Is visual modflow flex is suitable for groundwater modelling? is there any other computer language should be known to work in modflow related software?like c and fortran etc..?
The current core version of MODFLOW is MODFLOW-2005 v.1.11.00 . MODFLOW-2005 is the standard version of MODFLOW supported by the USGS Office of Groundwater and is the most stable and well-tested version of the code.
you can chose your best software based on your goals. it is really depends on what you need to simulate. each software suppose some thing slightly different for example if you need to link subsidence with groundwater level you will be needing some thing which has related option or tab but if you just need s.th just to simulate GW level there are plenty of software available to you. GMS is also a frequency use software which is linked with Arc map and visual, it is also very user friendly.
Modflow flex incorporates a series of routines useful to solve a wide range of hydrogeological applications. It is a user-friendly software, the user do not necessarily need to know any programming language.
Some experience with fortran is useful, but not necessary. Knowledge of hydrogeology is necessary.
There are graphical user interfaces (GUI) that run modflow that support manual input of data and/or link with geographic information systems or other databases. Modflow was developed by the USGS, and they have a repository of free software for groundwater: http://water.usgs.gov/software/lists/groundwater
and for hydrology in general: http://water.usgs.gov/software/
Additionally, there are private companies that charge for GUI software that run modflow and are possibly easier to use. The most common of these include GWvistas: http://www.groundwatermodels.com/ESI_Software.php
and Visualmodflow: http://www.waterloohydrogeologic.com/resources/visual-modflow-flex-resources