4.9.5 Runoff Model Representation

If the water balance model used to size the rain water harvesting system shows that there is no overflow (e.g., all of the stored water is used or evaporated), subtract the contributing roof area from the hydrologic model used to size flow control facilities to meet Core Element 6 requirements. See Chapter 4 in the 2004 SWMMEW and Appendix C: Sizing of LID Facilities in this Manual for detailed discussion of hydrologic modeling to meet the Core Elements.