Forecasting The Medium And Long-term Water Consumption Of Zhen Xiong By Grey Forecast Method

Urban water consumption forecasting is an important task in water projectplanning, Scientific and reasonable to forecast the city’s medium and long term waterconsumption, relates to the urban water resources long-term planning and management,it is also able to guide the development and utilization of urban water,the investment,constrcture in water infrastructure and the macro decision. To deal with thecontradiction between supply and demand of future urban water and guide the operationof the city’s water supply system, Urban water consumption forecasting has animportant significance.The key to make a reasonable water consumption forecast lies in choosingscientific and reasonable forecast method,in combination with Actual situation of theengineering practice and the urban characteristics. Based on the " special planning ofwater supply engineering of Zhen Xiong town (2009~2020)", This paper haveanalyzed the adverse factors in forecasting the medium and long term waterconsumption of Zhen Xiong town, discussed the suitable water consumption forecastmethod for Zhen Xiong town, the conclusions are as follows:1) In the adverse situation of shortage of historical water consumption data andlacking of related information material,we have made the choice among threeforecasting methods, the traditional water consumption index method、regressiveanalyze method and gray-forecasting method,which are all suitable for forecasting themedium and long-term water consumption.The results show that Grey forecasting method can use less original informationdata to build forecasting model, it also need not to consider distribution and changetrend of the original data, it is effective to solve the existing adverse factor in themedium and long-term water consumption prediction of Zhen Xiong town, such as lackof related information,shortage of historic water consumption data and so on.Therefore,gray forecast method is more suitable for forecasting the medium andlong-term water consumption of Zhen Xiong town.2) Combining historical consumption data of Zhen Xiong town with grey systemmodeling theory, the basic grey GM (1,1) model is established, the basic grey gray GM(1,1) model were carried out post-error exzamnation, the result shows thatposterior-variance-ratio C=0.054<0.35, small error probability P=1>0.95. Checked the grade table of model prediction accuracy, the results show that the accuracy ofprediction is good, the model can be used to predicte Zhen Xiong town waterconsumption.3) Residual Modification is applied in improving the basic GM (1,1) model, theresult show that posterior-variance-ratio C=0.05<0.054, small error probability P=1>0.95，the residual modified GM (1,1) model further improves the prediction precision.4) The basic gray GM (1,1) model does not consider the future disturbance’sinfluence on the system, according to this shortcoming,the article builds the newinformation replacement GM (1,1) model,the improved GM (1,1)mode fully considersthe future disturbance’s influence on the system, solving the defects of the basic grayGM (1,1) model.5) Combined with the prediction results of basic gray GM (1,1) model、 theresidual modified GM (1,1) model and new information replacement GM (1,1) model,the medium-term (to2015) water consumption of Zhen Xiong town is5.17~5.20million tons, long-term (to2020) water consumption is5.75~5.80million tons, thefuture water consumption will grow with a slow rate.