| Based on the data of Heihe River's annual maximum flood peak,precipitation and temperature in upper and middle side of Heihe,using linear tendency estimation,power spectrum,slip t-examine,Cramer's and relevant statistics,Heihe River's annual maximum flood peak flow,its appear time characteristic,and causes were analyzed.The result shows that the time evolution of annual maximum flood peak flow of Heihe is not stable,its sudden change year is in 1983.The change is in accordance with the temperature change of Heihe upper reach.The appearing time of annual maximum flood peak flow is postponed before the sudden change,and obviously ahead after the sudden change.The relation of the appearing time of Heihe's annual maximum flood peak and climate warming is close.Along with global climate warming,Heihe's annual maximum flood peak tends to appear ahead.The time evolution of Heihe's annual maximum flood peak flow is characterized by undulation with about a 3 years and 11 years period,its sudden change is around 1973.The maximum flood peak flow is correlated with the precipitation of Heihe's upside 3 days before flood peak appearing.The development tendency of annual maximum flood peak and annual average flow is similar. |