$10\mathrm{.}3\mathrm{.}12$ Consider $2\mathrm{.}83\frac{m^3}{s}$ of water flowing down a rectangular channel measuring $3$ m wide. The normal depth is $0\mathrm{.}91$ m $.$ A $1\mathrm{.}22$ m diameter pier is located in the ehannel, Find the water depth as it flows past the pier. Assume frictionless flow.