The construction diversion of this project adopts year-round cofferdam for water retaining and tunnel overflow. One initial diversion tunnel, namely, 1 # diversion tunnel, is arranged on the left bank of the river. The tunnel is in a double curve on the plane. The tunnel body section is a city gate tunnel type, and the net size of the section is 15 × 19m (width × height). The inlet base elevation is 2257.00m, the outlet elevation is 2247.00m, and the longitudinal slope is about 9.2 ‰. The top elevation of the intake tower is 2308.00m, and the tower height is 51m. The inlet elevation of 1 # diversion tunnel is 2261.0m, the inlet approach channel is 20.0m long, and the diffusion angle of the channel bottom plate is 7 °. The entrance gate chamber section is 25m long, and the gate chamber is divided into two holes, with a single hole size of 7.5 × 19.0m (width × height). The total length of the diversion tunnel is 1522.614m, and the longitudinal slope i=9.2 ‰. The diversion tunnel plug section is set at stake No. 0+743.243~0+803.243m. The outlet elevation of the diversion tunnel is 2247.0m, and the outlet approach channel is 30.0m long. The drawing content includes: general construction layout (1/2