Application of Depth-Averaged Velocity Profile for Estimation of Longitudinal Dispersion in Rivers

Document Type : Technical Note


1 Assist. Prof., Dept. of Civil Engineering, Sistan and Baluchestan University

2 Assoc. Prof., Dept. of Civil Engineering, Ferdowsi University of Mashhad


River bed profiles and depth-averaged velocities are used as basic data in empirical and analytical equations for estimating the longitudinal dispersion coefficient which has always been a topic of great interest for researchers. The simple model proposed by Maghrebi is capable of predicting the normalized isovel contours in the cross section of rivers and channels as well as the depth-averaged velocity profiles. The required data in Maghrebi’s model are bed profile, shear stress, and roughness distributions. Comparison of depth-averaged velocities and longitudinal dispersion coefficients observed in the field data and those predicted by Maghrebi’s model revealed that Maghrebi’s model had an acceptable accuracy in predicting depth-averaged velocity.


1- Tayfur, G., and Singh, V.P. (2005). “Predicting longitudinal dispersion coefficient in natural streams by artificial neural network.” J. of Hydraulic Engineering, 131 (11), 991-1000.
2- Deng, Z.Q., Singh, V.P., Bengtsson, L., and Adrian, D.D. (2002). “Longitudinal dispersion coefficient in single-channel streams.” J. of Hydraulic Engineering, 128 (10), 901-916.
3- McQuivey, R.S., and Keefer, T.N. (1976). “Convection model of longitudinal dispersion.” J. of Hydraulic Division American Society of Civil Engineering, 102 (10), 1409-1424.
4- پروین‌نیا، م.، رخشنده رو، غ.ر.، و منجمی، پ. (1387). "بررسی کیفیت و احیای روانابهای شهری در شیراز." مجله آب و فاضلاب، 66، 46-55.
5- ریاحی مدوار، ح.، و ایوب زاده، س.ع. (1387). "تخمین ضریب پراکندگی طولی آلودگی با استفاده از سیستم استنتاج فازی-عصبی انطباقی." مجله آب و فاضلاب، 67، 34-47.
6- Fischer, H.B. (1966). Longitudinal dispersion in laboratory and natural streams, Report No. KH-R-12, Keck Laboratory of Hydraulic and Water Resources, California Institute of Technology,Pasadena,California.
7-Fischer, H.B. (1975). “Discussion of simple method for predicting dispersion in stream by R.S. McQuivey and T.N. Keefer.” J. of Environment Engineering Division American Society of Civil Engineering, 101(3),
8- Maghrebi, M.F. (2003). “Discharge estimation in flumes using a new technique for the production of isovel contours.” Proceedings of International Conference on Civil and Environment Engineering, ICCEE,
9- Maghrebi, M.F., and Ball, J.E. (2006). “New method for estimation of discharge.” Journal of Hydraulic Engineering, 132(10), 1044-1051.
10- Seo, I.W., and Baek, K.O. (2004). “Estimation of the longitudinal dispersion coefficient using the velocity profile in natural streams.” Journal of Hydraulic Engineering, 130 (3), 227-236.
11-U.S. Geological Survey., (May 2008).
12- Godfrey , R .G., and Frederick, B.J. (1970). Stream dispersion at selected sites, Professional Paper No. 433-K,U.S. Geological Survey,Washington,D.C.
13- Bencala, K.E., and Walters, R.A. (1983). “Simulation of solute transport in mountain pool-and-riffle stream: a transient storage model.” Water Resources Research, 19(3), 718-724.