基于ANN技术的大型灌区节水改造后农田水环境预测

Prediction of farmland water environment after reconstruction of water-saving in the large-scale irrigation district based on the ANN technology

为了研究大型灌区节水改造后区域农田水环境的变化及可能引起的环境负效应,该文以中国黄河河套灌区为案例,通过区域水盐动态的监测和多年水文、地下水资料的分析,以三个不同尺度下的试验区为研究对象,用人工神经网络技术中的BP、RBF模型对农田地下水文和土壤水盐变化进行了系统预测,求得中国内蒙古河套灌区在未来不同节水水平下灌区地下水文、土壤水盐的变化趋势,并与传统的有限元数值法和水均衡法的结果进行了对比,得出的预测结果具有一定的合理性和一致性。说明人工神经网络技术在进行复杂系统的模拟预测中显示突出的优势,可获得较好预测效果,适合未来因子变化的区域趋势估计,提出了在气候干旱、土壤盐渍化灌区的科学引水量应存在一个适度的环境安全阀值,可以为大型灌区节水改造提供宏观管理决策依据。

In order to investigate the change of regional farmland water environment and its possible negative effect caused by reconstruction of water-saving in the large-scale irrigation district, the Hetao irrigation district of Inner Mongolia in the Yellow River valley for a study case was selected. Through the monitoring data of regional water and salt movement and analysis of data of many years＇ hydrology and groundwater in the three different scale research areas, the ANN technology （BP model and RBF model） was applied for prediction of farmland groundwater hydrology and soil water and salt movement in the three different scale research areas. Then, the movement trend of groundwater hydrology and soil water and salt contents were predicted in the Hetao Irrigation District in future different water-saving level years. Furthermore, the results of ANN model were compared with those of finite element method and hydrological budget method. As a result, the predicted results were rational and accordant. At the same time, the ANN method showed more advantage comparing with traditional method. This indicates that the ANN technology expresses prominent advantage in the prediction for the complicated system and can obtain better results. SO, the ANN is suitable for regional trend estimation in the future when the influence factors are changed. Furthermore, this paper brings forward a moderate environment safety threshold about water-saving of irrigation district in the arid and soil salinization irrigation areas. This can provide instructions for macro-management and decision of reconstruction of water-saving project in the large-scale irrigation district.