| As an important branch of Liaohe River system,Hunhe River Basin flows through two important industrial cities,Shenyang and Fushun.With the rapid development of society and economy on both sides,especially the rapid urbanization of Shenfu new town,the original natural river of Hunhe River in Shenfu section is gradually transformed into the river in the city,which leads to the serious deterioration of water ecological environment,and the local water quality of the main stream cannot reach the standard stably In the dry season,the water quality is even worse.This paper focuses on the analysis of the current situation of water pollution in the upper reaches of Shenfu section of Hunhe River and Changqing bridge from Pingqiao to the lower reaches,and further reveals the temporal and spatial variation law of water quality.It can be seen that the pollution in the main stream of Shenfu section of Hunhe River is relatively serious in the dry season,which is basically class V water,the water quality in the main stream in the wet season is basically class IV water,and the water quality in the discharge outlet of tributaries is inferior class V water throughout the year.In order to ensure that the water quality of the basin is stable and up to the standard all year round,the water quality of each section of the main stream is controlled within class IV water,the factors affecting the water quality of Shenfu section of Hunhe River are studied by using MIKE11 software from three aspects of point source,non-point source and river self purification.Finally,the corresponding water quality stable and up to the standard scheme is put forward.The main contents and conclusions of this paper are as follows:(1)Based on the consideration of the pollution of rainfall runoff and the influence of the hydrodynamic conditions of the Hunhe River,the rainfall hydrodynamic water quality model of the Shenfu section of Hunhe River is established.The measured discharge and water level data of Fushun(II)and Shenyang(III)hydrometric stations in typical years(October 2014 ~September 2015)in Hunhe River Basin were used to calibrate and verify the hydrodynamic parameters and rainfall parameters of the rainfall hydrodynamic model water quality model in Shenfu section.The comparison between the measured value and the simulation result shows that the maximum relative error of the flow is not more than 10%,the average is about 4%,the judgment coefficient R2 is close to 1,the average is above 0.9;the maximum relative error of the water level is not more than 1%,the maximum difference of the water level is not more than 20 cm,the average is about 13 cm.Based on the calibration and verification of the rainfall hydrodynamic model,the COD and ammonia nitrogen water quality data of the typical annual main stream monitoring section in Hunhe River Basin are used to calibrate and verify the water quality parameters of the rainfall hydrodynamic model water quality model in Shenfu section.Through the comparison of the measured values of COD and ammonia nitrogenconcentration of 6 main stream monitoring sections from hepingqiao in Fushun section of upstream to changqingqiao in Shenyang section of downstream,it is found that the relative error of water quality model is less than 10%,which meets the water quality accuracy requirements of the interruption surface in the hydrological information forecast specification,and the qualified rate is more than 70%,which can be used for operation forecast.The simulated value is similar to the measured value,which well reflects the law of water quality change in Shenfu section of Hunhe River Basin.The maximum relative error of COD concentration in each section is not more than 7%,with an average of about 3%,R2 of the measured and simulated value curves is close to 1,with an average of about 0.996;the maximum relative error of ammonia nitrogen concentration in each section is not more than9%,with an average of about 4%,R2 of the measured and simulated value curves is close to 1,with an average of about 0.997.(2)Based on the rainfall hydrodynamic water quality model,the influence of rainfall runoff,regulation of tributary river and sewage outfall,self purification capacity of river on river water quality is studied by simulating the process of river flow and water quality change.The collected rainfall runoff is discharged after being treated as class IV water,and the reduction rate of COD and ammonia nitrogen is relatively low in the dry season,of which only in April cod can meet the requirements of class IV water,and the reduction rate of COD and ammonia nitrogen in the wet season is relatively increased.In September,except for the section COD of changqingqiao,the water quality of other sections and months can meet the standards;after 50% reduction of runoff into the river by the principle of sponge City,the reduction rate of COD and ammonia nitrogen in the dry season is still low,COD of each section can meet the requirements of class IV water in April,and the reduction rate of COD and ammonia nitrogen in the wet season is significantly increased,with the maximum of12.64% and 19.72% respectively,and the water quality of each section reaches the standard rate of 100%.After class V water control of tributary river,the water quality of each section of the main stream can reach the standard stably in the whole year except January and February;after class IV water control,the water quality of each section of the main stream can reach the standard stably in the whole year,and basically meet the class III water requirements in the wet season.Under the condition of using artificial aeration to increase dissolved oxygen by1.5mg/L and 2.5mg/L,the reduction rate of ammonia nitrogen is within 10% from October to April,and the minimum concentration of ammonia nitrogen is 1.64mg/L,which still can not meet the requirements of class IV water;the reduction rate of ammonia nitrogen is significantly increased from May to September,with the highest section of Heping Bridge reaching 38%,and the most polluted section of Changqing bridge falling to within 1.5mg/L in May,with the reaching rate of 100%.(3)Without considering the ecological water quantity of the river,the regulation scheme for the water quality of Shenfu section of Hunhe River to reach the standard all year round is as follows: when the tributary river is controlled as class V water in the dry season,Dahuofang reservoir will discharge 2m3/s water on average every day in January and February,and Sanbaotun sewage plant will discharge 4m3/s water on average every day.In the wet season,the main sewage outfall will be closed;when the tributary river is controlled as class IV water in the dry season,the main sewage will be discharged in the wet season No water regulation is needed. |
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