Tectonic uplift of Mt.Lushan indicated by the steepness indices of the river longitudinal profiles
In this study,we extracted nine river profiles from a 5-m DEM of the Mt.Lushan region.Knickpoints of two types,namely the vertical-step knickpoint and the slope-break knickpoint,are recognized,and are compared with the geological settings to determine their origins.At the same time,we calculated the channel steepness index (ksn) and concavity (θ) of separated parts of these rivers,using the stream-power incision model.The results show that these rivers are almost in a transient state represented by the occurrence of knickpoints.The vertical-step knickpoints are related to inhomogeneous substrates and the slope-break knickpoints are ascribed to the lowering of the base level due to rapid mountain uplift.The parts of the rivers below the slope-break knickpoint have a relatively large ksn,which probably indicates a shift from low rate at early uplift to a later high rate.The steepness index in the south of the mountain is larger than that in the north,which might be induced by different uplift rates or substrates.
NETL
NSTL
万方数据
维普
