Research on the Evaluation of the Fairness of Economic and Social Water Use in the Yellow River Basin.

Wading projects are likely to bring about changes of the original hydrodynamic conditions of the river, and this may further affect the flood discharge capacity of the river course. Thus, it is of great significance to study the flood risk of the river course with or without the wading projects, so that we can well maintain the project, regulate river course and ensure regional flood control security. Based on the random simulation of four uncertain factors, namely peak flood discharge, initial water level, river course roughness and dike elevation, this paper analyzed the stress of aqueduct under flood action, and then calculated the water surface line of the river. Combined with theforce conditions and water surface line calculation results, the conventional Monte Carlo method and the Monte Carlo method based on Latin hypercube sampling were both used to calculate the flood risk of river course with or without an aqueduct. The results show that: 1 When the water level in Gangqian Aqueduct is 0.5, 1.0, 1.5 and 2.0 m, the flood discharge capacity of Qingfeng Mountain stream, compared with its designed discharge of 1 200 m³/s, respectively decreases by 36.68%, 27.87%, 19.00% and 10.05%. 2 In the case of having no aqueduct in its river course, the flood risk of Qingfeng Mountain stream course is 0.007. In the case of having Gangqian Aqueduct in its river course, when the water level in the aqueduct was 0.5, 1.0, 1.5 and 2.0 m respectively, the flood risk of Qingfeng Mountain stream course is 0.34, 0.045, 0.016, 0.012 in turn. 3 Keep the water level in Gangqian Aqueduct at the highest value within the safe range. When the discharge of Qingfeng Mountain stream exceeds 1 600 m³/s, the flood risk of its river course still rises significantly with the increase in the flood flow. Therefore, in this case, Gangqian Aqueduct would have to be scrapped to ensure the flood discharge capacity of Qingfeng Mountain stream. 4 Both the conventional Monte Carlo method and the Monte Carlo method based on Latin Hypercube Sampling are suitable for assessing the influence of aqueduct on flood risk of river course, and the latter has better convergence. In summary, building adueducts in river courses would have a negative impact on the river courses' flood discharge capacity. It results in the flood discharge capacity of the river course being lower than the designed discharge, and further, led to the flood risk of river course increasing. To a certain extent, raising water level in the aqueduct can reduce the flood risk of river course. The fairness of water use is one of the key factors to be considered in the balanced allocation of water resources. Aiming at the problem that the fairness of water use in the basin is not considered enough in the different industries, an evaluation method based on multi-factor Gini coefficient in different industries is proposed. The Gini coefficient between industry water consumption and industry scale is used to represent industry water fairness. The comprehensive Gini coefficient of water use in the basin is calculated based on the proportion of water consumption in each industry to represent the fairness of water use in the basin. Taking the Yellow River Basin as an example, this paper calculates the Gini coefficient and analyzes the variation of the fairness of water use of different industries in nine provinces of the Yellow River Basin from 1980 to 2020. Take 1995 and 2005 before and after the integrated water regulation of the Yellow River as examples, the impact of integrated water regulation on the fairness of water use in the basin was compared and analyzed. The results show that over the past 40 years, the fairness of water use in domestic, industry, urban public, and agriculture were "highly fair", "relatively fair", from "highly fair" to "relatively fair", and from "relatively fair" to "highly fair", respectively. The proportion of agricultural water use exceeds 70%, and the Gini coefficient of watershed water use is mainly affected by agricultural water use, the comprehensive Gini coefficient of economic and social water use in the basin is 0.16-0.25 from 1980 to 2020, which is in a downward trend, indicating that the fairness of economic and social water use in the basin has gradually improved, changing from "relatively fairness" to "highly fairness" . The fairness of water use for domestic and agriculture is gradually improved, and the fairness of public water use in industry, especially in urban areas, has decreased significantly. This is mainly because the differences in water use quotas for domestic and agriculture between 9 provinces in the basin have decreased, while the differences in water use quotas for the tertiary industry have increased. The integrated water regulation of the Yellow River has effectively controlled the total water use in the basin, promoted the improvement of agricultural water use efficiency and the reduction of water quota differences between provinces, and improved the fairness of agricultural water use and water use in the entire basin. [ABSTRACT FROM AUTHOR]