Simplify the following text for a Grade 4 native English-speaking person.
Original: The terrain is generally rugged , characterized by rounded hills , with altitudes up to 735 m. The climate is one of the driest of Indonesia with annual rainfall between 800mm and 1000mm .
Simplified: The climate is one of the driest of Indonesia . Each year between 800mm and 1000mm of rain falls in the park area .