农业非点源污染物在排水沟渠中的模拟与应用

Simulation and Application of the Agricultural Non-point Source Pollutants in Drainage Ditch

排水沟渠系统是农业非点源污染田间产污和外界受纳水体之间的过渡带.通过对排水沟渠系统不同级别排水沟渠间递推关系以及农田排水和非点源污染物在其中迁移转化过程的分析,应用水动力学基本方程和污染物迁移转化方程,构建了农田排水及其中非点源污染物在排水沟渠中的一维迁移模型,并对模型求解进行了探讨;在此基础上,以黄河上游青铜峡灌区第一排水沟沟渠系统为例,结合具体情况,通过对研究区初步概化,进行了模型示例运用.通过对模型计算结果的合理性分析,排水沟渠系统逐日排水量模拟结果与实测数据结合较好,Nash-Suttcliffe模拟效率系数达到0.82,其中典型污染物浓度过程也较为合理,表明所建农业非点源污染物排水沟渠模型具有较好的应用效果.

Drainage ditch system is the transitional zone between yield in the field and receiving waters for agricultural non-point source pollutants.Based on the brief analysis of the migration and transformation process of agricultural non-point source pollutants in drainage ditch system,the one-dimensional transport model of agricultural non-point source pollutants in drainage ditch system was constructed on the basis of the equation of continuity of flow and pollutants migration transform.Taking the Di Yi drainage ditch system,in the Qing-Tong-Xia irrigation district at the Yellow River upstream,as an example,combining with actual situation,the drainage discharge and concentration of nitrate nitrogen and total phosphorus were simulated by this model.The results show that the simulated drainage discharge accords with measured data approximately and Nash-Suttcliffe coefficient is 0.82,the simulated concentration of nitrate nitrogen and total phosphorus in farmland drainage was reasonable.