Processes reshaping the Ebro delta
Processes reshaping the Ebro delta
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DOI：
10.1016/s0025-3227(97)00076-5
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发表时间：
1997-12
期刊：
影响因子：
2.9
通讯作者：
J. Jimenez;A. Sánchez-Arcilla;Herminia I. Valdemoro;V. Gracia;F. Nieto
中科院分区：
文献类型：
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作者：
J. Jimenez;A. Sánchez-Arcilla;Herminia I. Valdemoro;V. Gracia;F. Nieto
由于来自埃布罗河的沉积物供应有限，其三角洲主要以沿岸侵蚀和增生海岸伸展交替的形式进行重塑，三角洲的整体地表没有明显的变化。详细分析了目前迫使这些过程(波浪和平均水位振荡)的主要动因对沿海过程的贡献。通过这种方式，波浪的特征表现为短期/季节性变化、沿岸泥沙输送模式、岸面的长期跨岸输送和风暴影响。虽然研究区属于小潮区，波浪是迫使海岸在年尺度上演变的主要因素，但平均水位波动(气象潮汐和长期相对平均海平面变化)起着不可忽视的作用。此外，还对海浪和风暴潮进行了联合分析，以确定导致海岸反应“冲动”类型的条件。最后，应用经典的三角洲三元分类方法，从泥沙供给变化的角度考虑河流顶点，以一种“动力学的方式”对三角洲进行分类。此外，还测试了考虑平均水位变化(潮汐除外)对三角洲分类的影响。包括RSLR的影响对于与河流无关的三角洲来说变得相关，因为它表明三角洲无法承受它。将这一因素纳入三元分类的主要问题是，RSLR更多地是一个“被动”因素，而其他被考虑的因素是“主动”的，因为它们诱导了更多可感知的形态过程。
Due to the limited supply of sediment from the Ebro river, its delta is mainly subject to reshaping processes in the form of alongshore alternation of erosive and accretive coastal stretches, without a significant change in the overall subaerial surface of the delta. The main agents presently forcing these processes (waves and mean water-level oscillations) are analysed in detail as a function of their contribution to coastal processes. In this manner, waves are characterised in terms of short-term/seasonal changes, longshore sediment transport pattern, long-term cross-shore transport at the shoreface and storm impacts. Although the study area is a microtidal one, and waves are the main agent forcing coastal evolution at yearly scales, mean water-level oscillations (meteorological tides and long-term relative mean sea-level variations) play a non-negligible role. Additionally, a joint analysis of waves and storm surges has been done in order to characterise conditions inducing an ‘impulsive’ type of coastal response. At last, the classical ternary classification of deltas has been applied in a ‘dynamical way’ by considering the river vertex in terms of the variation in sediment supply. Moreover, the effects of considering mean water-level variations (other than tides) on the deltaic classification has also been tested. The inclusion of RSLR influence becomes relevant for ‘river-independent’ deltas since it indicates the inability of the delta to withstand it. The main problem to include this agent in the ternary classification is that RSLR is more of a ‘passive’ factor, whereas the other considered agents are ‘active’ in the sense that they induce more perceivable morphological processes.