Reasons:

1. The Amazon River is located in a tropical rainforest climate zone, with high temperatures and heavy rainfall throughout the year.

2. The river basin is large, reaching 6,915,000 square kilometers, accounting for 40% of the area of ​​South America, making it the river with the largest river basin in the world.

3. There are many tributaries, with more than 15,000 tributaries, and a large amount of water flowing into it.

4. The population and cities in the areas it flows through are sparse, and the amount of water used for industrial and agricultural production and life is small.