The concentration is directly given by the coefficient, which already includes a conversion factor to mass per cubic feet.
  3. Coefficients and Exponents:

    • coeff: Represents the coefficient in the washoff equation.
    • expon: The exponent used in the washoff calculations.
    • These values are specific to each pollutant and land use type.
  4. Return Value:

    • The function returns the calculated pollutant concentration in the washoff.

Role in Urban Hydrology Modeling ๐Ÿ™️๐Ÿ”๐Ÿ’ง

  • This function is crucial for understanding the dynamics of pollutant transport from urban surfaces during storm events.
  • It aids in the assessment of water quality impacts from different land uses and helps in designing strategies for pollution mitigation in urban runoff.

Implications for Stormwater Management ๐ŸŒง️๐ŸŒณ๐Ÿšง

  • The landuse_getWashoffQual function is vital for predicting the environmental impact of urban development on water bodies.
  • It supports the effective planning and implementation of green infrastructure and other best management practices for stormwater quality control.

In summary, the landuse_getWashoffQual function in SWMM5 plays a pivotal role in simulating pollutant washoff processes, providing valuable insights for urban water quality management and environmental protection. ๐ŸŒง️๐Ÿ”ฌ๐Ÿ“Š๐ŸŒŠ๐Ÿ™️๐ŸŒณ๐Ÿšง๐Ÿ”๐Ÿ’ง๐ŸŒ๐Ÿ“ˆ๐ŸŒ†๐ŸŒฆ️๐ŸŒ๐Ÿ”ฌ๐Ÿ’ป๐ŸŒŽ๐Ÿšฐ

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