Is this a crossword question ? If so ... could be Hydrology or Hydrogeology ....if not post in Technology and Science.
If it is a crossword Q them you are better off to post in Quizzes and Puzzles.
Let's see - How It Works, Technology & Science (main section), Science, (sub-section) and now AB Suggestions.
How many more categories are you going to post your question in? And are we all going to get some of your illiterate abuse if we attempt to help you?