Preprints
https://doi.org/10.5194/hess-2021-422
https://doi.org/10.5194/hess-2021-422

  07 Sep 2021

07 Sep 2021

Review status: this preprint is currently under review for the journal HESS.

Exploring river–aquifer interactions and hydrological system response using baseflow separation, impulse response modelling and time series analysis in three temperate lowland catchments

Min Lu1,2, Bart Rogiers1, Koen Beerten1, Matej Gedeon1, and Marijke Huysmans2,3 Min Lu et al.
  • 1Institute for Environment, Health and Safety, Belgian Nuclear Research Centre, Mol, 2400, Belgium
  • 2Department of Earth and Environmental Sciences, KU Leuven, Leuven, 3001, Belgium
  • 3Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussels, 1050, Belgium

Abstract. Lowland rivers and shallow aquifers are closely coupled and their interactions are crucial for maintaining healthy stream ecological functions. In order to explore river–aquifer interactions and lowland hydrological system in three Belgian catchments, we apply a combined approach of baseflow separation, impulse response modelling and time series analysis over a 30–year study period at catchment scale. Baseflow from hydrograph separation shows that the three catchments are groundwater-dominated. The recursive digital filter methods generate a smoother baseflow time series than the graphical methods, and yield more reliable results than the graphical ones. Impulse response modelling is applied with a two–step procedure. The first step where groundwater level response is modelled shows that groundwater level in shallow aquifers reacts fast to the system input, with most of the wells reaching their peak response during the first day. There is an overall trend of faster response time and higher response magnitude in the wet (October–March) than the dry (April–September) periods. The second step of baseflow response modelling shows that the system response is also fast and that simulated baseflow can capture some variations but not the peaks of the separated baseflow time series. The time series analysis indicates that components such as interflow and overland flow, contribute significantly to stream flow. They are somehow included as part of the separated baseflow, which is likely to be overestimated from hydrograph separation. The impulse response modelling approach from the groundwater flow perspective can be an optional method to estimate the baseflow, since it considers some level of the physical connection between river and aquifer in the subsurface. Further research is however recommended to improve the simulation, such as giving more weight to wells close to the river and adding more drainage dynamics to the model input.

Min Lu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-422', Anonymous Referee #1, 29 Sep 2021
    • AC1: 'Reply on RC1', Min Lu, 23 Oct 2021
  • RC2: 'Comment on hess-2021-422', Frank Schwartz, 27 Oct 2021
    • AC2: 'Reply on RC2', Min Lu, 20 Nov 2021

Min Lu et al.

Min Lu et al.

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Short summary
This research not only provides insights into the river-aquifer interactions over the past 30 years but also serves as a benchmark study for predicting their interactions under future climate scenarios. The results show that the lowland catchments are groundwater-dominated and the lowland hydrological system from precipitation impulse to baseflow response is a very fast response system. This study also provides an option to assess baseflow from the groundwater flow (level) persepctive.