Abstract
A large proportion of nutrients and sediment is mobilised in catchments during storm events. Therefore understanding a catchment's hydrological behaviour during storms and how this acts to mobilise and transport nutrients and sediment to nearby watercourses is extremely important for effective catchment management. The expansion of available in-situ sensors is allowing a wider range of water quality parameters to be monitored and at higher temporal resolution, meaning that the investigation of hydrochemical behaviours during storms is increasingly feasible. Studying the relationship between discharge and water quality parameters in storm events can provide a valuable research tool to infer the likely source areas and flow pathways contributing to nutrient and sediment transport. Therefore, this paper uses 2years of high temporal resolution (15/30min) discharge and water quality (nitrate-N, total phosphorus (TP) and turbidity) data to examine hysteretic behaviour during storm events in two contrasting catchments, in the Hampshire Avon catchment, UK. This paper provides one of the first examples of a study which comprehensively examines storm behaviours for up to 76 storm events and three water quality parameters. It also examines the observational uncertainties using a non-parametric approach. A range of metrics was used, such as loop direction, loop area and a hysteresis index (HI) to characterise and quantify the storm behaviour. With two years of high resolution information it was possible to see how transport mechanisms varied between parameters and through time. This study has also clearly shown the different transport regimes operating between a groundwater dominated chalk catchment versus a surface-water dominated clay catchment. This information, set within an uncertainty framework, means that confidence can be derived that the patterns and relationships thus identified are statistically robust. These insights can thus be used to provide information regarding transport processes and biogeochemical processing within river catchments.
Highlights
Storm events generate significant transport of nutrient fractions and sediment in catchments
The decrease in concentration of nitrate-N in the groundwater over this period is supported by the fortnightly grab samples collected as part of the Hampshire Avon DTC from the borehole at Kingston Deverill 2.7 km upstream from Brixton Deverill, where nitrate-N concentrations decreased from 7.4 mg L−1 to 6.4 mg L−1 between July 2013 and November 2013
The detailed uncertainty analysis incorporated in this work has allowed us, for the first time, to assess the quality of the data available, cascading this uncertainty information through the analysis presented
Summary
Storm events generate significant transport of nutrient fractions and sediment in catchments. The recent expansion of the use of in-situ sensors to monitor nutrient parameters routinely at high temporal resolution is making detailed analysis of catchment behaviours in response to storm flow activation more feasible Parameters such as turbidity have been used to investigate storm behaviours as it can be measured at high frequency and has been shown to be a reasonable surrogate for the transport of sediment and sediment-associated contaminants such as phosphorus (as particulate P), ammonium and particulate organic nitrogen fractions which cannot be measured directly with existing sensor technologies (Grayson et al, 1996; Kronvang et al, 1997; Stubblefield et al, 2007). The more recent introduction of novel sensors systems and bankside automated photometers means that parameters such as nitrate-N and total phosphorus can be investigated at higher temporal resolutions than previously possible
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
