If you want to enter the research field then you should obtain a PhD since it will train your writing and communication skill as well. If you want to further study for your work then a master is already enough since its syllabus will cover the most updated information.
I m currently applying...
Is there any good website or online journal giving theory and real practice of the Water Quality Modelling. As I want to further study it but I don't have the engineering background. Thanks a lot.