Research papersWavelet-cointegration prediction of irrigation water in the irrigation district

- Fluctuations of rainfall, irrigation water and ETc with multi-time scales are showed.
- Cointegration relations amongst the original and decomposed time series are revealed.
- We proposed the wavelet-cointegration prediction model of irrigation water.

Affected by various influencing factors, many time series analysis methods are used to predict irrigation water. However, it is often assumed to be stationary for the hydrologic time series which will result in an insignificant “spurious regression”. Actually, irrigation water is largely determined by rainfall and crop water requirement in the irrigation district. With the wavelet analysis method, the varying fluctuation characteristics of rainfall, irrigation water, and crop water requirement with multi-temporal scales are exhibited. The cointegration equilibrium relationship amongst their original time series and decomposed time series are also revealed by the cointegration theory. Combining the wavelet analysis method with the cointegration theory, the wavelet-cointegration prediction model of irrigation water is proposed. The results show that the model has the available prediction accuracy, and the relative errors of all predicted years are less than 5%, except 2004 and 2012.