Ammianus Marcellinus Res Gestae 24.1.11

[11] On the following day another thing happened, this time a disaster. For a hurricane arose, which stirred up numerous whirlwinds and caused such general confusion, that many tents were rent asunder and numerous soldiers were prevented by the force of the gale from keeping a firm footing and were hurled to the ground on their faces or on their backs. On that same day another equally dangerous thing happened. For the river suddenly overflowed its banks and some grain-ships were sunk, since the sluices built of masonry, which served to hold in or let out the water used for irrigating the fields, were broken through; but whether this was a device of the enemy or was due to the weight of the waters could not be learned.