Why was the yarden flooded before Sodom was burnt?

ב"ה Shalom, In Parashat Lech Lecha, (Bereshit 13:10), it does not say that the Yarden was flooded. It states that the Jordan plain all the way to Tzoar had plenty of water. Interestingly though, the Malbim in his commentary on the Torah describes at length the geological aspects of the area based on the science known to him in his time. All the best