Analysis Of The Quality And Potential Utilization Of Rainwater On Campus

With the speed-up of urbanization in China,water shortage has become a common issue faced by many cities.Meanwhile the severity and frequency of floods in a wide range increase,which are serious threats to people's life and property.Rainwater is an important element of the city water circulating system.Therefore,effective rainwater collection and usage has certain practical significance,the construction of sponge cities which are capable of natural accumulation,infiltration,and purification has been clearly stated in the central working conference on urbanization.Under the rapid development of urban construction in Nanjing,the national master plan of Jiangbei district illustrates that new district should have ecological livable functions.The construction of sponge city will be an important step in the new district's construction.The main work and relevant conclusions of this research are as follows:(1)Based on the domestic and overseas research actuality of city rainwater utilization theory and technique,this paper systemically analyze the annually rainfall data,monthly rainfall data and daily rainfall data in Nanjing from 1951?2012.The average annual rainfall of Nanjing is roughly 1037mm,and the main flood season is from May to September;the rainfall frequency,capacity is relatively high,and the heavy rain days showed an obvious growth;relevant rainfall control measurements in flood season should be adopted.(2)Aims to analyze the time-varying change of road and roof rainfall water quality,the correlations between different water quality indexes and the influence factors,this study would specifically conduct the monitoring of rainfall indexes to the collected water samples of road and roof rainfall on the Nanjing university of Information Science&Technology.The research result show that with the increase of rainfall,the concentration of various pollutants showed a downward trend;road rainwater quality was relatively poorer than roof rainwater;the various pollutants showed a certain correlation between each other;the main factors affecting the rainwater quality is the number of antecedent dry days and the amount of rainfall.(3)In addition,the paper will also analyze the types and characteristics of rainfall pollutants build-up function and wash-off function.Based on this,build-up and wash-off model would be established.The build-up and wash-off function can be used to describe the exponential trends of roof pollutant concentrations in the initial and middle periods,but the scope of application is limited;and the SWMM model would be adopted to simulate the changes of rainwater quality.(4)It is also known by calculation that the amount of east campus rainwater that can be used every year is about 15 million cubic meters;according to rainwater utilization measures of sponge city,suggestions about rainwater utilization of campus would be given.After the cost analysis and calculations of rainfall utilization project investments,the saved annual water charges is around 134300 RMB,which shows great economic,ecological and environmental benefits.