基于InfoWorks ICM模型的白龙江流域甘肃段水质模拟及分析

Water quality simulation and analysis in Gansu section of Bailong River Basin based on InfoWorks ICM model

针对白龙江沿岸农业种植、畜禽养殖等产业发展影响河流水质的问题,以甘肃省南部白龙江流域为研究对象,采用改进输出系数模型计算丰、平、枯水年等典型水文情景下流域内工业、农村生活垃圾、农村生活污水、畜禽养殖、城镇生活污水、城镇径流和农田径流等污染源污染负荷,基于InfoWorks ICM构建了白龙江水动力水质模型,模拟分析COD、TN、NH_(4)^(+)-N和TP等污染负荷分布特征,评估了最不利水文条件下白龙江水质污染风险,验证了该模型在流域水质污染模拟评估的适用性。研究结果表明,不同水文情景下污染物入河负荷主要来源存在显著差异,如丰水年和平水年农田径流是COD污染的主要来源,污染负荷分别达到1382.56、1058.98 t,而枯水年污染源主要是城镇径流。污染物负荷存在明显空间差异,研究区内子流域污染负荷空间分布不均匀,高污染负荷主要出现在中下游子流域。白龙江水质在汛期和非汛期差异较大,非汛期水质更差。通过模拟最不利水文情景(枯水年非汛期)发现,研究区内白龙江NH_(4)^(+)-N浓度最大位置出现在中下游,最高可达1.43 mg·L^(-1),且中下游TP浓度较高,最高值为0.35 mg·L^(-1),难以满足Ⅲ类水体水质要求,存在水污染风险。利用改进输出系数模型评估污染物负荷具有较好的可靠性,基于InfoWorks ICM构建的河流水动力水质模型在污染物时空分布评估适用性较强,为我国河流水质模拟和流域水环境治理提供示范参考和决策依据。

Aiming at the problems of river water quality affected by the development of agricultural planting,livestock and poultry breeding and other industries along Bailong River,the Bailong River basin in southern Gansu Province was taken as the research object.The improved output coefficient model was used to calculate the pollution load of industrial,rural domestic waste,rural domestic sewage,livestock and poultry breeding,urban domestic sewage,urban runoff and farmland runoff in the basin under typical hydrological scenarios such as abundant,flat and dry years.Based on InfoWorks ICM,the dynamic water quality model of the Bailong River was constructed.The distribution characteristics of COD,TN,NH_(4)^(+)-N,TP and other pollution loads were simulated and analyzed,and the risk of water pollution in the Bailong River under the most unfavorable hydrological conditions was assessed,and the applicability of the model in the simulation and assessment of water pollution in the basin was verified.The results showed that the main sources of pollutant load into the river were different under different hydrological scenarios.For example,farmland runoff was the main source of COD pollution in wet and normal years,and the pollution load reached 1382.56 t and 1058.98 t respectively,while the pollution source in dry years was mainly urban runoff.There were obvious spatial differences in pollutant loads,and the spatial distribution of pollution loads in sub-basins in the study area was not uniform,and high pollution loads mainly appeared in the middle and lower sub-basins.The water quality of Bailong River was different in flood season and non-flood season,and the water quality in non-flood season was worse.Through the simulation of the most unfavorable hydrological scenario(non-flood season in dry year),it was found that the maximum concentration of NH_(4)^(+)-N in the Bailong River in the study area appeared in the middle reaches,reaching up to 1.43 mg/L,while the TP concentration was higher in the middle and lower reaches,reaching the highest value of 0.35 mg/L,which was difficult to meet the water quality requirements of ClassⅢwater bodies,and there was a risk of water pollution.The improved output coefficient model had good reliability in the assessment of pollutant load,and the hydrodynamic water quality model based on InfoWorks ICM had strong applicability in the assessment of spatial and temporal distribution of pollutants,which provided demonstration reference and decision-making basis for river water quality simulation and watershed water environment management in China.