Study On High Efficient Interception Efficiency Of Urban Runoff Based On Conductivity

Non-point source pollution has become one ofthe important sources of Dianchi Lake pollution, thus pollutant source control is a vital means to treat thewater environment of Dianchi. In order to maximize the efficiency of pollutants retention under the annual runoff retention rate meets 50%, SWMM(Storm Water Management Model) was applied for analysis in this paper, an SWMM model of study area was established. Model parameters were calibratedby measured data on August 2, 2013 and August 8, 2013 and verified by measured data on August 18, 2014. The NS efficiency coefficient reaches 0.930, 0.727 and 0.869 respectively in three times ofrunoff quantitysimulation. In runoff quality simulation, NS efficiency coefficients of SS, CODCr, TN, TPwere reached 0.820,0.826,0.580,0.713; 0.768,0.659,0.529,0.551; 0.808,0.835,0.603,0.512 respectively in corresponding sessions. The runoff quantity and quality model is accurate and reasonable to some extent. Relevance of TN and conductivity(akind of rapid water quality index)was analyzedin the research.Results showed that TN has significant and stable linear correlation with conductivity in all rain sessions,theoverall correlation coefficient R2 of the regression equation is 0.802, and the linear correlation equation is reliable. TN will be able to be measured real-time and the sluice gate in the inteceptingwell will be hoisted simultaneously as monitor runoff conductivity online,therefore stormwater can be selected, electric controledin the runoff process. Based on simulation results of 15 years duration rainfall, data screening combined spreadsheet method was used to statistics out TN and conductivity corresponding with different runoff retention proportions. It is found that take a unified control conductivity value in all intercepting wells in the research area will achieve a more efficient pollutants retention. Two conductivity intercepting ways(way one: each intercepting wells has one intercepting conductivity value, way two: The entire area has unified conductivity value) and two traditional methods(way three: ways likeoverflow weirand retention groove intercepting well, wayfour: skipping weirintercepting well) are compared with interception efficiency in the study, order of pollutant intercepting efficiency is: way two> way one > way three > way four. All pollutants intercepting efficiencyof way one and way two is steady more higher than its runoff retention ratio,among them, way two is the highest of all. For way two, the order of four kinds of pollutants intercepting efficiency is: CODCr> SS> TN> TP. When annual runoff retention rate reaches 50% in the study area, TN control value of way two is 5.51 mg / L, corresponding conductivity value is 301.42μS / cm, under such conditions, pollutant intercepting ratio of SS, CODCr, TN, TP can achieve 69.4%, 70.6%, 60.5%, 56.6% respectively, pollutants load of SS, CODCr, TN, TP can be trapped 279.14,92.98,7.08,0.79 t per year, four kinds of pollutants load in the entire study area were 402.36,131.72,11.71,1.39 t per year. Forway two, the high efficient segment of pollutants intercepting efficiency was explored at the same time, while the annual runoff retention rate range from 20% to 70%, the difference between the pollutants and runoff retention rate is in a larger range of values and more efficient, as a result,it is reasonable to control the annual runoff retention rate in this range.