The presence of ripples superimposed on an active sand ridge is the most usual situation under low-to moderate-energy conditions in the wave-dominated, tideless Ebro Delta coast. Four types of small-scale bedforms were identified, from the critical threshold of sediment motion to wash-out conditions: (i) small undulations with η < 0.5 cm and λ ~8 cm, formed as a precursor of wave ripples when the Shields parameter was just below the theoretical critical; (ii) 2D wave ripples with η = 1.2 cm and λ = 7–10 cm; (iii) mixed 2D/3D current-dominated ripples with a maximum of η ~1.5 cm and λ = 10–15 cm; and (iv) 3D wave-current ripples with a maximum of η ~2.2 cm and λ = 7–20 cm. Ripple degradation was observed to occur when the energy of the hydrodynamic regime increased (wash-out conditions) and under low-energy hydrodynamic conditions, when ripples progressively decayed mainly as a consequence of biological activity. The wave ripples were static, while the current-dominated ripples migrated towards the SE at a rate of ~10 cm/h.

The potential role of ripple migration as an additional long-term mechanism of sediment transport is addressed. On the Ebro Delta shoreface, 3D ripple migration follows the direction of sand ridge migration towards the SE. The respective migration rates and their differences in size support the hypothesis that a subordinate part of sand ridge migration can result from the contribution of ripple migration under low to moderate regimes, suggesting that in specific environments the dynamics of small-scale bedforms can play a subordinate but not negligible role in the evolution of larger bedforms.

在波浪主导的无潮埃布罗三角洲海岸，在低能量至中能量条件下，最常见的情况是叠加在活动沙脊上的涟漪的存在。从沉积物运动的临界阈值到冲洗条件，确定了四种类型的小规模床形：（i）当Shields参数时，η<0.5 cm和λ〜8 cm的小起伏是波浪波动的先兆刚好低于理论临界值；（ii）二维波波动，η= 1.2 cm，λ= 7-10 cm；（iii）混合2D / 3D电流主导的波纹，最大η〜1.5 cm，λ= 10-15 cm；（iv）3D波电流波动最大为η〜2.2 cm，λ= 7–20 cm。当流体动力状态的能量增加（冲刷条件）和在低能量流体动力条件下，会发生波纹降解。当波纹主要由于生物活性而逐渐衰减时。波浪纹波是静态的，而电流主导的纹波以〜10 cm / h的速度向SE迁移。

解决了涟漪迁移作为泥沙输送的附加长期机制的潜在作用。在埃布罗三角洲（Ebro Delta）岸面上，3D波纹迁移遵循砂脊向东南迁移的方向。各自的迁移率及其大小差异支持以下假设：沙脊迁移的下级部分可能是由低速到中度状态下涟漪迁移的贡献导致的，这表明在特定环境中小规模岩床的动力学可以起次要作用。但在更大的床形演化过程中作用不容忽视。