We report results from an empirical study of the anisotropic structure of e
roding landscapes. By constructing a novel correlation function, we show qu
antitatively that small-scale channel-like features of landscapes are coupl
ed to the large-scale structure of drainage basins. We show additionally th
at this two-scale interaction is scale-dependent. The latter observation su
ggests that a commonly applied effective equation for erosive transport may
itself depend on scale.