Anti-freezing and heat-preservation water inlet system suitable for river bypass subsurface flow constructed wetland and control method

The invention provides an anti-freezing and heat-preservation water inlet system suitable for a river bypass subsurface flow constructed wetland and a control method. Water inlet pipelines of the water inlet system comprise a non-winter water inlet pipeline and a winter water inlet pipeline. The non-winter water inlet pipeline is lower than the top of filler and higher than the bottom of a maximumfrozen soil layer of the region. The winter water inlet pipeline of the constructed wetland is lower than the bottom of the maximum frozen soil layer of the region and higher than the top of an earthing layer of a water outlet pipeline. The non-winter water inlet pipeline and the winter water inlet pipeline are each provided with a water inlet valve. By switching between the upper-layer water inlet pipeline system and the lower-layer water inlet pipeline system and fully utilizing a frozen soil layer formed by a riverway at low temperature in winter, freezing prevention and heat preservationof the subsurface flow con