Question on open channel flows

[kcmei]

1. The problem statement, all variables and given/known data
Flow in an open channel is shown in Figure 1. The flow in the channel is 2.6m^3/s /m the bed slope is 1/1250 and Manning's n is 0.02. The gate opening is 0.5m.

a) calculate the normal and critical depths for the flow in the channel

b) calculate M2 and M3 surface profiles that occur in the channel

c) determine the position of the hydraulic jump

d) how might the channel be modified to stabilise the position of the hydraulic jump for different discharges.

http://img138.imageshack.us/img138/4764/imgp0331ec8.th.jpg (http://img138.imageshack.us/my.php?image=imgp0331ec8.jpg)

3. The attempt at a solution

I have tried the first part but am not sure if its correct:

http://img247.imageshack.us/img247/4679/imgp0333xs9.th.jpg (http://img247.imageshack.us/my.php?image=imgp0333xs9.jpg)

I know this is my first post but I have tried for some time on this question now, please could anyone kindly give me a hand :)