$8$ A trapezoidal channel, $B=4\mathrm{.}5m,m=0\mathrm{.}5$ and $n=0\mathrm{.}020,$ has $S_0=0\mathrm{.}01.$ There is a break in grade to the horizontal at a section. The depth of flow at the junction is $3\mathrm{.}0$ m when the discharge is $30\mathrm{.}0\frac{m^3}{s}.$ Sketch the resulting water$-$surface profile on the sloping channel. Assume that a jump with sequent depth ratio of $1\mathrm{.}75$ takes place on the sloping channel.