In general, the velocity of a wave does not change upon reflection. This principle holds true for both sound waves and water waves.
When a wave encounters a boundary or obstacle, such as a reflective surface, a portion of the wave energy is reflected back into the medium from which it came. The reflected wave travels in the opposite direction of the incident wave. However, the velocity of the wave remains the same before and after reflection.
In the case of sound waves, their velocity depends on the properties of the medium through which they propagate. For example, in air, sound travels at a certain speed. When a sound wave reflects off a surface, it will still travel at the same speed in the air.
Similarly, water waves also exhibit this behavior. The velocity of water waves depends on the depth of the water and other factors. When a water wave reflects off a surface, such as a wall or a shoreline, its velocity remains unchanged as it continues to propagate through the water.
It's worth noting that although the velocity remains the same, other characteristics of the wave, such as its direction and amplitude, may be affected by reflection.