Study On Variation Of Water Quality And Quality Of Artificial Water System In Sponge Campus

The rapid urban development and the aging of urban infrastructure have caused a series of urban problems,especially urban water problems.China has actively responded to addressing the issue by taking measures like the treatment of black smelly water bodies,the construction of sponge cities and the construction of integrated pipelines,among which,sponge city initiative has obtained remarkable achievements in urban storm water management.Actually,sponge city initiative are being piloted in two China's cities,while its effect on water quality has not yet been monitored,therefore,the study on the effect of this initiative plays a positive role in its planning and design,construction,operation and governance.Based on the monitoring of water in new campus of Tianjin University,this paper aims to test the water quantity and water quality,and to study the water balance before and after rainfall,changes of water quality before and after rainfall under different underlying surfaces,as well as the evolution of water environment under sponge city background.The main contents and findings of this paper are as follows:?1?Runoff control rate and surface runoff coefficient can be calculated after monitoring water quantity and the balance of field water quantity.Then the controlled rainfall rate in the field was learnt as 43.73%,and the calculated control rainfall reaches12.957mm,not as high as 18.75mm as specified in the Sponge City Construction Technology Guide.The reason is that only accumulated water in the catchment area was considered when calculating rainfall runoff control,forgetting the storage function of the sponge city in Inner Lake.In the planning and design,the integrated runoff coefficient is expected to be 0.54,and the runoff coefficient is 0.563 after calculating water balance,a difference of 4.1%?<10%?.It is considered that the planned runoff surface runoff coefficient is equivalent to the integrated runoff coefficient after construction.?2?Through the monitoring of the water quality of the accumulated water in different underlying surfaces of the sponge campus and the surrounding communities,the differences of quality of the accumulated water after rainfall were learnt.The changes of water quality in the runoff before and after rainfall were analyzed to study the pollutants carried by the rainfall runoff and to learn the rainfall runoff's water quality controlling ability in two campuses of Tiajin University.It is found that the turbidity and TP in the new campus are obviously lower than those of the Jin Cai Yuan and Huarun Central Parks,indicating that the removal efficiency of the sponge campus in turbidity and TP is obvious.The abnormally high TN content is mainly contributed by a large amount of nitrogen of the fertilization residues in the green land.NH₄⁺-N,TN and TP in the Inner Lake began to show a partial decrease in June,and experience a larger decrease in July,suggesting sponge campus plays an important role in removing the pollutants in surface runoff.?3?Peiyang New Campus artificial water planning and design for the landscape with Class IV water.According to the water quality monitoring results of physical and chemical indicators at each monitoring point in artificial water system,it is concluded that within the second year?2016-09-20 to 2017-7-28?of Lake construction period?2015?,TN tests of Huxiao River and Weijin River surpass the limiting value of water of Grade IV water.The COD tests of Inner Lake and Weijin River exceed the limiting value of water of Grade IV.The inner lake water quality more school school,Wei Jin River pollution is more serious.