Reducing Dry Weather Flow in InfoSWMM: A Systematic Approach

Reducing Dry Weather Flow in InfoSWMM: A Systematic Approach

When modeling wastewater systems, you may need to adjust the overall dry weather flow while preserving the mean flow patterns. InfoSWMM provides an elegant solution through its pattern-based flow modification system. This method allows for precise control over flow reductions without disrupting the underlying flow distribution.

Implementation Process:

First, navigate to the Operations tab within the Attribute Browser. Here, create a new Flow Pattern that will serve as your reduction multiplier. For instance, if your goal is to reduce flows by 15 percent, enter a pattern value of 0.85 (representing 85% of the original flow). Next, connect this pattern to your system by applying it in the Node DWF DB Table. Once implemented, this adjustment will systematically reduce all dry weather flows throughout your simulation by the specified percentage while maintaining the relative relationships between flow components.

This approach offers several advantages: it preserves the temporal distribution of your flows, maintains system-wide consistency, and allows for easy modification if different reduction factors need to be tested. The method is particularly useful when calibrating models or evaluating system capacity under various flow scenarios.

Technical Note: The reduction occurs uniformly across all dry weather flows, so consider carefully whether this global approach aligns with your modeling objectives before implementation.