Deep Drilling for Groundwater in Bengaluru, India: A Case Study on the City’s Over-Exploited Hard-Rock Aquifer System

Round 1

Reviewer 1 Report

Generally, the article looks okay and worthwhile to me.

I'd suggest not using "GW" and instead spelling out "groundwater."

Also, more clearly delineate sub-catchments for the wells. Are you referring to surface water catchments generating runoff that enters the well(s) where they intersect the land surface? Are they not capped.

Please more clearly delineate/explain the sub-catchments, perhaps using satellite imagery. Note that predicted radii of influence in pumping tests are generally based on broad flow through primary porosity in sedimentary/similar rocks rather than discrete fractures in igneous rocks.

Note any limitations of those approaches applied to this study. Finally, it's possible to have a sustainable situation with recent water (without tapping older water), as identified through isotopes.

Please better articulate the argument based on isotopes.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Comments on the manuscript titled "Deep Drilling for Groundwater in Bengaluru, India: A Case Study on the City’s Over-exploited Hard-rock Aquifer System".

The authors of the above-cited paper used data derived from borewell drillers in order to check for the evolution of borewell depth (as a proxy for declining water table depth as shown by other studies for eg. Sekhar et.al 2018, Tomer et.al 2020?) in Bangalore urban and rural in the last decades. They do carry borewell camera inspections from Electronic City in order to double-check the aquifer characteristics found by other studies in the rural part for eg. Ballukraya and Srinivasan, 2019. Lastly, stable isotope data were used to check, if currently pumped groundwater can be of recent rainfall or if it is paleo-groundwater.

The article is well organized and adequately discussed and interprets the problem caused. However, the authors should provide a few clarifications in their revised version. 

1. Line 87: expand “S-Indian”
2. Figure 2: the coordinates (lat-long) are not clearly visible.
3. Line 138: Elaborate on Camera data. What are the parameters/details collected from camera?
4. Line 141: if possible include a photograph/clip of identified dry and yielding fractures as a figure.
5. Figure 8: Increase the font size of Legend items.
6. Nowhere in the text, Figure A1 & A2 of Appendix are discussed.

Author Response

Please see the attachment

Author Response File: Author Response.docx