Crystal River Cruising and low water levels

[USCAdventurer]

i will be taking my first crystal cruise on a rhine river cruise in november from basel to amsterdam.  i'm also new to this board and i wanted to ask and find out if anyone has experienced problems on their river cruises due to low water levels.  i've been reading about this issue.  i'm really looking forward to the river cruise sine i've never done one before and i think it will be a fabulous adventure!  i'm so positive about it, that even before i've take my first river cruise, i just booked a second crystal river cruise for december, 2020  which will be a danube christmas market cruise.  my first cruise will be on the crystal bach and the second will be on the crystal ravel, both are identical boats or ships or whatever you call them?