What are river systems? Why are they so important to the earth?

River systems are systems takes water from the mountains, down to the ocean or sea. As you can see in this diagram the river's source of water is the mountain. The rain falls from the sky and the mountains are the first to catch the rain drops. The rain water runs down the mountain and joins a small river, then all the small rivers merge into the main river. After passing all the habited areas the river enters the wetlands. After, the main river splits again to tiny separate rivers. Finally, after the rivers long journey it comes to rest by entering the ocean.

River Systems