Comprehensive weighted recognition method for hydrological abrupt change: With the runoff series of Jiajiu hydrological station in Lancang River as an example
Abrupt change is an important manifestation of hydrological process with dramatic variation in the context of global climate change,the accurate recognition of which has great significance to understand hydrological process changes and carry out the actual hydrological and water resources works. The traditional method is not reliable at both ends of the samples. The results of the methods are often inconsistent. In order to solve the problem,we proposed a comprehensive weighted recognition method for hydrological abrupt change based on weighting by comparing of 12 commonly used methods for testing change points. The reliability of the method was verified by Monte Carlo statistical test. The results showed that the efficiency of the 12 methods was influenced by the factors including coefficient of variation (Cv),deviation coefficient (Cs) before the change point,mean value difference coefficient,Cv difference coefficient and Cs difference coefficient,but with no significant relationship with the mean value of the sequence. Based on the performance of each method,the weight of each test method was given following the results from statistical test. The sliding rank sum test method and the sliding run test method had the highest weight,whereas the RS test method had the lowest weight. By this means,the change points with the largest comprehensive weight could be selected as the final result when the results of the different methods were inconsistent. This method was used to analyze the daily maximum sequence of Jiajiu station in the lower reaches of the Lancang River (1-day,3-day,5-day,7-day and 1-month). The results showed that each sequence had obvious jump variation in 2004,which was in agreement with the physical causes of hydrological process change and water conservancy construction. The rationality and reliability of the proposed method was verified.