Determination of Key Risk Supervision Areas around River-Type Water Sources Affected by Multiple Risk Sources: A Case Study of Water Sources along the Yangtze’s Nanjing Section

Environmental Risk Assessment of the Zhengrunzhou Water Source under the Influence of Oil Spill Accidents at the Wharf Group

To compensate for the research defects of strong subjectivity in determining oil spill amount, insufficient consideration of wharf distribution, and incomplete indexes for reflecting the influence degree of oil spill accidents on water sources, and to enhance the supervision efficiency of the supervision department, this paper constructs a risk assessment system of water sources under the influence of the wharf group. The system includes a wharf group division method considering the wharf distribution situation; the calculation method of oil spill amount at wharves considering the oil tank capacity of main ship types and the production supervision risk at the wharves; the calculation method of the oil spill amount at the wharf group considering the wharf number, distribution density, production supervision risk and wharf oil spillage; the determination method for the influence degree of oil spill at the wharf group on the water sources and judgment method of supervision level at the wharf group, which takes the arrival time of oil slicks, the duration of over-standard petroleum concentration and the maximum over-standard multiple of petroleum concentration at the water intake as indexes; the method of determining the risk of oil spill accidents at the water source considering the cumulative effect of oil spill at the wharf group on the risk of the water sources; and the environmental risk assessment method of water sources considering oil spill accident risk and the anti-risk ability. Applying this system to the environmental risk assessment of the Zhengrunzhou water source in Zhenjiang City, we discovered that the flow field, wind field, oil spill location and oil spill amount were correlated with the influence degree of oil spill accidents on water sources, for which the flow field demonstrated the strongest correlation, while the wind field presented the weakest. The supervision level of the wharf group is mainly sub-key or non-key levels, but the level of the wharf group SD07 is approximate to the key supervision level during rising tide. Due to the strong anti-risk ability of the Zhengrunzhou water source, the environmental risks of the Zhengrunzhou water source under different working conditions are scarcely different and belong to the medium-risk level.

Environmental risk analysis of surface water based on multi-source data in Tianjin Binhai New Area, China

The study on environmental risk of surface water is of great practical significance for the ecological security of water environment and water pollution treatment, and it can provide a certain reference basis for risk prevention and control of water environment. The Tianjin Binhai New Area faces severe water shortage and serious water pollution, but few studies have been reported on surface water environment risk in this area. Therefore, in this study, based on Gaofen-6 remote sensing image, the factors including land use, landscape index, population density, and enterprise source are integrated to develop the evaluation model of surface water environment risk index. It is developed using analytic hierarchy process from two aspects of hazard of risk source and sensitivity of risk receptor. The comprehensive risk of Tianjin Binhai New Area is classified using mean standard deviation method. The result indicates that the developed model could better quantify the impact of various factors on the surface water environment, and comprehensively and accurately depict the spatial distribution of surface water environmental risk. Generally, the areas of higher and high risk grades are mainly concentrated on the west of Binhai Street, Beitang Street, and Hangzhou Road Street. The risk grade in most other areas is medium, and it is low in coastal and northernmost areas. This study not only clarifies the distribution of surface water environmental risks in Binhai New Area, but also develops an evaluation model, which can provide reference for the evaluation of water environmental risks in other areas. Through the investigation and research on the current situation of water pollution, social and economic development, and other factors of the streets and towns in Binhai New Area, it is found that in recent years, the urbanization of Binhai Street, Beitang Street, and Hangzhou Road Street has developed rapidly, and the intensity of human activities is high, which has a great impact on the water environment. The research results are consistent with the actual situation, which can provide theoretical and technical support for the prevention, control, and management of water environmental risks in Binhai New Area.

Environmental Risk Assessment and Regulatory Rating of Water Sources along the Yangtze River’s Nanjing Section under the Influence of Multiple Risk Sources

To complement the current studies of risk assessment on water sources which seldom consider the distribution effects of multiple risk sources concentration, and improve the efficiency of water source supervision, this study establishes a method system for risk assessment of water sources and regulatory rating evaluation under the distribution effects of multiple risk sources concentration. The method system includes: (1) utilizing the single-risk source impact index to characterize the risk impact degree of the single-risk source on the water source, the index calculation method of single-risk source impact considers the risk degree and the distribution location of risk source; (2) using the multiple risk sources impact index to characterize the risk impact degree of the multiple risk sources on the water source, the index calculation method of multiple risk sources considers the impact index of single-risk source, the number of risk sources, and the distribution concentration of multiple risk sources; (3) the environmental risk assessment and regulatory rating evaluation method consider multiple risk sources impact index, anti-risk ability of water source, and the importance of water source. This method system has been applied to the environmental risk assessment and regulatory rating of eight water sources along the Nanjing Yangtze River, with excellent achievements. As the results reveal, eight water sources suffer 437 risk impacts from 175 risk sources, 69.04% of which are low-risk impacts and 13 are high-risk impacts. Longtan water source suffers the most risk impacts of 86, among which eight are high-risk impacts. The impacts of multiply-risk sources on the eight water sources are high-risk impacts. The impact index of multiple risk sources increases from the upstream water sources to the downstream water sources, reaching the maximum value of 5.267 at the most downstream Longtan water source. Though the environmental risk and supervision rating of Longtan water source is high, those of other water sources are rated as medium.