"When you see me, weep"

This is the message that was revealed in a rock in the River Elbe during the dry summer of 2018. It's a famine stone: messages have been carved into river stones in years of famine. That is, a kind of hydrological record of the past and a warning message from the people of that time. The oldest still legible engraving on the Elbe dates back to 1616.

I remember the message as I impatiently wait for the rains and look at the water level statistics of the Ounas River: the water level of the Ounas River is at a record low for the 2000s (Ketomella measuring point). As far as I know, no starvation stones have appeared in the river and food here nowadays is mostly brought in from elsewhere, but the sad message makes me wonder what the starvation stone height of the Ounas River would be. How much water is needed to sustain life in the area?

You can follow the water level from this link: https://wwwi2.ymparisto.fi/i2/65/