Hydrogeological assessments can be undertaken on a number of levels and are usually a minimum requirement if an abstraction licence is required. If the drilling conditions or hydrology of the area are more complex additional surveys may need to be undertaken, two of the most Common are Indicated Below:
Basic desktop survey(to include but not limited to)
Full Hydrogeological assessment(to include but not limited to)

There are two main ways of going about this, they are; undertaking a hydrogeological assessment or a borehole prognosis and water divining or dowsing.

Groundwater flow Equation:
The groundwater flow equation, in its most general form, describes the movement of groundwater in a porous medium (aquifers and aquitards). It is known in mathematics as the diffusion equation, and has many analogs in other fields. Many solutions for groundwater flow problems were borrowed or adapted from existing heat transfer solutions.

Calculation of groundwater flow:
To use the groundwater flow equation to estimate the distribution of hydraulic heads, or the direction and rate of groundwater flow, this partial differential equation (PDE) must be solved. The most common means of analytically solving the diffusion equation in the hydrogeology literature are:

Laplace, Hankel and Fourier transforms (to reduce the number of dimensions of the PDE), similarity transform (also called the Boltzmann transform) is commonly how the Theis solution is derived, separation of variables, which is more useful for non-Cartesian coordinates, and Green's functions, which is another common method for deriving the Theis solution — from the fundamental solution to the diffusion equation in free space.

Hydrogeological Surveys:-
For Borehole Site Investigations
groundwater availability studies and management
water resources management
aquifer mapping and modeling
well-field designs
groundwater monitoring
aquifer studies
Borehole condition assessment,
groundwater recharge
groundwater quality assessment
determination of groundwater abstraction patterns
borehole density etc.