Runoff Surface Suggestions for Future #SWMM5 's and #SWMM6 - with added Emojis

Expanding Runoff Surface Types for Upcoming SWMM Versions 💧🌍🌆🌦

The Storm Water Management Model (SWMM) has been an instrumental tool in simulating urban hydrological processes. Over the years, SWMM has evolved, adding new features and capabilities 🚀. One area ripe for expansion is the classification of runoff surfaces 🌿🌃.

Current Runoff Surfaces in SWMM:

• Impervious with Depression Storage 🏢: Accounts for evaporation ☁ but not infiltration 🕳.
• Pervious 🌱: Considers depression storage, evaporation, infiltration, and potentially groundwater connection 🌊.
• Impervious without Depression Storage 🛣: Represents quick runoff from surfaces like roofs and gutters.

Enhancements in SWMM4 and SWMM5 introduced more intricate routing capabilities 🌐 and the integration of Low Impact Development (LID) methodologies 🌳🌼.

Proposed Enhancements for Future SWMM Iterations 🌟:

To reflect the complexity of urban terrains more accurately, there's a proposal to expand the number of runoff surfaces from the current 3 to a more comprehensive 12 📊. Each of these surfaces should have customizable properties, such as:

1. Flag for depression storage 🚩.
2. Flag for evaporation 🌬.
3. Flag for infiltration 🌀.
4. Flag for groundwater connection 🌍💧.
5. Flag for RDII (Rainfall-Dependent Infiltration/Inflow) 🌧⚡.
6. Flag for LID integration 🌸🏞.
7. Customizable widths and slopes 📏📐.

The existing SWMM framework provides a single slope and width for various runoff surfaces, which doesn't always mirror real-world scenarios. By allowing each surface to have distinct characteristics, it could enhance the model's accuracy and simplify the calibration process 🎯📉.

Technical Implications ⚙🖥:

Implementing these changes would entail:

• Adapting the SWMM 5 file import process to accommodate the expanded surfaces 📂.
• Modifying the Enums.h file to account for the new SubAreaType classifications 📑.
• Adjusting the runoff linkages in various modules, including Subcatch.C, RDII.C, Gwater.C, and LID.C 🔄🔧.

c
enum SubAreaType {
  IMPERV0,  // impervious surface without depression storage
  IMPERV1,  // impervious surface with depression storage
  PERV     // pervious surface
  // ... Additional surfaces can be added here
};

While these enhancements would certainly increase the model's complexity, the benefits in terms of accuracy and representation of real-world conditions could be invaluable for urban hydrologists and planners 🌆🌍🌧🌳.