APPEARANCE CHARACTERISTICS OF RIVER BED CONFIGURATION AND CONTROLLING FACTORS OF STEP-POOL STRUCTURE IN A GRANITIC HEADWATER CATCHMENT

Abstract

 The objective of this work was to investigate the relation between river-bed gradient and river bed configuration in a granitic headwater catchment. Further, we investigated the relationship between the step structure and controlling factors such as river course characteristics or slope angle of river bank. As a result of field survey, the transition of river bed configuration (transition of waterfall, cascade, step, and riffle from the upstream to the downstream) according to the river bed gradient was observed. The relation between the step height and maximum diameter of the step construction gravel was different between the antidune type and keystone type. In case of antidune type, maximum diameter of the step construction gravel was positively related with friction velocity. Whereas, maximum diameter of the step construction gravel of keystone type increased with the increment of river-bed gradient and step width.