There is very likely a sizable cave that exists beneath the river bed, the entrance to which had heretofore been clogged by sediment, which has been washed away by recent rains. Could also be that a choke deep in the cave itself has been washed out, joining it to another cave, which provided enough throughput to drain the river entirely underground.
Sometimes this can be affected by human activities(such as mining, as has happened with aquifer withdrawals and phosphate mining in Central Florida and Clear Springs
After reading, it is true but indeed needlessly alarming. Changing underground water levels are influencing the rotation of the Earth, but it's mainly happening in India and East Europe, way far from the east of France.
"The researchers found the answer in Eurasia. "The bulk of the answer is a deficit of water in Eurasia: the Indian subcontinent and the Caspian Sea area," Adhikari said.
The finding was a surprise. This region has lost water mass due to depletion of aquifers and drought, but the loss is nowhere near as great as the change in the ice sheets.
So why did the smaller loss have such a strong effect? The researchers say it's because the spin axis is very sensitive to changes occurring around 45 degrees latitude, both north and south. "This is well explained in the theory of rotating objects," Adhikari explained. "That's why changes in the Indian subcontinent, for example, are so important.""
Well, allmost all the water that gets consumed by people still end up in the rivers afterwards ...
(Sinkholes occur when an already-significant underground cavity, typically formed by water dissolving the rock, gets close to the surface and the roof falls in.) https://en.wikipedia.org/wiki/Sinkhole
> geologists say the river disappearance is due to large cracks in the karstic riverbed, which empty the river underground like a siphon. It is perhaps the important spring floods that washed away the sediment patches that blocked the holes and fissures.