FLUCTUATIONS IN THE LOCAL FORMATION WATERS AND RUNOFF FORECASTING IN REGIONS OF THE NORTHWESTERN OF RUSSIA

Abstract

The time series of waters of local formation of federal subjects of theNorthwestern Federal Districtare analyzed by the method of the “Periodicities”. The periods with the length of 4, 8 and 11 years are repeated in these time series more often than the others. The most times (8 from 10) are revealed the sinusoids with the period of 11 years. The training forecasts of the local runoff are computed with the lead time of 5 years by the sinusoids with these periods, by the revealed sinusoids with periods larger than 29 years (long periods), and by the combination of sinusoids with the period of 11 years and long periods. The results of the training forecasts are tested by the new independent data. The best forecast results are achieved by the combination of the sinusoids with period of 11 years and with long periods. The scheme of prediction with the best forecast results engages the sine with the period, revealed in the most number of time series of runoff of local formation. This points out for the expedience of estimation of the repetitiveness of the same periods in the different time series under analysis, modelling and forecasting waters of local formation both in the administrative and physico-geographical regions, for example, basins of rivers and lakes. The forecasting results may be improved if some regularities of time lag of sinusoids with revealed periods to each other will be found and applied for calculations of the future runoff.