Engineers working on land development projects in Southern California could benefit from including the County of San Diego Modified Rational Method. Their Hydrology Manual describes a particular way of calculating the combination of drainage systems at junctions. Refer to Chapter 3.4 of the Hydrology Manual: https://www.sandiegocounty.gov/dpw/floodcontrol/floodcontrolpdf/hydro-hydrologymanual.pdf
Disclaimer: The development, release, and timing of any features or functionality described or discussed for our products in this User Feedback Forum for Autodesk Water Products and Services remains at our sole discretion. This User Feedback Forum for Autodesk Water Products and Services is not a commitment, promise, or legal obligation to deliver any functionality, is intended solely to outline and gather feedback about our general product direction, and should not be relied on in making purchasing decisions.
Thank you for the suggestion and thanks to those who voted/commented.
This is now under consideration for future development.