浅表层 meaning in English

lamina zonalis

The surfacial sediment on the yellow river delta is so sensitive to ocean hydrodynamic condition , especially waves that soil failed and came into being a lot of unstable features : bumps and hollows , flute and groove cast of silt and collapse
黄河三角洲潮滩浅表层沉积物由于对海洋动力尤其是波浪作用的敏感，会发生破坏，形成塌陷、凹坑、粉砂流冲沟等一系列灾害地质现象。