Detailed Overview of landuse_getWashoffQual Function in SWMM5 🌧️🔬📊

 

Detailed Overview of landuse_getWashoffQual Function in SWMM5 🌧️🔬📊

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 📝

• 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 🌊🧮

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 🏙️🔍💧

• 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 🌧️🌳🚧

• 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. 🌧️🔬📊🌊🏙️🌳🚧🔍💧🌍📈🌆🌦️🌐🔬💻🌎🚰

Detailed Overview of landuse_getExternalBuildup Function in SWMM5 🌿🔍📊

 

Detailed Overview of landuse_getExternalBuildup Function in SWMM5 🌿🔍📊

The landuse_getExternalBuildup function in SWMM5 is designed to calculate pollutant buildup due to external loading over a specified time step. Here's a detailed breakdown of its functionality, with added explanations:

Function Prototype 📝

• Input:
  • i: Landuse index.
  • p: Pollutant index.
  • buildup: Existing buildup at the start of the time step (measured in mass per unit area).
  • tStep: Time step duration in seconds.
• Output: Returns the pollutant buildup at the end of the time interval (mass per unit area).
• Purpose: To determine the increase in pollutant buildup due to external sources during a given time step.

Process Flow and Computation 🌐🧩

1. Maximum Buildup Determination:

   • Retrieves the maximum allowable buildup (maxBuildup) for the specific land use and pollutant.

2. Scaling Factor and Time Series Index:

   • sf (scaling factor): Modifies the rate of buildup based on specific land use characteristics.
   • ts (time series index): Points to the relevant time series data for buildup rates.

3. Initial Condition Check:

   • At the start of the simulation (when NewRunoffTime is 0), the function immediately returns zero, indicating no buildup increment.

4. Buildup Rate Calculation:

   • If a valid time series index (ts) is present, it fetches the buildup rate (in mass/unit/day) from the time series table (Tseries[ts]), scaling it with the scaling factor (sf).

5. Buildup Computation:

   • Calculates the total buildup at the end of the time interval by adding the product of the rate and the time step (converted from seconds to days).
   • Ensures that the calculated buildup does not exceed the predefined maximum buildup (maxBuildup).

6. Return Value:

   • The function returns the computed buildup value, which represents the accumulated pollutant mass per unit area at the end of the time step.

Function's Role in SWMM5 🌎🚰

• Integral to modeling the accumulation of pollutants on different land uses over time.
• Helps in understanding the impact of external loading sources on urban runoff quality.
• Crucial for designing and evaluating strategies to mitigate pollutant discharge into stormwater systems.

In summary, the landuse_getExternalBuildup function in SWMM5 is vital for accurately predicting pollutant buildup from external sources on various land uses, thereby aiding in the effective management of urban runoff and water quality. 🌿📈🔬🌧️🏙️📊🧪💧🔄🌍📊🔍🌆

Detailed Overview of landuse_getCoPollutLoad Function in SWMM5 🌧️🔍📊

 

Detailed Overview of landuse_getCoPollutLoad Function in SWMM5 🌧️🔍📊

The landuse_getCoPollutLoad function in SWMM5 is a specialized component for calculating the washoff mass added by co-pollutants. This function plays a significant role in the accurate assessment of pollutant washoff in urban runoff modeling. Here's a detailed breakdown of its functionality:

Function Prototype 📝

• Input:
  • p: Index of the primary pollutant.
  • washoff[]: Array containing the washoff rates for pollutants (measured in mass per second).
• Output: Returns the washoff mass contributed by the co-pollutant (measured in mass).
• Purpose: To determine the additional washoff mass contributed by a co-pollutant of a given primary pollutant.

Process Flow and Computation 🌐🧩

1. Co-Pollutant Check:

   • The function first checks if the primary pollutant p has an associated co-pollutant, identified by the index k.
   • The index k is retrieved from the Pollut[p].coPollut property.

2. Washoff Computation:

   • If a co-pollutant exists (k >= 0), the function calculates the additional washoff contributed by this co-pollutant.
   • The washoff contribution w is determined by multiplying the washoff rate of the co-pollutant (washoff[k]) by the co-pollutant fraction (Pollut[p].coFraction).

3. Mass Balance Update:

   • The function updates the mass balance totals for buildup loads to ensure consistency in the overall mass balance.
   • This update is done through the massbal_updateLoadingTotals function, which accounts for the mass contribution factor (Pollut[p].mcf) of the pollutant.

4. Return Value:

   • The computed additional washoff mass w is returned.
   • If no co-pollutant exists, the function returns 0.0, indicating no additional washoff from co-pollutants.

Role in SWMM5 🏙️💧

• Essential for modeling complex interactions between different pollutants in urban runoff.
• Helps in understanding how the presence of one pollutant can influence the washoff behavior of another, providing a more realistic representation of pollutant dynamics in urban water systems.

Implications for Urban Hydrology 🌳🚧

• This function is crucial for accurately assessing pollutant loads in stormwater runoff, particularly in areas with diverse pollutant sources.
• It aids in the formulation of effective stormwater management and treatment strategies, especially in environments with intricate pollutant interrelationships.

In conclusion, the landuse_getCoPollutLoad function in SWMM5 is pivotal in enhancing the precision of pollutant washoff modeling, reflecting the complex nature of urban runoff pollution. Its ability to account for co-pollutant interactions significantly improves the understanding and management of urban water quality. 🌧️📈🔍🌍💧🌆🚰🔬🌳📊🚧🏙️💧🔄📈🔬🌍💧🌆🚰🔬