 Swales can be incorporated in urban designs along streets or parklands and add to the aesthetic character of an area.Typical swales are created with longitudinal slopes between 1% and 4% in order to maintain flow capacity without creating high velocities, potential erosion of the bioretention or swale surface and safety hazard.In steeper areas check banks along swales or dense vegetation can help to distribute flows evenly across swales and slow velocities.