i am a student of computer science engineering.i want to do masters in environmental engineering.i am having some questions regarding that:
1)whether a computer science student is eligible for masters in environmental engineering?
2)what are the job opportunities in environmental engineering?
3)which country is better to this course?

1) I think the 2 subjects are completely unrelated I'm afraid... computer science would be of no real relevance. You would need a first degree in civil engineering, environmental science, geology etc.

2) They WERE fairly good, at least until last september, but now opportunities in environmental/civils are quite scarce. (In the UK that is)

3) Plenty of good places to study this in the UK. I dont know about elsewhere.