"Computer Program NCALC User's Manual--Verification of Manning's Roughness Coefficient in Channels"

In Reply Refer To:                               February 19, 1987
WGS-Mail Stop 415


Subject:  PUBLICATIONS--"Computer Program NCALC User's Manual--
                        Verification of Manning's Roughness
                        Coefficient in Channels" by Robert D.
                        Jarrett and Harold E. Petsch, Jr.

We are pleased to distribute this report which provides
information on the verification of Manning's n-values in channels.
The report includes: (1) a suggested approach and onsite data
needs to conduct an n- verification The U.S. Geological Survey has
conducted a number of n- verification studies. However, additional
verification and validation are needed for our hydraulic
investigations.  Most verification has been for relatively clear-
water flow, in relatively uniform and stable channels, and for
flows confined to the main channel.  In hydraulic investigations,
we and others conduct studies on streams that do not fit these
conditions, particularly during floods.  The report outlines a
number of research needs.  In order to increase our under-
standing of roughness coefficients, it is important to identify
possible n-verification reaches for investigation.  If reaches are
identified, it is important to report them to the Regional Surface
Water Specialists, who will forward the information to Robert
Jarrett and the Chief, Office of Surface Water.

Additional copies of the report and the computer program may be
obtained from Pat Griffith, U.S. Geological Survey, Water
Resources Division, Colorado District, MS-415, Lakewood, Colorado.

                                    Verne R. Schneider
                                    Chief, Office of Surface Water


WRD Distribution:  FO-LS, SL