Application of AHP in flood combination calculation of check dam system

Check dam is an important water and soil conservation measure for comprehensive treatment of small watershed in the Loess Plateau. The reinforcement of sick and dangerous check dam is an important measure to ensure the safe operation of check dam and promote the high-quality development of the Yellow River basin. How to scientifically and reasonably determine the flood control standard of each dam and do a good job in flood combination and hydrological calculation is a key technical problem to be solved in the reinforcement design of check dam system engineering. Taking the dam system project of Wan'angou small watershed in Shanxi Linxian County as an example, the overall layout of the dam system project is shown in Fig.1. Based on the relevant theory of "AHP", starting from the upstream of the main and branch ditches in the basin, comprehensively analyze the distribution location of each dam and its impact on the downstream, construct the hierarchical structure model of large and medium-sized silting dams in the dam system, as shown in Fig. 2, from which the distribution characteristics of the dam system in the basin and the correlation between the upstream and downstream dams can be intuitively and quickly analyzed, and on this basis, determine the flood control standard, flood combination and hydrological calculation of each dam. It can be seen intuitively in Fig. 2 that during the design of danger removal and reinforcement, the check dam and the reasons for the improvement of flood control standards need to be improved. For example, two large (1) check dams GZ4* and GZ5* in level 1, first because there are residential areas in the downstream influence area, the flood control standards are increased to large (2) check dams DZ4* and DZ5* according to the specification requirements; Secondly, since its downstream is the large (1)check dam G1 in level 2, considering the flood combination, it is raised to the large (1) check dam GZ4* and GZ5*. At the same time, from Fig.2, it can be determined that the flood combination is analyzed and the hydrological calculation is carried out according to the three conditions of single dam, series dam and parallel dam, for example, the large (1) check dam GD6 in level 5 is calculated according to three parallel check dams.