[Observium] Alert based on a % Variation in BW on a port

Does anyone know if it is possible to set an alert based on a variation (up or down) in bandwidth (BW) from, say the average BW value over x mins/hrs.

Average is already computed by Observium as displayed on rrd based graphs. I think it would be a matter of tapping into these values somehow.

Currently it lloks like this can only be accomplished based on a port's "hard" BW rating (eg. 1Gbps port BW rate is 1Gbps).

This would be very useful to determine when there are variations in traffic BW that could be detrimental to performance of an application for example.

Thanks.