Overflow Tests on Grass-Covered Embankments at the Living Lab Hedwige-Prosperpolder: An Overview

Round 1

Reviewer 1 Report

All comments are in attached file

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

We first like to thank you for your efforts taken to comment on our initial manuscript. This enabled us to revise the manuscript where needed. Below, we explain how we used your comments.

Main (manuscript type): by addressing your detailed concerns, we hope to have submitted a proper article now.

Part 1: Introduction: references have been added to earlier overflow tests, and also to somewhat related wave overtopping and wave impact tests.

Part 2: Materials and methods

• motivation for the research is now given more in general in §2.2.2. Elements from further down the manuscript related to this were moved here, and an explanation is given for the duration of the tests (as requested by Reviewer 2)
• §2.2.3: thank you for the suggestion to expand the title, this has been adopted
• PTV is now explained upon introduction
• figure 5 has been replaced according to your suggestion; this is really an improvement

Part 3: Results

• lines 173-184 (original version) have been moved as suggested
• Your comment on the length of the original table is absolutely right, now a much more concise version has been included and the most remarkable findings are discussed in the text.
• standard tests: meant was 'reference' (or baseline) tests; this has been corrected, thank you for pointing out to this.
• ERT and GPR were moved to the methods section, yet the additional explorations using grout (not in the parts of the dike with the overflow tests, but more in between various overflow test locations) were kept at this place.
• Regarding the repair and protection measures (originally lines 251-254, now lines 280-284), brief additions were made to explain this, while keeping the focus of the manuscript on the impact of external factors and defects.
• Section 3.2 does contain 'Results' in our view, therefore we did not move this to the Methods section as suggested.
• Regarding the visual observations etc.: a reference has been added here, and it has been described how these various human sensory observations were vital to the execution of these large scale field tests (very concisely, this speaks from e.g. the observations implied in lines 275-278). From my (first author) own 20+ years of experience with large scale field tests, it is my impression that these observations are essential for the execution of such tests (not just the processing of the results, but already for a proper course of the tests themselves), although this is hardly ever reported, if not even explicitly disregarded. 

Part 4: the conclusions have been expanded now, with both the better-than-CIRIA71-results for the undamaged sections, and some more details on the nature and process of the earlier failure at damaged sections. The large variation in the results of our tests, and the knowledge that such damages at other real life locations will also vary a lot, convinced us that giving any number (or range) suggesting precision in this matter would not be appropriate.

Hopefully, the manuscript is now more in accordance with your standards.

Reviewer 2 Report

The manuscript introduced a performed test program and the initial results. A series of 25 overflow tests that applying overflow generator to grass-covered embankments was executed to test the strength of the protective layer against erosion at various conditions. The test conditions involved reference sections (with a high-quality grass cover), sections with anomalies (e.g., the presence of vegetation and animal burrows), and repair measures. The experimental intensity and treatment sizes are surprisingly large, and the work was done in great detail.

This is just as the authors said “this opened up the opportunity to learn more about the strength of the dikes under simulated extreme conditions”. The initial results provide insight into the protection capability of the grass-covered dike from erosion. The manuscript is well organized and fluently written. 

There are a few minor comments as follows: 

(1)Line 34, is “LL HPP” an abbreviations, please define it before use. 

(2)Fig.1a, suggest to labeling the elements of base, tank, and bridge in the figure and improve the clarity of current text.

(3)Line138, Handheld probe and measuring tape, what specific variables to measure? 

(4)What are the design principles for the durations of different tests?

Author Response

Dear Reviewer,

We would like to thank you for your efforts for considering our manuscript and providing us with some comments. 

The manuscript has been modified according to the comments of both reviewers, with respect to your comments the following improvements were made:

1. The abbreviation "LL HPP" has been defined at the first instance now (in line 33 of the revised manuscript).
2. Thank you for the suggestion, the figure has been improved by labelling the various parts.
3. The variables to measure by handheld probe and measuring tape are specified in the text now.
4. Lines 118-124 now give the rationale behind the duration of the various tests.

Hopefully, the revised manuscript will meet your approval.

Round 2

Reviewer 1 Report

Accept in present form