Urban rainstorm floods have become one of the most significant natural disasters that restrict the healthy development of the economy and society. It is imperative to reduce the risk of urban rainstorm flood disasters, which is growing along with urbanization, during the process of urban planning and construction. However, because of the complexity of urban elements, it is quite difficult to identify sensitive indicators of urban rainstorm flood disasters to provide effective guidance on flood control. In this study, the composition of urban elements was systematically proposed based on Descriptive Framework for Cities and Communities, including natural, structural, and social elements, and then a specific indicator system was established. Furthermore, Random Forest Model was used to determine the relative importance of the indicators that are closely related to the direct economic loss that reflects the severity of urban rainstorm flood disasters. Considering four cities in China, Beijing, Tianjin, Chongqing, and Shanghai, with different topographical and hydrological conditions, as examples, the sensitivity indicators of urban rainstorm flood disasters were identified, and the results were verified based on the catastrophe evaluation method. The results indicate that urban rainstorm flood disasters are the most sensitive to surface water resources, and are the least sensitive to relief degree of land surface. Finally, specific measures to mitigate urban rainstorm flood disasters were proposed.@en

The benefits of water resource utilization include social benefits, economic benefits, and ecological environmental benefits, so it is difficult to evaluate them comprehensively by adopting the traditional cost-income analysis method. Catastrophe evaluation method, which majors in dealing with uncertain problems, evaluates system synthetically based on the internal mechanism of the system. It calcu-lates the evaluation value of the system in the condition that the relative importance of the indexes is determined and the exact weights are unknown. In this paper, the comprehensive evaluation model of water resources utilization benefits is established based on the catastrophe evaluation method. Moreover, the method which embodies the important roles of various benefits effectively is applied to evaluate the comprehensive benefits of different water resources utilization schemes from 2000 to 2005 in Zhengzhou City of China. The results show that the method has good flexibility and provides a new idea for a comprehensive evaluation of water resources utilization benefits.@en

Despite the rapid development of risk analysis in dam engineering, there is a relative absence of research on the environmental impact of dam break. As a systematic theory, set pair analysis has a good effect in dealing with uncertainties, although the result is relatively rough and easy to distort. A connection degree of five grades and a generalized set of potential are introduced to improve traditional set pair analysis. Combined with the index system, the evaluation model of the environmental impact of dam break is established, which is based on generalized set pair analysis. Taking Sheheji Reservoir dam as an example, a comparison of evaluation results of fuzzy mathematics theory and generalized set pair analysis is made, which verifies the scientificity and practicability of the method proposed in this paper. The results show that the evaluation grade of the environmental impact of dam break at Sheheji Reservoir is serious, and appropriate management measures should be taken to reduce the risk.@en

The evaluation of the benefits of urban water resource utilization, which include supporting life and industrial and agricultural production, is important for decision-making and policy formulation in urban water management. However, since life cannot be quantified in terms of economic value, it is difficult for traditional economic analysis methods to comprehensively evaluate the benefits of urban water resource utilization. Output per unit water and the proportion of water to resource inputs were proposed to evaluate these benefits. An evaluation index system was established based on catastrophe theory, which evaluates the system under the condition that the relative importance of indices is determined and the exact weights are unknown. Emergy theory, which reflects the process of energy conversion, was introduced to analyze various benefits of urban water resource utilization. By applying these methods to evaluate these benefits in Zhengzhou, China, the author verified the rationality of the proposed methods, providing new ideas to evaluate these benefits.@en