Rail operator, First Great Western said:
We are still able to operate services between Oxford and Didcot Parkway, however we have had to reduce the number of services in operation and journey times will be extended, therefore an amended train service is in operation on this route.
Services between Bristol Parkway and Swindon. The line between Bristol Parkway and Swindon has also been affected by flooding. Services from Swindon will be diverted via an alternative route, which will mean extended journey times and services from South Wales will be subject to speed restrictions near Bristol Parkway.
More top news
A 24-year-old man has been arrested on suspicion of murder after the body washed up on the Thames shoreline.
Seven people have now been arrested after a man died from serious head injuries
The 38-year-old officer was on his way home from a night shift when he collapsed. His death is not being treated as suspicious.