Study On Runoff Pollution Control Of Different Urban Underlying Surfaces

The problems of runoff pollution and urban waterlogging caused by the rapid development of urbanization and the lack of runoff pollution control measures are becoming increasingly prominent.It is important to study the low impact development for urban rainfall and runoff pollution control.In this paper,the grass swale experiment device was set up first,and the traditional water-planting way of grass swale was improved.Four kinds of runoff loads and four kinds of runoff pollutant concentration loads of the runoff was designed,and passed through the grass swale experimental device with different water-planting ways.The runoff and runoff pollutant reduction effect of the grass swale was studied.The results show:The addition of the water distribution canals increased the capacity of runoff reduction of the grass swale on the whole;With the increase of runoff load,the ability of grass swale to reduce the runoff showed a downward trend;When the runoff flow was 300L/h,with the increase of the length of water distribution canals,the ability of grass swale to reduce the runoff was also increased;When the runoff flow is more than 300L/h,the optimal water distribution canals length is 3m,and the increase of the length of the water distribution canals will reduce the grass swale runoff reduction ability;The addition of water distribution canals can improve the the grass swale removal rate of TP,NH₃-N and COD,and the highest removing length of the water distribution canals is 3m;For SS,the addition of water distribution canals has no significant effect on its removal rate;The grass swale removal rate of various pollutants decreased with the increase of runoff flow.The grass swale removal rate of various pollutants increased with the increase of initial pollutant load in runoff.In addition,based on the interpretation of different underlying surfaces geography information and the information of the reduction of runoff and pollutants and the unit cost of different low-impact development measures,the multi-objective model of low impact development measures is established in this paper.The genetic algorithm is applied to solve the model,and the optimum combination of different kinds of low impact development measures under different runoff and pollutant reduction levels is achieved,so as to reach the target of lowest cost at the same time.Thus the low impact development measures in the target area were optimized.