1 Human activities may be varied by the addition of freshwater because it can determine/vary what food, crops, and sea animals that come into the area. Additionally, it has determined when civilizations have thrived and begun or unfortunately fail and in extreme measures go extinct.
2 Practices that can help us as human beings include showers, drinking water, washing hands, etc. When we use some of these examples they help us keep clean and live life with a low risk of sickness.