Two successive knickpoints with a 10% slope were constructed 1 m apart on a sandy bed in a rectangular flume with a longitudinal slope of 0.003. Bed erosion and knickpoint migration were studied experimentally for different discharges. The performance of two grade-control structures–Newbury rock riffles (NRR) and cross-vane riffles (CVR)–were studied experimentally for the stabilization of each knickpoint. Both of the structures were successful in controlling the bed erosion; however, the NRR operated relatively better than the CVR for they could concentrate the flow at the middle part of the channel to produce more regular contours with less local erosion and bed settlement. The experiments demonstrated that the construction of a control structure was not only effective in the stabilization of a knickpoint but also retarded the migration of its neighboring counterpart.

在具有0.003纵向倾斜度的矩形水槽中的沙床上，相隔1 m的位置连续构造两个倾斜度为10％的拐点。实验研究了不同流量下的河床侵蚀和拐点迁移。通过实验研究了两个坡度控制结构的性能-纽伯里岩石浅滩（NRR）和交叉叶片浅滩（CVR）-用于稳定每个拐点。两种结构均能成功地控制床层侵蚀。但是，NRR比CVR相对更好，因为它们可以将流量集中在通道的中部，以产生更规则的轮廓，而减少局部侵蚀和床层沉降。