Thanks mate

no it should not affect the valve but might deadhead the pump .. Hope that answers your question..

Will there be any afflux of water due to placing of rectangular notch as it reduces original cross sectional area of flow

If you switch on the pump without opening the valve then according to me the force of water can damage the valve......Does it damages or not? Please correct me...

would be thankful if you can put the video of inclined rectangular weir .....

Encontré este video tal vez les pueda servir kzfaq.info/get/bejne/b894i5Veqc6nkXk.html