Explaining the Variability in High?Frequency Nitrate Export Patterns Using Long?Term Hydrological Event Classification

Runoff events play an important role in nitrate export from catchments, but the variability of patterns between and catchments is high dominant drivers remain difficult to disentangle. Here, we rigorously asses if detailed knowledge on runoff event characteristics can help explain this variability. To end, conducted a long-term (1955–2018) classification using hydro-meteorological data, including rainfall characteristics, soil moisture snowmelt, six neighboring mesoscale with contrasting land use. We related these high-frequency concentration monitoring (2013–2017) concentration-discharge (CQ) relationships. Our results show that low-magnitude rainfall-induced dry antecedent conditions exported lowest concentrations loads exhibited highly variable CQ by low fraction active flow paths, revealing spatial heterogeneity sources within increased impact biogeochemical retention processes. In contrast, high-magnitude or snowmelt-induced highest converged similar chemostatic across all without exhibiting source limitation. homogeneous catchment wetness activated number paths higher availability during high-flow seasons. Long-term data indicated summer decreased snow-influenced events. These trends will likely continue cause low-flow seasons changes timing peaks