Real time terrain generation is a vital part in the development of realistic computer simulations and games. Dynamic terrain
generation influences the realism of simulation, because its participants have to adapt to the current environment conditions. Dynamically
generated primary terrain is transformed in order to reflect natural phenomena, such as thermal and water erosion, avalanches or glaciers. In
this article a possibility of primary terrain transformation with application of artificial neural networks is shown. The networks are trained by
evolutionary algorithms to solve a problem of a water erosion phenomenon. Obtained results show that application of such neural networks
to this problem can significantly reduce the processing time needed to perform the process of modeling the natural phenomena.