Water Quality Evaluation And Water Environmental Capactity Calculation Of The Tributary Of The Yangtze River In Yichang

In recent years, with the high-speed development of social economy in our country, the water environmental pollution is becoming more and more important, the calculation of water environmental capacity of the receiving water is of great significance.In this work, a tributary was chosen as the research target, the quality of water environment was evaluated with international standard methods, including COD, NH₃-N and TP as the main contamination index, was calucated and studied using one-dimensional water environmental capacity model. The main research results are listed as following:1) The water environmental quality of the a tributary was assessed using the method of single factor evaluation method,water quality of the section and the river was assessed.The main contaminants of the 5 monistoring section cross section in a tributary were evaluated, the results showed that the sequence of pollution level of the five monitoring cross section was as followings: Fengjia Village> Tangdu River > Stele Beachland > Huangbo Bridge General Rock. Caused by cross section and river evaluation results, a certain level of the main pollution factor is of water pollution in COD, NH₃-N and TP.2) After the division of calculating elements, confirmation of the water quality target and background concentrtion, determination of the trash ports, the hydrological conditions in different water period including the Q of flow rate and the u of flow velocity and, the integrated degradation coefficient K of the contaminant are estimated and determined with the one-dimensional water quality and water environmental capacity model. The adaptation of the one-dimensional water quality model was verified through the comparison of the simulated values and measured values on Huangbo Bridge section. The results showed that of the simulated values of COD, NH₃-N and TP in the Huangbo Bridge section are consistent with the actually measured values. After model parameters calibration, the values of COD, NH₃-N and TP were simulated and validated with 100% yield basing on the 40% of relative error.3) The water environmental capacity of a tributary was calculated with one-dimensional model. The environmental capacities of COD were 562.8t/a, 899.0t/a, 2379.5t/a, NH₃-N were 34.9t/a, 55.9t/a, 171.3t/a, and TP were 6.8t/a, 10.7t/a, 33.3t/a, repectively, during drought period, normal period and wet period. It was founded that the main contamination was focused on the section of Stele Beachland-Fengjia Village, which covered 70% of the total environmental capacity in a tributary.Based on above studies, such as water quality evaluation, environmental capacity calculation and the analysis of pollution, the maximum pollutants loading can be obtained, which could be help to use the water resource through controlling the quantity of pullutants discharge on purpose.