1. The problem statement, all variables and given/known data A rectangular channel has a width of 2 meters, and an slope of 1:80. The Manning's number for the entire channel is n = 0,014. In this situation the depth is y= 1,50m. The flow of water is normal. Further down the slope decreases to 1:150 and the width increases to b=3 meters. The waterflow Q and the MAnning's number is the same as in the situation above. Find the depth of water, y. 2. Relevant equations Hydraulic radius R = A/P Manning formula for gravity flow: Q= 1/n*A*R*S0^1/2 Froude number U/(√(g*y)) 3. The attempt at a solution I have the water flow Q= 17,04m^3/s from before. Since I also have Manning's number, width and slope, I'm thinking Manning's formula for gravity flow. However, not having the new depth prevents me from calculating the hydraulic radius - which is a part of Manning's formula so it would end up looking like this: 17,04= 1/0,014*(3*y)*?^(2/3)*(1/150)^(1/2). (? being the place where the number for hydraulic radius would go). So I'm kind of stuck at this point. Any suggestions would be appreciated.