Streamflow measurements involves obtaining a continuous record of stage,

making periodic discharge measurements, establishing and maintaining a relationship between the stage and discharge, and applying the stage$-$discharge relationship to the stage record to obtain a continuous record of discharge. Explain the derivation and use of the stage$-$discharge approach in predicting streamflow. In your

explanation, also discuss two $(2)$ key parameters that affect the long term $(25$ years into the future$)$ streamflow prediction.