IIRC from an article about low levels on the Rhine or somewhere a few years back, one issue that creates is that it reduces the theoughput possible for cargo shipping on the river.

searches

Sounds like it’s an issue on the Rhine this year too.

https://www.reuters.com/business/environment/shipping-problems-continue-rhine-water-level-falls-again-2026-07-27/

Shipping problems continue as Rhine water level falls again

Shallow water after this summer’s heatwave and scarce rainfall means cargo vessels are only able to sail partly loaded on the river, increasing costs for cargo owners. It ​also means loads must be spread among several vessels sailing part ​loaded, also increasing costs and creating an unwelcome extra expense for German ⁠industry currently showing signs of recovery.

Vessels are ​often able to sail only 15% to 20% full or less, but sailings are continuing, ‌a ⁠commodity trader said.

I suppose that if it’s enough of an issue and shows up frequently, it might be possible to dredge a channel.