Roughness Values-Kutters Equation
Roughness Values--Kutter’s Equation
Channel Type and Description | Minimum | Normal | Maximum |
---|---|---|---|
Brass, smooth | 0.009 | 0.010 | 0.013 |
Steel; Lockbar and welded | 0.010 | 0.012 | 0.014 |
Steel; Riveted and spiral | 0.013 | 0.016 | 0.017 |
Cast iron; Coated | 0.010 | 0.013 | 0.014 |
Cast iron; Uncoated | 0.011 | 0.014 | 0.016 |
Wrought iron; Black | 0.012 | 0.014 | 0.015 |
Wrought iron; Galvanized | 0.013 | 0.016 | 0.017 |
Corrugated metal; Subdrain | 0.017 | 0.019 | 0.021 |
Corrugated metal; Storm Drain | 0.021 | 0.024 | 0.030 |
Kutter’s Coefficients n for Closed Non-Metal Conduits
Channel Type and Description | Minimum | Normal | Maximum |
---|---|---|---|
Lucite | 0.008 | 0.009 | 0.010 |
Glass | 0.009 | 0.010 | 0.013 |
Cement; Neat, surface | 0.010 | 0.011 | 0.013 |
Cement; Mortar | 0.011 | 0.013 | 0.015 |
Concrete; Culvert, straight and free of debris | 0.010 | 0.011 | 0.013 |
Concrete; Culvert with bends, connections, and some debris | 0.011 | 0.013 | 0.014 |
Concrete; Finished | 0.011 | 0.012 | 0.014 |
Concrete; Sewer with manholes, inlet, etc., straight | 0.013 | 0.015 | 0.017 |
Concrete; Unfinished, steel form | 0.012 | 0.013 | 0.014 |
Concrete; Unfinished, smooth wood form | 0.012 | 0.014 | 0.016 |
Concrete; Unfinished, rough wood form | 0.015 | 0.017 | 0.020 |
Wood; Stave | 0.010 | 0.012 | 0.014 |
Wood; Laminated, treated | 0.015 | 0.017 | 0.020 |
Clay; Common drainage tile | 0.011 | 0.013 | 0.017 |
Clay; Vitrified sewer | 0.011 | 0.014 | 0.017 |
Clay; Vitrified sewer with manholes, inlet, etc. | 0.013 | 0.015 | 0.017 |
Clay; Vitrified subdrain with open joint | 0.014 | 0.016 | 0.018 |
Brickwork; Glazed | 0.011 | 0.013 | 0.015 |
Brickwork; Lined with cement mortar | 0.011 | 0.013 | 0.015 |
Sanitary sewers coated with sewage slimes, with bends and connections | 0.012 | 0.013 | 0.016 |
Paved invert, sewer, smooth bottom | 0.016 | 0.019 | 0.020 |
Rubble masonry, cemented | 0.018 | 0.025 | 0.030 |