The methods of Kendall s and Spearman s rank verification were used to analyze the variation tendency of the annual runoffs of the Weihe river at Linjiacun gauging station,the Qianhe river at Qianyang gauging station and the Qingjiang river at Yimenzhen gauging station.

The paper studies the randomness, tendency and periodicity of precipitation in the Yellow River basin by analytical methods of multi time series based on the data of mean areal precipitation process of the whole river basin and 29 Grade III regions generated by the last 50-year monthly precipitation of more than 1,000 hydrometeorological stations suited in the basin and surrounding area.

Water resources have characteristics of tendency and persistence.

On the basis of the runoff data recently collected from mountain-pass stations in the Hexi area of Gansu Province, the statistic characteristics of runoff, including auto-correlation, long-term continuity, runoff variation in different decades, and statistic components (trend, period) are analyzed, and a predictive statistic model is established for the prediction of annual runoff.

Based on statistics of fire in China in the past years,the characteristics of developing trend and periodical fluctuation are found in fire regularity in China.

It is valuable to study fire regularity and trend.