利用DRAINMOD模型模拟银南灌区稻田排水过程

宁夏灌区大量的农田排水是目前造成黄河及其周边地表水域污染的原因之一。为了改善灌区水管理状况，该文利用美国农业部所推荐的田间水文模型——DRAINMOD，对宁夏银南灌区稻田排水过程进行了模拟研究。结果表明：模拟的农沟排水量与试验观测值极为接近，年平均排水量误差仅为0.4%；日地下水埋深预测值的Nash Sutcliffe效率系数达到了0.86；由于理论方法无法考虑田间水位的动态变化，按照平均田间水位计算的生长期内排水量超过实测值36%。这表明利用模型可以更详细地描述田间水文过程，并灵活地对灌区长期运行进行预测。

Rice fields drainage process simulation in Yinnan irrigation district with DRAINMOD model

The agricultural drainage in Ningxia irrigation district is a main contributor of non-point source pollution to the Yellow River and other surrounding water bodies. In order to improve water management situation, rice fields drainage process simulation in Yinnan irrigation districe was analyzed with DRAINMOD model recommended by USDA. Results show that the simulated drainage volume from the field ditch is extremely close to the observed value, and the relative error of annual drainage volume is only 0.4%; the Nash Sutcliffe's coefficient for daily water table is 0.86. The drainage volume from previous analytical approach was also analyzed, but the relative error was as high as 36%. The reason is that the daily water table fluctuation could not be considered with the analytical method, and using a single average water table resulted in over-estimation of the drainage. This study demonstrats that the model can describe the drainage process more precisely and evaluate the long-term behavior more flexibly.