Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.5194/hess-26-6227-2022
Lizenz creative commons licence
Titel (primär) Disentangling scatter in long-term concentration–discharge relationships: the role of event types
Autor Saavedra, F.A.; Musolff, A.; von Freyberg, J.; Merz, R.; Basso, S.; Tarasova, L.
Journal / Serie Hydrology and Earth System Sciences
Erscheinungsjahr 2022
Department HDG; CATHYD
Band/Volume 26
Heft 23
Seite von 6227
Seite bis 6245
Sprache englisch
Topic T4 Coastal System

Relationships between nitrate concentrations and discharge rates (CQ) at the catchment outlet can provide insights into sources, mobilization and biogeochemical transformations of nitrate within the catchment. Nitrate CQ relationships often exhibit considerable scatter that might be related to variable hydrologic conditions during runoff events at sampling time, corresponding to variable sources and flow paths despite similar discharge (Q) rates. Although previous studies investigated the origins of this scatter in individual or in a few catchments, the role of different runoff event types across a large set of catchments is not yet fully understood.

This study combines a hydrological runoff event classification framework with low-frequency nitrate samples in 184 catchments to explore the role of different runoff events in shaping long-term CQ relationships and their variability across contrasting catchments. In most of the catchments, snow-impacted events produce positive deviations of concentrations, indicating an increased nitrate mobilization compared to the long-term pattern. In contrast, negative deviations occur mostly for rainfall-induced events with dry antecedent conditions, indicating the occurrence of lower nitrate concentrations (C) in river flows than their long-term pattern values during this type of event. Pronounced differences in event runoff coefficients among different event types indicate their contrasting levels of hydrologic connectivity that in turn might play a key role in controlling nitrate transport due to the activation of faster flow paths between sources and streams. Using long-term, low-frequency nitrate data, we demonstrate that runoff event types shape observed scatter in long-term CQ relationships according to their level of hydrologic connectivity. In addition, we hypothesize that the level of biogeochemical attenuation of catchments can partially explain the spatial variability of the scatter during different event types.

dauerhafte UFZ-Verlinkung
Saavedra, F.A., Musolff, A., von Freyberg, J., Merz, R., Basso, S., Tarasova, L. (2022):
Disentangling scatter in long-term concentration–discharge relationships: the role of event types
Hydrol. Earth Syst. Sci. 26 (23), 6227 - 6245