GGU-SLUGTEST: Solvation of the equations

By substituting and solving from the previous equations we get:

and

where:

y₀ : Drawdown in well at t = 0 [m]

y_t : Drawdown in well at t > 0 [m]

t : Time [s]

R_e : Range [m]

The range R_e of a slug or bail test was determined with the aid of an electro-analogue model. The following relationship applies for a perfect well (H = L_w):

The following equation is used for an imperfect well:

where H is defined as the distance between the groundwater base and the at-rest water level in metres. The coefficients A, B and C are determined from a diagram as a function of L_e /r_w.

We can write:

where:

Because D is known for each well, the result for the water level history as a function of the value of k_f is:

On the basis of this derivative, the principle of an evaluation after BOUWER & RICE (1976) rests upon finding a value for k_f which minimises the deviation between the measured and the calculated water levels.