| The songhua river is one of China’s seven major river systems. The pressure on the pollution treatment will be intensified with the rapid economic development of songhua river basin. If the water environment problem is treated thoroughly, we must carry on the scientific management plan with the river basin as a unit, follow the rules of the hydrology, and understand its pollution distribution change law of time and space so that the pollution can be controlled efficiently. In this paper, the results of WASP water quality simulation will achieve visualization in GIS on the basis of the GIS technology, which provides the scientific basis and the decision plan for the water pollution related department so that it can monitor and control the water quality and deal with the pollution.This paper analyzes the internal and external research condition about the water quality assessment, simulation and visualization. According to the complexity of the pollutant species of municipal district of Harbin section of songhua river and the serious problem of water environment destruction, I gather the information of the flow characteristics, hydrology and the pollution source of Harbin section of songhua river and the measured information. Based on the above data, I assess the water quality from the perspective of annual variation, water period variation and the variation along the flow by the single-factor assessment methodology and the comprehensive water quality index methodology and analyze and grasp the change rule in time and space of main pollutants COD, BOD5 and NH3-N of songhua river from 2009 to 2014.By WASP7.3 model from U.S. environmental protection agency(USEPA)for water quality analysis simulation program of Harbin section of songhua river in October 2013-2014, finally I make use of the established WASP water quality model and Tracking Anayslt extension module in GIS to achieve the output of results of water quality simulation based on thematic map of the space position, and display the water level and the pollutants concentration.The results showed that the most polluted river is ashi river and hulan river. Harbin songhua river in October from 2009 to 2014. Among the six countries accused of monitoring cross section, water quality to class III section(16.7%), type IV section(52.7%), V class or bad V kind section accounted for 30.6%. Owing to the frozen, water quality of the low flow period goes worse apparently. Exceed standard section is in ashi river and other cross sections are all fulfill the requirements of water function area planning. The pollution levels of Harbin section of songhua river: hulan estuary under section > ashi estuary under section > big dingzi mountain section >Zhu Shuntun section. The main pollution factor is ammonia nitrogen. The simulation results accord with the requirement of model precision, and they can reflect the relationships between pollutants concentration of research domain and time and space objectively. As far as the simulation result of single index is concerned, the simulation effect of NH3-N is the best, whose simulation values and the error of the measured values are controlled within 3%, whereas COD simulation effect is relatively inferior. Most simulation error absolute value is between 10% and 20%. The simulation results will show every water quality grades every six hours through the Tracking Anayslt extension module in GIS, and output the visualized theme map of the flood period, normal flow period and low flow period of the control unit in 2013. |
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