Hydroclimatic variability and riparian wetland restoration control the hydrology and nutrient fluxes in a lowland agricultural catchment

Songjun Wu*, Doerthe Tetzlaff, Tobias Goldhammer, Chris Soulsby

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


Climate change and riparian management are major drivers of hydrological change, with important implications for nutrient fluxes in lowland streams. However, the coupling of hydrological and nutrient dynamics is complex due to time-variant flow paths, interacting biogeochemical processes and variation in land use, fertilization levels and management measures. Here, we assessed the long-term (30 year) changes in climate, discharge, groundwater levels and stream water quality in a mixed land use catchment (Demnitzer Mill Creek catchment, DMC) in northern Germany. The catchment was subject to wetland restoration and subsequent beaver (Castor fiber) recolonization over the last 15 years. Climatic variability is the primary driver of the hydrological regime, with discharge and groundwater variations closely coupled to increases in annual air temperature and fluctuations of annual rainfall. Over the past 8 years, stream flows have been greatly reduced during a prolonged drought period. Meanwhile, beaver dams have also moderated flow regimes and facilitated groundwater recharge. In terms of water quality regimes, the concentration-discharge (C-Q) relationship for nitrate (NO3-N) and soluble reactive phosphate (SRP) showed positive and negative chemodynamic behavior respectively, whilst dissolved organic carbon (DOC) exhibited chemostatic behavior. These differences were dictated by the intrinsic properties of each solute in terms of contrasting catchment storage and immobilization processes. Moreover, the changing hydrological conditions regulated such patterns and strengthened the C-Q relationships for nutrients during the drought. As an integrated result of drought and wetland restoration, nutrient concentrations and fluxes in stream water have been reduced in recent years. Headwater catchments like DMC, where much of the hydrochemical signature of larger, downstream river networks are generated, are critical observatories for integrating understanding of the linkages between water quality and land management in an era of climate change.

Original languageEnglish
Article number126904
Number of pages15
JournalJournal of Hydrology
Issue numberPart B
Early online date4 Sept 2021
Publication statusPublished - 1 Dec 2021

Bibliographical note

Funding Information:
Songjun Wu is funded by the Chinese Scholarship Council (CSC). We acknowledge contributions from Chris Soulsby funded by the Leverhulme Trust’s ISOLAND project, and support from Elisabeth Schuette, Thomas Rossoll, Sarah Krocker and former staff of the IGB chemical analytics and biogeochemistry lab, for nutrient and DOC analyses, and for compiling the long-term DMC dataset. We also thank Lukas Kleine for helping with data collection, Aaron Smith for help with data analysis and Xiaoqiang Yang for the support on storm event detection.


  • DOC
  • Drought
  • Long-term monitoring
  • Nitrate phosphorus
  • Nutrient export
  • Riparian restoration


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