# 146

Dear Zohair Qadem , Yasir Abduljaleel , Mustapha Amiri , Abdelghani Qadem , Mohamed Lasri , Oussama Obda , Henrique Pizzo , Ali Salem

I read your paper:

Identification of Optimal Groundwater Storage Sites in a Semi-Arid Region: A GIS-Based Analytic Hierarchy Process (AHP) Approach

My comments:

1- Very interesting project and clearly described.

As in all my comments I do not enter into the project itself, as in this highly technical undertaking, simply because it is not my field. What I do, as in all other articles, is to address the MCDM applied, whatever it might be.

2- In page 3 you say “The methodology used for evaluation integrates sophisticated methods such as the Analytic Hierarchy Process (AHP)”

If there is something that AHP does not posses is sophistication. It is a very simple method, easy to understand and that does not require research or/and rationality, because its descriptive nature is related to human perception, which is a typical descriptive feature and irrational.

The latter is not a derogatory expression, but as Google describes it “An irrational decision is a decision that goes against or counter to logic. Summing-up: Rational decisions are carefully considered and negative outcomes are weighed. Nonrational decisions are based on intuitive judgment”

In my opinion we are constantly applying it in our daily life, but it does not mean that it can be used to evaluate alternatives in most projects.

The other process is called ‘normative’, that uses norms and established conditions.

“The normative approach sets out the ideal standards for rationaldecision-making, while the descriptive approach delves into the nuances of how people make decisions based on their cognitive processes and psychological biases”. This is not my definition

3- page 3 “This study provides valuable insights for strategic planning of groundwater management”

I do not agree with the underlined sentence, because strategic planning is far for being intuitive. I believe that drilling a well is based in many rational studies not on what the experts say

4- In page 5 you should explain what ‘delineation’ means; same for remote sensing and GIS

5- In page 8. It is a pleasure to read so detailed and documented observations about the three different areas. Well done.

6- Page 14 “Assessing consistency and comparisons for bias”

This is for me one important point, but why there should be consistency?

If we consider Rainfall (a), Lithography (b), Slope (d), and we determine for instance that a> b, and b>d, then, a >d? Mathematically, yes, it is correct, but is it in the field? Maybe it is, or maybe it is not; that is for the experts to decide, but is it a must? This is my point. What if it is not? I find here something very usual, especially inAHP, that assumes that theoretical conclusions apply to real life

At the end of the 19th Century, scientistssaid that theoretically, nothing heavier than air could fly. Applying aerodynamics theory, unknown then, it was demonstrated that it was not true. The problem in your example is that AHP is not mathematically prepared to address this type of problems. Its elemental theory cannot be applied to complex scenarios. There is no axiom or theorem that supports the AHP need for consistency or transitivity.

7- In Page 16 Table 4, where the weights values come from? Weights are normally between 0 and 1

Where is the interaction? For that, you would need a network not a lineal hierarchy as in AHP

8- In page 17 “These values reflect the estimated impact of one factor compared to another within a specific context”

I am afraid that you are mistaken, since impact means that you modify something, not the case here.

9- In page 18 “Sensitivity analysis is the study that measures the contribution or impact of variables in the unperturbed output result from models applied and permits recognition of layers, which are more critical for the analysis”

Sorry, this is not the definition of SA, or as I presume you made an involuntary error. SA measures the strength of solution or potential impact, due to variations in the importance of diverse criteria, and you are right in your lest sentence.

10- On page 22 “Interaction of diverse geographical, geological, and climatic factors”

Very true, but AHP does not do it. Interaction means that you have to analyze all criteria simultaneously not single pairs. As a trivial example, suppose that three barmen compete to prepare three different drinks using oranges, lemonS, cherries and pears, but in different quantities. In this case what AHP does is to compare juices of orange with lemons, orange with cherries, and orange with pears.

Each barman must use only these four fruits, but mixing all together and this giving a final taste of the mix, whatever it might be,not a couple of them separately.

The same in your example, you must to blend the different special layers, not determining pairs and then adding them up. Remember that the result not always is equal to the sum of the parts.

Curiously you agree with this in the underline paragraph when speaking about interaction.

These are my comments

I hope they can help you

Nolberto Munier