Terrain morphology has been on the radar of Computer Graphics for more than twenty years and various techniques have been presented. These algorithms range from fractal and multifractal surface generation, to physically-based models of erosion and weathering. From all the weathering phenomena that can be observed in Nature, the hydraulic erosion has the major visual importance. This presentation will focus on description of various erosion methods as introduced in Computer Graphics. Hydraulic erosion algorithms will be described in details as well as their implementation on the CPU and the GPU. The simulations show the terrain morphogenesis and can be used for animations as well as for static scene models generation.