For those who ere in Fallas Valencia in september 2021, there was a Dana in the area and in the fisrt day of fallas there was torrential rain and wind and several fallas were damaged.
That's what a normal Dana may cause, this is being more severe and it is lasting many days, moving along the east coast of Spain. This was so big that even touched inland and some rests reached even madrid in the night of the fatal events, it was a very big storm for a few minutes with very strong winds, it was scaring and it was just a rest of that Dana.
Dana is a new term, we always called it Gota Fría or Cold drop. It's not a new thing,every year we have one or two of these events and every few years one more severe may take place. You have torrential rains but locally very very strong rains, the problem this time is when the Dana didn't move, so instead of having floods of +100 l/m2 in a place, reached 500 l/m2 in a day, and this is what happened in the area in the west of Valencia. It almost didn't rain in the affected cities.
Seems that affected rivers were Magro river, affluent of Jucar River. I remember crossing that river by A3 highway in Requena when coming from Madrid, it is tiny with very little water, if any, that can hardly be called a river. The flood from this river was partially stopped by a dam but still affected Algemesi town mainly, not as bad as the other towns but still flooded with mud. Affected also Requena and Utiel where the heavy rains took place.
The other flood was in the dried river of Poio/Poyo, feed from the waters fallen in Chiva and Turis of +500 l/m2 in 24h. In some places raind in 24h more than it rained in the previous two years. That caused the flood, i would call it a tsunami. There were no dams to stop it. this ravine "barranco" has a capacity of 900m3/s
and this was recorded
until the water washed away the measurement systems
Turia river got + 2000 m3/s but the new riverbed is designed to deal with up to 5000 m3/s. The 1957 flooding of Valencia was over 3000m3/s that time the heavy rains hit the course of the Turia river directly.
For comparison, the Rhine River has an average volume of 2100 m3/s.