Time series analysis of incoming water volumes to Mosul dam from Tigris river and use it for prediction

Data of monthly volumes of discharges reaching Mosul Dam reservoir for aperiod of (15) years, multiplied by (12) month and thus get a time series consisting of(180) value for monthly volumes of discharges are organized and collected for years( 1985 1999 ). A synthetic time series were obtained by applying multiplicativedecomposition of a time series method. Where normal method (which depends on thevalues of the two components (trend and seasonal) only) was applied on the historicaldata after conversion to the normal distribution , and the standard error (MAPE) of thismethod was (39%). For the purpose of improving the results were an amendment in thisresearch on this method by using the modified method in this research which adoptingthe values of components other than the series (cycles and random) and enter them inthe calculation the values of synthetic time series by multiplying their approximatevalues in the results of the values of synthetic time series extracted by the normalmethod above , in terms of improved the error measure value (MAPE) of the modifiedmethod to (32%).The results showed the effectiveness of the modified method used in thisresearch in the prediction of incoming water volumes for years ( 2000 2004 ), wheretests showed conformity (average, standard deviation, autocorrelation coefficient,density analysis) and there is a match between the predicted values with historicalvalues.