Authorities hold grave fears for a farmer who was swept away by floodwaters in Victoria's west.

The 88-year-old man was driving near Hamilton, 300 km west of Melbourne, when his vehicle was swept into a dam on Wednesday evening.

Emergency Management Commissioner, Craig Lapsley, said State Emergency Services (SES) volunteers found the man's vehicle but no trace of the farmer.

"The road was covered with water and it appears the vehicle is now in the dam," Lapsley told media on Thursday.

"There's no sight of the person, the endeavors done by the police running into the night couldn't find him, and there's been every attempt to find where he might be in the district.

Parts of Victoria's west have been inundated by 100 mm of rain in the past three days, making it the most severe September deluge in 100 years for much of the region.

Daniel Andrews, premier of Victoria, said the floods had affected 18 local government areas in the state's west and forced the closure of 13 schools and 180 roads.

Andrews said that emergency services had rescued 17 people from floodwaters so far.

Andrews warned against entering floodwaters in a vehicle or by foot.

The rainfall triggered landslides along the iconic Great Ocean Road, which draws tens of thousands of tourists each year, with the SES warning that more landslides are likely.

"Further landslides may occur with current weather conditions, and the threat will remain once rain and showers have passed," an SES alert said.

Andrews announced that grants of up to 970 U.S. dollars were available immediately for residents forced to evacuate their homes with further rebuilding grants to be made available when the threat had passed.

Source : XINHUA