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Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments

Ockenden, M.C.; Deasy, C.E.; Benskin, C.McW.H.; Beven, K.J.; Burke, S.; Collins, A.L.; Evans, R.; Falloon, P.D.; Forber, K.J.; Hiscock, K.M.; Hollaway, M.J.; Kahana, R.; Macleod, C.J.A.; Reaney, S.M.; Snell, M.A.; Villamizar, M.L.; Wearing, C.; Withers, P.J.A.; Zhou, J.G.; Haygarth, P.M.

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Authors

M.C. Ockenden

C.E. Deasy

C.McW.H. Benskin

K.J. Beven

S. Burke

A.L. Collins

R. Evans

P.D. Falloon

K.J. Forber

K.M. Hiscock

M.J. Hollaway

R. Kahana

C.J.A. Macleod

M.A. Snell

M.L. Villamizar

C. Wearing

P.J.A. Withers

J.G. Zhou

P.M. Haygarth



Abstract

We hypothesise that climate change, together with intensive agricultural systems, will increase the transfer of pollutants from land to water and impact on stream health. This study builds, for the first time, an integrated assessment of nutrient transfers, bringing together a) high-frequency data from the outlets of two surface water-dominated, headwater (~ 10 km2) agricultural catchments, b) event-by-event analysis of nutrient transfers, c) concentration duration curves for comparison with EU Water Framework Directive water quality targets, d) event analysis of location-specific, sub-daily rainfall projections (UKCP, 2009), and e) a linear model relating storm rainfall to phosphorus load. These components, in combination, bring innovation and new insight into the estimation of future phosphorus transfers, which was not available from individual components. The data demonstrated two features of particular concern for climate change impacts. Firstly, the bulk of the suspended sediment and total phosphorus (TP) load (greater than 90% and 80% respectively) was transferred during the highest discharge events. The linear model of rainfall-driven TP transfers estimated that, with the projected increase in winter rainfall (+ 8% to + 17% in the catchments by 2050s), annual event loads might increase by around 9% on average, if agricultural practices remain unchanged. Secondly, events following dry periods of several weeks, particularly in summer, were responsible for high concentrations of phosphorus, but relatively low loads. The high concentrations, associated with low flow, could become more frequent or last longer in the future, with a corresponding increase in the length of time that threshold concentrations (e.g. for water quality status) are exceeded. The results suggest that in order to build resilience in stream health and help mitigate potential increases in diffuse agricultural water pollution due to climate change, land management practices should target controllable risk factors, such as soil nutrient status, soil condition and crop cover.

Citation

Ockenden, M., Deasy, C., Benskin, C., Beven, K., Burke, S., Collins, A., …Haygarth, P. (2016). Changing climate and nutrient transfers: Evidence from high temporal resolution concentration-flow dynamics in headwater catchments. Science of the Total Environment, 548-549, https://doi.org/10.1016/j.scitotenv.2015.12.086

Journal Article Type Article
Publication Date Apr 1, 2016
Deposit Date Oct 18, 2019
Publicly Available Date Mar 28, 2024
Journal Science of the Total Environment
Print ISSN 0048-9697
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 548-549
DOI https://doi.org/10.1016/j.scitotenv.2015.12.086

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