India's longest river - the Ganges - has been left swollen by monsoon rains, which have killed at least 500 people.
Tens of thousands of people have also been left stranded in the mountainous region of the northern state of Uttrakhand.
More top news
Five people were killed and dozens more were injured after a car and knife attack in the capital on Wednesday afternoon.
Among those expected to attend the ceremony will be former US President Bill Clinton and ex-Northern Ireland first minister Peter Robinson.
Five people have been killed and 40 injured after a car and knife attack in London on Wednesday.