What is the length of all the rivers in Ireland combined?

Question: What is the length of all the rivers in Ireland combined?
- Keywords:
  country,
  Ireland,
  river
Asked by Tom the bomb to William on 7 Nov 2018.
- William answered on 7 Nov 2018:
  
  I know the longest river is the Shannon at 360km but i don’t know how long all of them would take

Question: What is the length of all the rivers in Ireland combined?