INSTABILITY OF FLAT BED IN ALLUVIAL CHANNELS

THE OCCURRENCE OF DIFFERENT BED FORMS HAS BEEN CONSIDERED AS AN INSTABILITY IN THE FLAT BED FLOW. A GENERAL FUNCTIONAL RELATIONSHIP HAS BEEN DEVELOPED FOR THE INSTABILITY OF FLAT BED WHEN IT IS REPLACED BY EITHER DUNES OR RIPPLES. THE EXPERIMENTS INDICATE THAT TWO DISTINCT RELATIONSHIPS EXIST FOR THE TWO INSTABILITIES. A REGION OF TRANSITION EXISTS IN BETWEEN THE TWO FUNCTIONS WHERE EITHER INSTABILITY MAY OCCUR. THE STABILITY FUNCTION IS USEFUL TO PREDICT THE OCCURRENCE OF DIFFERENT BED FORMS. /ASCE/