In simple words it can be defined as a vertical drop of the stream over a horizontal line and in a more complex manner it can be understood to be the slope of the stream’s channel or rise over run. In order to find the gradient we need to see the vertical difference divided by the given horizontal distance. So if we know two points for eg. “a” and “b” , by connecting it and knowing the difference in elevation between A and B we can calculate the average gradient along the given stream.