Temporal moment analysis of tracer discharge in streams: Combined effect of physicochemical mass transfer and morphology
2000 (English)In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 36, no 10, 2985-2997 p.Article in journal (Refereed) Published
In environmental applications it is often of interest to predict the rates at which contaminant mass is discharged at a given cross section of streams and rivers. We present a Lagrangian methodology for evaluating tracer discharge (mass per unit time) at specified control cross sections (CCS) of streams. The key transport processes included in the analysis are advection, degradation/decay, and kinetically controlled mass transfer in storage zones and in bed sediment. The transport in the bed sediment is described as a diffusion process, where the tracer may sorb onto the sediment. We have derived a general solution for tracer discharge in the Laplace domain wherefrom temporal moments are computed. The derived solutions may account for deterministic changes in morphological characteristics along stretches of streams. The results are illustrated for zeroth and first two moments where we show the combined effect of advection, degradation, physicochemical mass transfer, and morphology. For illustrative purposes, we assume morphology to change downstream following power laws suggested by Langbein  and Leopold and Maddock . The moments depend nonlinearly on the downstream distance, following power laws that reflect the power laws for the hydraulic geometry. We define two main dimensionless parameters, namely, kinetic storage parameter alpha* and bed parameter M, that control the amount of tracer mass eventually discharged at any given CCS. For M approximate to greater than or equal to 0.3 the most dominant mechanism that controls the amount of ultimately discharged tracer mass is the exchange with the bed sediment. Once estimated from field data for stretches of specified streams, the dimensionless parameters can be used in the derived expressions for predictive purposes.
Place, publisher, year, edition, pages
2000. Vol. 36, no 10, 2985-2997 p.
reactive solute transport, transient storage model, longitudinal dispersion, nonsorbing solutes, geological media, immiscible flow, riffle stream, bed forms, simulation, sorption
IdentifiersURN: urn:nbn:se:kth:diva-20064ISI: 000089589600015OAI: oai:DiVA.org:kth-20064DiVA: diva2:338757
QC 201005252010-08-102010-08-10Bibliographically approved