1. A method for mapping a karstic region modified by karstification phenomena, comprising: a/ creating a geological model of the karstic region comprising cells, the geological model is a gridded matrix of a subsoil area based on a plurality of subsoil measurements, said model comprising at least one seed zone comprising cells of the model, the seed zone including an area of the subsoil having an epikarst, a known fracture or a similar geological phenomenon, and at least one target zone comprising cells of the model, each cells of the model having coordinates; b/ determining a seed cell in the cells of the at least one seed zone; c/ determining a target cell in the cells of the at least one target zone; d/ if a distance between the seed cell and the target cell is above a predetermined distance: d1/ determining a bifurcation zone based at least on the coordinates of the seed cell, the coordinates of the target cell, a distance distribution, and an angular distribution, d2/ determining a bifurcation cell in said bifurcation zone; d3/ re-iterating step d/ with a cell based on said bifurcation cell as the seed cell; e/ determining trajectory cells in the geological model based on the seed cell, the target cell and bifurcation cells determined in step d/; f/ for each current cells in the trajectory cells, f1/ determining conduits characteristics based on a predetermined conduit density distribution, a predetermined conduit aperture distribution and trajectory cells connected to said current cell; f2/ determining cell characteristics based on the conduits characteristics of said current cell; g/ determining a reservoir in said karstic region based on determined conduits characteristics and determined cell characteristics; h/ displaying a revised geological model of the subsoil with the reservoir based on the determined conduit characteristics and determined cell characteristics; and i/ drilling a well based on the display of the revised geological model.