Policy-Driven Sustainable Saline Drainage Disposal and Forage Production in the Western San Joaquin Valley of California

Round 1

Reviewer 1 Report

Dear colleagues,

thank you for the interresting paper. I have just several minor comments:

Fig. 1 - describe all the items accordingly (sites, coulours....); what is the difference between the triangular and circle marked sites ?

In some tables - what do te red numbers mean ? Somewhere explained, somewhere not...

Did you sample or anyhow evaluate also soil or well water (lysimeters, piezometers,) ? I mean water tables, movement and aslo water quality. If not, please mention or explain in the methodology section. So far, the well water is referred just in the conclusion...

Author Response

Please find responses to Reviewer comments attached.

Author Response File: Author Response.pdf

Reviewer 2 Report

REVIEW: Policy-driven sustainable saline drainage disposal and forage production in the western San Joaquin Valley of California

First of all, I would like to congratulate the authors because it is a very interesting research and the manuscript is very well written and explained. My main concern in this review is the adequacy of this paper to the principal research lines defined in the special issue. The manuscript described in detail the behavior of two different crops with different water quality resources, but does not address the governance issues related to water allocation or environmental impact. Some questions arise in these topics that could be interesting to answer:

• Where are the resources coming from?
• Who controls water distribution?
• Who manages the quality of the river and how is it done?
• Which are the concrete impacts of the public policies in this reduction of salt pollution?
• Are there any collective management in the governance of the water used in San Joaquin Valley and how is this affecting to irrigation management?

In conclusion, I would recommend this paper to be published in Sustainability Journal, but not in this special issue.

Author Response

Please find responses to Reviewer comments attached.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper deals with an important issue and provides an useful tool that could be (hopefully) used by policy makers

The methodological approach seems appropriate to achieve the aim declared, most of the results presented are interesting as well

However, a major lack of the manuscript is the quality of presentation and discussion. Each section (Introduction, Methods, Results and Discussion) is too long and too colloquial and sometimes essential information are missing or presented in an improper way. The introduction can be just well summarized. As regards methods, please just describe clearly all the methods used, but nothing more. Results should be better presented and more properly discussed. Please comment the results right after having shown them and do not forget to point out their relevance.

To clarify what I mean, here go some examples of:

Unnecessary comments

• lines 259-261
• line 326

Missing information

• provide details on water analysis;
• table 4, the word soil is missing;
• table 5, what is the parameter reported in this table? First introduce the parameter, then how you measured and what is the aim of the analysis. Moreover, why some numbers are in read?

Inappropriate colloquial writing

• line 352, two to three;
• line 360, reported below;
• line 403, "data quality check" is not an expression that clarifies what you have done; 

Results not well presented

• Quality of Figures 5, 6 and 7 should be improved
• Figures 3 and 4 are not necessary
• Figure 13-16 could be grouped and the quality improved

Improper results discussion:

• lines 629-631. From where did you draw this conclusion? 

With the manuscript in its actual form, it's difficult for the reader to select the important aspects among such a big (but mostly unnecessary) and not well organized amount of information. A major reorganization of the paper is strongly advised.

Author Response

Please find responses to Reviewer comments attached.

Author Response File: Author Response.pdf

Reviewer 4 Report

This paper is well written and timely, and seeks to 1) assess root zone salinity in field sites of drainage water irrigated ‘Jose’ tall wheatgrass and alfalfa, and 2) calibrate the CSUID-ID tool. 

However, I am very concerned about its statistics, which makes me question the analyses.  However, perhaps this can be cleared up by the first author getting some help from the other authors.

The conclusion of the paper seems to be missing some general lessons from the soil salinity analysis--it lists the results of each plot, but what does this all mean?  Any overall thoughts? Comparisons to the rest of the SJV perhaps?

Abstract

• You do not need the acronyms TWG and ALF here.
• What Basin?

Comments:

• Check for consistency-- ‘Jose’ tall wheatgrass vs Jose tall wheatgrass vs tall wheatgrass.
• Line 42: Bay-Delta estuary Delta?
• When you refer to a reference directly, you still need to include the name. For example, “[8] examined the suitability...” should be “Suyama et al. [8] examined the suitability…”
• Line 237: Fields 3-1
• Line 241: No parenthesis.
• Line 242: Need to write out “Water District” or refer to WD previously in manuscript. Similar issue in Line 257.
• Numerous spacing, punctuation, and consistency errors throughout manuscript. Tables have poor spacing, making them hard to read.
• Section 2.8: Did you perform the regressions or is this a feature of the ESAP-Calibrate program? I would like more info about the “spatially referenced regression model”. 
• Table 6: This is concerning. R² values cannot be “Significant at P < 0.01”. Are you talking about your models’ F statistics?  Or P values of your coefficients?  You are averaging R² values across multiple models?
• Table 7: Again, I am concerned about the confusion regarding R². Also, there is no standard deviation listed.
• Section 3.3 Forage Analysis: You have p-values listed with correlation coefficients. What are you testing to get these? Did you estimate a function?
• Figure 8 and 10. Legends and sample site labels need to be more legible.

Author Response

Please find responses to Reviewer comments attached.

Author Response File: Author Response.pdf

Reviewer 5 Report

In this manuscript, the authors conducted field EM38 surveys and soil and forage sampling to assess the spatial and temporal distribution of root zone salinity in several fields cropped with wheatgrass and alfalfa.

In general, this is a comprehensive study that highlights the importance of soil monitoring for saline drainage disposal management.

However, the manuscript was poorly written and it seems that the authors were in a rush to publish their results without an in-depth evaluation of the model accuracy and implications for agricultural management. Please see below for my main concerns.

1. The use of EM38 data for monitoring and mapping soil salinity is not novel and actually it has been used over 40 years. Then what is the novelty and significance of this study?

2. The authors mentioned in the abstract and introduction (lines 208-213) that they used the soil salinity data for the calibration of a transient hydrological model (CSUID-ID). However, no methods or results were presented for this CSUID-ID model. The authors only showed a snapshot of the model program in the discussion section. How did the CSUID-ID model calculate the salt mass balance? How were the model parameters determined? What is the model mass balance vs. estimated mass balance and thus what is the model error?

3. In Figure 8, the authors showed the estimated soil salinity at different depths of the root zone. However, similar maps were not shown in Figure 10 in the other field. In addition, the statistical model allows for the estimation of model uncertainty across the field. The authors should plot these uncertainty values to illustrate where the estimation of soil salinity is inaccurate.

4. Lines 414: How did you transform and de-correlate the EM signals? Please provide the mathematical formula so that others can repeat your results.

5. The authors showed the results for plant tissue analysis. How did the nutrients of plant tissue correspond to the soil salinity level in space and time? What are the implications?

6. Lines 661-663: Where is the result of the remote sensing-based regression model built with the vegetation indices?

7. The title of the manuscript is “Policy-driven sustainable saline drainage disposal and forage production in the western San Joaquin 3 Valley of California”. However, the authors did not discuss how the spatial and temporal variations of soil salinity were affected by policy changes during the study period nor did they discuss any implications of direct of the soil salinity maps for informing management decisions.

Author Response

Please find responses to Reviewer comments attached.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I am very pleased about the new approach of the paper and how you have adapted the new version to the special issue topic.

Author Response

See attached response to all reviewers.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript was extensively revised accordingly to the suggestions received.

Author Response

See attached response to all reviewers.

Author Response File: Author Response.pdf

Reviewer 4 Report

General comments: I have reviewed the updated manuscript, as well as the other reviewers’ comments.  I have listed some minor items to address below.  My larger concern is that I am not convinced the paper is quite there yet with regards to its stated purpose, to “optimize the sustainability of this reuse facility by maximizing evaporation potential while achieving cost recovery”. 

In the authors’ comments to each of the reviewers, they state, “Since this Special Issue of Sustainability focuses on policy perspectives related to sustainable salinity management we have attempted to show how a unique selenium contamination problem impacting irrigated agriculture resulted in State and federal environmental policy that fundamentally changed irrigation management in the San Joaquin Valley of California. We describe the agricultural stakeholder response to the new policy and the role of a dedicated reuse facility that has provided irrigators time to develop sustainable management practices. We describe a research project geared to improve and optimize these practices that involves the use of electromagnetic instrument technology and associated techniques map salinity on selected forage fields and show how data provided by these techniques can be interpreted and used to further develop and calibrate a vadose zone simulation model for future decision support. We conclude with our future goal of bridging the gap between complex sensing techniques that result from deployment of the EM38 instrument and sensor-informed transient model application and the irrigator who relies primarily on his/her experience to gain knowledge. Our aim has been to show the connectivity between environmental protection and irrigation sustainability policy and irrigation practice and how well directed research can lead to better overall outcomes.

We believe that the insights and lessons learned in the 15 years since the authorization of the multi- stakeholder Grassland Bypass Project can inform irrigation sustainability in other arid zones constrained by rising salinity levels in soils and in receiving waters.”

There are several goals here: a) “…to show how a unique selenium contamination problem impacting irrigated agriculture resulted in State and federal environmental policy that fundamentally changed irrigation management in the San Joaquin Valley of California…”, b) “…describe the agricultural stakeholder response to the new policy and the role of a dedicated reuse facility…”, and c) “…describe a research project…”. 

I recommend that the authors use the goals outlined in their reviewer response to guide and tighten up their introduction and redirect their summary and conclusion.  The authors will best know how to do this, but perhaps they can reduce/combine the parts of the introduction focused on the research project, and increase/move up the policy/program info (Section 1.2 and 1.3). Being a bit more judicious about what background info to include may help as well.  In particular, making the last paragraph more closely align with the review response would help.   

For the summary, it seems disjointed.  Perhaps break this up into separate discussion and conclusion sections?  The way the information about the CSUID-1D model is included seems out of place or perhaps overly highlighted? At any rate, the flow needs some attention

This is a nice paper, and vastly improved.  It has all the correct information, it just needs a bit more editing attention to be ready for publication.

Minor things:

1. Check Table 2 footnotes ( - or = ; inconsistent use of periods—perhaps a semicolon would be of use?)

2. Extra period in first paragraph of pg. 11

3. [12] begins first complete sentence on pg. 3

4. Missing space in last line of third paragraph on pg. 2 (ha^-1albeit)

5. ‘Jose’ or Jose in last sentence of pg. 12

6. First sentence of last paragraph on pg. 16 reads, “As mentioned previously, leaching fractions were consistently highest and soil salinities (ECe) lowest in the surface soil layers (0-30 cm) and for the 90–120 cm soil depths (Table 7).” I believe this should be something like, “As mentioned previously, leaching fractions were consistently highest and soil salinities (ECe) lowest in the surface soil layers (0-30 cm) (Tables 6 and 7).”, no?

7. Last two sentences in first paragraph of pg. 17 read, “For TWG fields 10-6 and 13-1, the majority of the field had LF’s between 10 to 20%, and for field 10-6, a substantial area of the field had LF’s of 20-30%. For alfalfa field 13-2, a majority of the field (79–98%) had a LF less than 10 %. For alfalfa field 13-6, much of the field (44 – 69%) had LF’s between 20 to 30% and substantial portions of the field (30-45%) had LF’s of 20-30%, depending on the season and the year.” This should be, “For TWG fields 13-1, the majority of the field had LF’s between 10 to 20%, and for field 10-6, a substantial area of the field had LF’s of 20-30%. For alfalfa field 13-2, a majority of the field (79–98%) had a LF less than 10%. For alfalfa field 13-6, much of the field (44 – 69%) had LF’s between 10 to 20% and substantial portions of the field (30-45%) had LF’s of 20-30%, depending on the season and the year.”

8. Figure 5 - Horizontal lines and gaps between columns are inconsistent. Font is quite small. Plot names should be in titles of graphs.  Legend should technically be ECw.  Another option would be to have different colors—then you could have the plot names in a single legend.

9. Table 3 - The mean for chloride (152) does not fall within the range {29.0, 76.4}. Neither does that of the saturation percentage (m = 53.8; range = {62.7, 156}).

10. Table 5 - My original comment was:

This is concerning. R2 values cannot be “Significant at P < 0.01”. Are you talking about your models’ F statistics? Or P values of your coefficients? You are averaging R2 values across multiple models?

 Your response:

Table 6 is now table 5 - The models shown for each field were fitted for each of the four depth increments but only the bulk average ECe (0-120 cm depth) results were shown. Yes the p-value is for the F-statistic for each regression model. Averaging of R2 was not performed however a separate model can be created for bulk average ECe in the ESAP-calibrate program.

a) I understand that you did not average R². Yet, the heading in your table indicates you are averaging R². Please clarify. Perhaps include “averaged over 0-120 cm” elsewhere. b) In a similar vein, the superscripts indicating significance are oddly placed. To avoid adding another column with your Fs (which I admit is overkill), this could be clarified by changing your footnotes to “Estimated model is significant at…” or some such. c) In the table description/title, it should be squared not square.

11. Table 6 - In the footnote, it seems as though you are saying the R-squared values are significant/not significant. This is incorrect. I suggest “The highlighted values are where the selected MLR model estimation was not significant” or similar.

12. Table 7 - Since you are reporting percentages, the mean values for 13-1, 13-2, and 13-6 in Spring 2016 should be whole numbers. Also, perhaps you should report numbers to the tenth place value as your means do not appear to be at the midpoint of your confidence intervals—I assume due to rounding. Example: 30-60 depth, 10-6, Spring 2016 has a mean of 22, but the confidence interval is 20 to 26? Most of the data for 13-2 is similar.

13. First paragraph under section 3.5 – I am not sure the last sentence is fully supported by the figure. Can you elaborate or clarify?

14. Section 3.5 - Can you remind the reader why you are focusing on field 10-6? Because it was not drained?

15. Last sentence of first paragraph, pg. 19 – It looks like site 3 in the fall has the highest salinity level (>23.5). As such, the last sentence seems a bit unclear. Please elaborate/clarify.

16. Section 3.6, first paragraph – R squared, not square. Sometimes you have a hyphen, sometimes not. Make it consistent throughout manuscript.

17. Last paragraph, pg. 22 – Table 6 shows that the 60-90 and 90-120 depths have the highest EC_e for fields 13-2 and 13-1.

18. Second to last sentence, third paragraph, pg. 23 – But, the “12 sampling sites” changed from spring to fall (from figures 7 and 8)?

Author Response

See attached response to all reviewers.

Author Response File: Author Response.pdf

Reviewer 5 Report

The authors have significantly revised the manuscript based on the comments and improved the readability of the study. Now it is easy to follow and clear to the readers.

Author Response

See attached response to all reviewers.

Author Response File: Author Response.pdf