Final answer:
The incorrect statement about the Po river valley is that it empties into the Red Sea; it actually flows into the Adriatic Sea.
Step-by-step explanation:
The statement about the Po river valley that is not true is "it empties into the Red Sea". The Po River actually flows from the west to the east across northern Italy, eventually emptying into the Adriatic Sea, part of the Mediterranean Sea. It is one of the most prominent rivers in Italy and is indeed densely populated along its banks. The Po River Valley is known for its fertile soils and as a significant agricultural area, rather than being flanked by deserts.