Characteristics of long-term change in rainfall at Tsudaka Farm of Okayama University were analyzed with data during the 20 years, from 1979 to 1998. The typical results were as follows: (1) The average of annual rainfall was 1203 mm at average, 1726 mm at maximum, and 666 mm at minimum. (2) The decreasing rate of the annual rainfall was 5.37 mm/year. (3) Trend of rainfall intensity in each rainfall duration showed an increase of which rate were 0.005~0.256 mm/h/year, contrary to the annual trend. (4) Rainfall intensities in n-years probability were estimated using the maximum rainfall intensity for each rainfall duration.
Tsudaka Farm of Okayama University