QGIS – Extract Single Contour from DTM Data

Question

I understand that Contour data can be extracted at particular intervals fairly easily, but have been recently mapping a number of Flood Water Design levels which are denoted to the nearest 0.001m.
It is quite time and computationally hungry to generate all these contours, only to then delete pretty much all of them out to get the particular level contours I am looking for.

Is there a way, in QGIS, of generating only a single (or single elevation if not continuous) contour at a specified value from .tif based Lidar DTM data?

Answer 1

You can use r.contour:

Produces a vector map of specified contours from a raster map.