The River Nith is just one of several rivers to have overflowed their banks
Warnings have been issued for the towns of Kelso and Coldstream as the level of the River Tweed continued to rise.
Experts from the Scottish Environment Protection Agency, (Sepa) said the river was expected to reach a peak at about 0300 GMT.
Floods hit towns across central and southern Scotland as heavy downpours and strong winds took hold.
A missing person thought to have fallen into a river near Falkirk was later accounted for, police said.
Ten severe flood warnings were issued for various rivers.
The most serious areas were on the River Earn, the Tweed, Ettrick, Yarrow and Teviot in the Borders, the Isla in Perthshire and the Nith in Dumfries and Galloway.
Earlier fears that people might have had to be evacuated from homes in Hawick after the Teviot burst its banks appeared to have subsided, but experts said they would continue to monitor the situation into Friday.
Major trunk roads, including the A9, M8 and M80 were also badly affected as were many minor roads across central and southern Scotland.
For much of the later part of Thursday, driving conditions were reported to be treacherous, because of surface water and flooding, with the main trunk roads connecting Glasgow, Stirling and Perth all badly affected.
The Whitesands area of Dumfries was closed.
Fire and rescue services were called out to the Moffat, Wamphray and New Galloway areas with reports of animals trapped by flood waters and vehicles stuck.
In Central Scotland parts of the A9 were closed between Plean and Torwood, resulting in East Plean Primary School being shut.
There was also localised flooding on roads in Strathclyde, Tayside and Perthshire.
The BBC Weather Centre warned some areas could see as much as a month's rain within 36 hours.
Flooding hit the Scottish Borders as the Teviot Water in Hawick overflowed
BBC forecaster Tomasz Schafernaker said he expected there to be a brief respite from the rain on Friday, but this would be followed by another spell of wet weather on Saturday.
He said the threat of flooding was not necessarily because of torrential rain but because the ground had become saturated from persistent, heavy downpours.
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