Experimental and numerical validation of the dead-zone model for longitudinal dispersion in rivers

Abstract

Experimental results of longitudinal dispersion in rivers are discussed in the light of new findings with respect to the "dead-zone" theory. Both the experiments made by authors as well as some literature results are taken into consideration. The dead-zone model parameters, namely the relative dead-zone volume, penetration time of the tracer into dead-zones, constant mean flow velocity and dispersion coefficient, are obtained with the use of the nonlinear least square technique applied to the image functions of concentration time-distributions. The statistical moments of the concentration time distributions as functions of distance are also analyzed. Expressions for statistical moments, recently obtained by authors, are found to agree well with both experimental and computational results. RÉSUMÉDes résultats expérimentaux concernant la dispersion longitudinale dans une rivière sont discutés au vu de nouvelles découvertes de la theorie des zones d'eau morte. On prend en consideration des mesures réalisées par les auteurs, ainsi que des résultats tirés de la littérature. On a applique la technique non-linéaire de moindres carrés aux fonctions temps de concentration-distributions, pour obtenir les paramètres du modèle de zones d'eau morte. A savoir : Ie volume relatif des zones d'eau morte, Ie temps de penetration du marqueur dans les zones d'eau morte, la vitesse moyenne constante et Ie coefficient de dispersion de l'écoulement. On a analyse également les moments des distributions temps-concentration, traites comme des fonctions de la distance. On constate que les expressions des moments statiques, obtenues récemment par les auteurs, s'accordent bien avec les résultats expérimentaux ainsi qu'avec ceux des calculs.

Estimation of parameters of the transient storage model by means of multi-layer perceptron neural networks / Estimation des paramètres du modèle de transport TSM au moyen de réseaux de neurones perceptrons multi-couches

“…The total friction factor is extremely difficult for evaluation with the available data, the achieved error is unacceptable and it makes the method inapplicable in most cases. In certain situations it might lead to similar results to those obtained by means of other techniques (see Czernuszenko et al, 1998), but it requires a very good knowledge of the stream characteristics. Therefore, even the results based on the SY method, also dependent on friction factor f, are only to illustrate the possible differences introduced by different methods.…”

“…The database used in this paper was put together by Cheong & Seo (2003). They collected the measurements from the studies of Fisher (1968), Godfrey & Frederick (1970), Nordin & Sabol (1974), Graf (1995) and Czernuszenko et al (1998). The database is composed of 58 measurements, obtained for river reaches which vary significantly in time and space scales, as well as in hydrological regime.…”

A physicochemical model for colloid exchange between a stream and a sand streambed with bed forms

“…Exchange between streams and groundwater aquifers has Rowinski, 1997;Czernuszenko et al, 1998]. A new model explicitly represents stream-subsurface exchange as a diffusive process [Worman, 1998] but still requires curve fitting to determine the exchange coefficient.…”

A comprehensive one-dimensional numerical model for solute transport in rivers

“…After the introduction of the TSM, transient storage processes have been studied in a variety of small mountain streams, as well as large rivers, and it was shown that simulation results of tracer study data considering the transient storage impact have good agreement with observed data. Also, it was shown that the interaction between the main channel and storage zones, especially in mountain streams, has a great effect on solute transport behavior (D'Angelo et al, 1993;DeAngelis et al, 1995;Morrice et al, 1997;Czernuszenko et al, 1998;Chapra and Runkel, 1999;Chapra and Wilcock, 2000;Laenen and Bencala, 2001;Fernald et al, 2001;Keefe et al, 2004;Ensign and Doyle, 2005;Van Mazijk and Veling, 2005;Gooseff et al, 2007;Jin et al, 2009). In this study, a comprehensive model, called TOASTS (third-order accuracy simulation of transient storage), able to obviate shortcomings of current models of contaminant transport, is presented.…”