एक आयताकार चैनल में, चैनल के तल में स्थानीय उभार (hump) के कारण क्या होता है?

Which of the following equations signifies that 'the free surface of water is parallel to the bed of the channel'? (where dhdx is the rate of change of water depth along the channel)

_____ can be defined as 'the rise of water level, which takes place due to the transformation of unstable supercritical flow to stable subcritical flow'.