周期迭加预报是中长期水文预报的一种实用模型。针对该模型中用方差分析方法无法处理而舍弃的最终残余系列，提出了最终余波概念及相应的分析方法，实现了对最终余波的信息挖掘利用。应用结果表明，改进后的模型更好地利用了径流系列的信息，提高了预报的精度。

Period superposition forecasting model is a practical method in mid - to - long - term hydrological forecasting. According to the analysis and informative extraction of "the last remnant period" defined in the paper, this paper presents an improved model of period superposition forecasting. The feasibility and validity of the improved model are verified by the forecasted results in its practical application.