پیش بینی تقاضای آب توسط روند و تجزیه و تحلیل هارمونیک

Water demand forecasting in water supply systems is one of the basic strategic management tasks of water supplying companies. This is done using specially designed water consumption models which generate data necessary for planning operational activities. A high number of water demand forecasting methods proposed in the literature points to the complexity and significance of the problem for current operation of water supplying companies. However, it must be observed that no universal method applicable to any water supply system has been developed so far. In addition to this, there is no method which could be considered referential relative to other methods. For this reason, it is necessary to continue the research on forecasting methods enabling effective forecasts based on suitably selected sets of input quantities. This paper proposes a solution for water consumption forecasting in a water supply system, wherein hourly water consumption is determined by trend analysis and harmonic analysis. Trend analysis consists in estimating parameters of models for individual phases of a cycle, while harmonic analysis is based on the assumption that a time series consists of sine and cosine waves with different frequencies known as harmonics. In addition, relationships between structural parameters of individuals harmonics and ambient temperature are investigated using the least squares method.