Simplify the following text for a Grade 5 native English-speaking person.
Original: The rain washed sand piles from the dumping grounds away to the rivers again and again and made some of the rivers shallower , especially into the Sakawa , into which huge volumes of ash fell , resulting in temporary dams .
Simplified: The rain washed away the sand piles from the dumping grounds and into the rivers again and again . This made some of the rivers shallower , especially the Sakawa .