The integrated Shields parameter exceeding 0.25 divided by the integrated total Shields parameter

This data represents the integrated Shields (Shields, 1936) parameter exceeding 0.25 divided by the integrated total Shields parameter. The Shields parameter (non-dimensional bed shear stress) value of 0.25 is assumed to be the threshold for creating disturbed patches. This value is several times larger than that required to initiate traction bedload transport (~0.05) and falls in the middle of the ripple and dune bedform stability field. It represents conditions when the seabed is highly mobile and where patches of disturbed habitat are likely to be created.Shields, A. 1936. Application of similarity principles and turbulence research to bed-load movement. Mitteilunger der Preussischen Versuchsanstalt f¨ur Wasserbau und Schiffbau 26: 5-24

本数据集为积分后大于0.25的希尔德斯参数（Shields parameter）与总希尔德斯参数积分值的比值。希尔德斯参数即无量纲底切应力，0.25这一数值被认定为形成扰动斑块的临界条件。该阈值约为启动牵引式底沙输运所需临界值（约0.05）的数倍，且处于沙纹与沙丘床形的稳定区间中点。该比值表征海床处于高活动性、且大概率形成生境扰动斑块的工况条件。

参考文献：Shields, A. 1936. 相似原理与湍流研究在底沙运动中的应用. Mitteilungen der Preußischen Versuchsanstalt für Wasserbau und Schiffbau 26: 5-24