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. 🌿📈🔬🌧️🏙️📊🧪💧🔄🌍📊🔍🌆