The archaeologist George F. Dales, who excavated at Mohenjo-daro in 1964, and hydrologist Robert L. Raikes propose a theory around the decline of the Indus civilization which involves large flooding and a back-up of the Indus for perhaps a century in ancient times. While not much evidence for this theory has since emerged, it does raise questions and point to the enormous importance of water, river behaviour and water storage during Indus times, a phenomena that we see of great import in most ancient Indus sites.
Above: Flood damage at Mohenjo-daro is evidenced by slumping brick masonry (center), which presumably reflects erosion of the city's unfired brick foundations during their prolonged immersion in lakw water. The Harappans simply leveled masonry and built on top of it.