A mother who killed three of her children after driving her four-wheel-drive into a lake in Melbourne’s outer south-west has had her sentence reduced by eight-and-a-half years on appeal.

Akon Guode was sentenced to 26 years and six months’ jail last year after pleading guilty to the murders of four-year-old twins Hanger and Madit, and the infanticide of 17-month-old Bol.

The three children, along with their sister five-year-old sister Alual, were in the car when Guode drove into a suburban lake at Wyndham Vale in April 2015.

She also pleaded guilty to the attempted murder of Alual, who survived after she was pulled from the water.

But the Court of Appeal today downgraded the sentence to 18 years’ jail.

Guode will now serve a minimum 14 years’ jail before she is eligible for parole.

Rescuers heading towards Alon Guode’s car. Photo: Supreme Court of Victoria

The Victorian Supreme Court previously heard Guode had suffered severe psychological trauma from the civil war in South Sudan, after watching her husband being murdered.

In sentencing her at the time, Justice Lex Lasry said Guode had had an “extraordinarily difficult life” but the reason she drove her children into the lake remained unclear.

He said the case had tested “the sympathy and compassion of the community”.

“In my opinion, your actions were the product of extreme desperation, rather than any form of vengeance,” he said.

The Court of Appeal said it accepted the balance of Guode’s mind was “disturbed” after she gave birth to her youngest child, but the sentence was excessive.

“Having particular regard to the fact that the balance of her mind was disturbed when she committed the offences … the Court of Appeal accepted that the sentence imposed by the sentencing judge was manifestly excessive,” it said.

The Supreme Court was told Guode had to make three deliberate turns of her steering wheel to navigate through the only open access point towards the lake.

One witness described seeing the four-wheel-drive going “full bolt into the water”.

Several people ran down to try to rescue those inside and observed Guode standing nearby the driver’s door “not saying or doing anything”.

One witness smashed the rear window of the car and freed the submerged baby Bol from his child seat.

But Bol, along with Hanger and Madit, could not be revived.

During sentencing last year, Guode became inconsolable as the judge relayed the details of her life.

-ABC