Meanwhile, conditions have been so bad in the north of England that the army was drafted in to help cope after more than a month’s rain fell in 24 hours.
The fourth named storm of the season brought record rainfall to many areas, with Perthshire and the Borders being hit by around 140mm in 48 hours.
Flooding on the River Tay has been the worst seen in the past 12 years.
Provisional Met Office figures suggest 352mm fell in 24 hours in the Lake District – which would be a new British record.
Flooding and landslides caused chaos across Scotland, with homes having to be abandoned as rivers burst their banks in the Borders and Tayside.
Around 600 people were evacuated from households in the Borders town of Hawick, while a train bound for Glasgow was left stranded at Carlisle station with passengers having to sleep on board overnight.
There were no trains running between England and Scotland via Preston and many roads were also closed.
On the M90, teams were deployed to pump and clear flood water, while the A82 and M9 were also affected.
In Perth, the unconfirmed sighting of an otter in the city’s Mill Street underlined the severity of weather conditions throughout Perth and Kinross.
The Queen’s Bridge in Perth was closed last night as the River Tay was expected to reach its highest level for more than a decade.
Tayside firefighters had water pumps in action to tackle flooding in the Bridge of Earn area.
A caravan park was evacuated in Aviemore, next to the River Spey, but all residents were accounted for.
There were multiple diversions on roads throughout the country and high wind warnings on most bridges. Motorists in northern Stirlingshire faced a 46-mile diversion due to flooding at Lochearnhead.
Homes close to the River Esk in Langholm were also evacuated on Saturday night as water breached the bank.
Elsewhere in the Borders, Hawick Rugby Club’s grounds were also left under water.
Almost 20 properties in Blair Atholl were evacuated for a time on Saturday after the Garry Burn burst its banks.
Scottish ferry services were also on amber alert, with passengers warned that sailings from Oban, Mallaig and Uig to Barra, Harris, Skye, the Uists, Coll and Tiree could be disrupted or cancelled.
“This has been a particularly severe event, with multiple parts of Scotland feeling the impacts of flooding,” said Marc Becker, hydrology manager at the Scottish Environmental Protection Agency (Sepa). “This event has seen some of the highest river flows for a considerable time.
“The River Tay at Perth peaked at levels not seen since 2006 and the Teviot at Hawick was the second highest in 30 years. The Teith at Callander was the second-highest in 45 years.
“The team at Sepa are continuing to monitor the situation and watching river levels closely.”
Storm Desmond sparked three meetings of the Scottish Government’s resilience committee, which includes emergency services and transport operators.
“Over the last 24 hours Scotland has faced torrential rain and severe winds,” said Deputy First Minister John Swinney.
“Thankfully, it does appear the weather is now returning to normal, meaning the recovery phase is now under way. Experts will be at affected sites throughout the day, assessing damage and beginning repairs.
“However, although water levels are dropping, they remain very high and continued vigilance is needed. These water levels can in themselves be dangerous, so I continue to urge people to pay heed to road closures and weather warnings, as well as any local advice provided by police or the fire service.”
Although yesterday saw a respite from the rain and the sun even broke through in some areas, further downpours are expected today and for the rest of the week.
The Met Office has issued yellow ‘be aware’ warnings for southern Scotland and northern parts of England until Thursday.