Chloe describes escaping from van in river

An eight-year-old girl has described how she unbuckled her seatbelt and escaped by going "up for air" after the van she was in plunged into a NSW river drowning her mother, sister and brother.

Chloe Kabealo was the sole survivor when the white van slid off a muddy road into the Tweed River at Tumbulgum in early April.

Her mother, 43-year-old Stephanie King, and siblings Ella Jane, 11, and Jacob, seven, tragically drowned.

"I unbuckled my seatbelt and I tried to go up for air and then I just kept floating up out of something and then I got out," Chloe told reporters on Sunday at a Tweed Heads fundraiser for the family.

"They were all loved and they will never be forgotten."

Chloe's father, Matt Kabealo, on Sunday said he was "shattered" but staying strong for his daughter.

The accident happened after the region had been hit by heavy rains that followed Cyclone Debbie.

It was the worst flooding in northern NSW in 40 years.