A better way to warn of flash floods

a flood tore through the Ahr valley, in north-west Germany. None of the towns upon which it visited death and destruction had had warning of how bad it would be. That warning should have been supplied by automatic flood-level gauges sited upstream, in the river itself. It would have permitted evacuation of houses in particular danger. But the gauges were destroyed by the torrent before they could supply meaningful information.Relying on instruments which are, by their very location, vulnerable to being swept away, is hardly an ideal approach to tracking impending floods. But Michael Dietze of , the German Research Centre for Geosciences, suggests an alternative. On May 26th he proposed to the annual meeting of the European Geosciences Union, in Vienna, that a network of seismometers of a sort more usually employed to record earthquakes might do the job.