Mountains play a significant role in providing water and food supply to the millions of people in the world. ... Mountains offer 60-80 percent of the world's freshwater. According to UNO, almost one billion people live in mountain areas, and over half of the human population depends on mountains for water and nutrition.
A hilly area has lots of hills: The countryside round here is very hilly. ... The rather literary word undulating is also used to describe this type of landscape: This village is surrounded by forests.