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Mountain river sinuosity

by Colin Stark last modified 2006-02-09 16:13

A study of the processes of lateral erosion and meandering in bedrock channels.

 

Regionalized sinuosity of Japan

   

It has long been hoped that quantitative analysis of landscape would allow measurement of the climatic boundary conditions that control landscape evolution. So far, however, the quantitative properties of terrain chosen for study have been remarkably undiagnostic of climatological parameters.

We have recently succeeded in making the first measurement of one aspect of the local climatology of a landscape purely from analysis of its digital elevation model (DEM). Our analysis of SRTM data for mountain catchments across the NW Pacific reveals a linear correlation between typhoon strike frequency, the coefficients of variation of monthly rainfall and daily river discharge, and channel sinuosity. In contrast, average rainfall and discharge do not correlate with sinuosity.

Our observations can be explained with the aid of a 1d morphodynamic channel model in which bedrock erosion is a threshold function of bed shear stress. The model suggests that greater discharge variability drives faster bank versus bed erosion, induces more channel mobility, and by extension produces greater channel sinuosity.



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