Hi Michael:   I have read ...

Hi Michael:

I have read the comments and I agree with everyone. Geophysics is the way to go, however the hard thing is to set up the surveys and find the correct locations. I will try to give you a walkthrough, that in a very general way I believe it applies to any case study:
 

1. You have to start by analyzing geological maps to study the soil type and stratigraphy. So you can at least have a very broad image of whats happening down there and where the water could possible be stored.

2. A very brief hidrological analysis will let you know where it rains and how much it does. You can compare it with stream flows and try to close the water balance. It is important that you define if it rains, how much of that rain can be going to groundwater. Later on, that will be your recharge. If you have no recharge, you will dry the acuifer and all the work is done pointless.

3. By looking at a DTM and going on field trips you can start implying possible locations to perform geophysical surveys. First, start with Vertical Electric Sounding (VES) which are cheaper and give you one directional information. With the VES interpretation you will know better where you need to search deeper and plan on 2D ERT (Electric Resistivity Tomography), that is pretty much like x-rays of the ground. With a good interpretation, you can stop any time. 

4. If things are not so clear this far, you will need to bore exploration wells, which are cheaper. Direct information can be compared with indirect data from ERT and VES. Just now you can start making decissions.

I hope you can use this information. If you have any further question, please don't hesitate to contact me:
evillagomez@live.com

Have a great day,

Eduardo.