The decrease of lake area is also one of the reasons for the flood. If the lake area is reduced, the function of regulating rivers will be reduced. In addition, celestial gravity, spring tides, small tides, or tsunamis caused by earthquakes can also cause floods.
Of course, in addition to all the reasons, there are inevitably human factors. When a large number of trees are cut down, the surface loses vegetation protection, and a large number of sand and stones are washed away by rain and flow into rivers, which will cause siltation and increase the possibility of floods. In addition to deforestation, poor farming methods and overgrazing on the hillside will also make the land lose the protection of vegetation and accelerate the phenomenon of soil erosion on the hillside, and there are other reasons that jointly cause flooding.