2.4　Rating Curve

2.4.1　If there is a hydrometrical gauging station in the vicinity of the dam（plant）site s，upstream or downstream，observation of water level and investigation of flood and low flow levels may be carried out at the dam（plant）site，the slope of water surface in the river reach be analyzed，and the stage-discharge relation of the hydrometrical gauging station after rectification be adopted at the design sections.

2.4.2　If there is no hydrometrical gauging station at the river reach of dam（plant）site，the rating curve at design section shall be calculated by using hydraulic formula according to the longitudinal profile and crosssection diagrams of the river reach and based on the investigated and estimated water surface slopes of flood and low flow.(https://www.daowen.com)

2.4.3　For the proposed rating curve，it shall be verified by using actually measured and investigated water level and discharge data.