Method for judging river water backflow of municipal sewage pipe network

The invention discloses a method for judging river water backflow of a municipal sewage pipe network, and belongs to the technical field of municipal drainage pipe networks. The method comprises the following steps: 1, sample collection: respectively collecting a river water sample, a water sample of a well without backflow risk and a water sample of a municipal sewage well to be detected; step 2, microalgae culture and data acquisition: the three water samples collected in the step 1 are subjected to microalgae culture under the conditions of normal temperature and illumination, and the three water samples subjected to microalgae culture are taken out regularly and quantitatively for OD680 detection as quantitative data of microalgae density; and step 3, backward flow risk calculation: when the backward flow risk is greater than 0.2, judging that a large river water backward flow risk exists at the municipal sewage well to be detected. A low-cost and high-efficiency river water backflow judgment method is pr