Effects of worn cutwater/throat in pump

[arm83]

Hi everyone,
I have been searching online for information about the effects of a worn cutwater/throat in pumps but have not been too sucessful. Can anyone help ?
Thanks alot.

 

[Enkidu]

as the throat area increases, the BEP of the pump moves further out, and the curve flattens.
It is pretty much direct - if the throat area increases by 10%, the pump BEP moves out 10% - at some point, the impeller will end up limiting.