EFDC simulation of fishway in the Diversion Dahaerteng River to Danghe Reservoir, China

In order to mitigate the threat that hydraulic engineering will have on the fish's living environment, fish migration can be accomplished by building fishway. This paper takes the Diversion Dahaerteng River to Danghe Reservoir project in Gansu, China as an example. Through field investigation and data analysis, it was found that the main fish in the study area was Triplophysa. Through the comparison of the advantages and disadvantages of the fishways, it is determined that the fishway and the nature-like fishway are suitable. By constructing the evaluation method, the 19 indicators of the fishway were scored from the aspects of ability to lure fish, ability to pass fish, fish adaptability, engineering quantity, operation and maintenance, and the nature-like fishway was determined to be the best choice. The surface runoff from March to August is calculated by the P-III curve to simulate the flow field of the Dahaerteng River under the conditions of maximum, minimum and average runoff. The flow velocity of the simulation results is suitable for the Triplophysa migration, and the right bank is suitable for building nature-like fishway. The fishway section is rectangular, with a slope of 1%, a width of 2 m, and a total length of 520 m. It is arranged with a staggered baffle, and the revetment is rough masonry stones. The inside of the fishway is inlaid with pebbles so that the roughness of the fishway is more than 0.03. Then, numerical simulation calculations were carried out for the fishways composed of the partitions of 10m and 5m apart. The comparison shows that the fishway with the partition gap 5m is closer to the right bank of the river, which is suitable for Triplophysa migration and survival. For later evaluation and adjustment, an observation room and a fish collection pool are provided near the entrance of the fishway, and an observation room is provided near the exit. This paper can provide reference for the planning, construction and post evaluation of fishways.