Comprehensive evaluation of urban water supply security based on the VIKOR-TOPSIS method.

To determine the security status of urban water supplies, a comprehensive evaluation model of urban water supply security based on the VIKOR and TOPSIS models is proposed. The comprehensive evaluation value K is obtained as the evaluation result, and the larger K is, the higher the safety of the urban water supply. The results show that the security of the water supply in Tianjin increased from 0.2300 in 2015 to 0.8026 in 2018. Although it slightly decreased to 0.5439 in 2019, it was still at a high level and increased to 0.7508 in 2020. The urban water transmission and distribution status, the service level of the water supply industry, and the status of sewage treatment play positive roles in affecting the safety of the water supply in Tianjin, and the status of urban water sources and the urban water use status are the main factors that reduced the safety of the urban water supply. According to the results of an obstacle degree model and the actual conditions in the study area, it is suggested that Tianjin should continue to focus on the development of water resources and the utilization of unconventional water sources and actively promote the construction of a water-saving society.

Prediction of the migration and accumulation of pollution based on the use of a deicing agent.

In this study, we simulated and predicted the accumulation of deicing agents in the soil and water system of the study area (a ski resort in Beijing, China) and discussed the environmental impact of deicing agents on the surrounding water system and soil under a standardized dosage. The widely used sodium chloride deicing agent was selected, and the standardized dosage of the deicing agent was estimated. Analysing the prediction results of the changes in chloride ion content in water systems and soils after the use of deicing agents from 2021 to 2029 leads to the conclusion that the use of deicing agents will increase the chloride ion content of the study area. It is predicted that chloride ion content in the water system and soil will increase year-by-year from 2021 to 2026, achieving a stable trend after 2027. It is concluded that the deicing agent has no obvious effect on the surrounding water body and soil under the standardized dosage. This research is intended to fill the gap in quantitative research on the environmental impact of deicing agents, to provide a reference and guidance for the engineering application of deicing agents, and to offer support for the improvement of deicing agent management measures.