The authors regret that there were errors in Equations (1) and (2). The equations should be corrected to read as follows.

Equation (1):
1
where and denote the hydraulic conductivity tensors, h, Ss and R represent pressure head, specific storage and recharge or discharge (positive and negative) components of the aquifer, respectively.
Equation (2):
2
where, Sy denotes the specific yield.