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Doctoral thesis, 2021

Phosphorus transport in the landscape – Integrating high-frequency monitoring, phosphorus geochemistry and modelling to improve water management

Lannergård, Emma

Abstract

Eutrophication is one of today’s most challenging water quality issues, despite considerable efforts to reduce phosphorus (P) input to surface waters. We need to explore new tools and techniques to improve the nutrient status of our waters and facilitate the management of catchment-scale P transport. This thesis includes research on P stored in lake and streambed sediment, timing and delivery of P in the system, processes influencing this transport and predictions by water quality modelling. The results show that significant amounts of P are stored in the catchment sediments, with some streams showing comparable concentrations to lakes. Phosphorus fractions are influenced by land cover and stream order. Some fractions could be important P sources during low flows when there is a significant risk of eutrophication associated with small increases in concentration. High-frequency (HF) monitoring is an important tool to increase understanding of catchment-scale P dynamics. Especially during intermediate and high flow events, the finer temporal resolution of HF data is essential for load calculations. Also, these events showed a dominant clockwise C-Q hysteresis response that suggests fast mobilisation of particles from the streambed and riparian areas. HF data was valuable in water quality modelling to describe temporal patterns but was challenging to calibrate and evaluate with standard performance statistics. Further work is needed on efficient and transferrable methods to analyse HF data. With an improved knowledge of P stores and the use of HF data, better-informed management decisions can be made to ensure water management that reduces catchment-scale P transport.

Keywords

Phosphorus transport; water management; environmental assessment; phosphorus legacy; high-frequency monitoring; proxy relations; C-Q analysis; water quality modelling; INCA-PEco

Published in

Acta Universitatis Agriculturae Sueciae
2021, number: 2021:84
ISBN: 978-91-7760-845-5, eISBN: 978-91-7760-846-2
Publisher: Swedish University of Agricultural Sciences

Authors' information

Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment

UKÄ Subject classification

Oceanography, Hydrology, Water Resources

URI (permanent link to this page)

https://res.slu.se/id/publ/114380