Magnitude of horizontal velocity

Hello everyone,

I got water velocity results from my EFDC model. I printed out the results as netcdf file using Export function in View 2D Plan of Grid & Data. The water velocity was expressed by three components such as VEL_X, VEL_Y, and VEL_Z. How to get the magnitude of horizontal water velocity? How to add two vectors?
Thank you for considering.


Vxy is SQRT (VEL_X^2 + VEL_Y^2)
Vxyz is SQRT (VEL_X^2 + VEL_Y^2 + VEL_Z^2)