Downstream changes in DOC:inferring contributions in the face of model uncertainties

Tiwari, Tejshree and Laudon, Hjalmar and Beven, Keith and Agren, Anneli M. (2014) Downstream changes in DOC:inferring contributions in the face of model uncertainties. Water Resources Research, 50 (1). pp. 514-525. ISSN 0043-1397

PDF (wrcr20711)
wrcr20711.pdf - Published Version

Download (563kB)


Dissolved organic carbon (DOC) is a central constituent of surface waters which control its characteristic color and chemistry. While the sources and controls of headwater stream DOC can be mechanistically linked to the dominant landscape types being drained, much remains unknown about the downstream controls at larger spatial scales. As DOC is transported from the headwaters to catchment outlets, the fate of stream DOC is largely dependent on the interaction of varying catchment processes. In this study, we investigated the main mechanisms regulating stream DOC in a mesoscale catchment. A landscape-mixing model was used to test the role of landscapes in determining stream concentrations. The quantity of DOC lost to in-stream processes was calculated using bacterial respiration and photooxidation rates. We investigated whether there was a change in water pathways using a mass balance model and comparison of hydrology between a headwater catchment and the entire catchment. A Monte Carlo approach was used to test robustness of the model assumptions and results to uncertainty in the process parameterizations. The results indicated that during high- and intermediate-flow conditions, DOC concentrations were regulated by the contributing upstream landscape types. During base flow, the connectivity between the mesoscale river and the upstream landscape reduced resulting in large residuals in the landscape model which could not be explained by the in-stream processes. Both the mass balance model and a specific runoff comparison between upstream/downstream sites independently indicated large input of deep groundwater during base flow. Deep groundwater was important for diluting stream DOC concentrations during base flow. Key Points Landscape types determine stream chemistry during high and intermediate flows Deep groundwater has large influences on stream chemistry during baseflow DOC lost to instream processes were small

Item Type:
Journal Article
Journal or Publication Title:
Water Resources Research
Additional Information:
©2014. American Geophysical Union. All Rights Reserved.
Uncontrolled Keywords:
ID Code:
Deposited By:
Deposited On:
14 Aug 2014 10:24
Last Modified:
13 Sep 2022 00:42