Abstract
The possible trends and quasi-periodic variations in temperature and hydrologic time series are investigated by using both parametric and nonparametric statistical tests. Long term trends in both temperature and hydrologic time series are detected. The quasi-periodic variations in annual maximum hydrologic data of the Shinano River are found to have the periods of 3.3, 6~7, and 17~19 years. The variation with a period of 17~19 years corresponds with bidecadal variations of ocean and climate in the North Pacific Ocean. Non-stationary hydrologic extreme analysis was made to study extreme values and return periods of annual maximum precipitation. The 50- 100- 200- and 300-year return values estimated from MLM are found to increase by 40~50 mm per 100 years.
