What are the assumptions of evapotranspiration calculation in Xin 'anjiang model?

Assumptions for evapotranspiration calculation of Xin 'anjiang model include the following points:

1. Assuming that the evapotranspiration changes with time, but it is relatively stable, it can be considered as a quasi-stable process.

2. Assume that the comprehensive influence coefficient of the underlying surface is unchanged, that is, assume that the comprehensive influence coefficient of the underlying surface is unchanged.

3. It is assumed that the water storage in the basin is evenly distributed, that is, the water storage at all points in the basin is equal.

4. It is assumed that the evaporation of the basin is certain and is not affected by weather and climate conditions.

Assuming that the water circulation in the basin is closed, the water vapor input outside the basin is not considered.