Dissipation
In Hydrology, dissipation is the process of converting mechanical energy of downward flowing water into thermal and acoustical energy. Various devices are designed in stream-beds (river-banks) to reduce the kinetic energy of flowing waters to reduce their erosive potential on banks and river bottoms. Very often these devices look like small waterfalls or cascades, where water flows vertically or over riprap to lose some of its kinetic force.