Floods and Escapes

Cradock, the town at the centre of Karoo Plainsong, sits on the banks of the Great Fish River. Normally sluggish, the river does occasionally produce a devastating flood. This is what happened in the 1970s. I remember reading about it in the newspaper while I was at university in Grahamstown. So powerful were the flood waters that they ripped trees and vegetation from the banks and carried them downstream until they found an obstruction in the shape of the bridge that crosses the Great Fish at Cradock.

A thick mat of drowned foliage began to weave itself around the legs of the bridge, and against its sides, and finally choked the roadway itself. The bridge had in effect become a dam wall. Water started to build up behind it. The riverbanks upstream were overwhelmed and floodwaters began to seep into the town's streets. Many houses were washed away, many buildings had to be demolished. The floodwaters even claimed piles of papers and maps in the office of the town planners.

I heard about the loss of these papers when I visited Cradock a while ago. It turns out they weren't the only documents to be washed away...
It got me thinking that for some people, the floods might very well have been an ill wind. If police records were lost, then arrests might no longer be made. Prosections would not proceed. Court cases might have to be dropped. There were no electronic backups in those days, only carbon copies - which probably went the same, soggy way of the originals. Once a piece of paper was gone, the evidence was gone. The crime simply vanished.
In Karoo Plainsong, one of the characters needs a police record to disappear. Would the floodwaters reach high enough to sweep the most recent documents away?
The ones at the top of the pile?