Authors: Pierre Ngnepieba ¹; François Xavier Le Dimet ¹; Alexis Boukong ^2,3; Gabriel Nguetseng ⁴

• 1 System identification and optimization in physics and environment
• 2 Université de Dschang
• 3 Faculté Agronomique et des Sciences Agricoles
• 4 Université de Yaoundé I

Inverse modeling has become a standard technique for estimating hydrogeologic parameters. These parameters are usually inferred by minimizing the sum of the squared differences between the observed system state and the one calculed by a mathematical model. Since some hydrodynamics parameters in Richards model cannot be measured, they have to be tuned with respect to the observation and the output of the model. Optimal parameters are found by minimizing cost function and the unconstrained minimization algorithm of the quasi-Newton limited memory type is used. The inverse model allows computation of optimal scale parameters and model sensi-tivity.