|Those with decreasing rainfall intensities|
could be Singing in the Rain, with lower
stresses on their buried municipal
Wang's Ph.D. thesis at the University of Guelph describes changes in frequent and extreme rainfall trends. The thesis is available here. Confidence limits on 2-year, 5-year, 10-year and 25-year rainfall intensities for durations of 5 minutes to 2 hours show no significant changes in most cases and decreasing rainfall intensities at many stations.