Characteristics of daily flow variation in the Yangtze River,1, optimum determination of delay time for reconstruction of a phase space

To explore the properties of daily flow variation in the Yangtze River and its prediction by using a new approach, the issue of chaotic properities of daily flow at Yichang station has been addressed systematically and fully Based on the obtained results, some new models have also been developed The findings from this comprehensive exploration are divided into several parts. This paper contains the first part, in which the stress is put on optimum determination of delay time The determination of delay time is very important for chaotic analysis.Two traditional methods(autocorrelation and real vector) are applied to this determination.In addition, a new method, named as general correlation function method, has been put forward.The results show that the general correlation function method is a reasonable and operational method for determination of delay time