---
title: "Roughness Coefficients"
canonical: "https://help.innovyze.com/space/xps/19662948/Roughness%20Coefficients"
format: markdown
---
The following roughness coefficients for overland flow were suggested by the US Army Corps of Engineers in the ***Flood Runoff Analysis Engineering Design Manual***, EM 1110-2-1417, August 1994.


| **Surface ** | ***n***** Value** |
| --- | --- |
| Asphalt & concrete | 0.05 - 0.15 |
| Bare packed soil free of stone | 0.10 |
| Fallow - no residue | 0.008 - 0.012 |
| Conventional tillage - no residue | 0.06 - 0.12 |
| Conventional tillage - with residue | 0.16 - 0.22 |
| Chisel plow - no residue | 0.06 - 0.12 |
| Chisel plow - with residue | 0.10 - 0.16 |
| Fall disking - with residue | 0.30 - 0.50 |
| No till - no residue | 0.04 - 0.10 |
| No till (20 - 40 percent residue cover) | 0.07 - 0.17 |
| No Till (60 - 100 percent residue cover) | 0.17 - 0.47 |
| Sparse rangeland with debris: |  |
| 0 percent cover | 0.09 - 0.34 |
| 20 percent cover | 0.05 - 0.25 |
| Sparse vegetation | 0.053 - 0.13 |
| Short grass prairie | 0.10 - 0.20 |
| Poor grass cover on moderately rough bare surface | 0.30 |
| Light turf | 0.20 |
| Average grass cover | 0.40 |
| Dense turf | 0.17 - 0.80 |
| Dense grass | 0.17 - 0.30 |
| Bermuda grass | 0.30 - 0.48 |
| Dense shrubbery and forest litter | 0.40 |