Morphodinamical study of the lower Oka estuary (Mundaka-Ibarrangelu, Urdaibai Biosphere Reserve)

Company / Centre:
Basque Government

During the study period, the lower estuary sedimentary system itself and its different constitutive elements have reached naturally the characteristic morphological features in the affected area. This natural process is much more stable, long lasting and safe in order to warranty the future of the "Mundaka wave". Possible future dredgings and dumpings in the Urdaibai lower estuary should take into account that: a) the sand volume to be extracted should be kept as minimum as possible in order to reduce the estuarine system response; b) the layout of those dredgings should respect the natural disposition of the estuarine main channel, and the Arketa final meander should be located close to the eastern rocky margin in order to reduce its erosive capacity against the southern area of the Laida beach; and c) sand dumping area should be located in the outer estuary, in a position to be determined based on the volume of sediment involved and the time of the year proposed for the operations. After the last massive sand dumping, the estuarine system needed 3 years to equilibrate the dramatic consequences provoked to the traditional quality of the "Mundaka wave".