Influence of flow angle on local scour depth in steep gravel river

Basing on the field observation and investigation in steep gravel rivers in northwest of China, flow angle is an important parameter for calculating the local scour which directly related to the security of erosion protection structure and bridges. The movable bed flume experiment was designed to measure the local scour depth with varied flow angle under same flow and sediment conditions. About 8 series experiment data with 4 flow angle (30° ,45° ,60° ,90° ) were analyzed. And the experiment data prove that the relation of flow angle and local scour depth seems as h_b(α)/h_b(90°)=(α/90°)^2/3 acceptable precision.