Underground dams (Groundwater dam) are very efficient and advantageous dams that used to trap groundwater and store all or most of it below the surface for extended use in a localized area. In some cases they are also built to prevent saltwater from intruding into a freshwater aquifer. Underground dams are typically constructed in areas where water resources are minimal and need to be efficiently stored, such as in deserts with high rate of evaporation.The most important thing in the object of underground dam studies and construction is “Site selection” that need deep knowledge about geology and hydrogeology because in spite of surface dam(common dam) that you see the features and processes, in these kind of dams you don’t see anything at the first steps. And you should compensate the geological and hydrogeological features by your background geological field experiences and indirect method such as geophysics and because sometimes these study have gone wrong, some underground dams have failed in achieving their goals and couldn’t satisfy client’s demands. So because of our very comprehensive background about groundwater exploration and very good correlations of key personnel’s experiences and knowledge between these two objects, our company have started to enter studying and selecting the best positions by take into account all aspects that are vital for the processes of studying and constructing that dams to prevent the fail of these marvelous and useful dams.