Kiniro Mosaic , APplanet . comanimekiniromosaic , mosaic , , TV Status Finished Airing Episodes 12 Genres Comedy , Slice of Life , manga , LN truetitletext Pouty Smug <| sep |> I ' ll attempt to answer the question more from an engineering point of view than an historical one , and see what conclusion we reach . First thing first As with a lot of other info in Wikipedia the 171 k number seems vastly overinflated and comes from a new yorker article , every academic paper i have found on the subject moves in the 2585 k range . The event consisted not only on the failure of the Banqiao dam that being the largest but on the failure of other 61 dams , from large like Banqiao and Shimandan to 58 small dam failures . The average annual rainfall of the region is about 1000 mm per year , but during the storm there was a single day rainfall of 1060 mm , and during the next 5 days the accumulated rainfall was 1600 mm . This amount of rain is consistent with a 1 in 10 , 000 year flood statistically we expect it to happen once every 10 , 000 years and the Banqiao dam was designed with a 1 in 1 , 000 year flood in mind , the rainfall greatly exceeding this amount . Other dams were designed with even smaller floods in mind , the Shimadan dam had a 1 in 500 year flood design and most of the small dams were designed for a 1 in 50 or 1 in 100 flood . From the engineering point of view , so far , we can say that mother nature was the cause since the design periods seem acceptable for the magnitude of the dam . However , negligence took a part on the failure . After the fact it was found that the Banqiao dam had an overstorage of 32 million m 3 before flood season , in a region where most rains come during this period this is reckless and limited the capacity of the dam for flood control . It was also found that poor maintenance of the sluice gate greatly diminished their capacity since they were filled with slit , so soon it reached a point that more water came into the reserve that could get out . In conclusion , even in the best case scenario with no human negligence the chances of the dam failing were quite high , since the rain greatly exceeded what anyone expected , however the fact that negligence DID happen only increased the chances of this failure . Lack of contingency plans made the number of lives lost much higher than it should be , the authorities had several days to issue evacuation plans to all the zones that were at risk , but there was no plan in place for this warnings . A lack of understanding of the authorities on the chances of the Banqiao dam failing it was tough as an indestructible dam made them have a false sense of security and concentrate on other troubled areas while ignoring the most critical one , no one expected the Banqiao dam to fail . Sources The World ' s most catastrophic dam failures . Si Yi . Lessons from Catastrophic Dam Failures in August 1975 in Zhumadian , China Yao Xu et al .