The invention provides an operation method of a hydraulic dam group for controlling a riverbed to greatly scour and deposit in a compound channel, which comprises the following steps of: alternately adopting a dynamic
operation mode of
dam collapse in a
flood season, dam lifting in a non-
flood season, dam lifting in a
main channel and
dam collapse in a beach land on the interyear by combining the interannual deposition characteristic and hydrological cycle of channel
silt, and establishing a graded dredging mechanism at the same time; and regular monitoring and desilting are conducted on the upstream reach of the hydraulic dam located on the upstream, and normalized maintenance and desilting are conducted on the surface of the hydraulic dam structure. According to the running mode of
dam collapse in the annual
flood season and dam rising in the non-flood season,
water conservation in the non-flood season with relative water shortage can be guaranteed, manual intervention is not adopted in the flood season with relatively abundant water,
flood discharge and sand flushing of the riverway are relatively natural, it is guaranteed that the annual water amount of the riverway is considerable, and the
water quality of the riverway is improved. A natural means is utilized to ensure that riverbed
siltation is not excessively developed; the running mode of the full-year main groove dam rising and beach land dam collapse ensures that the
water source is reserved in the flat water year or the
dry water year, and meanwhile, the easily-deposited beach land part is subjected to water flushing. By adopting the hydraulic dam
group operation mode provided by the invention, great
erosion and deposition of a riverbed can be relieved.