Taking theory to the field: streamflow generation mechanisms in an intermittent Mediterranean catchment

Gutierrez-Jurado, Karina Y.; Partington, Daniel; Shanafield, Margaret

doi:https://doi.org/10.5194/hess-25-4299-2021

Articles | Volume 25, issue 8

https://doi.org/10.5194/hess-25-4299-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Data acquisition and modelling of hydrological, hydrogeological...

https://doi.org/10.5194/hess-25-4299-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 8

Research article

|

03 Aug 2021

Research article |

| 03 Aug 2021

Taking theory to the field: streamflow generation mechanisms in an intermittent Mediterranean catchment

Karina Y. Gutierrez-Jurado, Daniel Partington, and Margaret Shanafield

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Final revised paper (published on 03 Aug 2021)
Supplement to the final revised paper
Preprint (discussion started on 21 Jan 2021)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on hess-2020-659', Anonymous Referee #1, 23 Feb 2021

General comments

This study is a follow-up of a 2019 research paper by Gutierrez-Jurado et al. where an integrated surface-subsurface hydrological model (ISSHM) was applied to explore the processes that lead to the transition from a dry streambed to a flowing stream in non-perennial streams. Here an adapted version of this ISSHM was applied to the Pedler creek catchment. The authors consider different streamflow generating mechanisms for three catchment areas based on the catchment topography and six detailed soil profiles. They use Hydrogeosphere to simulate a set of eight scenarios (3 of these are discarded because of high computation times) with different hydraulic conductivity parameters and an (un)incised river network. The results show that different flow generating mechanisms ensue in different catchment areas, based on the soil properties (or topography).

I strongly recommend for the authors to improve the readability of their manuscript. The sometimes odd sentences make it hard for the reader to grasp the content.

Specific comments

The introduction needs to be thoroughly revised (see technical corrections). It would be interesting to include a compact review of past modeling efforts of non-perennial rivers as in l40 the authors touch on that only briefly. Also, in the paragraph on using numerical models for this purpose (l39-l50), the dis(advantages) of such models can be more broadly addressed. Although the goal of the study is mentioned, a hypothesis or research question is missing here and should be specified.

In Sections 2.2.1 to 2.2.3 the authors state the most dominant streamflow generating processes for the different topographical areas they consider. It is unclear however where these hypothesis originate from as no references to existing literature are made.

If I understand the modeling setup correctly, different hydraulic conductivity parameters were chosen for sand and loam. The authors should mention clearly how these parameters were obtained and what parts of the model were calibrated. Also, I’m questioning the suitability of using a numerical model to look at the impact of subsurface hydraulics to stream flow generation, as the authors indicate in the discussion (l422-424) a conceptual model might be a better fit.

Technical corrections

See attachment

Citation: https://doi.org/10.5194/hess-2020-659-RC1
- AC1: 'Reply on RC1 and RC2', Margaret Shanafield, 12 Apr 2021
  
  We thank the two anonymous referees for their considerate and comprehensive comments. We are glad to see that both reviewers are broadly supportive of this manuscript and had no fundamental issues with the methodology or results.
  Referee 1 has provided extensive edits to improve the readability of the manuscript. We appreciate the they have taken to not just suggest revision of the text, but to be specific in how to make this improvement. Given this level of detail, it should be no problem to meet the referee’s request. Moreover, we are happy to reformulate the objective as a research question, to add the requested background on parameter selection and model setup, and to include more lengthy discussion of how these results are useful in other catchments with different geology.
  Finally, both referees noted that the use of a numerical model in unsaturated, very transient conditions along a stream network is not trivial; however, we seek to understand and separate the contributions of various physical processes in generating and sustaining this periodic flow; as explained in the introduction, separating these physical processes requires a process-based, integrated model. We will add more background detailing the past use of numerical models for understanding streamflow generation, so that the logical progression of complexity that led to this modelling effort is clearer.
  
  Citation: https://doi.org/10.5194/hess-2020-659-AC1
RC2:
'Comment on hess-2020-659', Anonymous Referee #2, 18 Mar 2021

Please see attached.

Citation: https://doi.org/10.5194/hess-2020-659-RC2
- AC2: 'Reply on RC1 and RC2', Margaret Shanafield, 12 Apr 2021
  
  We thank the two anonymous referees for their considerate and comprehensive comments. We are glad to see that both reviewers are broadly supportive of this manuscript and had no fundamental issues with the methodology or results.
  Referee 1 has provided extensive edits to improve the readability of the manuscript. We appreciate the they have taken to not just suggest revision of the text, but to be specific in how to make this improvement. Given this level of detail, it should be no problem to meet the referee’s request. Moreover, we are happy to reformulate the objective as a research question, to add the requested background on parameter selection and model setup, and to include more lengthy discussion of how these results are useful in other catchments with different geology.
  Finally, both referees noted that the use of a numerical model in unsaturated, very transient conditions along a stream network is not trivial; however, we seek to understand and separate the contributions of various physical processes in generating and sustaining this periodic flow; as explained in the introduction, separating these physical processes requires a process-based, integrated model. We will add more background detailing the past use of numerical models for understanding streamflow generation, so that the logical progression of complexity that led to this modelling effort is clearer.
  
  Citation: https://doi.org/10.5194/hess-2020-659-AC2

Peer review completion

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

ED: Publish subject to revisions (further review by editor and referees) (25 Apr 2021) by Insa Neuweiler

AR by Margaret Shanafield on behalf of the Authors (03 May 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (16 May 2021) by Insa Neuweiler

RR by Anonymous Referee #2 (24 May 2021)

ED: Publish as is (16 Jun 2021) by Insa Neuweiler

Short summary

Understanding the hydrologic cycle in semi-arid landscapes includes knowing the physical processes that govern where and why rivers flow and dry within a given catchment. To gain this understanding, we put together a conceptual model of what processes we think are important and then tested that model with numerical analysis. The results broadly confirmed our hypothesis that there are three distinct regions in our study catchment that contribute to streamflow generation in quite different ways.