Complex sentence: On November 2, water levels in the city reached 5.35m above the average low water mark, rising so quickly that people who went out with dry feet couldn't go home half an hour later.
Split into simpler sentences: On November 2, water levels in the city reached 5.35m above the average low water mark. The water rose so high that the people who went out with dry feet couldn't go home half an hour later.