Dear Najim,

Numerical models are valuable decision support tools.

3D mapping and modeling is a particularly important step to reproduce the natural processes related to the functioning of aquifers. Numerical models make it possible to simulate the natural process, both from the point of view of quality and quantity of the water resources. Thus they are valuable decision support tools, particularly in the context of global changes.

For example we can establish profiles of pollutant transfer in the basement, simulate the interaction surface water-groundwater waters in the genesis of floods and flooding, understand the impact of extreme events (eg drought), test the effectiveness of preventive or corrective measures vis-à-vis pollution or climate change and its impact.

With my best regards

Prof. Bachir ACHOUR

Surely, it is a valuable tool in taking the preliminary decision ans pre-desicion especially if there is a risk.

yes, good to assess the feasibility before doing the actual study.

Dear prof Najim,

YES, Certainly, it is important, especially for agriculture. If we can model and predict water availability of next season, authorities can advice farmers accordingly; for examples selection of crops according to amount of water available, commencement of  growing season etc. 

SENA RATNAYAKE

It all depends on the research question/resource problem. If these are specific and the modelling is tailored to these (with adequate data to support it), then models are great tools, either hydraulic or hydrochem models. However, all too often these days many models are based on "conceptual 3d models" which are just drawings in reality, and/or on small amounts of data. When the model stretches its limits it can be a resource user/maanger's nightmare....and I have seen these scenarios end up in courts quite a few times. There tends to be this stigma attached to a model, once it is produced, that it is always right. Because some models are expensive to produce and very time consuming, there is a reluctance to keep re-visiting them...but this is imperative if we are to use models as tools, and not as "information". 

Dear Dr. Patricia Mokhtarian,

In my opinion, it is necessary to assess the feasibility before doing the actual water resource projects.

Regards,

S. Mehdi Mohammadizadeh

Dear Dr Najim, a couple of matters: (i), there is a motto used in the introduction of the book by professor Rushton, KR (2003). Groundwater Hydrology, Conceptual and computational models, Wiley, 416pp: "understand groundwater flow before you intent to model it"... many a case there is a strong failure in groundwater evaluation due to ignoring  this simple concept; (ii) the meaning of “resource” must also be clearly understood, when dealing with "resource" then the monetary value of water must be included as a variable in the model, I do not know if there is such a model that includes this factor in its calculations. Or perhaps you were simply referring to “water”, then use this word and confusions could be avoided.  Do get saudos,jjoel carrillor

Dera prof.  Najim. It is quite impossible to quantify certain components of the natural resources using empirical data because  of their multidimensional dynamic nature. This is very true for  the behaviour of water resources  as they undergo different  processes  within the hydrosphere. Therefore, application of numerical models to estimate certain components is important. But some mathematical models are very complicated  and validation also very unlikely. 

Dear Prof. Jose joel Carrillo-Rivera

I fully agree with you. One most important factor is monetary value but in the case of water, it is mostly neglected. In most of the countries, water for irrigation is free and its economics is fully neglected. I think, in addition to the monetory value of water, the opportunity cost of use of water by one sector on the other sectors need to be considered (eventhough it is very complicated). It will be also interesting if we can model the impactys of water usage (on environment and ecosystems, on fisheries, on navigation, etc.)

Dear Professor Ivan Silva,

Thank you for your answer. Yes, validation of models for some critical components are very difficult and in many cases not even accurate due to complicated nature of the processes and unavailability of reliable data. Anyway, modeling of resources in many cases employ a simplified approach to represent the nature / processes in order to make decisions in a rational and a simplified way.