Irrigation Control through Acoustic Proximal Sensing of the Onset of Surface Water
Round 1
Reviewer 1 Report
Manuscript deals with the problem of measuring free water on the surface of agricultural soils by the real-time acoustic method of remote sensing. The chosen topic is also relevant in relation to changing climatic conditions. The article is written at a good scientific level. I have no comments on it and I suggest it for publication in the Remote Sensing Journal.
The aim of the research, the results of which are given in the manuscript, was to design a device that could be mounted on a mobile irrigator and which would allow the measurement of water level changes on the soil surface on the basis of acoustic sensing. The measurements were performed under laboratory conditions as well as under field conditions on a specific sheep farm in New Zealand.
The acoustic remote sensing device, which contained linear fields for transmitting and receiving the signal according to the achieved results, allowed monitoring of free water and control of irrigation equipment in real time.
I consider the conclusions in the manuscript to be original.
I did not find any serious defects in the work or in the presentation or ethical problems.
Research in this area is relatively specific (perhaps for this reason, only 24 references are listed in the manuscript) and can have practical implications in the field of irrigation systems and their use in agricultural practice. This is positive in relation to warming and the growing problem of drought.
In my opinion, the keywords are consistent with the content of the article.
In conclusion, I can state that after studying the article, I do not have any serious comments and manuscript „Irrigation Control Through Acoustic Proximal Sensing of the Onset of Surface Water“ meets the requirements and can be published in a Journal Remote Sensing
Author Response
The authors are grateful for the time taken by the Reviewer, and their very supportive comments.
The Reviewer did not request any changes.
We have now added a further 2 citations.
Reviewer 2 Report
The paper presents an interesting study related to how acoustics can be used to obtain the presence of water on an agricultural field. The paper should be published after a few comments are addressed; these are given below.
Lines 16-18: These lines are vaguely written and need to be edited to give a better overview of the hydrological processes. What is a “waste of a precious resource”? More clarification is required.
Lines 40-49: Provide citations indicating the hydrological processes in this section.
Line 50: What is meant by “scales”?
Line 110-111: Why 4 cycles and 8 cycles of a sinusoidal wave? How was the number of cycles selected?
Line 109: What is meant by "centers"? Is this the center-to-center distance?
Line 115: What is the number of bits associated with the DAC?
Line 129: What is meant by "well-formed"?
Lines 131-132: The authors should explicitly mention here that the speakers are piezoelectric and so the speakers can also
function as microphones.
Line 138: What is meant by "flexible"? What are the max and min distances?
Figure 4: How was this figure calculated?
Lines 166-167: What would be the processing time for this embedded system?
Lines 210: What algorithm was used for detection of the fraction of soil surface? Can a figure be provided in the paper
showing how this algorithm operates?
Figure 8: The system is not clearly visible in the picture, and so a figure should also be provided showing the loudspeaker
and microphone array geometry. The figure should also clearly show the mathematics of the theory described in the paper.
Author Response
The authors would particularly like to thank the Reviewer for their careful and constructive comments and questions. We agree with all points raised and have made comprehensive changes to our manuscript as follows.
Lines 16-18: These lines are vaguely written and need to be edited to give a better overview of the hydrological processes. What is a “waste of a precious resource”? More clarification is required
Reply: We have re-expressed this to provide greater clarity. The lines now read “Irrigation is a useful crop enhancement procedure up to the point where free surface water appears. However, over-irrigation can lead to an accumulation of free water on the soil surface, which in turn results in overland flow and a high risk of contaminant loss”(Lines 16-18). A more detailed description of the soil hydrological processes is given in the introduction section (Lines 42-59), where we can also provide citations.
Lines 40-49: Provide citations indicating the hydrological processes in this section
Reply: Three new citations ([2], [3], and [4]) have been added, related to soil infiltration and overland flow (Lines 43-44).
Line 50: What is meant by “scales”?
Reply: “across scales” has been changed to “of various sizes” (Line 50).
Line 109: What is meant by "centers"? Is this the center-to-center distance?
Reply: We have rephrased this to make it clear that it is the center-to-center distance (Line 109).
Line 110-111: Why 4 cycles and 8 cycles of a sinusoidal wave? How was the number of cycles selected?
Reply: There are two propagation paths: directly between the speaker and microphone arrays; and from speaker array to the ground and then to the microphone array. The pulse duration is selected so that there is no overlap between reception of transmissions via these two paths for a given speaker-microphone geometry. We have added text to describe this pulse duration selection algorithm (Lines 110-111).
Line 115: What is the number of bits associated with the DAC?
Reply: We have added the resolution (16 bit) for the DAC and corrected the ADC resolution from 24 bits to 16 bits (Line 122).
Line 129: What is meant by "well-formed"?
Reply: Close to the speakers the beam pattern has a lot of fine structure. We have changed this sentence to read “…so the beam has a range-independent far-field shape at the ground.” (Line 135).
Lines 131-132: The authors should explicitly mention here that the speakers are piezoelectric and so the speakers can also function as microphones.
Reply: The word “piezoelectric” has been added so that it is clearer that the speakers are piezoelectric. ( Line 136).
Line 138: What is meant by "flexible"? What are the max and min distances?
Reply: We have removed the words “..but be flexible” to avoid any confusion. (Line 145).
Figure 4: How was this figure calculated?
Reply: Two new sentences have been added to explain the calculation method and the third sentence has been modified accordingly. (Lines 153 – 160).
Lines 166-167: What would be the processing time for this embedded system?
Reply: An explicit indication is now given of the processing time required, and a citation provided. (Lines 176-180).
Lines 210: What algorithm was used for detection of the fraction of soil surface? Can a figure be provided in the paper showing how this algorithm operates?
Reply: We have added citation [24] which describes the algorithm. (Line 223)
Figure 8: The system is not clearly visible in the picture, and so a figure should also be provided showing the loudspeaker and microphone array geometry. The figure should also clearly show the mathematics of the theory described in the paper.
Reply: A zoomed image of one the arrays is now provided, together with the array height h and spacing 2h referred to in the earlier mathematics.
