Over the past decade the NRCS CN Method (particularly the selection of a composite CN) has been shown to be fairly inaccurate when modeling smaller storm events (< 2 inches). The problem is an underestimation of runoff depth and this affects designs for water quality and stream channel...
Hello psmart
I'm interested in this hydrograph because I'm curious and it applies to portions of Montana. I'm found some old documents that have the hydrograph, but it's based on set time of concentrations. I'm looking for the original unit hydrograph data or methodology on how to obtain it.
I'm interested in modeling a 10-day runoff event with a Q1/Q10 =0.2. HydroCAD provides an hydrograph for Q1/Q10 = 0.4. Does anyone know where I can find the information to develop a similar hydrograph for Q1/Q10 = 0.2?
