A three-year-old girl and her Jack Russell dog have been found almost 24 hours after they wandered away from their home on a 368,000-hectare pastoral property in Western Australia's flood-affected Pilbara region.

Key points: Noreena Downs station was inundated with flooding rain from Cyclone Blake

Noreena Downs station was inundated with flooding rain from Cyclone Blake A major search, including three helicopters, was deployed to find Matilda

A major search, including three helicopters, was deployed to find Matilda Police described the search area as a "very challenging" environment

WA Police confirmed Matilda had been found safe and well about 3.5 kilometres south of the Noreena Downs Station homestead where she lives.

Authorities were seriously concerned for the girl's safety as the station, about 150km north of Newman, was recently inundated with rain from ex-Tropical Cyclone Blake, causing flooding and road closures.

The heavy rain filled a number of creeks surrounding the property and police described the environment in the area as "very challenging".

Toddler trapped by rising water

Pilbara police superintendent Kim Massam said he believed Matilda had become trapped by rising creek water.

"We think that Matilda had walked through a creek bed, which was close to her house [but] that creek rose due to heavy rains in the area, trapping Matilda on the other side of the creek from the homestead," he said.

"Her panicked parents did all they could. We had helicopters brought into the area, station people from around supported it, police, local SES, all of those support people.

Much of the Pilbara, including the vast Noreena Downs Station, has experienced heavy rain. ( Facebook )

"The information we have is that the station was inundated with water and there was only about 600 metres of clear land that was the search area, everything else was inundated with water, which really raised our concerns that Matilda had washed away."

Praise for girl and for dog

Superintendent Massam said everyone involved in the search was elated when Matilda was found.

"It's just an amazing feeling. I've had my team out there on the phone just elated, I could only imagine how excited the family was," he said.

Sorry, this audio has expired Meet Matilda, the three-year-old 'free spirit' from WA who survived 24 hours in the remote Pilbara

"Growing up on the station, I'm sure she's a free spirit and her backyard is probably millions of acres.

"It'd rained out there, the station was inundated with water and, you know, very fortunately she didn't succumb to some of those creeks that we were very concerned about."

Superintendent Massam says everyone involved in the search was ecstatic over the result. ( ABC News: Kendall O'Connor )

Superintendent Massam also praised the girl's pet dog.

"That little puppy stayed with her that whole time, alongside her through what was an unsheltered evening," he said.

"That little dog will be the toast of the station tonight."

WA Emergency Services Minister Fran Logan praised everyone involved in the search, including State Emergency Service volunteers from Newman who arrived first and searched through the night.

"It was a helicopter that spotted her, which was fantastic and they immediately went to where she was … and she was there, tired, probably cold after last night as well and the dog was with her.

Noreena Downs Station, a 368,000-hectare pastoral property in WA's Pilbara, is currently suffering heavy flooding. ( Facebook )

'It's a great story and really congratulations to everyone and I'm sure her parents must be overjoyed, she's fine, well and back at home."

Superintendent Massam said the support from industry was also amazing.

"We had helicopters donated by surrounding stations, industry, BHP, FMG. It was just an amazing push for resources to assist," he said.

The search came exactly one year after the nearby Pilbara town of Tom Price was rocked by the loss of mother-of-two Felicity Shadbolt after an extensive air and land search.