Design of gutters and pipes for vertical discharges in roof stormwater drainage

The app returns the gutter dimension and the no. of vertical discharge pipes for draining a fixed flow-rate from a surface

Roof widthLc(m) 
Roof lengthHc(m) 
Roof slopeic(°) 
Projection roof surfaceS(m2) 
Rainfall intensityj(mm/h) 
Surface type  
Coefficiente Efflussoϕ( ) 
Rainfall Flow-rateQ(l/sec) 
Channel choice    
Channel typeBxH(cmxcm)
Suggested slopei(%) 
% Filling rateoh/H%(%) 
Ks m1/3 s-1 
Channel flow rateQgl/sec) 
Vertical pipe choice    
Pipe DNDNl/sec) 
Pipe flow-rateQd(mm) 
Number of pipesNd(mm) 
Distance between pipesLd(m)