In a river segment, modeled as a gradually varied flow in a rectangular channel, the bottom width is $5$ m$.$ The river carries a discharge of $20$ m$^3/$sec$.$ The depth at the upstream section $($Section A$)$ is $2\mathrm{.}0$ meters, and it reduces to $1\mathrm{.}5$ meters at a downstream section $($Section B$).$ Calculate the average energy slope between these two sections. For your calculations, assume a Manning$$s coefficient $($n$)$ of $0\mathrm{.}016.$