water resource or geotechnical?

I am looking at taking a masters either in water resource, geotechnical or environmental engineering. or master of science in water security with a hydrology or hydrogeology focus. I am having such a hard time deciding. my undergrad is in petroleum so i’ve learned about how fluids flow underground and interact with the rock pores. other than that I haven’t really taken a specific course in any of the above, but i want to work with water or soil, not anything mechanical. what are the job prospects for them?