1. Use the reservoir's regulation function and control ability to control and regulate floods in a planned way to avoid flood losses in downstream flood control areas. In order to ensure the flood control safety of the project itself, reservoirs that do not undertake flood control tasks are usually called reservoir flood control dispatching.

2. When the flood control area is close to the downstream of the reservoir, and the area between the reservoir and the flood control area is small, the flow rate is not large or changes gently, the interval flow rate can be ignored or regarded as a constant. In this case, the reservoir can adopt a fixed flood discharge mode, and when the flood does not exceed the flood control standard, the downstream river flow can be controlled not to exceed the safe river flow. Fixed flood discharge dispatching is generally divided into one-stage fixed flood discharge and multi-stage fixed flood discharge.

3. First-class fixed flood discharge. There is only one safe discharge in the flood control area, and the reservoir discharges flood with a fixed flow. The part where the inflow exceeds the discharge is stored in the reservoir until the reservoir water level reaches the flood control high level.

4. Multi-stage fixed flood discharge. When there are several different flood control standards and safe discharge downstream of the reservoir, the reservoir adopts several constant flow flood discharge methods. Generally, it is controlled at different levels according to the principle of "large water discharges more, small water discharges less". Some reservoirs are classified according to reservoir water level control, while others are classified according to inflow flood flow control.