Experimental and Numerical Study of Advection- Dispersion of Pollutant in a Gravel Bed Rivers

Authors

1 Ph.D. Student of Water Structures Engineering, Sari Agricultural Sciences and Natural Resources University,Sari, Iran

2 Assoc. Prof., Dept. of Water Engin., Sari Agricultural Sciences and Natural Resources University, Sari, Iran

3 Assist. Prof., Faculty of Engineering, University of Maragheh, Maragheh, Iran

4 Assoc. Prof., Faculty of Engineering, University of Maragheh, Maragheh, Iran

Abstract

Water quality assessment of rivers, in order to insure human health and environmental sustainability, is one of the most important purposes of the physical and numerical models of solute transport in rivers. In this research, some tracer experiments were done and also the numerical model of OTIS was used to simulate solute transport. This model predicts the solute BT curve for a given hydraulic and geometrical parameters at downstream sections of river with respect to concentration of pollutant resource at upstream boundary condition. The experiments were conducted in a flume with length, width and depth of 12, 1.2 and 0.8m. Two longitudinal slopes of 0.004 and 0.007 and three discharges of 7.5, 11.5 and 15.5 (l/s) were selected for the experiments. A given mass of NACL solution was instantaneously injected into upstream of the flume and then the breakthrough curves were plotted based on the measured electric conductivity values along the centerline of the flume for the different sections at downstream of the injection point. To assessment the goodness of the simulated and observed BT curves, the statistical indices including the root mean square error (RMSE), Nash and Sutcliffe (NS) and mean absolute error (MAE) were extracted. With comparison of the observed BT curves with the numerical results (obtained with OTIS), the longitudinal dispersion coefficient values in different reach of flume were calculated. Analysis of the results showed that for a constant longitudinal slope and discharge, by increasing the distance from the injection location, the coefficient of dispersion was increased. Also, for constant slope, with enhancing the discharge rate, the dispersion coefficient was increased but for a given discharges, the dispersion coefficient was decreased with increasing the longitudinal -slope.

Keywords

References

 Chapra SC, 1997. Surface Water-Quality Modeling. McGraw-Hill Series in Water Resource and         Enviromental Engineering, New York, NY, USA.
Chanson H, 2004. Environmental Hydraulics of Open Channel Flow. Elsevier Butterworth- Heinemann, London.
          Deng ZQ, Singh VP and Bengtsson L, 2001. Longitudinal dispersion coefficient in straight rivers. Journal      of Hydraulic Engineering 127(11): 919–927.
       Deng ZQ, Bengtsson L, Singh VP and Adrian DD, 2002. Longitudinal dispersion coefficient in single-    channel streams. Journal of Hydraulic Engineering ASCE, 128(10): 901-916.
         Elder JW, 1959. The dispersion of marked fluid in turbulent shear flow. Journal of Fluid Mechanics 5: 544-560.
         Ezadinia E, Saadatpour A and Heidarpour, 2016. Estimating longitudinal dispersion coefficient of pollutant in open channel flows using artificial neural networks. Journal of Water and Soil Science- Universiy of Tabriz 26:225-238
Fischer HB, 1968. Methods for predicting dispersion coefficients in natural streams with application to lower reaches of the Green and Duwamish rivers. Washington. US. Geological Survey Professional Paper 582 -A.
Fischer HB, List EJ, Koh, RCY, Imberger J and Brooks NH, 1979. Mixing in Inland and Coastal Waters. Academic Press New York: 104-138.
Kashefipour M, 2007. Prediction of longitudinal dispersion coefficient in natural rivers using artificial neural networks. Iranian Journal of Hydraulic 3: 15-25.
          Liu H, 1977. Predicting dispersion coefficient of streams. Journal of Environment Engineering Division 103(1): 59–69.
         Mahmoodian Shooshtari M, 2010. Principles of Flow in Open Channels. Shahid Chamran University Press, Ahvaz, Iran.
Meddah S, Saidane A, Hadjel M and Hireche O, 2015. Pollutant dispersion modeling in natural streams using the transmission line matrix method. Journal of Water 7: 4932-4950.
Riahi Madvar H and Ayyoubzadeh SA, 2007. Estimating longitudinal dispersion coefficient of pollutant using adaptive neuro-fuzzy inference system.Isfahan Journal of Water and Wastewater 19(3):34-46.
 Sahay RR, 2013. Predicting longitudinal dispersion coefficients in sinuous rivers by genetic algorithm. Journal Hydrology Hydromech 61(3): 214–221.
Sedghi-Asl M, 2010. Investigation of the limits of the dupuit analogue for steady gradually varied flow through course porous media. Ph.D. Thesis. Irrigation and reclamation department. University of Tehran.
Soltangerd-Faramarzi S, Taghizadeh R and Ghasemi M, 2015. Estimation of dispersion coefficient in rivers with different data mining methods. Iranian Water and Soil Research Journal 46(3):385-394.
Tayfur G and Singh VP, 2005. Predicting longitudinal dispersion coefficient in natural streams by artificial neural network. Journal of Hydraulic Engineering 131(11): 991-1000.
Taylor GI, 1953. Dispersion of soluble matter in solvent flowing slowly through a tube. Proc Royal Soc London Ser. A, 219:186-203.
Taylor GI, 1954. The dispersion of matter in turbulent flow through a pipe. Proc Royal Soc London Ser. A, 223:446-468.
  Wagener T, Camacho LA and Wheater HS, 2002. Dynamic identifiability analysis of the transient storage               model for solute transport in rivers. Journal of Hydroinormatics 4(3): 199-211. 
Wallis SG, Piotrowski A, Rowinski PM and Napiorkowski JJ, 2007. Prediction of dispersion coefficients in a small stream using artificial neural networks. Proceeding of the 32nd IAHR Congress, Venice, Paper B2b-083-O.
Zaramella M, Marion A, Lewandowski j and Nutzmann G, 2016. Assessment of transient storage exchange and advection-dispersion mechanisms from concentration signatures along breakthrough curves. Journal of Hydrology 538: 794-801.
Water and Soil Science
Volume 28, Issue 4
January 2019
Pages 127-139

Files

Share

How to cite

Statistics