Numerical Modeling of Surface Water and Groundwater Interactions Induced by Complex Fluvial Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan
Round 1
Reviewer 1 Report
Concept /Methodology:
The article title speaks of „Groundwater Interactions Induced by Complex Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan“. This is a bit misleading as the reader expects more infos about human activities in the article, which are just briefly addressed. As well some passages are repeated to some extent. Overall however, the manuscript presents an interesting GSFLOW numerical study. Important sensitive water budget data for local wet and dry seasons in terms of management, as well as some interesting model extensions are supportive for the scientific community.
Methodology, figures and tables are well organized, data and results match. Besides that still a significant english grammar check is required, including wording and style. In view of wording often wrong terms or even parts of sentences occur. This has to be optimized and personal proposals are given below.
Where announced, also units should be double checked. A note: Numbers and units should always be kept together, also check the space between numbers and units.
Further details are outlined below.
Abstract
Line 30/ grammar/please correct as: „with the high slope in the PPGB lead to…“
Introduction
Lines 49-50/ grammar/please correct as: „The processes included in the IHMs… groundwater interactions and others [2].“
Line 63 / grammar/please correct as: „The SWATMOD model couples the Soil Water Assessment Tool (SWAT) model…“
Line 69 / style /please correct as: „to simulate the processes that affect surface water quality.“
Line 70 / wording /please correct as: „The HydroGeoSphere model allows…connect rivers the groundwater systems.“
Lines 73-74/ grammar/style/please correct as: „The CATHY model is a process-based model… groundwater flow and surface runoff. The WetSpass MODFLOW model…“
Lines 79-80/ grammar/style/please correct as: „… the water balance near the land surface for MODFLOW focussing large catchment areas.“
Line 81 / grammar/please correct as: „The GSFLOW model has integrated the Precipitation Runoff Modeling System (PRMS) with MODFLOW…and groundwater. The GSFLOW model is also…“
Lines 87-88 / grammar/please correct as: „In the GSFLOW model, the coupling process…iterative techniques to solve interdependent governing equations…“
Lines 91-92 / style /understanding/please correct as: Proposal: „Specifically, Critical connections in the
GSFLOW model refer to the unsaturated zone flow as well as stream interaction modules in MODFLOW.“
Lines 100-101 / grammar/style/please correct as: „different water resources issues…climate change and water quality.“
Lines 103-105 / grammar and understanding /please correct as: Proposal: „In view of the complex amounts of input data established in the GSFLOW model, the development of a simulation model for a case study covering a large area with multiple watersheds is a great challenge.“
Line 108 / grammar/please correct as: „elevation varies significantly.“
Lines 110-111 / grammar/wording/ please correct as: Proposal: „Due to the combination… (…deposition, precipitation)…the landforms have evolved differently over time in the upstream and downstream areas of the PPGB“
Lines 114-116 / grammar/understanding/wording/ please correct as: Proposal: „The effects of complex landforms and human activities have to be clarified before implementation of the IHMs in the PPGB. The present study utilizes the GSFLOW numerical model to assess the SGIs in the PPGB.“
Lines 121-127 / grammar/understanding/wording/style please correct as: Proposal: „and quantified according to the detailed interaction dynamics in the PPGB. The calibration and validation of the model is based on three-year observations from January 2015 to December 2017. The evaluation of the developed model relies on different statistical parameters... A scenario of an artificial recharge reservoir was considered to assess the local impact of increased recharge on water balance variations in the simulation area“
2. Materials and Methods
Line 133 / grammar/please correct as: „Eurasian Plate forms the Taiwan Island…“
Line 134 / grammar/understanding/ please correct as: „The area covers approximately 1300 km2, with the land surface elevation varies from the north to the south.“ (to which extent?! Please state numbers here)
Line 136 / grammar/please correct as: „subtropical and rainfall is alternately affected…“
Line 144 / grammar/please correct as: „monsoons and total precipitation…“
Lines 147-148 / grammar/wording /please correct as: Proposal: „have led altered the landscape differently in…“
Line 149 / grammar/ please correct as: „defined as the upstream area of the confluence point…“
Line 151 / grammar/ please correct as: „are generally in the north-south…“
Line 154 / grammar/ please correct as: „The aquifer of the PPGB…“
Line 154 / grammar/ please correct as: „of tertiary age rocks.“
Line 156 / grammar/ wording / please correct as: Proposal: „Formation are of the Eocene-Oligocene age, located in the eastern part of the plain.“
Line 157 / grammar/ please correct as: „stretching from north to south…“
Lines 165-166 / grammar/ wording / please correct as: Proposal: „There are 51 hydrogeological investigation
stations and 126 monitoring wells are available in the groundwater basin.“
Line 168 / grammar/ please correct as: „layers, and separated with by low permeable marine sequences.
Line 170 / grammar/ wording and sense!/please correct as: „also conducted included pumping tests…“
Line 178 / grammar/ please correct as: „PPGB the groundwater recharge varies…“
Line 201 / grammar/ please correct as: „In the GSFLOW model…“
Line 208 / grammar/ please correct as: „The three regions for the GSFLOW model …“
Lines 210-212 / grammar/ please correct as: „The PRMS model … land-use…The PRMS model uses … “
Line 216 / grammar/ please correct as: „In the PRMS model… “
Lines 219-220 / wording / understanding / please correct as: Proposal: „impervious sealed zones … In the PRMS model the subsurface… “
Line 222-223 / grammar / wording / understanding/ structure/ please correct as: Proposal: „volumetric water flowing downslope, which may be further removed by plants or combined with groundwater.“
Line 208 / understanding / please correct as: Proposal: „lost to subsurface sinkholes in the groundwater reservoirs“
Line 232 / grammar/ please correct as: „land-use“
Line 253/ „…can be the specified head?“ What do you mean here? hydraulic head? The way it is written here it does not become clear to the reader. Please give a better explanation here.
Lines 263-264/ „…method of characteristic?“ What do you mean here? The way it is written here it does not become clear to the reader. Please give a better explanation here.
3. Conceptual Models and Numerical Considerations
Line 279 / grammar/ please correct as: „the GSFLOW model then…“
Line 290/ grammar/ please correct as: „200 m…“ numbers and units always together without separation in one! line.
Line 308 / grammar/ please correct as: „The MODFLOW-2005 model enables …“
Lines 309-310 / Proposal: „the specified hydraulic head boundary condition…constant hydraulic head boundary condition…“
Lines 315-316 / Proposal: „constant hydraulic head boundary condition. The specified hydraulic head boundaries are assigned to the inlet valleys of the rivers on the boundaries (see Figure 4). Note that the hydraulic head…“
Lines 317-318 / Proposal: „Such specified hydraulic head…allow for assigning hydraulic head values“
Lines 324-326 / grammar/ please correct as: Proposal „(i.e., the northern segment…)… Kaaping river (i.e., the southern portion segment of the Li-lin Bridge station)…“
Line 328 / grammar/ please correct as: „of the PPG…“
Line 333 / grammar/ please correct as: „for the GSFLOW model …“
Lines 337-338 / please double check the units here, always keep numbers and units in one line together:
„0.8 to 106 md-1“ or do you rather mean: 0.8 to 106 md ?
Line 339 / same as before, please double check the units here:
„70 to 80 md-1“ or do you rather mean: 70 to 80 md ?
Line 341 / same as before, please double check the units here:
„110 md-1“ or do you rather mean: 110 md ?
Line 343 / same as before, please double check the units here:
„70 md-1“ or do you rather mean: 70 md ?
Line 343 / wording/ please correct as: Proposal: „are occur along the downstream area…“
Line 349 / grammar/ please correct as: „In the MODFLOW model…“
Lines 357-358 / style/ please correct as: Proposal: „We found that PPGB-recharge and PPGB-pumping rates were the main
sensitive parameters regarding model calibration“
Line 367 / grammar/ please correct as: „land-use types…“
Line 387/ grammar/ please correct as: „In the GSFLOW model …“
4. Results and Discussion
Line 398 / grammar/ please correct as: „the PPG, namely…“
Line 399 / Proposal: „total hydraulic head…“
Line 402 / grammar/ style/ please correct as: „limited in to…in the model, and that these parameters…“
Lines 420-422 / grammar/ please correct as: „northeastern…of the PPGB. The hydraulic head …decrease from the northeastern… “
Lines 424-425/ Proposal: „simulated hydraulic head values…We found that the patterns of hydraulic head distributions…“
Lines 429-438 / Proposal: „hydraulic head differences …means of hydraulic heads …7b shows that the hydraulic head differences….significantly constrained the hydraulic head variations…These areas with large hydraulic head differences…the highest variation of hydraulic heads… River also show relatively high hydraulic head differences“
Line 453 / grammar/ please correct as: „show are two orders of magnitude…“
Lines 463 / 464 grammar/ wording/ style/ please correct as: Proposal: „Besides that, the calculated normalized root mean-square errors (NRMSE) showed different results for the two selected streamflow stations. They are In detail these NRMSE’s were 465 0.67 for the Li-lin Bridge and 0.24 for the Xing She Da Qiao stations.“
Line 476 / grammar/ please correct as: „can vary in three orders of magnitude differences.“
Lines 489-491 / Proposal: „The simulated groundwater hydraulic head distributions: (a) the distribution of averaged
groundwater hydraulic heads in the PPGB; (b) differences of the averaged hydraulic heads between…“
Line 512/ grammar/ please correct as: „also present the statistics…“
Line 516 / grammar/ please correct as: „constant hydraulic head…“
Lines 586-588 / grammar/ please correct as: „water resources management…efficient water resources management“
Lines 589-590/ grammar/ please correct as: „land-use … allow for the assessment…“
Line 600 / grammar/ please correct as: „However the relatively small…“
Line 621 / grammar/ please correct as: „to the soil zone…“
Line 635 / grammar/ please correct as: „and a complex river network.“
Line 655 / grammar/ please correct as: „indicate that the high impacts between groundwater and surface water systems…“
Line 670 / grammar/style/ please correct as: „the initial stage was 40 m and was , specified based on the averaged …“
Lines 674-675 / grammar/ please correct as: „In the GSFLOW model…case without the lake … while the case with the lake…“
Line 677 / grammar/ please correct as: „as the precipitation in the lake area…“
Line 691 / grammar/ please correct as: „components in the PRMS…“
5. Conclusions
Line 709 / grammar/ please correct as: „solutions are limited to ±1 m“
Line 713 / Proposal: „averaged hydraulic heads…“
Line 734 / grammar/ please correct as: „are obviously near rivers and indicate that the high impacts between groundwater and surface water systems…“
Author Response
We thank reviewer 1 for the valuable comments. The manuscript has been revised based on the comments and suggestions raised by the reviewer.
In the following, we have listed the point by point comments and the associated responses for the reviewer. Thanks for the valuable comments.
Reviewer #1
The article title speaks of „Groundwater Interactions Induced by Complex Landforms and Human Activities in the Pingtung Plain Groundwater Basin, Taiwan“. This is a bit misleading as the reader expects more infos about human activities in the article, which are just briefly addressed. As well some passages are repeated to some extent. Overall however, the manuscript presents an interesting GSFLOW numerical study. Important sensitive water budget data for local wet and dry seasons in terms of management, as well as some interesting model extensions are supportive for the scientific community.
Methodology, figures and tables are well organized, data and results match. Besides that still a significant english grammar check is required, including wording and style. In view of wording often wrong terms or even parts of sentences occur. This has to be optimized and personal proposals are given below.
Where announced, also units should be double checked. A note: Numbers and units should always be kept together, also check the space between numbers and units.
Response: Thank you for the comment. We had made the unit to be consistent with the SI Units (International System of Units). Specifically, the space between numbers and units were revised through the manuscript. The details can be found in the following point-by-point responses.
Further details are outlined below.
Abstract
Line 30/ grammar/please correct as: „with the high slope in the PPGB lead to…“
Response: Thank you. The error is revised. Please check line 30 in the revised manuscript.
Introduction
Lines 49-50/ grammar/please correct as: „The processes included in the IHMs… groundwater interactions and others [2].“
Response: Thank you. The error is revised. Please check lines 49-50.
Line 63 / grammar/please correct as: „The SWATMOD model couples the Soil Water Assessment Tool (SWAT) model…“
Response: The error is fixed. Please check line 63. Thanks.
Line 69 / style /please correct as: „to simulate the processes that affect surface water quality.“
Response: Thank you. The error is revised. Please check line 69.
Line 70 / wording /please correct as: „The HydroGeoSphere model allows…connect rivers the groundwater systems.“
Response: Thank you. The error is revised. Please check lines 70-71.
Lines 73-74/ grammar/style/please correct as: „The CATHY model is a process-based model… groundwater flow and surface runoff. The WetSpass MODFLOW model…“
Response: The error is revised. Please see lines 73-75. Thank you.
Lines 79-80/ grammar/style/please correct as: „… the water balance near the land surface for MODFLOW focussing large catchment areas.“
Response: The error is fixed. Please check line 79.
Line 81 / grammar/please correct as: „The GSFLOW model has integrated the Precipitation Runoff Modeling System (PRMS) with MODFLOW…and groundwater. The GSFLOW model is also…“
Response: Thank you. The error is revised. Please check lines 81-83.
Lines 87-88 / grammar/please correct as: „In the GSFLOW model, the coupling process…iterative techniques to solve interdependent governing equations…“
Response: Thank you. The error is revised. Please check lines 87-88.
Lines 91-92 / style /understanding/please correct as: Proposal: „Specifically, Critical connections in the GSFLOW model refer to the unsaturated zone flow as well as stream interaction modules in MODFLOW.“
Response: Thank you. The error is revised. Please check lines 91-92.
Lines 100-101 / grammar/style/please correct as: „different water resources issues…climate change and water quality.“
Response: The error is revised. Please check lines 100-101.
Lines 103-105 / grammar and understanding /please correct as: Proposal: „In view of the complex amounts of input data established in the GSFLOW model, the development of a simulation model for a case study covering a large area with multiple watersheds is a great challenge.“
Response: Thank you. The error is revised. Please check lines 103-105.
Line 108 / grammar/please correct as: „elevation varies significantly.“
Response: The error is revised. Please check line 108.
Lines 110-111 / grammar/wording/ please correct as: Proposal: „Due to the combination… (…deposition, precipitation)…the landforms have evolved differently over time in the upstream and downstream areas of the PPGB“
Response: The error is revised. Please check lines 108-111 in the revised manuscript. Thank you.
Lines 114-116 / grammar/understanding/wording/ please correct as: Proposal: „The effects of complex landforms and human activities have to be clarified before implementation of the IHMs in the PPGB. The present study utilizes the GSFLOW numerical model to assess the SGIs in the PPGB.“
Response: Thank you. The error is revised. Please check lines 115-116.
Lines 121-127 / grammar/understanding/wording/style please correct as: Proposal: „and quantified according to the detailed interaction dynamics in the PPGB. The calibration and validation of the model is based on three-year observations from January 2015 to December 2017. The evaluation of the developed model relies on different statistical parameters... A scenario of an artificial recharge reservoir was considered to assess the local impact of increased recharge on water balance variations in the simulation area“
Response: Thank you. The error is revised. Please check lines 121-127.
- Materials and Methods
Line 133 / grammar/please correct as: „Eurasian Plate forms the Taiwan Island…“
Response: Thank you. The error is revised. Please check line 133.
Line 134 / grammar/understanding/ please correct as: „The area covers approximately 1300 km2, with the land surface elevation varies from the north to the south.“ (to which extent?! Please state numbers here)
Response: Thanks for the comment. The error is revised. Please check lines 134-135.
Line 136 / grammar/please correct as: „subtropical and rainfall is alternately affected…“
Response: The error is revised. Please check line 136.
Line 144 / grammar/please correct as: „monsoons and total precipitation…“
Response: Thanks for the comment. Please check line 144.
Lines 147-148 / grammar/wording /please correct as: Proposal: „have led altered the landscape differently in…“
Response: Thank you. Please check line 147-148 for the revision.
Line 149 / grammar/ please correct as: „defined as the upstream area of the confluence point…“
Response: Thank you. Please check lines 148-149.
Line 151 / grammar/ please correct as: „are generally in the north-south…“
Response: The error is revised. Please check line 151.
Line 154 / grammar/ please correct as: „The aquifer of the PPGB…“
Response: Thank you. The error is revised. Please check line 154.
Line 155 / grammar/ please correct as: „of tertiary age rocks.“
Response: The error is revised. Please check line 155. Thanks for the comment.
Line 156 / grammar/ wording / please correct as: Proposal: „Formation are of the Eocene-Oligocene age, located in the eastern part of the plain.“
Response: Thank you. The error is revised. Please check line 156.
Line 157 / grammar/ please correct as: „stretching from north to south…“
Response: The error is revised. Please check line 157 for the revision.
Lines 165-166 / grammar/ wording / please correct as: Proposal: „There are 51 hydrogeological investigation stations and 126 monitoring wells are available in the groundwater basin.“
Response: Thank you. The error is revised. Please check lines 165-166.
Line 168 / grammar/ please correct as: „layers, and separated with by low permeable marine sequences.
Response: Thank you. The error is revised. Please check line 168.
Line 170 / grammar/ wording and sense!/please correct as: „also conducted included pumping tests…“
Response: The error is revised. Please check line 170. Thank you.
Line 178 / grammar/ please correct as: „PPGB the groundwater recharge varies…“
Response: The error is revised. Please check line 178.
Line 201 / grammar/ please correct as: „In the GSFLOW model…“
Response: Thank you. The error is revised. Please check line 204.
Line 208 / grammar/ please correct as: „The three regions for the GSFLOW model …“
Response: Thank you. Please check line 212.
Lines 210-212 / grammar/ please correct as: „The PRMS model … land-use…The PRMS model uses … “
Response: Thank you. Please check lines 214-216.
Line 216 / grammar/ please correct as: „In the PRMS model… “
Response: The error is revised. Please check line 220.
Lines 219-220 / wording / understanding / please correct as: Proposal: „impervious sealed zones … In the PRMS model the subsurface… “
Response: Thank you. Please check lines 223-224 for the revision.
Line 222-223 / grammar / wording / understanding/ structure/ please correct as: Proposal: „volumetric water flowing downslope, which may be further removed by plants or combined with groundwater.“
Response: Thank you. The error is revised. Please check lines 226-227.
Line 228 / understanding / please correct as: Proposal: „lost to subsurface sinkholes in the groundwater reservoirs“
Response: Thank you. The error is revised. Please check line 232.
Line 232 / grammar/ please correct as: „land-use“
Response: Thank you. The error is revised. Please check line 236.
Line 253/ „…can be the specified head?“ What do you mean here? hydraulic head? The way it is written here it does not become clear to the reader. Please give a better explanation here.
Response: Thank you. It is the specified hydraulic head. We have modified these sentences. Please check lines 256-258. Thanks for the comment.
Lines 263-264/ „…method of characteristic?“ What do you mean here? The way it is written here it does not become clear to the reader. Please give a better explanation here.
Response: The method of the characteristic (MOC) is the algorithm that was used by the previous investigation cited in the manuscript. We have added some statements to define and make the explanation clear. Please check the lines 267-269 in the revised manuscript. Thank you for the comment.
- Conceptual Models and Numerical Considerations
Line 279 / grammar/ please correct as: „the GSFLOW model then…“
Response: Thank you. The error is revised. Please check line 297.
Line 290/ grammar/ please correct as: „200 m…“ numbers and units always together without separation in one! line.
Response: The error is revised. Please check line 308.
Line 308 / grammar/ please correct as: „The MODFLOW-2005 model enables …“
Response: Thank you. The error is revised. Please check line 326 for details.
Lines 309-310 / Proposal: „the specified hydraulic head boundary condition…constant hydraulic head boundary condition…“
Response: Thank you. The error is revised. Please check lines 327-328.
Lines 315-316 / Proposal: „constant hydraulic head boundary condition. The specified hydraulic head boundaries are assigned to the inlet valleys of the rivers on the boundaries (see Figure 4). Note that the hydraulic head…“
Response: Thank you. The error is revised. Please check lines 333-335.
Lines 317-318 / Proposal: „Such specified hydraulic head…allow for assigning hydraulic head values“
Response: The error is revised. Please check lines 336-337.
Lines 324-326 / grammar/ please correct as: Proposal „(i.e., the northern segment…)… Kaaping river (i.e., the southern portion segment of the Li-lin Bridge station)…“
Response: Thank you. The error is revised. Please check lines 343-345.
Line 328 / grammar/ please correct as: „of the PPG…“
Response: Thank you. The error is revised. Please check line 347.
Line 333 / grammar/ please correct as: „for the GSFLOW model …“
Response: Thank you. The error is revised. Please check line 352.
Lines 337-338 / please double check the units here, always keep numbers and units in one line together:
„0.8 to 106 md-1“ or do you rather mean: 0.8 to 106 md ?
Response: Thank you. As for the first response. We have adjusted the unit and the number to fit together. The rules of SI Units (International System of Units) are used through the manuscript. The unit of “md-1” refers to meter per day (or “m/d” with another form). We have made the unit with the format “m/d” through the manuscript. Please check line 357.
Line 339 / same as before, please double check the units here:
„70 to 80 md-1“ or do you rather mean: 70 to 80 md ?
Response: Thank you. We have made the unit with the format “m/d” through the manuscript. Please check line 358.
Line 341 / same as before, please double check the units here:
„110 md-1“ or do you rather mean: 110 md ?
Response: We have made the unit with the format “m/d” through the manuscript. Please check line 360 for the comment.
Line 343 / same as before, please double check the units here:
„70 md-1“ or do you rather mean: 70 md ?
Response: Thank you. We have made the unit with the format “m/d” through the manuscript. Please check line 362 for the comment.
Line 343 / wording/ please correct as: Proposal: „are occur along the downstream area…“
Response: Thank you. The error is revised. Please check line 362.
Line 349 / grammar/ please correct as: „In the MODFLOW model…“
Response: The error is revised. Please check line 368.
Lines 357-358 / style/ please correct as: Proposal: „We found that PPGB-recharge and PPGB-pumping rates were the main sensitive parameters regarding model calibration“
Response: Thank you. The error is revised. Please check lines 376-377.
Line 367 / grammar/ please correct as: „land-use types…“
Response: Thank you. The error is revised. Please check line 386.
Line 387/ grammar/ please correct as: „In the GSFLOW model …“
Response: The error is revised. Please check line 407. Thank you for the comment.
- Results and Discussion
Line 398 / grammar/ please correct as: „the PPG, namely…“
Response: Thank you. The error is revised. Please check line 420.
Line 399 / Proposal: „total hydraulic head…“
Response: The error is revised. Please check line 422.
Line 402 / grammar/ style/ please correct as: „limited in to…in the model, and that these parameters…“
Response: Thank you. Please check lines 425-426.
Lines 420-422 / grammar/ please correct as: „northeastern…of the PPGB. The hydraulic head …decrease from the northeastern… “
Response: Thank you. The error is revised. Please check lines 444-446.
Lines 424-425/ Proposal: „simulated hydraulic head values…We found that the patterns of hydraulic head distributions…“
Response: Thank you. The error is revised. Please check lines 448-450.
Lines 429-438 / Proposal: „hydraulic head differences …means of hydraulic heads …7b shows that the hydraulic head differences….significantly constrained the hydraulic head variations…These areas with large hydraulic head differences…the highest variation of hydraulic heads…River also show relatively high hydraulic head differences“
Response: Thank you. We have added “hydraulic” in front of the “head” through the manuscript to make the presentation clear. Please check lines 453-462.
Line 453 / grammar/ please correct as: „show are two orders of magnitude…“
Response: Thank you. The error is revised. Please check line 478.
Lines 463 / 464 grammar/ wording/ style/ please correct as: Proposal: „Besides that, the calculated normalized root mean-square errors (NRMSE) showed different results for the two selected streamflow stations. They are In detail these NRMSE’s were 465 0.67 for the Li-lin Bridge and 0.24 for the Xing She Da Qiao stations.“
Response: Thank you. The error is revised. Please check lines 488-490.
Line 476 / grammar/ please correct as: „can vary in three orders of magnitude differences.“
Response: Thank you. Please check line 501.
Lines 489-491 / Proposal: „The simulated groundwater hydraulic head distributions: (a) the distribution of averaged groundwater hydraulic heads in the PPGB; (b) differences of the averaged hydraulic heads between…“
Response: Thank you. Please check lines 514-515.
Line 512/ grammar/ please correct as: „also present the statistics…“
Response: Thank you. The error is revised. Please check line 537.
Line 516 / grammar/ please correct as: „constant hydraulic head…“
Response: Thank you. The error is revised. Please check line 541.
Lines 586-588 / grammar/ please correct as: „water resources management…efficient water resources management“
Response: The error is revised. Please check lines 611-613.
Lines 589-590/ grammar/ please correct as: „land-use … allow for the assessment…“
Response: The error is revised. Please check lines 614-615.
Line 600 / grammar/ please correct as: „However the relatively small…“
Response: Thank you. The error is revised. Please check line 625.
Line 621 / grammar/ please correct as: „to the soil zone…“
Response: Thank you. The error is revised. Please check line 646.
Line 635 / grammar/ please correct as: „and a complex river network.“
Response: Please check line 660.
Line 655 / grammar/ please correct as: „indicate that the high impacts between groundwater and surface water systems…“
Response: Thank you. The error is revised. Please check line 680.
Line 670 / grammar/style/ please correct as: „the initial stage was 40 m and was , specified based on the averaged …“
Response: The error is revised. Please check line 695.
Lines 674-675 / grammar/ please correct as: „In the GSFLOW model…case without the lake … while the case with the lake…“
Response: Thank you. The error is revised. Please check lines 699-700.
Line 677 / grammar/ please correct as: „as the precipitation in the lake area…“
Response: The error is revised. Please check line 702.
Line 691 / grammar/ please correct as: „components in the PRMS…“
Response: Thank you. Please check line 716.
- Conclusions
Line 709 / grammar/ please correct as: „solutions are limited to ±1 m“
Response: Thank you. Please check line 734.
Line 713 / Proposal: „averaged hydraulic heads…“
Response: Thank you. The “hydraulic” was added in the text. Please check line 738.
Line 734 / grammar/ please correct as: „are obviously near rivers and indicate that the high impacts between groundwater and surface water systems…“
Response: Thank you. Please check line 759.
Reviewer 2 Report
This paper reports on the surface and groundwater interactions (SGI) for the Pingtung Plain Groundwater Basin (PPGB) in Tiawan. The authors have utilised a fairly commen SGI modelling approach in a regionalised approach to construct water budgets within various climate and land-use variability. The SGI modelling of the PPGB provides an imprtant regional resource for not only water management but for also determining nutrient and contaminant flows in the basin. Generally, the methods used were appropriate although there is some important information on parameterisation of the model missing and I have some concerns about the use of a lake as a Hydrologic Response Unit (HRU).
The GSFLOW IHM has some 50 global parameters and 35 model-cell specific parameters. This paper provides a superficial overview of a few parameters used as input to the model. I think a more detailed account of the parameters and how they were derived is required. This could possibly be done in a table.
There is only one instance where an individual lake is used as a HRU, in all other instances it is a small watershed/sub-catchment. In order to truly determine the impact of individual lakes on SGI's it would be useful to analyse more than one lake.
How was calibration modified for each of the model modules. How were the models adjusted if GW levels were different? How was the PRMS module calibration modified what parameters were used i.e. evapotranspiration, rainfall, infiltration, etc.
How were the time-steps converted from monthly to daily?
Other minor comments include:
Line 137: for clarity and consistency, replace summer with wet/dry season as this is described, in terms of rainfall, in more detail in the methods section.
Line 147-148: sentence is poorly worded and meaning ambiguous.
Line 163: should read 'were conducted in 1995'.
Line 196-197: this sentence about GSFLOW is repetitive.
Line 411: What is long-term average rainfall for the region.
Figure 1: caption should identify transects as situated in the upstream or downstream fan.
Figure 3: Workflow is not clear in the diagram. The way the diagram is presented means that following successful calibration of MODFLOW you receive a result but it is not clear what triggers the PRMS circuit. Should the PRMS circuit not be linear with MODFLOW?
Figure 6: Rainfall for each station is required, using the closest weather station.
Author Response
We thank reviewer 2 for the valuable comments. The manuscript has been revised based on the comments and suggestions raised by the reviewer.
Reviewer #2
This paper reports on the surface and groundwater interactions (SGI) for the Pingtung Plain Groundwater Basin (PPGB) in Taiwan. The authors have utilised a fairly commen SGI modelling approach in a regionalised approach to construct water budgets within various climate and land-use variability. The SGI modelling of the PPGB provides an important regional resource for not only water management but for also determining nutrient and contaminant flows in the basin. Generally, the methods used were appropriate although there is some important information on parameterisation of the model missing and I have some concerns about the use of a lake as a Hydrologic Response Unit (HRU).
The GSFLOW IHM has some 50 global parameters and 35 model-cell specific parameters. This paper provides a superficial overview of a few parameters used as input to the model. I think a more detailed account of the parameters and how they were derived is required. This could possibly be done in a table.
Response: Thank you. This is a valuable comment. We have added a new table (Table 1) to present the calibrated parameter ranges in the study. Please see line 406 and Table 1 for details.
There is only one instance where an individual lake is used as a HRU, in all other instances it is a small watershed/sub-catchment. In order to truly determine the impact of individual lakes on SGI's it would be useful to analyse more than one lake.
Response: Thank you for the comment. The HRU of the artificial recharge is built based on the on-going project at Pingtung Plain for an artificial lake. We are interested in quantifying the impact of the artificial lake on the regional water interactions. There will be additional lakes added in the Pingtung plain groundwater basin. In the study, we had focused on the development of the model. The quantification of water interactions influenced by other lakes could be included in future research tasks.
How was calibration modified for each of the model modules. How were the models adjusted if GW levels were different? How was the PRMS module calibration modified what parameters were used i.e. evapotranspiration, rainfall, infiltration, etc.
Response: Thank you for your comment. Following the report of Marsktrom et al. (2008), the GSFLOW model was calibrated using the independent MODFLOW-2005 and PRMS models by running these models separately. In the study, similar processes were conducted to calibrate and validate the model. The GSFLOW model has the MODFLOW-2005 and PRMS models to be calibrated in iterative processes that follow the conceptual workflow shown in Figure 3. In the study, the calibration of the MODFLOW-2005 model was first conducted based on the best-fit of the groundwater observations and the associated hydrogeological parameters. The calibrated MODFLOW model was then used in the GSFLOW model to join the PRMS simulations to account for the interactions of surface water and groundwater. The calibration of PRMS used the observations of the streamflow. During the PRMS calibration in the GSFLOW, the parameters in the MODFLOW model need to be adjusted simultaneously. The calibration and validation might need a few loops to obtain the acceptable solutions that fit the observations from the monitoring wells and the streamflow stations. The calibration parameters in the PRMS had listed in the new table (i.e., Table 1). The description for the calibration processes was added to lines 294-296.
How were the time-steps converted from monthly to daily?
Response: Thank you for your comment. The time-step can be converted by a variable in an input file of MODFLOW-2005 in the GSFLOW simulation, namely “TSMULT”. In a typical MODFLOW simulation, TSMULT is the multiplier for the length of successive time steps. However, for a GSFLOW simulation, TSMULT is set to a value of 1. The number of time steps in a stress period (NSTP) and the length of a stress period (PERLEN) must be specified such that the time step length is 1 day and the period length of 1 day. The processes had presented in the study of Marsktrom et al. (2008). We had added the description in the manuscript. Please see lines 284-293 for details.
Other minor comments include:
Line 137: for clarity and consistency, replace summer with wet/dry season as this is described, in terms of rainfall, in more detail in the methods section.
Response: Thank you. The sentence was modified. Please check line 137.
Line 147-148: sentence is poorly worded and meaning ambiguous.
Response: Thank you. Please check lines 147-148.
Line 163: should read 'were conducted in 1995'.
Response: Thank you. The error was revised. Please check line 163.
Line 196-197: this sentence about GSFLOW is repetitive.
Response: Thank you. The error was fixed. Please check line 201.
Line 411: What is long-term average rainfall for the region.
Response: Thank you. The term “long-term” had been removed to make the description clear. The description of the monthly averaged precipitation was added in the text and in Figure 6. Please see lines 434-435 and the caption of Figure 6 for details.
Figure 1: caption should identify transects as situated in the upstream or downstream fan.
Response: Thank you. The description was added to the caption. Please check lines 194-197.
Figure 3: Workflow is not clear in the diagram. The way the diagram is presented means that following successful calibration of MODFLOW you receive a result but it is not clear what triggers the PRMS circuit. Should the PRMS circuit not be linear with MODFLOW?
Response: Thank you. Figure 3 was modified to fit the description of the text. We also modified the manuscript to make the presentation clear. Please check Figure 3 and the description on lines 285-298.
Figure 6: Rainfall for each station is required, using the closest weather station.
Response: Thank you. The rainfall data were replaced with the ones obtained from the closest stations. Thanks for the suggestion. Please see Figure 6 for the modified figure and the associated description on lines 434-435 and lines 507-508.
