Using seasonal trends superposition model,seasonal cycle-ARMA model odd combination,dynamic changes of Qitai Oasis groundwater was analyzed and forecasted,and adopted after test.the results show that the two time series models are suitable for the prediction of groundwater dynamics,a posteriori error ratio c and the frequency of small errors p were(0.22,0.99) and(0.21,1) respectively.However,after comparison of the overall combination the seasonal cycle-ARMA model has higher prediction accuracy.Application ...