Abstract
Recently, the increasing availability of spatial and temporal distributed hydrologic data is encouraging the use of distributed runoff models. This paper assumes that the most general representation of topography and rainfall is a random field, so that the rainfall-runoff system is best described by stochastic differential quation. The main object of this paper is to make clear one universal subbasin scale in the context of distributed runoff model. For this purpose, we pay attention to the variance of discharge at the outlet and propose how to solve the variance theoretically. Finally, we can obtain the relationship between the variance and the subbasin scale theoretically.
