This web site provides information on estimates of roughness values that have been made for Australian streams. It is hoped that by sharing this database, practitioners will be able to make improved estimates of roughness at other sites. We would also like to encourage people to submit examples that can be shared with others.
Roughness values come from a variety of sources and we have varying levels of confidence in the coefficients. The sources, in order of quality, are:
- Sites where there are direct measurements of discharge, water surface slope, flow depth and cross-sections. Manning's n-values can be calculated directly from these measured parameters.
- Reaches where Manning's n-values are estimated by calibration as part of hydraulic modelling undertaken for a flood study.
- Field assessments where n-values have been estimated based on pictorial guides or documented procedures. Although, we have less confidence in these values, they are likely to be more reliable that office based assessments.
The procedure used to estimate the roughness coefficient are explained in the entry for that particular location.
In 1982 a conference was held to discuss roughness coefficients where it was concluded that: "the most promising method for estimation of energy loss parameters in natural streams, and in particular n-values, would be based on a comprehensive data bank of descriptive and photographic information for typical stream reaches in Victoria or Australia". More than 20 years later, this website is that start of that project.
Database of roughness values for Australia streams
- by Locality
- by Stream Type
- by Estimation Method
Estimating floodplain resistance
- What is Stream Roughness?
- Estimation of floodplain resistance
- Other Websites about Roughness
- References for the selection of Roughness Parameters
