Exploring river–aquifer interactions and hydrological system response using baseflow separation, impulse response modelling and time series analysis in three temperate lowland catchments
- 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
- 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: closed
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RC1: 'Comment on hess-2021-422', Anonymous Referee #1, 29 Sep 2021
The study looks in details at the hydrological interactions between lowland rivers and shallow quifers in three different catchments in Belgium. In their analysis, the authors use a combined approach of baseflow separation, impulse response modeling and time series analysis over a 30-year period. Overall, the paper is well-written and the results are insightful and very useful to the hydrology community. I think the paper should be published after addressing the following minor/technical comments:
- Looking at Fig. 11(c), I can see a slight overestimation of the groundwater levels prior to 2000. Can the impulse response parameters be tuned to improve the fit to the data? Also the seasons, as decribed in the text, are not clear on the figure. Consider zooming in.
- Section 4.2.2: I am interested to look at the entire eigenvalue spectrums. I understand that the first mode at the 3 different sites dominate the rest of the modes. Does the spectrum die after the first leading modes? I expect the leading modes to change if there is some sort of an extreme rainfall event. It might be helpful to comment and discuss this further in the text.
- Do you expect the BFI estimates in these groundwater-dominated lowland catchments to change if the precipitation regimes change?
- The figures could be annotated better. For instance, in Fig. 13 does not label the black and the gray curves.
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AC1: 'Reply on RC1', Min Lu, 23 Oct 2021
Dear Anonymous Referee #1,
First of all, thank you very much for reviewing our paper. We are very grateful for your time and comments that help to improve the manuscript.
We have responded point-by-point to your comments and suggestions. Please check the detailed replies in the supplement, with your original comments in italic and our answers in blue. A revised manuscript which specifies the adjustments based on your comments will be provided at a later stage, awaiting the review from a second referee and the editor’s decision.
We are looking forward to your further assessment.
On behalf of all authors,
With best regards,
Min Lu
Corresponding author
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AC1: 'Reply on RC1', Min Lu, 23 Oct 2021
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RC2: 'Comment on hess-2021-422', Frank Schwartz, 27 Oct 2021
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-422/hess-2021-422-RC2-supplement.pdf
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AC2: 'Reply on RC2', Min Lu, 20 Nov 2021
Dear Prof. Dr. Franklin Schwartz,
Thank you very much for reviewing our paper entitled “Exploring river–aquifer interactions and hydrological system response using baseflow separation, impulse response modelling and time series analysis in three temperate lowland catchments (HESS-2021-422)”. We appreciate your time and comments which will help improving the manuscript.
In the supplement you will find our detailed responses and explanations (in blue) to your comments and suggestions (in italic). A revised manuscript will be prepared later with tracked changes made to the original manuscript based on your and other’s comments, awaiting the decision from the editor.
We are looking forward to your further assessment.
On behalf of all authors,
With best regards,
Min Lu
Corresponding author
-
AC2: 'Reply on RC2', Min Lu, 20 Nov 2021
Status: closed
-
RC1: 'Comment on hess-2021-422', Anonymous Referee #1, 29 Sep 2021
The study looks in details at the hydrological interactions between lowland rivers and shallow quifers in three different catchments in Belgium. In their analysis, the authors use a combined approach of baseflow separation, impulse response modeling and time series analysis over a 30-year period. Overall, the paper is well-written and the results are insightful and very useful to the hydrology community. I think the paper should be published after addressing the following minor/technical comments:
- Looking at Fig. 11(c), I can see a slight overestimation of the groundwater levels prior to 2000. Can the impulse response parameters be tuned to improve the fit to the data? Also the seasons, as decribed in the text, are not clear on the figure. Consider zooming in.
- Section 4.2.2: I am interested to look at the entire eigenvalue spectrums. I understand that the first mode at the 3 different sites dominate the rest of the modes. Does the spectrum die after the first leading modes? I expect the leading modes to change if there is some sort of an extreme rainfall event. It might be helpful to comment and discuss this further in the text.
- Do you expect the BFI estimates in these groundwater-dominated lowland catchments to change if the precipitation regimes change?
- The figures could be annotated better. For instance, in Fig. 13 does not label the black and the gray curves.
-
AC1: 'Reply on RC1', Min Lu, 23 Oct 2021
Dear Anonymous Referee #1,
First of all, thank you very much for reviewing our paper. We are very grateful for your time and comments that help to improve the manuscript.
We have responded point-by-point to your comments and suggestions. Please check the detailed replies in the supplement, with your original comments in italic and our answers in blue. A revised manuscript which specifies the adjustments based on your comments will be provided at a later stage, awaiting the review from a second referee and the editor’s decision.
We are looking forward to your further assessment.
On behalf of all authors,
With best regards,
Min Lu
Corresponding author
-
AC1: 'Reply on RC1', Min Lu, 23 Oct 2021
-
RC2: 'Comment on hess-2021-422', Frank Schwartz, 27 Oct 2021
The comment was uploaded in the form of a supplement: https://hess.copernicus.org/preprints/hess-2021-422/hess-2021-422-RC2-supplement.pdf
-
AC2: 'Reply on RC2', Min Lu, 20 Nov 2021
Dear Prof. Dr. Franklin Schwartz,
Thank you very much for reviewing our paper entitled “Exploring river–aquifer interactions and hydrological system response using baseflow separation, impulse response modelling and time series analysis in three temperate lowland catchments (HESS-2021-422)”. We appreciate your time and comments which will help improving the manuscript.
In the supplement you will find our detailed responses and explanations (in blue) to your comments and suggestions (in italic). A revised manuscript will be prepared later with tracked changes made to the original manuscript based on your and other’s comments, awaiting the decision from the editor.
We are looking forward to your further assessment.
On behalf of all authors,
With best regards,
Min Lu
Corresponding author
-
AC2: 'Reply on RC2', Min Lu, 20 Nov 2021
Min Lu et al.
Min Lu et al.
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