| Water quality and aquatic ecosystem in Suzhou Creek have improved gradually since the first and the second comprehensive administration achieved, but dissolved oxygen in water of city area is still low,the annual average content is less than 2mg/l.The influence of sediment consume oxygen begains to appear. In order to reduce sediment oxygen demand,the one of main projects of the third comprehensive administration of Suzhou Creek is sediment dredge. Whether dredging could effectively improve water DO in long time, it need to conside the impact of pumping stations along Suzhou Creek storm water overfall on sediment oxygen demand(SOD).In this dissertation,sediment flux model was used to establish SOD model on Suzhou Creek. The model was calibrated and validated by history materials and experimental data and can relatively succeed to simulate sediment oxygen demand.The main reason of sediment consume oxygen is input of TOC and TON. Using the SOD model simulate, result show that sediment oxygen demand is affected equally by TOC and TON when the concentrations of TOC and TON are less than 3mg/l,sediment oxygen demand is affected mostly by TOC when the concentrations of TOC and TON are more than 3mg/l.The impact of Pumping Stations along Suzhou Creek Storm Water Overfall on SOD was studied using of the SOD model. Result show that SOD increases 26.5 %-41.2% after storm water overfall average one time,which implies that the main reason of SOD increases is storm water overfall of pumping stations along Suzhou Creek,dredging can only remove Suzhou Creek SOD in short term, and combined sewer overflows (CSOs) will build up SOD and lead to low water DO problems in long term. Result show also that SOD changes between 7%-8.5% when CSOs increase or induce 10%,SOD can reduce 25.4% when CSOs reduce 30%,which implies that reduction of CSOs affects SOD obviously. So in order to improve Suzhou Creek qulity, the control on CSOs needs to strengthen.
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