An Integrated Hydraulic and Hydrologic Modeling Approach for Roadside Bio-Retention Facilities

Round 1

Reviewer 1 Report

The paper presents a sound and extensive work related with the hydraulic behaviour of a bio-retention drainage facility. Both experimental and numerical approaches were used.

In its actual organization the paper is difficult to follow. The paper writing style is more approximate with a technical report than with a research paper. Indeed, the methodology section is very synthetic and supported by figures and tables with data/labels that were not introduced or described in the text. There are also several details that are missing (both in the text or figures). It should be competed in such a way that it can be reproduced once published.

Results paper section should also be reworked and the figures should be improved. The authors should keep in mind that all labels/text present in the figures must be introduced in the paper or in the figure caption.

Results should be organized in a way that facilitate their interpretation. Figures and tables should be introduced in the text, immediately after they can be inserted and followed by appropriate explanations/comments. It is advised also to improve the graphs and merge the tables. For example, Figure 9 and similar, could the labels be unique for both graphs? Why a) and b)? The y axis label properly identified allows to omit additional text in the graphs. X axis could also be in hours and not date/time. Table 4 and similar, if consider to add a column with the type of catch they can be merged.

The paper should also clearly identify the method used for each one of the presented results.

The discussion section, besides the hydraulic results should also discuss the three different approaches (experimental, SWMM and FLOW3D) used to study the RBR.

A Conclusions paper section should also be included.

Author Response

1. Introduction - Thanks for the suggestion to improve the introduction. There are 56 citations used to highlight the specific problem, previous research focuses, research gaps, and the proposed research. If there are other suggestions like additional citations, we will gladly incorporate them into the introduction section. Other general introduction such as stormwater problems and evolution of stormwater management from downstream to source control can be found in the references.  It is assumed that the readers of this special edition have some fundamental ideas of stormwater management problems and low impact development.  However, if it is necessary to introduce the historic context of stormwater management, we can expand.
2. Methodology (Materials and Methods) - It has been completely revised with the introduction of the modelling concept (tracking of runoff through the system) on Line 106-108, detailed description of step (1) dual drainage model for a fully utilized underground RBR in Line 116; (2) hydraulic simulation of the inflow distribution pipe in Line 163; and (3) overall runoff control analysis with outflow adjustment in Line 239.  The case study part was also inserted right after the description of each step. 
3. Results - It has been completely revised with corrected figures and tables and described in the text.  Captions of figures have been refined to describe part (a) and part (b).  The results are all related to the case study. For the first investigation of catch basin effects (Line 258), results of each types (with its corresponding figures and tables) and their comparison have been described and explained in details.  No mixing of tables and figures.  Each type of catch basin has it own figure and table. Axis label of figures have been consistent. The second investigation of partially utilized RBR (Line 368) has been revised significantly.  All results are aligned with the methodology in the methodology section.
4. Discussions - Each investigation was discussed with reference to the detailed results (hydrologic model, experiments, and hydraulic analysis) in the results section (Line 258 and Line 368).
5. Conclusions and recommendation - added (Line 446).  Based on the investigations, conclusions were drawn and recommendation suggested. 
6. References - a few missing titles have been fixed and highlighted in red ([12], [15], [29], [44], [65].

Reviewer 2 Report

General comment

The paper “Integrated hydraulic and hydrologic modeling of roadside bio-retention facilities” uses a modelling framework to highlight the importance of inlet hydraulics and the effective length of a RBR in the City of Toronto. The paper is well written with a logical order. Some minor clarifications are required before it is suitable for publication. Below, you may find my specific comments.

Specific comments

1. Lines 260-262. A brief explanation is required to highlight the differences among the catch basins.
2. Lines 264-268. It should be explained why there are systematic discrepancies between measured and simulated water profiles in Figure 13. Also, the authors should describe how they manage to calibrate the model. For example, which were the model parameters under question and what values did they tried?
3. Lines 369-371. It is unclear to which paper you are referred to. If you are referred to your work this conclusion is rather arbitrary. Please explain more clearly.

Author Response

1. Methodology - It has been revised completely with the description of concept (tracking of runoff throughout the system in Line 109) and the detailed components (2.1. dual drainage model for the fully utilized RBR in Line 118; 2.2 hydraulic simulation of inflow distribution in Line 165; and 2.3 Overall runoff control analysis with outflow adjustment in Line 241.  The detailed case study was inserted right after the description of each component.
2. Results - It has been revised significantly with figures and tables improved. The comparison of different catch basin has been revised to compare the intercepting capacity differences among different catch basins (Line 357).  The CFD model calibration and criterion were described and the discrepancies between the measured and modelled water profiles were explained.
3. Discussion - Each investigation was discussed with additional details.
4. Conclusions and recommendations  added - conclusions are only drawn from the research results and recommendations are suggested with some citations from other researchers.
5. References - some missing titles have been fixed.
6. All revisions are highlighted in red.
7. Thanks for the suggestions to revise the specific parts of the paper.

Round 2

Reviewer 1 Report

The authors have properly addressed the main issues identified in revision 1 and the paper deserves to be published.