Question

why do water waves die out after some time

Answer 1

Sound waves, unlike electromagnetic waves, expend energy as they move. This is because sound is a pressure wave. It take real work, in the physics sense of work, to compress gas, or a solid, or a liquid, all three of which can conduct sound. Work requires energy and over time the energy is squeezed out of the wave and compression no longer occurs.

Answer 2

Because of very high temperature and change in season cycle. And most importantly the water present in rever is decreasing day by day