Mapping Interflow Potential and the Validation of Index-Overlay Weightings by Using Coupled Surface Water and Groundwater Flow Model

Round 1

Reviewer 1 Report

I have provided all my comments in the attached file 

Comments for author File: Comments.pdf

Author Response

We thank the reviewer for the valuable comments. The suggestions had made the presentation clear. Many comments are useful for us to extend the current study. We appreciate the comments raised by the reviewer.

Chuen-Fa Ni, Ph.D.,

Professor and Director

Graduate Institute of Applied Geology

National Central University

Author Response File: Author Response.docx

Reviewer 2 Report

Please see the attached general and specific comments.

Comments for author File: Comments.pdf

Author Response

We thank the reviewer for the valuable comments. The detailed editing suggestions had made the presentation clear. Many comments are useful for us to extend the current study. We appreciate the comments raised by the reviewer.

Chuen-Fa Ni, Ph.D.,

Professor and Director

Graduate Institute of Applied Geology

National Central University

Author Response File: Author Response.docx

Reviewer 3 Report

The present study focuses on assessing the interflow potential and quantifying the interflow in the downstream area of the Kaoping River in southern Taiwan.

The interflow is an important water source contributing to the river flow and
influences the near-surface water cycles in water resource management.

The Authors first calculate the interflow potential according to the modified index-overlay model, which employs the analytical hierarchy process (AHP) to calculate the
ratings and weightings of the selected factors. Then, they apply the  GSFLOW numerical model to link the index-overlay model to quantify the interflow potential for practical applications. The Authors use the Monte Carlo simulations to assess the influence of rainfall-induced variations on the interflow uncertainty in the study area. Results show that the high potential interflow zones are located in the high to middle elevation regions along the Kaoping River.

The study is interesting, but I would suggest the Authors to give more details (e.g. in section 3 of the paper) about the numerical model the apply (GSFLOW), the governing equations, spatial discretization of the computational domain. Do they test the result changing spatial discretization ?

Author Response

Response:

Thank you for the comment. The governing equation for MODFLOW was added to the manuscript. Please see lines 309-319 for details. The computational framework and the associated equations for the coupling of the MODFLOW and PRMS can be found in a previous study in Tran et al. (2020). In the manuscript, Figure 4 has shown the spatial discretization of the MODFLOW model and the defined HRUs for the PRMS. Note that the HRUs are the defined computational units for the PRMS model. 

In the study, the sub-model in the downstream area of the Kaoping River is extracted from the Pingtung Plain groundwater basin model. We used the size of the cells the same as that in the basin-scale model because the cell size is relatively small compared to the HRUs defined in the sub-model. The HRUs in the PRMS are the fundamental units (See Figure 4b) for calculating the surface water and groundwater interaction. The cells in the MODFLOW could represent well the overall behavior of the HRUs.  Therefore, the results based on different cell sizes were not tested in the study.

We thank the reviewer for the valuable comments. The detailed suggestions had made the presentation clear. Many comments are useful for us to extend the current study. We appreciate the comments raised by the reviewer.

Chuen-Fa Ni, Ph.D.,

Professor and Director

Graduate Institute of Applied Geology

National Central University