A computer-implemented method for determining a karstic region modified by karstification phenomena, comprising: a/ receiving a geological model (100, 300) of the karstic region comprising cells, said model comprising at least one first zone, named seed zone, comprising cells of the model and at least one second zone, named target zone, comprising cells of the model, each cells of the model having coordinates; b/ determining a first cell, named seed cell, in the cells of the at least one seed zone; c/ determining a second cell, named 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 third zone, named bifurcation zone, based on the coordinates of the seed cell, the coordinates of the target cell, a distance distribution, an angular distribution, d2/ determining a third cell, named 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 fourth cells, named 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 cell in the trajectory cells, f1/ determining, for the current cell, conduits characteristics based on a predetermined conduit density distribution, a predetermined conduit aperture distribution and trajectory cells connected to said current cell; f2/ determining, for the current cell, cell characteristics based on the conduits characteristics of said current cell. a/ receiving a geological model (100, 300) of the karstic region comprising cells, said model comprising at least one first zone, named seed zone, comprising cells of the model and at least one second zone, named target zone, comprising cells of the model, each cells of the model having coordinates; b/ determining a first cell, named seed cell, in the cells of the at least one seed zone; c/ determining a second cell, named 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 third zone, named bifurcation zone, based on the coordinates of the seed cell, the coordinates of the target cell, a distance distribution, an angular distribution, d2/ determining a third cell, named bifurcation cell in said bifurcation zone; d3/ re-iterating step d/ with a cell based on said bifurcation cell as the seed cell; d1/ determining a third zone, named bifurcation zone, based on the coordinates of the seed cell, the coordinates of the target cell, a distance distribution, an angular distribution, d2/ determining a third cell, named 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 fourth cells, named 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 cell in the trajectory cells, f1/ determining, for the current cell, conduits characteristics based on a predetermined conduit density distribution, a predetermined conduit aperture distribution and trajectory cells connected to said current cell; f2/ determining, for the current cell, cell characteristics based on the conduits characteristics of said current cell. f1/ determining, for the current cell, conduits characteristics based on a predetermined conduit density distribution, a predetermined conduit aperture distribution and trajectory cells connected to said current cell; f2/ determining, for the current cell, cell characteristics based on the conduits characteristics of said current cell.