Where can I find a good reference to determine the Manning Coefficients (N-Value)?
You can find very useful information including pictures, descriptions and values from the following publications: • Ven Te Chow: “Open-Channel Hydraulics”, McGraw-Hill Book Company, New York, 1959. Page 98-123. • U.S. Army Corps of Engineers: Hydraulic Reference Manual for HEC-RAS River Analysis System, Chapter 6. • Guy B. Fasken: Guide for Selecting Roughness Coefficient “n” Values for Channels, Soil Conservation Service, USDA, Lincoln, Nebraska, 1963 PROJECT TYPES AND COMPONENTS 13.