回归支持向量机集成模型在年径流预测中的应用

为进一步提高径流预测精度和泛化能力,根据回归支持向量机(SVR)特性及基本原理,提出考虑不同影响因子(输入向量)的SVR集成预测模型,以云南省南盘江西桥站1961—2007年径流预测为例进行实例研究。首先,利用相关分析法选取年径流预测的若干影响因子,依次构建不同影响因子的SVR单一模型对研究实例进行预测,并构建对应的RBF模型作为对比预测模型;然后,采用加权平均和简单平均2种方法对具有较好预测精度和互补性的单一模型的预测结果进行综合集成。结果表明基于SVR的加权平均和简单平均2种集成模型径流预测的平均相对误差绝对值分别为1.27%和1.54%,最大相对误差绝对值分别为2.99%和2.74%,其精度和泛化能力均大幅优于各单一模型以及基于RBF的加权平均和简单平均集成模型,表明加权平均SVR和简单平均SVR集成模型具有较高的预测精度和泛化能力。相对而言,加权平均集成模型赋予了预测效果好的模型更大的权重,预测精度和泛化能力均优于简单平均集成模型。预测模型和方法可为相关预测研究提供参考和借鉴。

Application of SVR Ensemble Model to Annual Runoff Forecasting

An ensemble model involving different impact factors (input vectors)based on support vector regression (SVR)is put forward to improve runoff prediction accuracy and generalization ability.The runoff at Nanpanjiang west bridge station in Yunnan from 1961 to 2007 is taken as a case study.First,a number of impact factors for annual run-off forecast are selected to build different models for the study of a single instance of SVR,and the corresponding RBF models are built as a comparison.In subsequence,the results of single models (which are accurate and comple-mentary)are integrated by using weighted average and simple average respectively.Results showed that:the average relative absolute error of weighted average and simple average ensemble model based on SVR was respectively 1.27%and 1.54%,and the maximum relative absolute error is 2.99% and 2.74%.The accuracy and generalization capa-bilities are significantly superior to the single models as well as the weighted average and simple average ensemble model based on RBF models.The weighted average ensemble model based on SVR has better accuracy and generali-zation capability than simple average because it gives more weight to the models with good prediction result.