University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 46 4 2015 12 22 Determination of Longitudinal Dispersion Coefficient Involving Tracer Experiment Data Determination of Longitudinal Dispersion Coefficient Involving Tracer Experiment Data 653 662 56789 10.22059/ijswr.2015.56789 FA Mehdi Mohammadi Ghaleni PhD Candidate, Water Resources Engineering, Department of Irrigation & Reclamation Engineering, University of Tehran, Karaj, Iran Kumars Ebrahimi Associate Professor, Department of Irrigation & Reclamation Engineering, University of Tehran, Karaj, Iran Mohammad Hosein Omid Professor, Department of Irrigation and Reclamation Engineering, University of Tehran, Karaj, Iran Journal Article 2015 05 23 Longitudinal dispersion coefficient is normally affected by many hydraulic parameters. So far three approaches namely, integral method, dye tracing filed measurements and empirical formulae have been widely employed to estimate the above mentioned coefficient in rivers and streams. In this paper a new equation of the longitudinal dispersion coefficient is devised and evaluated using an environmentally safe tracer plus the basic empirical equations. To achieve the aim, a length of 500 meters of a manmade concrete canal was chosen, to be used in carrying out the tracer tests. A set of experiments were conducted in Feb.2015, within three different mixing lengths, of: 45, 75 and 100 meters. The results show that differences of average, variance and maximum concentration between the measured vs estimated data using the lastly available equation) are equal to 79, 6, and 99 mg/lit while using the newly equation found in the present study they are respectively equal to 66, -1 and 44 mg/lit. Longitudinal dispersion coefficient is normally affected by many hydraulic parameters. So far three approaches namely, integral method, dye tracing filed measurements and empirical formulae have been widely employed to estimate the above mentioned coefficient in rivers and streams. In this paper a new equation of the longitudinal dispersion coefficient is devised and evaluated using an environmentally safe tracer plus the basic empirical equations. To achieve the aim, a length of 500 meters of a manmade concrete canal was chosen, to be used in carrying out the tracer tests. A set of experiments were conducted in Feb.2015, within three different mixing lengths, of: 45, 75 and 100 meters. The results show that differences of average, variance and maximum concentration between the measured vs estimated data using the lastly available equation) are equal to 79, 6, and 99 mg/lit while using the newly equation found in the present study they are respectively equal to 66, -1 and 44 mg/lit. https://ijswr.ut.ac.ir/article_56789_4a801acfe2389842c639e45e33a3f2e8.pdf