A simple low-cost approach for transport parameter determination in mountain rivers

Abstract

A simplified low-cost approach to experimentally determine transport parameters inmountain rivers is described,with an emphasis on the longitudinal dispersion coefficient(DL). The approach is based on a slug injectionof table salt (NaCl) as a tracer and specificconductance readings at different locations downstream of the injection spot. Observedspecific conductance readings are fit using the advection-dispersion equation withOTIS-P, yielding estimates of cross-sectional area and longitudinal dispersion coefficientfor various stream reaches. Estimates of theDLare used to assess the accuracy of sev-eral empirical equations reported in the literature. This allowed the determination ofcomplementary transport parameters related to transient storage zones. The empiricalequations yielded rather highDLvalues, with some reaching up an order of magnitudehigher to those obtained from tracer additions and OTIS-P. Overall, the proposedapproach seems reliable and pertinent for river reaches of ca. 150 m in length.