High-frequency monitoring of catchment nutrient exports reveals highly variable storm event responses and dynamic source zone activation

Phillip J. Blaen, Kieran Khamis, Charlotte Lloyd, Sophie Comer-Warner, Francesco Ciocca, Rick M. Thomas, A. Rob MacKenzie, Stefan Krause

Research output: Contribution to journalArticle (Academic Journal)peer-review

42 Citations (Scopus)
288 Downloads (Pure)


Storm events can drive highly variable behavior in catchment nutrient and water fluxes, yet short-term event dynamics are frequently missed by low-resolution sampling regimes. In addition, nutrient source zone contributions can vary significantly within and between storm events. Our inability to identify and characterize time-dynamic source zone contributions severely hampers the adequate design of land use management practices in order to control nutrient exports from agricultural landscapes. Here we utilize an 8 month high-frequency (hourly) time series of streamflow, nitrate (NO3-N), dissolved organic carbon (DOC), and hydroclimatic variables for a headwater agricultural catchment. We identified 29 distinct storm events across the monitoring period. These events represented 31% of the time series and contributed disproportionately to nutrient loads (42% of NO3-N and 43% of DOC) relative to their duration. Regression analysis identified a small subset of hydroclimatological variables (notably precipitation intensity and antecedent conditions) as key drivers of nutrient dynamics during storm events. Hysteresis analysis of nutrient concentration-discharge relationships highlighted the dynamic activation of discrete NO3-N and DOC source zones, which varied on an event-specific basis. Our results highlight the benefits of high-frequency in situ monitoring for characterizing short-term nutrient fluxes and unraveling connections between hydroclimatological variability and river nutrient export and source zone activation under extreme flow conditions. These new process-based insights, which we summarize in a conceptual model, are fundamental to underpinning targeted management measures to reduce nutrient loading of surface waters.
Original languageEnglish
Pages (from-to)2265-2281
Number of pages17
JournalJournal of Geophysical Research: Biogeosciences
Issue number9
Early online date7 Sep 2017
Publication statusPublished - 2017

Bibliographical note



  • Nutrients and nutrient cycling, Water quality, Extreme events, Hydroclimatology, Monitoring networks, sensor, in situ, NO3, DOC, river, hysteresis

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