We discuss area-slope relation of a landform evolved by a simple lattice mo
del of an erosion process. Observing a steady state of the model, where riv
er networks on the surface are stationary, we present the relation between
the power exponent of the area-slope relation and the parameters of the ero
sion process of the model. We show how to determine the parameters of the e
rosion process from observations of landform by making use of the area-slop
e relation. This method may be useful for morphological simulations of the
landforms.