Analysis of the Change Features and Trend in Runoff Volume of the East River

Abstract

Based on the hydrologic data collected in Boluo Hydrologic Station of the East River in Guangdong Province for 57 years, this thesis applied three methods—moving average method, Spearman rank correlation analysis, and Mann-Kendall testing method—to analyze the change features and trend in runoff volume of the East River. All these three methods reflected that the runoff volume of the East River was in non-significant progressive increase during 57 years. The results of moving average analysis and Spearman rank correlation analysis were basically the same. Moving average analysis showed the average runoff volume in May, June, September and October was in significant decrease (P=0.05) while that in July, August, December and from January to April was in significant progressive increase (P=0.05). Spearman rank correlation analysis showed that the average runoff volume in December and from January to April was in significant progressive increase (P=0.05) while that in May and June was in significant decrease. Mann-Kendall test showed that the average runoff volume in the first quarter and the fourth quarter was in continuous progressive increase after 1959 and the increase trend reached a significant level after 1975 (P=0.05) while the average runoff volume was in alternative change law of non-significant progressive increase and non-significant decrease in the second quarter and the third quarter.