The invention relates to an ecological flow assessment method for fish
tidal river network migration channel maintenance. The method comprises the following steps: constructing a one-dimensional
tidal river network hydrodynamic model by using
river network data; setting different incoming water flows and tidal condition scenes, inputting a one-dimensional
tidal river network hydrodynamic model, and outputting the flow velocity of each river channel of the
river network; obtaining a flow velocity suitability curve of the target fishes, and substituting the flow velocity of each river channel of the
river network into the flow velocity suitability curve to obtain a suitable migration river channel; according to the river network
water flow direction, the water
system circulation between the suitable migration rivers is calculated; calculating the adjusted total length of the suitable migration river channel by taking the water
system connectivity as a weight; and determining the
fish migration ecological flow according to the adjusted mapping relation between the total length of the suitable migration river channel and the incoming
water flow. The method solves the problem that in the prior art, only the longest total length of the river channel suitable for
fish migration is considered for the ecological flow, the
connectivity between the river channels is not considered, and the
local optimum problem is caused, so that the
fish migration requirement is difficult to meet.