基于水质水量耦合模型的湟水西宁市段生态流量计算及模拟分析

Ecological Flow Calculation and Simulation Analysis of Huangshui River in Xining Section Based on Water Quality and Water Quantity Coupling Model

考虑未来枯水期湟水生态流量、水质将面临不稳定达标风险,提出量化计算与数值模拟相结合的方法确定满足水质水量目标的湟水西宁市段生态流量。基于实测流量、断面、污染源等现状调查及分析,采用不同频率最枯月平均值法、改进年内同频率展布法、生态水力半径法3种方法计算了湟水西宁市段生态流量,并与Tennant法的计算结果进行合理性分析比较。利用MIKE11水动力和水质模块构建了水质水量耦合模型,利用率定后的模型,以COD、NH3-N作为主要污染物指标,通过模拟不同生态流量下泄过程,分析了3种计算方法对应的下泄方案对湟水西宁市段水质的影响,优选出合理的生态流量的下泄方案,得出了满足水质水量需求的湟水西宁市段生态流量,为湟水西宁市段的水生态保护及区域水资源配置方案提供理论支撑。

Considering that the ecological discharge and water quality of Huangshui River in low water period in the future will be faced with the risk of not meeting the standards,a method combining quantitative calculation and numerical simulation is put forward to determine the ecological discharge of Huangshui River in Xining Section meeting the target of water quality and quantity.Based on the survey and analysis of actual discharge,river section and pollution sources,the ecological discharge in Xining Section of Huangshui River is calculated by using three methods,including the average value of the last month with different frequencies,the improved annual distribution method with the same frequency and the ecological hydraulic radius method,and the rationality analysis and comparison are made with the calculation results of Tennant method.The coupling model of water quantity and water quality is built with MIKE11 hydrodynamic power and water quality module.Taking COD and NH3-N as the main pollutant indexes,the model after utilization rate is determined,and the influence of drainage schemes corresponding to three calculation methods on the water quality of Xining Section of Huangshui River is analyzed by simulating different ecological discharge processes,and a reasonable ecological discharge scheme is optimized.The ecological discharge of Huangshui River in Xining Section meeting the demand of water quality and quantity is obtained,which provides theoretical support for water ecological protection and regional water resources allocation scheme of Huangshui River in Xining Section.