Figure 5 . Transient evolution of the trunk profile (a & c) and network of tributaries (b & d) in Case 3 (spatially uniform to bottom-heavy) throughksn -Eavg (a & b) andksn-q -Eavg (b & d) parameter spaces. Layout of individual panels is like Figure 4. Six representative time slices are shown; t1 shows time at 10 kyr model time (i.e., first timestep following change in rainfall), t6 is at final steady state. Time intervals are not equal in duration but t1-t6 are the same timestep for all panels. Note range in ksn values and erosional efficiency values spanned at final steady state in panels (a) and (b). Also, note the relatively muted responses by the trunk profile relative to the network of tributaries in bothksn and ksn-q . Star in panel (a) shows expected erosional efficiency calculated from equation (1b) based on the final mean rainfall of 2.68 m/yr (2.68ยทKp ) at steady state, which corresponds to a predicted mean ksn of ~275. Note offset between this value and range of erosional efficiency andksn values exhibited at t6.