Perennial Crop Dynamics May Affect Long-Run Groundwater Levels
Round 1
Reviewer 1 Report
Dear Editor,
I have read the article entitled: Perennial crop dynamics may affect long-run groundwater levels. In this research, the authors aimed to investigate the interaction between perennial crop production and groundwater use within a framework that considered the dynamic of both.
General Comments:
This is an interesting article and deserves to be published, after considering some suggestions as explained below:
Specific Comments:
Line 69: Please consider: Aside from Franklin et al. [12] ...
Footnote page 2: Please correct: production.
Line 106: The results you indicate (in the introduction) correspond to your research? I suggest no considering results in the introduction.
Line 139: What does subindex “t” mean?
Line 143: Where are explained the details of groundwater pumping costs?
Line 146: LEPA. I suggest considering, for example: “Center pivot using Low Energy Precision Application (LEPA)”.
Line 155: Calibration of what? What do you calibrate?
Line 178: What does Z mean?
Line 186: Table 3 should appear after being mentioned in the text (at most on the next page).
Line 251: Figure 1: I suggest adding: (1) x-axis title indicating the year, (2) y-axis title indicating surface (acres). The title is the same as written in the caption.
Line 346: I suggest considering: “annual crops”.
Best regards!
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Based on modelling work, this study evaluated the costs of different irrigation strategies. Especially, the focused on the shift of irrigated areas from annual crop to perennial crop, and different irrigation water sources. Overall, the structure is good and the results are well analysed. My main concerns are related to model setup and validation. Please check the following comments and consider a major revision.
- This section gives much more background information, but less information about this research. It is better to adjust the structure. Especially, some quantitative results should be presented to show the relationship between perennial crop and groundwater level.
- For the modelling framework, there are some assumptions. However, why do you assume those conditions? Are the assumptions reliable? The sections related to assumptions should be improved.
- These is a section “Calibration”. However, there is not results to show the model performance. Without validation, it is hard to know the reliability of the model. However, this is the basic part of the whole study, which should thus be directly or indirectly evaluated.
Author Response
Please see the attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors,
In my opinion the theme of the article is innovate and very interesting for the readers of the journal.
This research combines the economic dynamics of perennial crops and groundwater management, therefore extending the literature on both topics.
There has been little modelling of the potential effect of increased perennial crop production on groundwater use and the implications for public policy.
Characteristics of perennial crops including large fixed costs from planting, multi-year periods of establishment and senescence, age-dependent productivity and input requirements are all included in the model here.
The resulting transitional dynamics imply a strong incentive to pump groundwater in the face of surface water reductions, which may be exacerbated by market pressures favouring perennial crops.
Also, the study shows that simpler models used in the literature are limited in their ability to capture such effects and therefore may not be reliable aids for policy analysis in periods of water scarcity.
Given the probable impacts of climate change in California, this underscores the need for further research on the economics of irrigated perennial crops and their influence on groundwater pumping.
The authors found that including dynamics of both perennial crops and groundwater levels can have a significant impact on water demand for irrigation and land use transitions over time.
A better understanding of such issues may help policymakers anticipate likely changes in irrigated agriculture in areas affected by California’s SGMA regulations, especially since established perennial crops are likely to factor heavily into land and water acquisitions during SGMA’s transitional period until 2040
The manuscript under revision is well structured; the language is well correct and clear. The title and abstract clearly describe the content of the manuscript.
In my opinion the manuscript is ready to be published. Congratulations!
Best regards.
Author Response
Please see the attached.
Author Response File: Author Response.pdf
