Complex sentence: This helped avert disastrous floods in the region, by dropping 500 lb (227 kg) bombs and firing 5 in (127 mm) rockets at the ice, thus allowing the rivers to keep flowing and not get clogged up.
Split into simpler sentences: This helped avert disastrous floods in the region, dropping 500 lb (227 kg) bombs and firing 5 in (127 mm) rockets at the ice. This allowed the rivers to keep flowing and not get clogged up.