- Tokyo Geographical Society
- Journal of Geography (Chigaku Zasshi) (ISSN:0022135X)
- vol.113, no.4, pp.512-523, 2004-08-25 (Released:2009-11-12)
This paper analyzes the characteristics of daily precipitation during the monsoon season from June to September for 21 years from 1976 to 1996 in Nepal, which is situated in the southern Himalaya. The average monsoon precipitation, and the number of rainy days in Nepal are 1, 410 mm, and 73 days, respectively. On the basis of the total monsoon precipitationand the number of rainy days, 1978, 1984, and 1985 are classified as wet years, and 1977, 1979, and 1992 are classified as dry years. Nepal is divided into six regions on the basis of the statistical characteristics of total monsoon precipitation and number of rainy days.On the other hand, the distribution pattern of 5-year probable rainfall in Nepal, is considerably different from that of average monsoon precipitation. Five-year probable rainfall is small in northern Nepal, and becomes large toward the south. On the basis of 5-year probable rainfall, which is regarded to be the threshold value of heavy rainfall in Nepal, heavy rainfall occurred more frequently in 1981 and 1987. These years did not agree with the wet years based on total precipitation and number of rainy days, indicating that the occurrence of heavy rainfall that causes water hazards in Nepal does not synchronize with wet years.