The anomalous confinement in tokamaks could be explained by a model which takes explicitly into account the magnetic field line topology (equilibrium between islands and a stochastic region). It is shown how the properties of this topology affect the particle motion. This topology could be self-sustained by the difference of conductivity between the stochastic region and the islands, which depends on the temperature gradient. The resulting particle and heat flows are calculated by recurrence analysis between island chains. Finally, a preliminary comparison between the model and JET data is given: the peloidal mode number M associated to the perturbation should be between 10 and 20.