Implementing an Operational Framework to Develop a Streamflow Duration Assessment Method: A Case Study from the Arid West United States

Round 1

Reviewer 1 Report

Reviewer’s Report on the manuscript entitled:

Implementing an operational framework to develop a Stream-flow Duration Assessment Method (SDAM): A case study from the Arid West United States

The authors proposed a Streamflow Duration Assessment Method (SDAM) for the Arid West United States that can classify reaches as perennial, intermittent, or ephemeral.

General Comments:

The paper is well-written and comprehensive. However, the format should be according to the MDPI guidelines. The paper is also very long, and I suggest the authors to remove unnecessary texts to make it a bit shorter if possible.

The paper needs a Conclusion section. In the conclusion, please concisely write what the objectives of the paper were, what methods were proposed and what the limitations of the study are. Furthermore, please mention the data and software availability at the end of Conclusion.

Specific comments:

Lines 48 and 49. Please also add the following most recent articles describing the presence of gaps in streamflow time series (e.g., due to ice-jam in winter, instrument malfunctioning, etc.), ways to process them and study the impact of climate change on them:

https://doi.org/10.1016/j.ejrh.2021.100847

https://doi.org/10.1016/j.jhydrol.2018.11.076

Lines 213, 258, 267, 318, 328, 502, 524, 525, 528, 544, 572, 734, 773, 811, 966. Error! Reference source not found. Please fix this issue.

Line 397. Please avoid using subsubsubsections, so remove 2.4.5.1 and have its title italic like in line 402. Please use the same style for lines 189, 199, 222, 636, 683, 695.

Line 929. Please sat “Do not” instead of “Don’t”.

Please also add an acronym table at the end of the manuscript listing all acronyms used.

Please check the references for the authors’ names, volume, page numbers, etc. and ensure that they follow the MDPI guidelines.

Thank you for your nice contribution

Regards,

Author Response

1. The paper is well-written and comprehensive. However, the format should be according to the MDPI guidelines. The paper is also very long, and I suggest the authors to remove unnecessary texts to make it a bit shorter if possible.

We have removed some text from the description of the focus area studies (2.2.4), quality assurance (2.3), and some details about geospatial metrics (3.4.4).  

2. The paper needs a Conclusion section. In the conclusion, please concisely write what the objectives of the paper were, what methods were proposed and what the limitations of the study are. Furthermore, please mention the data and software availability at the end of Conclusion.

We have added a conclusion section after the discussion and before the acknowledgments (copied below). We did not develop any software as part of this project, but all code and statistical models are available in Supplement 2.

“This study illustrates the successful implementation of an approach to develop SDAMs described by Fritz and others [1] in the Arid West of the United States. We found that biological indicators were particularly useful because of their ability to reflect long-term patterns in streamflow duration exhibited at a site. Our final SDAM was more successful in distinguishing ephemeral from intermittent reaches than perennial from intermittent, consistent with SDAMs developed in other regions. The most substantial limitation was the scarcity of non-perennial reaches with sufficiently documented flow regimes that could be used to calibrate an SDAM. Thanks to the oversight of a regional steering committee comprised of technical experts who require streamflow duration information in their management and monitoring programs, we were able to ensure that this SDAM would be accessible and easy to use by its target audience, despite the statistical complexity underlying its classifications. All data collected for this study and code used for analysis are available in Supplement 2.”

3. Lines 48 and 49. Please also add the following most recent articles describing the presence of gaps in streamflow time series (e.g., due to ice-jam in winter, instrument malfunctioning, etc.), ways to process them and study the impact of climate change on them:

https://doi.org/10.1016/j.ejrh.2021.100847 

https://doi.org/10.1016/j.jhydrol.2018.11.076 

Thank you for suggesting these references. Data gaps in hydrologic records are brought up in section 4.5.3 (Get more and better hydrologic data), and we added text here highlighting these references:

“Recent advances in timeseries statistical analyses have enhanced our ability to characterize streamflow duration, even when gage or logger records are interrupted by gaps created by instrument malfunction or ice-jams [128,129].”

4. Lines 213, 258, 267, 318, 328, 502, 524, 525, 528, 544, 572, 734, 773, 811, 966. Error! Reference source not found. Please fix this issue.

These errors (references to supplemental material) have been fixed.

5. Line 397. Please avoid using subsubsubsections, so remove 2.4.5.1 and have its title italic like in line 402. Please use the same style for lines 189, 199, 222, 636, 683, 695.

Done. We agree that this improves readability.

6. Line 929. Please sat “Do not” instead of “Don’t”.

Header changed to “Statistical complexity does not need to create a barrier for end-users”

7. Please also add an acronym table at the end of the manuscript listing all acronyms used.

We have added a list of acronyms after acknowledgments and before references.

8. Please check the references for the authors’ names, volume, page numbers, etc. and ensure that they follow the MDPI guidelines.

We have reviewed the citations made several updates to conform to MDPI guidelines.

Reviewer 2 Report

This paper presents a new method to classifying streamflow duration of channel reaches based on indicators that are measured after a single brief visit (i.e., a rapid Streamflow Duration Assessment Method - SDAM). The focus of the investigation is on the Arid West US, where these methods have great practical relevance.

In my opinion, the investigated topic, the adopted methodologies, and the related findings are relevant to the field of water resources management. Moreover, the paper is well written, clear, and supported by proper figures and tables.

I think that the paper might be further improved by considering the following suggestions:

1. In the .pdf provided by the system, reference to the Supplemental Material systematically looks as “Error! Reference source not found”, suggest checking and correcting.

2. The title of subsection 2.2.2 (L 161) is the same of the previous one (2.2.1), suggest checking and replacing by the correct title.

3. When the quantitative criteria discriminating perennial/ephemeral/intermittent reaches are introduced (L 206-209), reasons/references supporting the adopted thresholds (5% zero-flow and 5% flowing days) might be added (e.g., L 944-946).

4. As the rapidity of the field sampling phase is a key aspect of the proposed method, I think that additional (though approximate) information concerning a standard field crew (how many people and related background) might help the interested reader.

5. In Table 6, I noticed that in some instances classifications are provided also without considering indicator 4 (Algae) and/or indicator 5 (Single indicators), I think that additional comment is required concerning these possible combinations.

Author Response

1. In the .pdf provided by the system, reference to the Supplemental Material systematically looks as “Error! Reference source not found”, suggest checking and correcting.

These errors (references to supplemental material) have been fixed.

2. The title of subsection 2.2.2 (L 161) is the same of the previous one (2.2.1), suggest checking and replacing by the correct title.

Thank you for catching this error. Header changed to “Identify candidate indicators”

3. When the quantitative criteria discriminating perennial/ephemeral/intermittent reaches are introduced (L 206-209), reasons/references supporting the adopted thresholds (5% zero-flow and 5% flowing days) might be added (e.g., L 944-946).

We have added this text to section 2.2.3:

“These criteria have been used in previous studies (e.g., [40]), and they serve to reduce the influence of extreme climatic events or rare instrumentation failure that could otherwise modify a classification [3].”

4. As the rapidity of the field sampling phase is a key aspect of the proposed method, I think that additional (though approximate) information concerning a standard field crew (how many people and related background) might help the interested reader.

At the end of section 2.2.2, we have added this text:

“At a typical site, a field crew consisting of two people could measure all indicators and complete an assessment in about an hour (not including time to identify aquatic invertebrates).”

5. In Table 6, I noticed that in some instances classifications are provided also without considering indicator 4 (Algae) and/or indicator 5 (Single indicators), I think that additional comment is required concerning these possible combinations.

The table caption was modified and now reads as follows:

Classification table for the beta SDAM AW. Blank entries in a column mean that the state of a certain indicator does not change the outcome. For example, if a reach has no hydrophytes, few aquatic invertebrates, and EPT taxa are present, it will be classified as At least intermittent, regardless of whether algae or fish are observed.