H Baba-Ali - ۱PHD Candidate, Islamic Azad University of Tehran-Sciences &Researches ,Department of Eng.And Faculty Member of Islamic Azad University of Khorramabad
A Shamsai - Prof. of Civil Eng. , Department of Civil Eng. , Sharif University of Technology, Tehran , Iran
Soheil Soroushnia - M. Sc. Student of Civil Eng. ,Islamic Azad University of Takestan ,Member of Young Researchers Club, Iran,
N Beheshtian - Graduated of Civil Eng. from Islamic Azad University of Khorramabad ,Member of Young Researchers Club, Iran

IN the riverine hydraulic studies such as tension and shear velocity computation, it is important to choose the correct roughness coefficient, because the main specification of flow resistance changes with roughness coefficient. According to river usage and use of empirical relations, we noticed that real roughness coefficient of KHORRAMABAD River according to mountainous region and coarse grain kind of it is near to 0.0261. According to river usage and creating systems of river bed in four different sections and flow surveying in base of river according to mountainous region and coarse grain kind of it, is near to 0.0261 and Among empirical relations, we can say that HENDERSON formula is the most appropriate formula for this river and Relation presented by BRAY (1967) The amounts are more than real amount and Peter-Meyer formula are also appropriate with high accuracy and have the capabilities for being used in LORESTAN Rivers. The amount of base flow(Q) that is less, affected on river usage, so that measurements error increased.

Roughness coefficient, HENDERSON formula, Peter-Meyer formula