The manuscript investigates the impact of aquifer geometry

on seawater intrusion in annulus shaped aquifer typical for islands

using analytical solutions based on the Ghijben-Herzberg

solution and hillslope-storage Boussinesq equation. The analytical

solutions are validated by comparison with data from laboratory

experiments, and then used to investigate the interface under different

geometries (convergent, rectangular, divergent). The results are interesting

and give some insight in the role of aquifer geometry on the seawater-freshwater

interface. I have a few comments the aquifer as described in the following. 

Comments:

line 145: "interface tip" and "tip location" should be defined. 

line 168: The underlying assumptions should be clarified here. 

Eq. (3): Different symbols phi should be used in the integrand and integration limit. What is phi

in the upper integration limit?

Eq. (6): Some more explanation is required on how this equation is obtain and what are

the assumptions.

line 292: The authors use the term "extent of seawater intrusion" repeatedly in the manuscript,

but it is never defined. The authors should clearly quantitatively define, which are the

diagnostics/observables that are used to assess aquifer vulnerability. 

Major problem of the present paper is the English language. Needs specific attention.

I believe the main contribution of the present paper is the saltwater intrution phenomenon regarding the geometry of the aquifer. 

The paper is based on analytical solutions and as it is mentioned in the paper analytical solutions for for slatwater intrution problems cannot incorporate complex factors. 

Page 7, lines 122-124 need more explanation

page 8, lines 149-153 , assumption (5) needs more exlanation 

page 9, w=θ(Lo +l2 -x) what is θ???? You used this symbol for the angle in previous text.

page 10, Eq. 6 needs more explanation. You mentioned substitution of Eq. 5 into Eq. 4. But Eq. 4 does not contain h. Did you solve Eq. 5 for φ??

page 14, the experimenta scale is very small.

The authors have not considered importants publications on saltwater intrution such as:

Pool,M.& Carrera,J. 2011 A correction factor to account for mixing in Ghyben-Herzbergand critical pumping rate approximations of seawater intrusion in coastal aquifers. Water Resources Research 47 (5), 1–9.

Mantoglou, A. 2003 Pumping management of coastal aquifers using analytical models of saltwater intrusion. Water Resources Research 39 (12), 1–12.