Say you have a problem – how can you plan what presents to get for this work if you do not know how many people will take part?

If you ask a child how many people will take part in this work very few will get it right first time. But if you ask all the school the numbers should group around the right number. And if you ask a very (very) large school one child might even get it right! Then you can get the presents!

Ensemble hydrological forecasting works the same way. The problem – ‘will the water go up or down during the day?’ or ‘will the water get in the houses?’. We do know know all the things that might take place during the day or how these things might work with each other so we must ask the program the same thing many times and look for the group of numbers that comes out most. This will be the most possible water state. But one of the numbers that only comes out a few times (or even only one time) might also be right. We must think about this when we tell people what to do.

]]>“Ensemble hydrological forecasting is…” the right form – as we know at this time – to show people in real-time how much or little we know about how much water will be there in some days. We run the systems many times to see which ways might be possible. More and more people under-stand, like and use it around the world. ]]>