A concrete and soil rectangular channel with a width that is wide compared to the water depth is flowing at a rate of $0\mathrm{.}7$ m$3/$s per unit width. Find the limiting water depth and the equal$-$flow depth for cases where the slope of the channel is $1/100,1/200,1/300,$ and $1/400,$ and examine whether the flow is upstream or crossing for each case. Here, the kinetic energy correction factor is $1\mathrm{.}1,$ and Manning's roughness coefficients for the concrete and soil channels are $0\mathrm{.}015$ and $0\mathrm{.}025,$ respectively.