Answer:
Adding more tributaries into river can change the physical characteristics of the river. 
 Explanation:
Tributary is the freshwater stream that falls into mainstream or river. 
- It is usually made up of cold water as a result of snowmelt. When many tributaries enter into a river, they can change the temperature of the river water instantly. 
- Each tributary brings sediments of its own area so when these enter into a river, they make water nutrient-rich. 
- Adding more tributaries can also impact mainstream discharge.