Consider a channel of rectangular cross-section with a constant width of 5 ft. A steady dis- charge of 10 cfs flows in the channel. At the inlet of the channel, the invert of the channel is at a constant elevation, but then due to the sill the invert elevation gradually increases by a total of za = 0.45 ft, remains constant for a distance, but then eventually gradually decreases until the invert is at an elevation, zb = 0.3 ft below the inlet invert elevation (see figure). The depth at the inlet is y1= 1.2 ft. In the following, head losses may be considered everywhere negligible and the flow is gradually varied everywhere. A. Determine the flow regime of the upstream inlet section, i.e., whether the upstream flow is subcritical or supercritical (or possibly critical) using two different approaches: i. compute the critical depth at the inlet section, and compare the upstream (inlet) depth to the critical depth at that section, and ii. compute the Froude number at the upstream (inlet) section, and infer from this value the flow regime