Precipitation trends of major world cities with implications for sustainable water infrastructure management

To investigate whether the predictions of increased precipitation magnitude and longer periods of low precipitation are manifesting itself in precipitation records of major world cities, the moving average and moving standard deviations were analyzed for trends. If the moving average of precipitation is increasing in time, then it is assumed that rainfall is trending upwards. Similarly, for increasing drought periods, it is assumed that if the moving standard deviation is increasing over time, then drought is increasing. For the 50 highest-populated world cities, it was found that Dhaka, Bangladesh was the city that was affected most for both flooding and drought, Kinshasa Congo had the highest upward trend for flooding, Manila, Philippines had the highest upward trend for drought, and Chengdu, China had a decreasing trend for both flooding and drought. The results were the same even after adjusting for population size, except that Shenzhen, China had the fastest decreasing trend for drought. Some precipitation data sets exhibited a cyclical nature, perhaps due to the oscillation of the El Nino-Southern Oscillation and/or the Pacific Decadal Oscillation.