Q. Describe the Slope - Area Method?

In the event of infeasibility of Velocity Area method on account of either rapid rise or fall of floods or lack of equipment or any other reason, the Slope-Area method is adopted for rough estimation of discharge.

The requirements of site are mostly similar to those in case of Velocity-Area method. In addition, the length of the reach in Slope-Area method is required to be reasonably stable, free from obstruction, straight and of uniform section for a length not less than 5 times the width of the channel and in any case not less than 300 m. The surface drop in this reach is also required to be not less than 150 mm. The gauges are read to 2 mm and the slope is worked out from the average of gauge observations at either end of the reach.