The Research On Precision Evaluation Comprehensive Analysis And Optimization Method Of Mid-and-long Term Runoff Forecasting Model At The Three Gorges

Runoff forecast is a quantitative or qualitative prediction technique of flow, water level and other hydrological elements in the future based on the objective law of hydrology. The forecast result is a important reference to the flood and drought prevention, water resources distribution management, reservoir regulation, and shipping management overall planning, and therefore the research of mid-and-long term runoff forecasting has important social significance and economic value. The accuracy and reliability of forecast results is an important standard to measure the quality of forecast service. According to the accuracy, precision and reliability requirements of "The hydrological forecasting standard", adopt a scientific and reasonable accuracy evaluation scheme is an effective method for the standardization of hydrological forecasting service. As a result of the complication of runoff variation, existence of input data error, limitation of forecasting model system structure and parameters identification capacity, the accuracy of runoff forecast result is difficult to make a further improve. In order to improve rationality of runoff forecast model to enhance forecast accuracy, forecasting model optimization method should be used in forecasting field.The objects of the research are Mean generating function model,Auto-regressive model based on wavelet transform,Nearest neighbor bootstrap regressive model based on wavelet transform used as mid-and-long term runoff forecast models at the Three Gorges which were developed for the Three Gorges cascade dispatching center from my research team. The research designed a accuracy evaluation scheme for mid-and-long term runoff forecast model at the Three Gorges. And adopted a comprehensive evaluation method to analyze and evaluate the accuracy and reasonable of forecast models from different aspects based on the accuracy evaluation results. The forecasting model comprehensive evaluation method provided a theoretical basis for model selection. The study had analyze the sources of runoff forecasting error and several optimization methods such as correction model, combination model based on information entropy method. The experimental results of above methods can significantly improve the long-term runoff model forecasts accuracy. The research also discussed the applicability and effectiveness of the variable weight combination forecasting model and optimization method of combination model combined with calibration technology used in the Three Gorges mid-and-long term runoff forecast and reached a preliminary conclusion.Based on above,this paper established a systematic approach of evaluation and optimization of mid-and-long term runoff forecast model.In order to make the theory of the Three Gorges runoff forecast model accuracy evaluation scheme, comprehensive analysis method and optimization method can better serve the society production.The research designed and developed a model of runoff forecast accuracy evaluation and optimization software module, which would be an extended system of The Three Gorges Cascade Hydropower Station Joint Optimization Dispatching Decision Support System developed for the Three Gorges cascade dispatching center.The module integrated mid-and-long runoff forecast model accuracy evaluation sub-module, mid-and-long runoff forecast model calibration sub-module, mid-and-long combination model sub-module and mid-and-long runoff forecast model joint optimization sub-module.The software module applied mid-and-long runoff forecast model accuracy assessment, mid-and-long runoff forecast model correction technology, combination forecasting model and other optimization methods to improve the precision of prediction of mid-and-long runoff forecasting.