The result indicates that the improved TWI, which integrated with aspect or terrain position or both of the two, is closer to the real than the simple TWI. On the basis of this paper, the following conclusions were reached:
(1) The value of the improved TWI on the sunny slope and the ridge decreases, comparing with the simple TWI;
(2) The value of the improved TWI on the shady slope and the valley increases, comparing with the simple TWI.
Further research is to explore the weight of the topographic position more scientific according to its influence
of soil moisture content. And a further test will be taken to verify the improved TWIs by the field survey data of the vegetation, soil and other elements in the experimental region.