Modulation of riverine concentration-discharge relationships by changes in the shape of the water transit time distribution

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint.

Downloads

Download Preprint

Authors

Mark Albert Torres, J. Jotautas Baronas 

Abstract

The concentrations of weathering-derived solutes in rivers and their co-variance with discharge are thought to reflect reactive-transport processes in hillslopes and to reveal the sensitivity of solute fluxes to climatic change. It is expected that discharge-driven changes in water transit times play some role in setting concentration-discharge (C-Q) relationships, but knowledge gaps remain. To explore the specific role of changes in the shape of the transit time distribution with discharge, we combine models to simulate C-Q relationships for major cations and Si as example solutes with contrasting affinities to partition into secondary phases. The model results are compared with an analysis of C-Q relationships using the Global River Chemistry Database.

We find that changes in the shape of the transit time distribution with discharge can produce a range of cation-Q and Si-Q relationships that encompasses most of the range observed in real catchments, including positive Si-Q relationships and variable cation to Si ratios. We find that C-Q relationships (characterized by power law exponents) can remain approximately constant, even as the Damköhler Number (ratio of transport timescale to reaction timescale) is varied over three orders of magnitude. So, in our model analysis, C-Q relationships are as sensitive to hydrologic variability as they are to reaction rates. Additionally we find that, depending on the storage-discharge relationship, changes in rainfall patterns can influence C-Q relationships. Altogether, our results suggest ways in which C-Q relationships may be non-stationary in response to climatic change and/or vary in space and time due to catchment hydrologic properties.

DOI

https://doi.org/10.31223/X5V306

Subjects

Geochemistry, Hydrology

Keywords

chemical weathering, concentration-discharge, water transit time

Dates

Published: 2020-10-21 13:09

Last Updated: 2020-10-21 20:09

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
No conflicts of interest

Data Availability (Reason not available):
Data available as described in manuscript

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.