Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Angermann, Lisa; Jackisch, Conrad; Allroggen, Niklas; Sprenger, Matthias; Zehe, Erwin; Tronicke, Jens; Weiler, Markus; Blume, Theresa

doi:https://doi.org/10.5194/hess-21-3727-2017

Articles | Volume 21, issue 7

https://doi.org/10.5194/hess-21-3727-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-21-3727-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 21, issue 7

Research article

|

21 Jul 2017

Research article |

| 21 Jul 2017

Form and function in hillslope hydrology: characterization of subsurface flow based on response observations

Lisa Angermann, Conrad Jackisch, Niklas Allroggen, Matthias Sprenger, Erwin Zehe, Jens Tronicke, Markus Weiler, and Theresa Blume

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Final revised paper (published on 21 Jul 2017)
Preprint (discussion started on 10 May 2016)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of Angermann et al., In situ investigation of rapid subsurface flow: Temporal dynamics and catchment-scale implication, HESSD', Anonymous Referee #1, 03 Jun 2016
- AC1: 'Response to reviewer's comments', Lisa Angermann, 03 Aug 2016
RC2: 'Comments to hess-2016-189', Anonymous Referee #2, 09 Jun 2016
- AC2: 'Response to reviewer's comments', Lisa Angermann, 03 Aug 2016
RC3: 'Review of „In situ investigation of rapid subsurface flow: Temporal dynamics and catchment-scale implication“ by L. Angermann et al.', Anonymous Referee #3, 14 Jun 2016
- AC3: 'Response to reviewer's comments', Lisa Angermann, 03 Aug 2016

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (02 Sep 2016) by Ross Woods

AR by Lisa Angermann on behalf of the Authors (25 Nov 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (28 Nov 2016) by Ross Woods

RR by Anonymous Referee #2 (12 Jan 2017)

Suggestions for revision or reasons for rejection

General comment
The authors have put a lot of effort into the revision of the manuscript and made substantial changes. I like the common theme of “form and function” and think it contributes substantially to the conceptualization of hydrological processes. It also gives the manuscript more structure. Overall, the manuscript reads better, and especially the discussion has improved, also by returning to the function and form concept. The figures are still very well done and contain a lot of information (sometimes almost too much).
I understand that the focus of the paper is now more to make a case for using GPR for subsurface investigation. For that the introduction should elaborate more on usage of geophysical methods and specifically GPR in hydrological process studies, advantages and challenges. There is a short paragraph on this (P. 3, L 25-32) with a mention of a few studies that have used GPR but no more information on these studies: what did they find? What were the shortcomings? How is this study trying to overcome shortcomings or close gaps? How does it go beyond the cited studies?
Overall, I am still not struck by a major scientific outcome of this study or a major progress in understanding the hydrological response of these small catchments better. The link between natural rainfall data and irrigation data with respect to elucidating hydrological functioning remains weak. The irrigation setup (intensity) is not comparable to natural conditions, and the natural rainfall events are too few to really say something about the functioning of the hillslopes and catchments under various conditions. My recommendation would be to put more emphasis then on the GPR part and show how this study advanced the usage of GPR in hydrological process studies.

Some specific comments
- Abstract, L 9: explanatory
- Intro: Again, in the introduction and throughout the manuscript, the terms “subsurface flow” and “preferential flow” are still used interchangeably which I find problematic. It would be good here to state early that the authors’ hypothesis is that subsurface flow at their sites happens through preferential flow features. Maybe there is evidence from other studies from the sites that the authors could cite? This has become a very well studied catchment.
- Intro: I would recommend to merge the two sections of the intro into one coherent text and also to move the paragraphs on form and function up, before the description of experimental approach.
- P. 8, L 12: Please do not write “etc” but instead, list all the measurements/observations types you collected.
- P. 8, L 21: Please state somewhere clearly when (date) the experiments were done, when the analyzed natural rainfall event occurred, when the irrigation experiment was carried out, that would make it easier to understand the sequence of experiments.
- P. 8, L 22: what is a ctd sensor? better write pressure transducer and specify the sensor type in parentheses
- I would revise the caption of Fig. 3; e.g. “Experimental methods applied in the stream-centered and hillslope-centered approaches, divided into the sampling during the natural rain event and the irrigation experiment.”; also: What does background mean?
- P. 9, L 1: missing word “bulk samples of the?”
- P. 9, L 3: piezometer sampling in the stream-centered approach is not listed in Fig 3
- After reading the description of experiments, I would recommend a separation into rain event and irrigation, rather than the separation into stream- and hillslope-centered. That might be easier to follow.
- P. 10, L 4-5: “plot had a slope..” and “..at the hillslope is..”
- P. 19, L 4: subsequent instead of consequent
- P. 19, L 12: “..was..vanishing”
- P. 33, L 7: “…preferential flow..”

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RR by Anonymous Referee #3 (18 Jan 2017)

Suggestions for revision or reasons for rejection

Second review of „Form and function in hillslope hydrology: characterization of subsurface flow based on response observations“ by L. Angermann et al.

Generally, the manuscript is in much better shape now. The authors really put a lot of effort into improving the manuscript. They did fairly address my critique on the lack of a story line, the small sample size in hydrograph separation and the justification of linking the observed processes in the irrigation experiment to the natural conditions and all other detailed comments.
I think this analysis deserves to be published, however, I remain conflicted about the separation of the data into two companion paper. There are three main reasons for my concern: (1) The authors made it clear that they use the form and function framework to present the different kinds of data in different manuscripts, i.e. the response dynamics and patterns are used to deduce the flow path in the first companion paper and the flow path is used to explain the structure in the second paper. As a reader, I feel this separation is an unnecessary artificial construct that makes the whole story lengthy. Why not include the data on structure right here in this manuscript? As a reader, I expect to back up the findings made here (flow path was deduced from response dynamics and patterns) with the data collected about the structure as presented in Jackisch et al. (2) I think that a paper that appears in a series of companion paper should still be stand-alone which I feel is not the case with both these manuscripts. And (3), looking at the second manuscript by Jackisch et al., I find a lot of overlap with the Angermann et al. manuscript. I suggest to put the key findings of the second companion paper into this manuscript by Angermann et al.
I feel that merging these two manuscripts will make a more balanced story of exploring subsurface flow in the context of the form and function framework and will improve the manuscript.
There continue to be some minor issues. I am being picky but I offer these comments to help improve readability.
- Page 13, lines 27-28: if you could not sample in high frequency but still calculated a weighted average, how many samples did you take? Is it a within-event average or an intra-event average?
- Figure 10 is too complicated, especially part A. There are too many symbols. Please revise. Maybe don`t use time on the x axis, but same axes as in B and C and denote the time of sampling for each subplot.
- P. 29 lines 26-31: It remains unclear, which information on form is discussed. For example, I can`t find any information about the hydraulic conductivity in this paper. I expect that form characteristics are part of the companion paper, but I think they would make a valuable addition to this paper as well (see my major concern above). Especially when reading the companion paper, I wonder if it would make sense to include the key findings presented in that paper to include in this paper, and make one from the two paper.
Typing errors
- Page 5, line 32: “Bulk samples of the ? ….” Add a word!
- Page 6, line2: “…, after the they… “ Delete “the”.
- Page 6, line 12: The plot had a slope (Add “a”.)
- Page 11, line 10: Add a preposition after “Comparison”.
- Page 13, line 7: miximum?
- Page 27, line3: preferential flow? (Add ”flow”.)
- Page 30, line 13: Add a preposition after “interpretation”
- Page 31, line3: “under pergiglacial conditions”, insert space.

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ED: Publish subject to revisions (further review by Editor and Referees) (03 Feb 2017) by Ross Woods

AR by Lisa Angermann on behalf of the Authors (17 Mar 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Mar 2017) by Ross Woods

RR by Anonymous Referee #3 (18 Apr 2017)

RR by Anonymous Referee #2 (18 Apr 2017)

ED: Publish subject to minor revisions (further review by Editor) (19 Apr 2017) by Ross Woods

AR by Lisa Angermann on behalf of the Authors (29 Apr 2017) Author's response Manuscript

ED: Publish as is (22 May 2017) by Ross Woods

AR by Lisa Angermann on behalf of the Authors (01 Jun 2017) Manuscript

Short summary

This study investigates the temporal dynamics and response velocities of lateral preferential flow at the hillslope. The results are compared to catchment response behavior to infer the large-scale implications of the observed processes. A large portion of mobile water flows through preferential flow paths in the structured soils, causing an immediate discharge response. The study presents a methodological approach to cover the spatial and temporal domain of these highly heterogeneous processes.