Research On Water Quality Regulation And Control Scheme Of Ecological Water Demand Based On MIKE11

Hunhe River is a typical seasonal river in the northern frigid region.Its water volume varies greatly.It has large water volume in flood season,small water volume in dry season,and even bare riverbed appears in some sections.In order to use water for urban landscape,more sluices and dams have been built on Hunhe River.All the sluices and dams have risen,and the river has been divided into small reservoirs of ladder type.The hydraulic conditions are poor,which is not conducive to the ecological environment of the river.In order to use water for landscape in non-flood season,almost all the sluices and dams rise,and there is no water to flow in the upstream and downstream of the river,which makes the ecological environment water demand of Hunhe River Basin seriously short.The water quality of non-flood season rivers is far worse than that of flood season,which seriously affects the ecological environment of the river.In order to ensure the river water quality and improve the river ecological environment,this paper first studies the impact of different pollution conditions on the ecological water demand,and then calculates the ecological water demand of different years and different pollution conditions in the study area.The coupling model of water quality and quantity in Shenfu section of Hunhe River is constructed by MIKE 11 software.Finally,the discharge scheme of Dahuofang Reservoir under different pollution conditions in Shenfu section of Hunhe River is worked out.By comparing the simulated water quality results of various schemes,the optimal discharge scheme of Dahuofang Reservoir is obtained.The main contents and conclusions of this paper are as follows:The necessity of ecological regulation and control was studied in three aspects:water quality,water quantity and hydrological change degree in Shenfu section of Hunhe River.The results show that the water quality in Shenfu section of Hunhe River is seriously polluted in non-flood season,and the tributary water system is more polluted than the main stream;the annual distribution of water is uneven,and the discharge of Dahuofang reservoir can not meet the ecological water quantity in non-flood season;the construction and operation of Dahuofang reservoir has seriously changed the original hydrological state of natural rivers in Shenfu section of Hunhe River,and the fluctuation of water quantity is large and the number of reversals is increased,so it is Water quality and quantity control measures with ecological objectives.The influencing factors of ecological water demand of Shenyang(3)Hydrological Station were analyzed by comparative analysis method.The results showed that before the tributary water quality was less than four types of water,the influencing factors of ecological water demand were self-purification water demand,basic water demand,seepage water demand,evaporation water demand,coastal vegetation water demand,and river runoff was inversely proportional to ecological water demand.When the water quality of the tributaries reaches four categories,the basic water demand will exceed the self-purification water demand and become the first influencing factor.The order of other factors remains unchanged,and the ecological water demand is proportional to the river runoff.When the tributaries of sewage outlets are banned,the water quality is the main factor affecting the ecological water demand.When the tributaries of sewage outlets reach five categories,the water quality will become the secondary factor affecting the ecological water demand.In view of the lack of hydrological data for calculating ecological water demand in the sub-district reach,a method for constructing the water quality and quantity coupling model of MIKE 11 in different years in the reach is proposed to obtain the water quantity of each section in the study area and prepare for simulating the discharge scheme of Dahuofang Reservoir.The ecological water demand of different pollution situations in Shenfu section of Hunhe River with sluice and dam as zoning nodes is calculated.The results show that the current ecological water demand of Shenfu section of Hunhe River is 9.53*108 m3,the current ecological water demand of banning the tributaries of sewage outlets is 8.81*108 m3,the ecological water demand of banning the tributaries of sewage outlets is 6.66*108 m3,and the ecological water demand of four tributaries is 3.12*108 m3.Based on the ecological water demand of four different distant and near pollution levels,the discharge scheme of Dahuofang Reservoir is formulated for each ecological water demand.In order to alleviate the water pressure of Dahuofang Reservoir,this paper chooses the effluent of Sanbaotun Sewage Treatment Plant as the external source water,assuming that the effluent water quality is 4 kinds of water and the daily discharge volume is 4.6 m3/s,and simulates the discharge volume of Dahuofang with different ecological water demand under the condition of external source,and observes the results of water quality improvement.The results show that the water quality improvement of Shenfu section of Hunhe River is the best in the five discharge schemes of Dahuofang Reservoir in dry water year(15 days before each month);the water quality improvement of Shenfu section of Hunhe River is the best in the case of external water source(5 days per month as a unit of circulating discharge);whether there is water source or not,the sewage discharge should be banned.When the tributaries reach 4 types of water,all the five schemes can improve the water quality.