| In recent years,many artificial lakes have been built in china's cities to improve the living environment of residents in urban or suburban areas.For the artificial lake in the city of resource-based water shortage and pollution-induced water shortage,and the effective utilization rate of the replenishment water is affected by water supplement schemes directly.To achieve the goal of ensuring the normal operation of the artificial lake under the condition that the total amount of recharge water remains unchanged,it is of paramount importance to optimize the water replenishment scheme for the artificial lake.The MIKE21 numerical model has been used to establish a 2D hydrodynamic and water quality model to compare different water replenishment schemes under multi-factor conditions for an artificial lake in Haidong City,Qinghai.(1)Considered the research progress at home and abroad and the actual demand of artificial lakes for water recharge.The indicators for evaluating the water replenishment scheme are the water exchange rate and flow velocity profile of water in artificial lakes.On this basis,the evaluation of multi-factor water supply scheme is carried out,and the near optimal water replenishment scheme is selected.The water replenishment scheme can be verified in combination with water quality numerical model.(2)By comparing the water exchange rate and flow velocity in artificial lakes with different number of artificial lake inlets and different form of water intakes,it is found that the scheme of three intakes is superior to that of single and double intakes.In addition,On the basis of 3# inlet which is opposite to the outlet as the main inlet,the minimum water exchange rate of three intakes staggered replenishment scheme is significantly higher than that of three intakes simultaneous replenishment scheme,and the effect of water replenishment is enhanced.(3)When the total amount of water is constant,the effects of four water supply cycle schemes are compared and analyzedwater.The results show that the exchange period of 15 days can effectively improve the water exchange rate of the artificial lake compared to that of 30 days,6 days and 3 days,and the average water exchange rate is as high as 72.69%.(4)By comparing the water exchange rate and flow field of the lake area under the two sets of inside island shape schemes,it is concluded that the shape of the inside island has a certain influence on the flow field in the artificial lake.The shape of the inside islands should be as round as possible to avoid the appearance of concave-convex staggered shape,otherwise it is not conducive to the water exchange in the lake area.(5)The effect of southeast wind and north wind on artificial lake water exchange rate is calculated and comparatively analyzed.It is found that the wind speed has a significant influence on the water exchange rate of the artificial lake,while the wind direction has little effect.These two kinds of wind stress have a greater impact on the flow field of the lake,and the flow rate is increased by more than three times compared with the windless situation;(6)Based on the optimal water replenishment scheme determined under the above multi-parameter evaluation,a water quality model was established to verify and evaluate the selected scheme.It is found that the concentration of TN was diluted by 70.0%,and the concentration of TP was diluted by 68.8%,which proves that the above influencing factors are the key factors in determining the final water replenishment scheme. |
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