Author(s): Zhigang Wang; Yongcan Chen; Zhaowei Liu; Dejun Zhu
Keywords: Primary need-to-control water quality index; Ice-covered rivers; Improved analytic hierarchy process (IAHP); Water environmental protection
Abstract: The identification of the primary need-to-control water quality indices which can reflect the main pollutants in the ice-covered rivers is one of the most important bases for river water environmental protection and recovering. However, as the influence factors are too many and complicated, including the importance of each water quality monitoring cross section, the variety of the water quality indices, the importance of each water quality index and so on, thus the primary need-to-control water quality indices are always difficult to be identified. Therefore, the corresponding improved analytic hierarchy process (IAHP) approach is proposed accordingly. In the IAHP, the importance of the water quality monitoring cross sections are quantified clearly and expressed in the evaluation of the weights of the Criteria Layer over the Object Layer. Meanwhile, the measured water quality data are also taken into consideration, and serve as the weights of the Indices Layer over the Criteria Layer. The determination of the IAHP interlayer weights makes the IAHP topological structure simplified. When applied to the urban reach of Mudan River (from Hailang Cross Section to Chaihe Bridge Cross Section), the IAHP approach can have its calculated results the primary need-to-control water quality indices in the ice-covered period of 2000 were ammonia nitrogen (NH3-N) and five-day biochemical oxygen demand (BOD5), which agreed with the actual fact very well. Through further analysis, it’s found that the IAHP’s calculated results are objective and don’t change with the up-to-standard water quality indices taking part in the calculation and the interlayer weights, thus the IAHP is recommended to be employed to identify the primary need-to-control water quality indices in ice-covered rivers.