Based on data from more than 100 alluvial rivers, a systematic comparison of flow shear stress and energy expenditure has been made between sand- and gravel-bed rivers, by plotting the relationships between channel shape (i.e. channel width-depth ratio) and hydraulic indices in a two-dimensional plane. These relationships show clearly that the four channel patterns, i.e. sand-bed meandering, sand-bed braided, gravel-bed meandering and gravel-bed braided, are located in 4 different areas that can be divided by 2 straight lines. Based on data from more than 100 alluvial rivers, a systematic comparison of flow shear stress and energy expenditure has been made between sand- and gravel-bed rivers, by plotting the relationships between channel shape (ie channel width-depth ratio) and hydraulic indices in a two-dimensional plane. These relationships show clearly that the four channel patterns, ie sand-bed meandering, sand-bed braided, gravel-bed meandering and gravel-bed braided, are located in 4 different areas that can be divided by 2 straight lines.